One document matched: draft-ietf-keyprov-dskpp-01.xml
<?xml version="1.0" encoding="US-ASCII"?>
<!-- $Id: ct-kip-two-pass.xml,v 1.7 2006/10/14 18:52:48 mnystrom Exp $ -->
<!-- Copyright 2006 RSA Security Inc. All rights reserved. -->
<!DOCTYPE rfc SYSTEM "rfc2629.dtd">
<?xml-stylesheet type='text/xsl' href='rfc2629.xslt' ?>
<?rfc toc="yes" ?>
<?rfc symrefs="yes" ?>
<?rfc sortrefs="yes"?>
<?rfc iprnotified="no" ?>
<?rfc strict="no" ?>
<?rfc compact="yes" ?>
<?rfc subcompact="yes" ?>
<rfc category="std" docName="draft-ietf-keyprov-dskpp-01.txt" ipr="full3978">
<front>
<title abbrev="DSKPP">Dynamic Symmetric Key Provisioning Protocol
(DSKPP)</title>
<author fullname="Andrea Doherty" initials="A." surname="Doherty">
<organization>RSA, The Security Division of EMC</organization>
<address>
<postal>
<street>174 Middlesex Tpk.</street>
<city>Bedford</city>
<region>MA</region>
<code>01730</code>
<country>USA</country>
</postal>
<email>adoherty@rsa.com</email>
</address>
</author>
<author fullname="Mingliang Pei" initials="M." surname="Pei">
<organization>Verisign, Inc.</organization>
<address>
<postal>
<street>487 E. Middlefield Road</street>
<city>Mountain View</city>
<region>CA</region>
<code>94043</code>
<country>USA</country>
</postal>
<email>mpei@verisign.com</email>
</address>
</author>
<author fullname="Salah Machani" initials="S." surname="Machani">
<organization>Diversinet Corp.</organization>
<address>
<postal>
<street>2225 Sheppard Avenue East, Suite 1801</street>
<city>Toronto</city>
<region>Ontario</region>
<code>M2J 5C2</code>
<country>Canada</country>
</postal>
<email>smachani@diversinet.com</email>
</address>
</author>
<author fullname="Magnus Nystrom" initials="M." surname="Nystrom">
<organization>RSA, The Security Division of EMC</organization>
<address>
<postal>
<street>Arenavagen 29</street>
<city>Stockholm</city>
<region>Stockholm Ln</region>
<code>121 29</code>
<country>SE</country>
</postal>
<email>mnystrom@rsa.com</email>
</address>
</author>
<date day="29" month="October" year="2007" />
<area>Security Area</area>
<workgroup>KEYPROV Working Group</workgroup>
<abstract>
<t>DSKPP is a client-server protocol for initialization (and
configuration) of symmetric keys to locally and remotely accessible
cryptographic modules. The protocol can be run with or without
private-key capabilities in the cryptographic modules, and with or
without an established public-key infrastructure.</t>
<t>Three variations of the protocol support multiple usage scenarios.
The four-pass (i.e., two round-trip) variant enables key generation in
near real-time. With the four-pass variant, keys are mutually generated
by the provisioning server and cryptographic module; provisioned keys
are not transferred over-the-wire or over-the-air. Two- and one-pass
variants enable secure and efficient download and installation of
symmetric keys to a cryptographic module in environments where near
real-time communication may not be possible.</t>
<t>This document builds on information contained in <xref
target="RFC4758"></xref>, adding specific enhancements in response to
implementation experience and liaison requests. It is intended,
therefore, that this document or a successor version thereto will become
the basis for subsequent progression of a symmetric key provisioning
protocol specification on the standards track.</t>
</abstract>
</front>
<middle>
<!-- ////////////////////////////////////////////////////////////////////////////////// -->
<section anchor="Section-Introduction" title="Introduction">
<section title="Scope">
<t>This document describes a client-server protocol for initialization
(and configuration) of symmetric keys to locally and remotely
accessible cryptographic modules. The protocol can be run with or
without private-key capabilities in the cryptographic modules, and
with or without an established public-key infrastructure. The
objectives of this protocol are to:</t>
<t><list hangIndent="6" style="symbols">
<t>Provide a secure method of initializing cryptographic modules
with symmetric keys without exposing generated, secret material to
any other entities than the server and the cryptographic module
itself.</t>
<t>Provide a secure method of generating and transporting
symmetric keys to a cryptographic module in environments where
near real-time communication is not possible.</t>
<t>Provide a secure method of transporting pre-generated (i.e.,
legacy) keys to a cryptographic module.</t>
<t>Provide a solution that is easy to administer and scales
well.</t>
</list></t>
<t>The mechanism is intended for general use within computer and
communications systems employing symmetric key cryptographic modules
that are locally (i.e., over-the-wire) or remotely (i.e.,
over-the-air) accessible.</t>
</section>
<section title="Background">
<t>A locally accessible symmetric key cryptographic module may be
hosted by, for example, a hardware device connected to a personal
computer through an electronic interface, such as USB, or a software
application resident on a personal computer. A remotely accessible
symmetric key cryptographic module may be hosted by, for example, any
device that can support over-the-air communication, such as a
hand-held hardware device (e.g., a mobile phone). The cryptographic
module itself offers symmetric key cryptographic functionality that
may be used to authenticate a user towards some service, perform data
encryption, etc. Increasingly, these modules enable their programmatic
initialization as well as programmatic retrieval of their output
values. This document intends to meet the need for an open and
inter-operable mechanism to programmatically initialize and configure
symmetric keys to locally and remotely accessible cryptographic
modules.</t>
<t>The target mechanism makes use of a symmetric key provisioning
server. In an ideal deployment scenario, near real-time communication
is possible between the provisioning server and the cryptographic
module. In such an environment, it is possible for the cryptographic
module and provisioning server to mutually generate a symmetric key,
and to ensure that keys are not transported between them.</t>
<t>There are, however, several deployment scenarios that make mutual
key generation less suitable. Specifically, scenarios where near
real-time communication between the symmetric key provisioning server
and the cryptographic module is not possible, and scenarios with
significant design constraints. Examples include work-flow constraints
(e.g., policies that require incremental administrative approval),
network design constraints that create network latency, and budget
constraints that sustain reliance upon legacy systems that already
have supplies of pre-generated keys. In these situations, the
cryptographic module is required to download and install a symmetric
key from the provisioning server in a secure and efficient manner.</t>
<t>This document tries to meet the needs of these scenarios by
describing three variations to DSKPP for the provisioning of symmetric
keys in two round trips or less. The four-pass (i.e., two round-trip)
variant enables key generation in near real-time. With this variant,
keys are mutually generated by the provisioning server and
cryptographic module; provisioned keys are not transferred
over-the-wire or over-the-air. In contrast, two- and one-pass variants
enable secure and efficient download and installation of symmetric
keys to a cryptographic module in environments where near real-time
communication is not possible.</t>
</section>
</section>
<!-- ////////////////////////////////////////////////////////////////////////////////// -->
<section anchor="terms" title="Requirements Notation and Terminology">
<t>The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in <xref
target="RFC2119"></xref>.<vspace blankLines="1" /></t>
<t>The following notations are used in this document:</t>
<t><list hangIndent="16" style="hanging">
<t hangText="||">String concatenation<vspace blankLines="1" /></t>
<t hangText="[x]">Optional element x<vspace blankLines="1" /></t>
<t hangText="A ^ B">Exclusive-OR operation on strings A and B (where
A and B are of equal length)<vspace blankLines="1" /></t>
<t hangText="ENC_X(Y)">Encryption of message Y with symmetric key X,
using a defined block cipher<vspace blankLines="1" /></t>
<t hangText="ENC_PX(Y)">Encryption using message Y with a public key
X<vspace blankLines="1" /></t>
<t hangText="KDF_X(Y)">Key derivation function that generates an
arbitrary number of octets of output using secret X and seed
Y<vspace blankLines="1" /></t>
<t hangText="DSKPP-PRF_X(Y,Z)">Pseudo random function that generates
a fixed number Z of octets using secret X and seed Y (used in DSKPP
methods for MAC computations and key derivation)<vspace
blankLines="1" /></t>
<t hangText="MAC_X(Y)">Keyed message authentication code computed
over Y with symmetric key X<vspace blankLines="1" /></t>
<t hangText="SIGN_x(Y)">Function that provides authentication and
integrity protection of message content Y using private key x<vspace
blankLines="1" /></t>
<t hangText="B64(X)">Base 64 encoding of string X <vspace
blankLines="1" /></t>
<t hangText="H(X)">Hash function applied to X<vspace
blankLines="1" /></t>
<t hangText="Alg_List">List of encryption and MAC algorithms
supported by the client<vspace blankLines="1" /></t>
<t hangText="Alg_Sel">Algorithms list selected by the server for the
DSKPP protocol run<vspace blankLines="1" /></t>
<t hangText="DSKPP client">Manages communication between the
symmetric key cryptographic module and the DSKPP server<vspace
blankLines="1" /></t>
<t hangText="DSKPP server">The symmetric key provisioning server
that participates in the DSKPP protocol run<vspace
blankLines="1" /></t>
<t hangText="Issuer">The organization that issues or authorizes
issuance of the symmetric key to the end user of the symmetric key
cryptographic module (e.g., a bank who issues one-time password
authentication tokens to their retail banking users)</t>
<t hangText="ID_C">Identifier for DSKPP client<vspace
blankLines="1" /></t>
<t hangText="ID_S">Identifier for DSKPP server<vspace
blankLines="1" /></t>
<t hangText="AUTHCODE">Client Authentication Code comprised of a
string of numeric characters known to the device and the server and
containing an identifier and a password (the AUTHCODE may be used to
derive the AUTHDATA during the DSKPP protocol exchange)<vspace
blankLines="1" /></t>
<t hangText="AUTHDATA">Client Authentication Data that may be
derived from the AUTHCODE or using the client private key,
k_CLIENT<vspace blankLines="1" /></t>
<t hangText="K">Key used to encrypt R_C (either K_SERVER or
K_SHARED)<vspace blankLines="1" /></t>
<t hangText="K_AUTHCODE">Secret key that is derived from AUTHCODE
and used for client authentication purposes<vspace
blankLines="1" /></t>
<t hangText="k_CLIENT">Private key of the DSKPP client<vspace
blankLines="1" /></t>
<t hangText="K_CLIENT">Public key of the DSKPP client<vspace
blankLines="1" /></t>
<t hangText="K_DERIVED">Secret key derived from a passphrase that is
known to both the DSKPP client or user and the DSKPP server<vspace
blankLines="1" /></t>
<t hangText="K_MAC">Secret key used for key confirmation and server
authentication purposes, and generated in DSKPP<vspace
blankLines="1" /></t>
<t hangText="K_MAC'">A second secret key used for server
authentication purposes in 2- and 1-pass DSKPP<vspace
blankLines="1" /></t>
<t hangText="K_SERVER">Public key of the DSKPP server<vspace
blankLines="1" /></t>
<t hangText="K_SHARED">Secret key shared between the DSKPP client
and the DSKPP server<vspace blankLines="1" /></t>
<t hangText="K_TOKEN">Secret key used for cryptographic module
computations, and generated in DSKPP<vspace blankLines="1" /></t>
<t hangText="K_CONFDATA">Key configuration data carried within the
key container<vspace blankLines="1" /></t>
<t hangText="R">Pseudorandom value chosen by the DSKPP client and
used for MAC computations, which is mandatory for 2-pass DSKPP and
optional for 4-pass<vspace blankLines="1" /></t>
<t hangText="R_C">Pseudorandom value chosen by the DSKPP client and
used as input to the generation of K_TOKEN<vspace
blankLines="1" /></t>
<t hangText="R_S">Pseudorandom value chosen by the DSKPP server and
used as input to the generation of K_TOKEN<vspace
blankLines="1" /></t>
<t hangText="URL_S">Server address as a URL<vspace
blankLines="1" /></t>
<t hangText="I">Unsigned integer representing a counter value that
is monotonically increasing and guaranteed not to be used again by
the server towards the cryptographic module<vspace
blankLines="1" /></t>
<t hangText="I'">Similar to I except I' is always higher than
I<vspace blankLines="1" /></t>
</list></t>
<t>The following typographical convention is used in the body of the
text: <XMLElement>.</t>
</section>
<!-- ////////////////////////////////////////////////////////////////////////////////// -->
<section anchor="Section-UseCases" title="Use Cases">
<t>This section describes typical use cases.</t>
<section anchor="UC1" title="Single Key Request">
<t>A cryptographic module hosted by a device, such as a mobile phone,
makes a request for a symmetric key from a provisioning server.
Depending upon how the system is deployed, the provisioning server may
generate a new key on-the-fly or use a pre-generated key, e.g., one
provided by a legacy back-end issuance server. The provisioning server
assigns a unique key ID to the symmetric key and provisions it to the
cryptographic module.</t>
</section>
<section title="Multiple Key Requests">
<t>A cryptographic module makes multiple requests for symmetric keys
from the same provisioning server. The symmetric keys may or may not
be of the same type, i.e., the keys may be used with different
symmetric key cryptographic algorithms, including one-time password
authentication algorithms, and AES encryption algorithm.</t>
</section>
<section title="Session Time-Out Policy">
<t>Once a cryptographic module initiates a symmetric key request, the
provisioning server may require that any subsequent actions to
complete the provisioning cycle occur within a certain time window.
For example, an issuer may provide a time-limited authentication code
to a user during registration, which the user will input into the
cryptographic module to authenticate themselves with the provisioning
server. If the user inputs a valid authentication code within the
fixed time period established by the issuer, the server will allow a
key to be provisioned to the cryptographic module hosted by the user's
device.</t>
</section>
<section title="Outsourced Provisioning">
<t>A symmetric key issuer outsources its key provisioning to a third
party key provisioning server provider. The issuer is responsible for
authenticating and granting rights to users to acquire keys while
acting as a proxy to the cryptographic module to acquire symmetric
keys from the provisioning server; the cryptographic module
communicates with the issuer proxy server, which forwards provisioning
requests to the provisioning server.</t>
</section>
<section title="Key Renewal">
<t>A cryptographic module requests renewal of a symmetric key using
the same key ID already associated with the key. Such a need may occur
in the case when a user wants to upgrade her device that houses the
cryptographic module or when a key has expired. When a user uses the
same cryptographic module to, for example, perform strong
authentication at multiple Web login sites, keeping the same key ID
removes the need for the user to register a new key ID at each
site.</t>
</section>
<section title="Pre-Loaded Key Replacement">
<t>This use case represents a special case of symmetric key renewal in
which a local administrator can authenticate the user procedurally
before initiating the provisioning process. It also allows for an
issuer to pre-load a key onto a cryptographic module with a
restriction that the key is replaced with a new key prior to use of
the cryptographic module. Another variation of this use case is the
issuer who recycles devices. In this case, an issuer would provision a
new symmetric key to a cryptographic module hosted on a device that
was previously owned by another user.</t>
<t>Note that this use case is essentially the same as the last use
case wherein the same key ID is used for renewal.</t>
</section>
<section title="Pre-Shared Transport Key">
<t>A cryptographic module is loaded onto a smart card after the card
is issued to a user. The symmetric key for the cryptographic module
will then be provisioned using a secure channel mechanism present in
many smart card platforms. This allows a direct secure channel to be
established between the smart card chip and the provisioning server.
For example, the card commands (i.e., Application Protocol Data Units,
or APDUs) are encrypted with a pre-shared transport key and sent
directly to the smart card chip, allowing secure post-issuance
in-the-field provisioning. This secure flow can pass Transport Layer
Security (TLS) and other transport security boundaries.</t>
<t>Note that two pre-conditions for this use case are for the protocol
to be tunneled and the provisioning server to know the correct
pre-established transport key.</t>
</section>
<section title="SMS-Based Key Transport">
<t>A mobile device supports Short Message Service (SMS) but is not
able to support a data service allowing for HTTP or HTTPS transports.
In addition, an application may use a cryptographic module to enforce
an acceptable level of protection for download of the symmetric key
via SMS. In such a case, the cryptographic module hosted by the mobile
device may initiate a symmetric key request from a desktop computer
and ask the server to send the key to the mobile device through SMS.
User authentication is carried out via the online communication
established between the desktop computer and the provisioning
server.</t>
</section>
<section title="Non-Protected Transport Layer">
<t>Some devices are not able to support a secure transport channel
such as SSL or TLS to provide data confidentiality. A cryptographic
module hosted by such a device requests a symmetric key from the
provisioning server. It is up to DSKPP to ensure data confidentiality
over non-secure networks.</t>
</section>
<section title="Non-Authenticated Transport Layer">
<t>Some devices are not able to use a transport protocol that provides
server authentication such as SSL or TLS. A cryptographic module
hosted by such a device wants to be sure that it sends a request for a
symmetric key to a legitimate provisioning server. It is up to DSKPP
to provide proper client and server authentication.</t>
</section>
</section>
<!-- ////////////////////////////////////////////////////////////////////////////////// -->
<section anchor="Section-Protocol" title="DSKPP Overview">
<section title="Entities">
<t>In principle, the protocol involves a DSKPP client and a DSKPP
server. The DSKPP client manages communication between the
cryptographic module and the provisioning server. The DSKPP server
herein represents the provisioning server.</t>
<t>A high-level object model that describes the client-side entities
and how they relate to each other is shown in <xref
target="Objects"></xref>.</t>
<figure anchor="Objects" title="Object Model">
<artwork><![CDATA[----------- -------------
| User | | Device |
|---------|* owns *|-----------|
| UserID |--------->| DeviceID |
| ... | | ... |
----------- -------------
| 1
|
| contains
|
| *
V
-----------------------
|Cryptographic Module |
|---------------------|
|CryptoModuleID
|Encryption Algorithms|
|MAC Algorithms |
|... |
-----------------------
| 1
|
| contains
|
| *
V
-----------------------
|Key Container |
|---------------------|
|KeyID |
|Key Type |
|... |
-----------------------
]]></artwork>
</figure>
<t>Conceptually, each entity represents the following:</t>
<t><list hangIndent="24" style="hanging">
<t hangText="User:">The person or client to whom devices are
issued<vspace blankLines="1" /></t>
<t hangText="UserID:">A unique identifier for the user or
client<vspace blankLines="1" /></t>
<t hangText="Device:">A physical piece of hardware or software
framework that hosts symmetric key cryptographic modules<vspace
blankLines="1" /></t>
<t hangText="DeviceID:">A unique identifier for the device<vspace
blankLines="1" /></t>
<t hangText="Cryptographic Module:">A component of an application,
which enables symmetric key cryptographic functionality<vspace
blankLines="1" /></t>
<t hangText="CryptoModuleID:">A unique identifier for an instance
of the cryptographic module<vspace blankLines="1" /></t>
<t hangText="Encryption Algorithms:">Encryption algorithms
supported by the cryptographic module<vspace blankLines="1" /></t>
<t hangText="MAC Algorithms:">MAC algorithms supported by the
cryptographic module<vspace blankLines="1" /></t>
<t hangText="Key Container:">An object that encapsulates a
symmetric key and its configuration data<vspace
blankLines="1" /></t>
<t hangText="KeyID:">A unique identifier for the symmetric
key<vspace blankLines="1" /></t>
<t hangText="Key Type:">The type of symmetric key cryptographic
methods for which the key will be used (e.g., OATH HOTP or RSA
SecurID authentication, AES encryption, etc.)<vspace
blankLines="1" /></t>
</list>It is assumed that a device will host an application layered
above the cryptographic module, and this application will manage
communication between the DSKPP client and cryptographic module. The
manner in which the communicating application will transfer DSKPP
protocol elements to and from the cryptographic module is transparent
to the DSKPP server. One method for this transfer is described in
<xref target="CT-KIP-P11"></xref>.</t>
</section>
<section title="Overview of Protocol Usage">
<t>DSKPP enables symmetric key provisioning between a DSKPP server and
DSKPP client. The DSKPP protocol supports the following types of
requests and responses:</t>
<t><list>
<t><KeyProvClientHello><vspace blankLines="1" /><list
hangIndent="4">
<t>With this request, a DSKPP client initiates contact with
the DSKPP server, indicating what protocol versions and
variants, key types, encryption and MAC algorithms that it
supports. In addition, the request may include client
authentication data that the DSKPP server uses to verify
proof-of-possession of the device. <vspace
blankLines="1" /></t>
</list><KeyProvServerHello><vspace blankLines="1" /><list
hangIndent="4">
<t>Upon reception of a <KeyProvClientHello> request, the
DSKPP server uses the <KeyProvServerHello> response to
specify which protocol version and variant, key type,
encryption algorithm, and MAC algorithm that will be used by
the DSKPP server and DSKPP client during the protocol run. The
decision of which variant, key type, and cryptographic
algorithms to pick is policy- and implementation-dependent and
therefore outside the scope of this document.</t>
<t>The <KeyProvServerHello> response includes the DSKPP
server's random nonce, R_S. The response also consists of
information about either a shared secret key, or its own
public key, that the DSKPP client uses when sending its
protected random nonce, R_C, in the <KeyProvClientNonce>
request (see below).</t>
<t>Optionally, the DSKPP server may provide a MAC that the
DSKPP client may use for server authentication.</t>
<t><vspace blankLines="1" /></t>
</list></t>
<t><KeyProvClientNonce><vspace blankLines="1" /><list
hangIndent="4">
<t>With this request, a DSKPP client and DSKPP server securely
exchange protected data, e.g., the protected random nonce R_C.
In addition, the request may include client authentication
data that the DSKPP server uses to verify proof-of-possession
of the device. <vspace blankLines="1" /></t>
</list><KeyProvServerFinished><vspace
blankLines="1" /><list hangIndent="4">
<t>The <KeyProvServerFinished> response is a
confirmation message that includes a key container that holds
configuration data, and may also contain protected key
material (this depends on the protocol variant, as discussed
below).</t>
<t>Optionally, the DSKPP server may provide a MAC that the
DSKPP client may use for server authentication.</t>
</list></t>
</list></t>
<t>To initiate a DSKPP session:<list hangIndent="4" style="format %d.">
<t>A user may use a browser to connect to a web server that is
running on some host. The user may then identify (and optionally
authenticate) herself (through some means that essentially are out
of scope for this document) and request a symmetric key.</t>
<t>A client application may request a symmetric key by invoking
the DSKPP client.</t>
<t>A DSKPP server may send a trigger message to a client
application, which would then invoke the DSKPP client.</t>
</list></t>
<t>To contact the DSKPP server:<list hangIndent="4" style="format %d.">
<t>A user may indicate how the DSKPP client is to contact a
certain DSKPP server during a browsing session.</t>
<t>A DSKPP client may be pre-configured to contact a certain DSKPP
server.</t>
<t>A user may be informed out-of-band about the location of the
DSKPP server.<vspace blankLines="1" /></t>
</list>Once the location of the DSKPP server is known, the DSKPP
client and the DSKPP server engage in a 4-pass, 2-pass, or 1-pass
protocol. Depending upon the policy and implementation, a DSKPP server
selects which variant of the protocol to use: 4-pass, 2-pass, or
1-pass. With the four-pass variant, keys are mutually generated by the
DSKPP server and DSKPP client; provisioned keys are not transferred
over-the-wire or over-the-air. Two- and one-pass variants enable
secure and efficient download and installation of symmetric keys to a
DSKPP client in environments where near real-time communication may
not be possible.<xref target="Figure-Overview"> </xref> shows which
messages get exchanged during each type of protocol run (4-pass,
2-pass, or 1-pass).</t>
<figure anchor="Figure-Overview"
title="The DSKPP protocol (with OPTIONAL preceding trigger)">
<artwork><![CDATA[+---------------+ +---------------+
| | | |
| DSKPP client | | DSKPP server |
| | | |
+---------------+ +---------------+
| |
| [ <---- DSKPP trigger ----- ] |
| |
| ------- Client Hello -------> |
| (Applicable to 4- and 2-pass) |
| |
| <------ Server Hello -------- |
| (Applicable to 4-pass only) |
| |
| ------- Client Nonce -------> |
| (Applicable to 4-pass only) |
| |
| <----- Server Finished ------ |
| (Applicable to 4-, 2-, and 1-pass) |
| |
]]></artwork>
</figure>
<t>The table below identifies which protocol variants may be applied
to the use cases from <xref target="Section-UseCases"></xref>:</t>
<t><figure anchor="map"
title="Mapping of protocol variants to use cases">
<artwork><![CDATA[----------------------------------------------------------
Protocol Applicable Applicable
Variant Use Cases Deployment Scenarios
----------------------------------------------------------
4-pass All but 3.6 and Near real-time
3.8 if mutual key communication is
generation is desired; possible
none if transport of
a pre-generated key
2-pass All Either near real-time
or non real-time
communication may be
possible
1-pass All but 3.8 Either near real-time
or non real-time
communication may be
possible]]></artwork>
</figure></t>
</section>
<section anchor="Subsection-FourPassUsage"
title="Four-Pass Protocol Usage">
<t>The 4-pass protocol flow is suitable for environments wherein there
is near real-time communication possible between the DSKPP client and
DSKPP server. It is not suitable for environments wherein
administrative approval is a required step in the flow, nor for
provisioning of pre-generated keys.</t>
<t>The full four-pass protocol exchange is as follows:<vspace
blankLines="1" />[<Trigger>]:<vspace blankLines="1" /><list>
<t hangText="6">[ID_Device], [ID_K], [URL_S], [R_S]<vspace
blankLines="1" /></t>
</list><KeyProvClientHello>:<vspace blankLines="1" /><list>
<t>[ID_Device], [ID_K], [R_S], Alg_List<vspace
blankLines="1" /></t>
</list><KeyProvServerHello>:<vspace blankLines="1" /><list>
<t>R_S, Alg_Sel, [K_SERVER], [DSKPP-PRF_K_MAC'("MAC 1 Computation"
|| [R] || R_S, len(R_S))<vspace blankLines="1" /></t>
</list><KeyProvClientNonce>:<vspace blankLines="1" /><list>
<t>AUTHDATA, ENC_PK_SERVER(R_C) OR AUTHDATA,
ENC_K_SHARED(R_C)<vspace blankLines="1" /></t>
</list><KeyProvServerFinished>:<vspace blankLines="1" /><list>
<t>K_CONFDATA, DSKPP-PRF_K_MAC("MAC 2 Computation"||R_C,
len(R_C))<vspace blankLines="1" /></t>
</list>The following subsections describe the exchange in more
detail.</t>
<section title="Message Flow">
<t>The 4-pass protocol flow consists of two round trips between the
DSKPP client and DSKPP server (see <xref
target="Figure-Overview"></xref>), where each round-trip involves
two "passes", i.e., one request message and one response
message:</t>
<t><list hangIndent="8" style="format Round-trip #%d:">
<t>Pass 1 = <KeyProvClientHello>, Pass 2 =
<KeyProvServerHello><vspace blankLines="1" /></t>
<t>Pass 3 = <KeyProvClientNonce>, Pass 4 =
<KeyProvServerFinished></t>
</list></t>
<section title="Round-trip #1: <KeyProvClientHello> and <KeyProvServerHello>">
<t>The DSKPP client sends a <KeyProvClientHello> message to
the DSKPP server. The message provides information to the DSKPP
server about the DSKPP versions, protocol variants, key types,
encryption and MAC algorithms supported by the cryptographic
module for the purposes of this protocol.</t>
<t>The DSKPP server responds to the DSKPP client with a
<KeyProvServerHello> message, whose content includes a
random nonce, R_S, along with information about the type of key to
generate, and the encryption algorithm chosen to protect sensitive
data sent in the protocol. The length of the nonce R_S may depend
on the selected key type. The <KeyProvServerHello> message
also provides information about either a shared secret key to use
for encrypting the cryptographic module's random nonce (see
description of <KeyProvClientNonce> below), or its own
public key. Optionally, <KeyProvServerHello> may include a
MAC that the DSKPP client may use for server authentication during
key replacement.</t>
</section>
<section title="Round-trip #2: <KeyProvClientNonce> and <KeyProvServerFinished>">
<t>Based on information contained in the
<KeyProvServerHello> message, the cryptographic module
generates a random nonce, R_C. The length of the nonce R_C may
depend on the selected key type. The cryptographic module encrypts
R_C using the selected encryption algorithm and with a key, K,
that is either the DSKPP server's public key, K_SERVER, or a
shared secret key, K_SHARED, as indicated by the DSKPP server. If
K is equivalent to K_SERVER, then the cryptographic module SHOULD
verify the server's certificate before using it to encrypt R_C in
accordance with <xref target="RFC3280"></xref>. The DSKPP client
then sends the encrypted random nonce to the DSKPP server in a
<KeyProvClientNonce> message, and may include client
authentication data, such as a certificate or MAC derived from an
authentication code and R_C. Finally, the cryptographic module
calculates a symmetric key, K_TOKEN, of the selected type from the
combination of the two random nonces R_S and R_C, the encryption
key K, and possibly some other data, using the DSKPP-PRF function
defined in <xref target="DSKPP-PRF"></xref>.</t>
<t>The DSKPP server decrypts R_C, calculates K_TOKEN from the
combination of the two random nonces R_S and R_C, the encryption
key K, and possibly some other data, using the DSKPP-PRF function
defined in <xref target="DSKPP-PRF"></xref>. The server then
associates K_TOKEN with the cryptographic module in a server-side
data store. The intent is that the data store later on will be
used by some service that needs to verify or decrypt data produced
by the cryptographic module and the key.</t>
<t>Once the association has been made, the DSKPP server sends a
confirmation message to the DSKPP client called
<KeyProvServerFinished>. Optionally,
<KeyProvServerFinished> may include a MAC that the DSKPP
client may use for server authentication. The confirmation message
includes a key container that holds an identifier for the
generated key (but not the key itself) and additional
configuration information, e.g., the identity of the DSKPP server.
The default symmetric key container format that is used in the
<KeyProvServerFinished> message is based on the Portable
Symmetric Key Container (PSKC) defined in <xref
target="PSKC"></xref>. Alternative formats MAY include PKCS#12
<xref target="PKCS-12"></xref> or PKCS#5 XML <xref
target="PKCS-5-XML"></xref> format.</t>
<t>Upon receipt of the DSKPP server's confirmation message, the
cryptographic module associates the provided key container with
the generated key K_TOKEN, and stores any provided configuration
data.<vspace blankLines="1" /></t>
</section>
</section>
<section title="Generation of Symmetric Keys for Cryptographic Modules">
<t>With 4-pass DSKPP, the symmetric key that is the target of
provisioning, is generated on-the-fly without being transferred
between the DSKPP client and DSKPP server. A sample data flow
depicting how this works followed by computational information are
provided in the subsections below.</t>
<section title="Data Flow">
<t>A sample data flow showing key generation during the 4-pass
protocol is shown in <xref target="keygen"></xref>.</t>
<figure anchor="keygen"
title="Principal data flow for DSKPP key generation - using public server key">
<artwork><![CDATA[+----------------------+ +-------+ +----------------------+
| +------------+ | | | | |
| | Server key | | | | | |
| +<-| Public |------>------------->-------------+---------+ |
| | | Private | | | | | | | |
| | +------------+ | | | | | | |
| | | | | | | | | |
| V V | | | | V V |
| | +---------+ | | | | +---------+ | |
| | | Decrypt |<-------<-------------<-----------| Encrypt | | |
| | +---------+ | | | | +---------+ | |
| | | +--------+ | | | | ^ | |
| | | | Server | | | | | | | |
| | | | Random |--->------------->------+ +----------+ | |
| | | +--------+ | | | | | | Client | | |
| | | | | | | | | | Random | | |
| | | | | | | | | +----------+ | |
| | | | | | | | | | | |
| | V V | | | | V V | |
| | +------------+ | | | | +------------+ | |
| +-->| DSKPP PRF | | | | | | DSKPP PRF |<----+ |
| +------------+ | | | | +------------+ |
| | | | | | | |
| V | | | | V |
| +-------+ | | | | +-------+ |
| | Key | | | | | | Key | |
| +-------+ | | | | +-------+ |
| +-------+ | | | | +-------+ |
| |Key Id |-------->------------->------|Key Id | |
| +-------+ | | | | +-------+ |
+----------------------+ +-------+ +----------------------+
DSKPP Server DSKPP Client DSKPP Client
(PC Host) (cryptographic module)
]]></artwork>
</figure>
<t>Note: Conceptually, although R_C is one pseudorandom string, it
may be viewed as consisting of two components, R_C1 and R_C2,
where R_C1 is generated during the protocol run, and R_C2 can be
pre-generated and loaded on the cryptographic module before the
device is issued to the user. In that case, the latter string,
R_C2, SHOULD be unique for each cryptographic module.</t>
<t>The inclusion of the two random nonces R_S and R_C in the key
generation provides assurance to both sides (the cryptographic
module and the DSKPP server) that they have contributed to the
key's randomness and that the key is unique. The inclusion of the
encryption key K ensures that no man-in-the-middle may be present,
or else the cryptographic module will end up with a key different
from the one stored by the legitimate DSKPP server.</t>
<t>Note: A man-in-the-middle (in the form of corrupt client
software or a mistakenly contacted server) may present his own
public key to the cryptographic module. This will enable the
attacker to learn the client's version of K_TOKEN. However, the
attacker is not able to persuade the legitimate server to derive
the same value for K_TOKEN, since K_TOKEN is a function of the
public key involved, and the attacker's public key must be
different than the correct server's (or else the attacker would
not be able to decrypt the information received from the client).
Therefore, once the attacker is no longer "in the middle," the
client and server will detect that they are "out of sync" when
they try to use their keys. In the case of encrypting R_C with
K_SERVER, it is therefore important to verify that K_SERVER really
is the legitimate server's key. One way to do this is to
independently validate a newly generated K_TOKEN against some
validation service at the server (e.g. by using a connection
independent from the one used for the key generation).</t>
</section>
<section title="Computing the Symmetric Key">
<t>In DSKPP, keys are generated using the DSKPP-PRF function
defined in <xref target="DSKPP-PRF"></xref>, a secret random value
R_C chosen by the DSKPP client, a random value R_S chosen by the
DSKPP server, and the key k used to encrypt R_C. The input
parameter s of DSKPP-PRF is set to the concatenation of the
(ASCII) string "Key generation", k, and R_S, and the input
parameter dsLen is set to the desired length of the key, K_TOKEN
(the length of K_TOKEN is given by the key's type):</t>
<t>dsLen = (desired length of K_TOKEN)</t>
<t>K_TOKEN = DSKPP-PRF (R_C, "Key generation" || k || R_S,
dsLen)</t>
<t>When computing K_TOKEN above, the output of DSKPP-PRF MAY be
subject to an algorithm-dependent transform before being adopted
as a key of the selected type. One example of this is the need for
parity in DES keys.<vspace blankLines="1" /></t>
</section>
</section>
<section title="Client Authentication">
<t>To ensure that a generated key K_TOKEN ends up associated with
the correct cryptographic module and user, the DSKPP client using
any of the methods described in <xref
target="Section-ClientAuthN"></xref>. Whatever the method, the DSKPP
server MUST ensure that a generated key is associated with the
correct cryptographic module, and if applicable, the correct
user.</t>
</section>
<section title="Key Confirmation">
<t>In four-pass DSKPP, the client includes a nonce R_C in the
<KeyProvClientHello> message. The MAC value in the
<KeyProvServerFinished> message MUST be computed on the
(ASCII) string "MAC 2 computation", the client nonce R_C using a MAC
key K_MAC. This key MUST be generated together with K_TOKEN using
R_C and R_S.</t>
<t>The MAC value in <KeyProvServerFinished> MAY be computed by
using the DSKPP-PRF function of <xref target="DSKPP-PRF"></xref>, in
which case the input parameter s MUST consist of the concatenation
of the (ASCII) string "MAC 2 computation", R_C, the parameter dsLen
MUST be set to the length of R_C:</t>
<t>dsLen = len(R_C)</t>
<t>MAC = DSKPP-PRF (K_MAC, "MAC 2 computation" || R_C, dsLen)</t>
</section>
<section title="Server Authentication">
<t>A DSKPP server MUST authenticate itself to avoid a false "Commit"
of a symmetric key that which could cause the cryptographic module
to end up in an initialized state for which the server does not know
the stored key. To do this, the DSKPP server authenticates itself by
including a MAC value in the <KeyProvServerHello> message when
replacing a existing key. The MAC value is generated using the
existing the MAC key K_MAC' (the MAC key that existed before this
protocol run). The MAC algorithm MUST be the same as the algorithm
used for key confirmation purposes. In addition, a DSKPP server can
leverage transport layer authentication if it is available.</t>
<t>When the MAC value is used for server authentication, the value
MAY be computed by using the DSKPP-PRF function of <xref
target="DSKPP-PRF"></xref>, in which case the input parameter s MUST
be set to the concatenation of the (ASCII) string "MAC 1
computation", R (if sent by the client), and R_S, and k MUST be set
to the existing MAC key K_MAC' . The input parameter dsLen MUST be
set to the length of R_S:</t>
<t>dsLen = len(R_S)</t>
<t>MAC = DSKPP-PRF (K_MAC', "MAC 1 computation" || [R ||] R_S,
dsLen)</t>
</section>
</section>
<section anchor="Subsecton-TwoPass" title="Two-Pass Protocol Usage">
<t>The 2-pass protocol flow is suitable for environments wherein near
real-time communication between the DSKPP client and server may not be
possible. It is also suitable for environments wherein administrative
approval is a required step in the flow, and for provisioning of
pre-generated keys. In the 2-pass protocol flow, the client's initial
<KeyProvClientHello> message is directly followed by a
<KeyProvServerFinished> message. There is no exchange of the
<KeyProvServerHello> message or the <KeyProvClientNonce>
message. However, as the two-pass variant of DSKPP consists of one
round trip to the server, the client is still able to include its
random nonce, R_C, algorithm preferences and supported key types in
the <KeyProvClientHello> message. Note that by including R_C in
<KeyProvClientHello>, the DSKPP client is able to ensure the
server is alive before "committing" the key. Also note that the DSKPP
"trigger" message MAY be used to trigger the client's sending of the
<KeyProvClientHello> message.</t>
<t>Essentially, two-pass DSKPP is a transport of key material from the
DSKPP server to the DSKPP client. Two-pass DSKPP supports multiple key
initialization methods that ensure K_TOKEN is not exposed to any other
entity than the DSKPP server and the cryptographic module itself.
Currently, three such key initialization methods are defined (refer to
<xref target="Section-Profiles"></xref>), each supporting a different
usage of 2-pass DSKPP:</t>
<t><list hangIndent="28" style="hanging">
<t hangText="Key Transport">This profile is intended for
PKI-capable devices. Key transport is carried out using a public
key, K_CLIENT, whose private key part resides in the cryptographic
module as the transport key.</t>
<t hangText="Key Wrap">This profile is ideal for pre-keyed
devices, e.g., SIM cards. Key wrap is carried out using a
symmetric key-wrapping key, K_SHARED, which is known in advance by
both the cryptographic module and the DSKPP server.</t>
<t hangText="Passphrase-Based Key Wrap">This profile is a
variation of the Key Wrap Profile. It is applicable to constrained
devices with keypads, e.g., mobile phones. Key wrap is carried out
using a passphrase-derived key-wrapping key, K_DERIVED, which is
known in advance by both the cryptographic module and DSKPP
server.</t>
</list><vspace blankLines="1" />The full 2-pass protocol exchange
when the key is transported using the client public key is as
follows:</t>
<t>[<Trigger>]:<vspace blankLines="1" /><list>
<t>[ID_Device], [ID_K], [URL_S],[R_S]<vspace blankLines="1" /></t>
</list><KeyProvClientHello>:<vspace blankLines="1" /><list>
<t>[ID_Device], ID_K, R_S, R_C, AUTHDATA, Alg_List<vspace
blankLines="1" /></t>
</list><KeyProvServerFinished>:<vspace blankLines="1" /><list>
<t>ENC_K_CLIENT ( K_TOKEN || K_MAC)), K_CONFDATA, ID_S,
DSKPP-PRF_K_MAC("MAC 1 Computation" || ID_S || R_C, len(R_C) ), [
DSKPP-PRF_K_MAC'("MAC 1 Computation" || ID_S || R_C), 16]<vspace
blankLines="1" /></t>
</list></t>
<t>The full 2-pass protocol exchange when the key is wrapped using a
shared key is as follows:</t>
<t>[<Trigger>]:<vspace blankLines="1" /><list>
<t>[ID_Device], [ID_K], [URL_S],[R_S]<vspace blankLines="1" /></t>
</list><KeyProvClientHello>:<vspace blankLines="1" /><list>
<t>[ID_Device], ID_K, R_S, R_C, AUTHDATA, Alg_List<vspace
blankLines="1" /></t>
</list><KeyProvServerFinished>:<vspace blankLines="1" /><list>
<t>ENC_K_SHARED(K_TOKEN || K_MAC), K_CONFDATA, ID_S,
DSKPP-PRF_K_MAC("MAC 1 Computation" || ID_S || R_C), [
DSKPP-PRF_K_MAC'("MAC 1 Computation "|| ID_S||R_C)]<vspace
blankLines="1" /></t>
</list>The full 2-pass protocol when the key is wrapped using a
passphrase based derived key is as follows:</t>
<t>[<Trigger>]:<vspace blankLines="1" /><list>
<t>[ID_Device], [ID_K], [URL_S],[R_S]<vspace blankLines="1" /></t>
</list><KeyProvClientHello>:<vspace blankLines="1" /><list>
<t>[ID_Device], ID_K, R_S, R_C, AUTHDATA, Alg_List<vspace
blankLines="1" /></t>
</list><KeyProvServerFinished>:<vspace blankLines="1" /><list>
<t>ENC_K_DERIVED(K_TOKEN || K_MAC), K_CONFDATA, ID_S,
DSKPP-PRF_K_MAC("MAC 1 Computation" || ID_S || R_C), [
DSKPP-PRF_K_MAC'("MAC 1 Computation" || ID_S || R_C)]<vspace
blankLines="1" /></t>
</list>The following subsections describe these exchanges in more
detail.</t>
<section title="Message Flow">
<t>The 2-pass protocol flow consists of one round trip between the
DSKPP client and DSKPP server, which consists of two "passes", i.e.,
one request message and one response message:</t>
<t>Round-trip #1: Pass 1=<KeyProvClientHello>, Pass
2=<KeyProvServerFinished></t>
<t><list hangIndent="4" style="format %c.">
<t>The DSKPP client sends a <KeyProvClientHello> message
to the DSKPP server. The message provides the client nonce, R_C,
and information about the DSKPP versions, protocol variants, key
types, encryption and MAC algorithms supported by the
cryptographic module for the purposes of this protocol. The
message may also include client authentication data, such as
device certificate or MAC derived from authentication code and
R_C. Authentication code is sent in clear only when underlying
transport layer can ensure data confidentiality. Unlike 4-pass
DSKPP, 2-pass DSKPP client uses the <KeyProvClientHello>
message to declare which key initialization method it supports,
providing required payload information, e.g., K_CLIENT for the
Key Transport Profile.</t>
<t>The DSKPP server generates a key K from which two keys,
K_TOKEN and K_MAC are derived. (Alternatively, the key K may
have been pre-generated as described in <xref
target="UC1"></xref>. K is either transported or wrapped in
accordance with the key initialization method specified by the
DSKPP client in the <KeyProvClientHello> message. The
server then associates K_TOKEN with the cryptographic module in
a server-side data store. The intent is that the data store
later on will be used by some service that needs to verify or
decrypt data produced by the cryptographic module and the
key.</t>
<t>Once the association has been made, the DSKPP server sends a
confirmation message to the DSKPP client called
<KeyProvServerFinished>. The confirmation message includes
a key container that holds an identifier for the key, the key K
from which K_TOKEN and K_MAC are derived, and additional
configuration information (note that the latter MUST include the
identity of the DSKPP server for authentication purposes). In
addition, <KeyProvServerFinished> MUST include two MACs
whose values are calculated with contribution from the client
nonce, R_C, provided in the <KeyProvClientHello> message.
The data will allow the cryptographic module to perform key
confirmation and server authentication before "committing" the
key. Note that the second MAC value that is intended for key
confirmation MAY only be used for replacing and existing
key.</t>
<t>Upon receipt of the DSKPP server's confirmation message, the
cryptographic module extracts the key data from the provided key
container, uses the provided MAC values to perform key
confirmation and server authentication, and stores the key
material locally.</t>
</list></t>
</section>
<section title="Key Confirmation">
<t>In two-pass DSKPP, the client is REQUIRED to include a nonce R in
the <KeyProvClientHello> message. Further, the server is
REQUIRED to include an identifier, ID_S, for itself (via the key
container) in the <KeyProvServerFinished> message. The MAC
value in the <KeyProvServerFinished> message MUST be computed
on the (ASCII) string "MAC 1 computation", the server identifier
ID_S, and R using a MAC key K_MAC. This key MUST be provided
together with K_TOKEN to the cryptographic module.</t>
<t>If DSKPP-PRF is used as the MAC algorithm, then the input
parameter s MUST consist of the concatenation of the (ASCII) string
"MAC 1 computation" and R, and the parameter dsLen MUST be set to
the length of R:</t>
<t>dsLen = len(R)</t>
<t>MAC = DSKPP-PRF (K_MAC, "MAC 1 computation" || ID_S || R,
dsLen)</t>
</section>
<section anchor="Subsecton-TwoPass-ServerAuth"
title="Server Authentication">
<t>A server MUST authenticate itself when attempting to replace an
existing K_TOKEN. In 2-pass DSKPP, servers authenticate themselves
by including a second MAC value in the AuthenticationDataType
element of <KeyProvServerFinished>. The MAC value in the
AuthenticationDataType element MUST be computed on the (ASCII)
string "MAC 1 computation", the server identifier ID_S, and R, using
the existing MAC key K_MAC' (the MAC key that existed before this
protocol run). The MAC algorithm MUST be the same as the algorithm
used for key confirmation purposes.</t>
<t>If DSKPP-PRF is used as the MAC algorithm, then the input
parameter s MUST consist of the concatenation of the (ASCII) string
"MAC 1 computation" ID_S, and R. The parameter dsLen MUST be set to
at least 16 (i.e. the length of the MAC MUST be at least 16
octets):</t>
<t>dsLen >= 16</t>
<t>MAC = DSKPP-PRF (K_MAC', "MAC 1 computation" || ID_S || R,
dsLen)</t>
</section>
</section>
<section anchor="Subsection-OnePass" title="One-Pass Protocol Usage">
<t>The one-pass protocol flow is suitable for environments wherein
near real-time communication between the DSKPP client and server may
not be possible. It is also suitable for environments wherein
administrative approval is a required step in the flow, and for
provisioning of pre-generated keys. In one-pass DSKPP, the server
simply sends a <KeyProvServerFinished> message to the DSKPP
client. In this case, there is no exchange of the
<KeyProvClientHello>, <KeyProvServerHello>, and
<KeyProvClientNonce> DSKPP messages, and hence there is no way
for the client to express supported algorithms or key types. Before
attempting one-pass DSKPP, the server MUST therefore have prior
knowledge not only that the client is able and willing to accept this
variant of DSKPP, but also of algorithms and key types supported by
the client.</t>
<t>Essentially, one-pass DSKPP is a transport of key material from the
DSKPP server to the DSKPP client. As with two-pass DSKPP, the one-pass
variant relies on key initialization methods that ensure K_TOKEN is
not exposed to any other entity than the DSKPP server and the
cryptographic module itself. The same key initialization profiles are
defined as described in <xref target="Subsecton-TwoPass"></xref> and
<xref target="Section-Profiles"></xref>.</t>
<t>Outside the specific cases where one-pass DSKPP is desired, clients
SHOULD be constructed and configured to only accept DSKPP server
messages in response to client-initiated transactions.</t>
<t>The 1-pass protocol when the key is transported using the client
public Key is as follows:</t>
<t><KeyProvServerFinished>:<vspace blankLines="1" /><list>
<t>ENC_K_CLIENT ( K_TOKEN || K_MAC)), K_CONFDATA, DSKPP-PRF_K_MAC
("MAC 1 Computation" || ID_S || I), [ DSKPP-PRF_K_MAC'("MAC 2
Computation"||ID_S||I')]<vspace blankLines="1" /></t>
</list> The 1-pass protocol when the key is wrapped using a shared
key is as follows:</t>
<t><KeyProvServerFinished>:<vspace blankLines="1" /><list>
<t>ENC_K_SHARED (K_TOKEN || K_MAC), K_CONFDATA,
DSKPP-PRF_K_MAC("MAC 1 Computation" || ID_S || I), [
PRF_K_MAC'("MAC 2 Computation" || ID_S || I')]<vspace
blankLines="1" /></t>
</list>The 1-pass protocol when the key is wrapped using a
passphrase derived key is as follows:</t>
<t><KeyProvServerFinished>:<vspace blankLines="1" /><list>
<t>ENC_K_DERIVED(K_TOKEN || K_MAC), K_CONFDATA,
DSKPP-PRF_K_MAC("MAC 1 Computation" || ID_S || I),
[DSKPP-PRF_K_MAC'("MAC 2 Computation" || ID_S || I')]<vspace
blankLines="1" /></t>
</list>The subsections below describe the 1-pass protocol in more
detail.</t>
<section title="Message Flow">
<t>The 1-pass protocol flow consists of one "pass", i.e., a single
message sent from the DSKPP server to the DSKPP client:</t>
<t>Pass 1: <KeyProvServerFinished></t>
<t><list hangIndent="4" style="format %c.">
<t>The DSKPP server generates a key K from which two keys,
K_TOKEN and K_MAC are derived. K is either transported or
wrapped in accordance with the key initialization method known
in advance by the DSKPP server. The server then associates
K_TOKEN with the cryptographic module in a server-side data
store. The intent is that the data store later on will be used
by some service that needs to verify or decrypt data produced by
the cryptographic module and the key.</t>
<t>Once the association has been made, the DSKPP server sends a
confirmation message to the DSKPP client called
<KeyProvServerFinished>. The confirmation message includes
a key container that holds an identifier for the key, the key K
from which K_TOKEN and K_MAC are derived, and additional
configuration information (note that the latter MUST include the
identity of the DSKPP server for authentication purposes). In
addition, <KeyProvServerFinished> MUST include two MACs,
which will allow the cryptographic module to perform key
confirmation and server authentication before "commuting" the
key. Note that unlike two-pass DSKPP, in the one-pass variant,
the server does not have the client nonce, R_C, and therefore
the MACs values are calculated with contribution from an
unsigned integer, I, generated by the server during the protocol
run.</t>
<t>Upon receipt of the DSKPP server's confirmation message, the
cryptographic module extracts the key data from the provided key
container, uses the two MAC values to perform key confirmation
and server authentication, and stores the key material
locally.</t>
</list></t>
</section>
<section title="Key Confirmation">
<t>In one-pass DSKPP, the server MUST include an identifier, ID_S,
for itself (via the key container) in the
<KeyProvServerFinished> message. The MAC value in the
<KeyProvServerFinished> message MUST be computed on the
(ASCII) string "MAC 1 computation", the server identifier ID_S, and
an unsigned integer value I, using a MAC key K_MAC. The value I MUST
be monotonically increasing and guaranteed not to be used again by
this server towards this cryptographic module. It could for example
be the number of seconds since some point in time with sufficient
granularity, a counter value, or a combination of the two where the
counter value is reset for each new time value. In contrast to the
MAC calculation in four-pass DSKPP, the MAC key K_MAC MUST be
provided together with K_TOKEN to the cryptographic module.</t>
<t>Note: The integer I does not necessarily need to be maintained by
the DSKPP server on a per cryptographic module basis (it is enough
if the server can guarantee that the same value is never being sent
twice to the same cryptographic module).</t>
<t>If DSKPP-PRF is used as the MAC algorithm, then the input
parameter s MUST consist of the concatenation of the (ASCII) string
"MAC 1 computation", ID_S, and I. The parameter dsLen MUST be set to
at least 16 (i.e. the length of the MAC MUST be at least 16
octets):</t>
<t>dsLen >= 16</t>
<t>MAC = DSKPP-PRF (K_MAC, "MAC 1 computation" || ID_S || I,
dsLen)</t>
<t>The server MUST provide I to the client in the Nonce attribute of
the <Mac> element of the <KeyProvServerFinished> message
using the AuthenticationCodeMacType defined in <xref
target="Section-AuthNData"></xref>.</t>
</section>
<section anchor="Subsecton-OnePass-ServerAuth"
title="Server Authentication">
<t>As discussed in , servers need to authenticate themselves when
attempting to replace an existing K_TOKEN. In 1-pass DSKPP, servers
authenticate themselves by including a second MAC value in the
AuthenticationDataType element of <KeyProvServerFinished>. The
MAC value in the AuthenticationDataType element MUST be computed on
the (ASCII) string "MAC 1 computation", the server identifier ID_S,
and a new value I', I' > I, using the existing MAC key K_MAC'
(the MAC key that existed before this protocol run). The MAC
algorithm MUST be the same as the algorithm used for key
confirmation purposes.</t>
<t>If DSKPP-PRF is used as the MAC algorithm, then the input
parameter s MUST consist of the concatenation of the (ASCII) string
"MAC 1 computation" ID_S, and I'. The parameter dsLen MUST be set to
at least 16 (i.e. the length of the MAC MUST be at least 16
octets):</t>
<t>dsLen >= 16</t>
<t>MAC = DSKPP-PRF (K_MAC', "MAC 1 computation" || ID_S || I',
dsLen)</t>
<t>The server MUST provide I' to the client in the Nonce attribute
of the <Mac> element of the AuthenticationDataType extension.
If the protocol run is successful, the client stores I' as the new
value of I for this server.</t>
</section>
</section>
</section>
<section title="Methods Common to More Than One Protocol Variant">
<t>The mechanisms contained in this section are used in more than one
variant of DSKPP.</t>
<section anchor="DSKPP-PRF"
title="The DSKPP One-Way Pseudorandom Function, DSKPP-PRF">
<section title="Introduction">
<t>All of the protocol variants depend on DSKPP-PRF. The general
requirements on DSKPP-PRF are the same as on keyed hash functions:
It MUST take an arbitrary length input, and be one-way and
collision-free (for a definition of these terms, see, e.g., <xref
target="FAQ"></xref>). Further, the DSKPP-PRF function MUST be
capable of generating a variable-length output, and its output MUST
be unpredictable even if other outputs for the same key are
known.</t>
<t>It is assumed that any realization of DSKPP-PRF takes three input
parameters: A secret key k, some combination of variable data, and
the desired length of the output. The combination of variable data
can, without loss of generalization, be considered as a salt value
(see PKCS#5 Version 2.0 <xref target="PKCS-5"></xref>, Section 4),
and this characterization of DSKPP-PRF SHOULD fit all actual PRF
algorithms implemented by cryptographic modules. From the point of
view of this specification, DSKPP-PRF is a "black-box" function
that, given the inputs, generates a pseudorandom value.</t>
<t>Separate specifications MAY define the implementation of
DSKPP-PRF for various types of cryptographic modules. <xref
target="Section-PRFRealizations"></xref> contains two example
realizations of DSKPP-PRF.</t>
</section>
<section title="Declaration">
<t>DSKPP-PRF (k, s, dsLen)</t>
<t>Input:</t>
<t><list hangIndent="6" style="hanging">
<t hangText="k">secret key in octet string format</t>
<t hangText="s">octet string of varying length consisting of
variable data distinguishing the particular string being
derived</t>
<t hangText="dsLen">desired length of the output</t>
</list></t>
<t>Output:</t>
<t><list hangIndent="6" style="hanging">
<t hangText="DS">pseudorandom string, dsLen-octets long</t>
</list>For the purposes of this document, the secret key k MUST be
at least 16 octets long.</t>
</section>
</section>
<section anchor="Subsection-Enc"
title="Encryption of Pseudorandom Nonces Sent from the DSKPP Client (Applicable to Four-Pass and Two-Pass DSKPP)">
<t>During 4- and 2-pass message exchanges, DSKPP client random
nonce(s) are either encrypted with the public key provided by the
DSKPP server or by a shared secret key. For example, in the case of a
public RSA key, an RSA encryption scheme from PKCS #1 <xref
target="PKCS-1"></xref> MAY be used.</t>
<t>In the case of a shared secret key, to avoid dependence on other
algorithms, the DSKPP client MAY use the DSKPP-PRF function described
herein with the shared secret key K_SHARED as input parameter k (in
this case, K_SHARED SHOULD be used solely for this purpose), the
concatenation of the (ASCII) string "Encryption" and the server's
nonce R_S as input parameter s, and dsLen set to the length of
R_C:</t>
<t>dsLen = len(R_C)</t>
<t>DS = DSKPP-PRF(K_SHARED, "Encryption" || R_S, dsLen)</t>
<t>This will produce a pseudorandom string DS of length equal to R_C.
Encryption of R_C MAY then be achieved by XOR-ing DS with R_C:</t>
<t>Enc-R_C = DS ^ R_C</t>
<t>The DSKPP server will then perform the reverse operation to extract
R_C from Enc-R_C.</t>
</section>
<section anchor="Section-ClientAuthN"
title="Client Authentication Mechanisms (Applicable to Four- and Two-Pass DSKPP) ">
<t>To ensure that a generated K_TOKEN ends up associated with the
correct cryptographic module and user, the DSKPP server MAY couple an
initial user authentication to the DSKPP execution in several ways, as
discussed in the following sub-sections. Whatever the method, the
DSKPP server MUST ensure that a generated key is associated with the
correct cryptographic module, and if applicable, the correct user. For
a further discussion of this, and threats related to man-in-the-middle
attacks in this context, see <xref
target="Section-Security"></xref>.</t>
<section title="Device Certificate">
<t>Instead of requiring an Authentication Code for in-band
authentication, a device private key and certificate could be used,
which was supplied with the cryptographic module by its issuer for
client authentication at the transport layer e.g TLS/HTTPS. When the
Device certificate is available and client authentication is not
provided in the transport layer, the DSKPP client may include a
device's certificate signed data for the authentication data.</t>
</section>
<section title="Device Identifier">
<t>The DSKPP server could be pre-configured with a unique device
identifier corresponding to a particular cryptographic module. The
DSKPP server MAY then include this identifier in the DSKPP
initialization trigger, and the DSKPP client would include it in its
message(s) to the DSKPP server for authentication. Note that it is
also legitimate for a DSKPP client to initiate the DSKPP protocol
run without having received an initialization message from a server,
but in this case any provided device identifier MUST NOT be accepted
by the DSKPP server unless the server has access to a unique key for
the identified device and that key will be used in the protocol.</t>
</section>
<section anchor="Section-AuthCode" title="Authentication Code">
<t>As shown in <xref target="onetime"></xref>, a key issuer may
provide a one-time value, called an Authentication Code, to the user
or device out-of-band and require this value to be used by the DSKPP
client when contacting the DSKPP server. The DSKPP client MAY
include the authentication data in its <KeyProvClientHello>
(and <KeyProvClientNonce> for four-pass) message, and the
DSKPP server MUST verify the data before continuing with the
protocol run.</t>
<t>Note: An alternate method for getting the Authentication Code to
the client, is for the DSKPP server to place the value in the
<TriggerNonce> element of the DSKPP initialization trigger (if
triggers are used; see <xref target="Section-InitDSKPP"></xref>) .
When this method is used, a transport providing privacy and
integrity MUST be used to deliver the DSKPP initialization trigger
from the DSKPP server to the DSKPP client, e.g. HTTPS.</t>
<figure anchor="onetime"
title="User Authentication with One-Time Code">
<preamble></preamble>
<artwork><![CDATA[
+------------+ Get Authentication Code +------------+
| User |<------------------------->| Issuer |
+------------+ +------------+
| |
| |
| |
V V
+--------------+ +--------------+
| DSKPP | Authentication Data | DSKPP |
| Client |----------------------->| Server |
+--------------+ +--------------+
]]></artwork>
</figure>
<t><vspace blankLines="1" />The Authentication Code, AUTHCODE, may
be considered as a special form of a shared secret between a User
and a DSKPP server. The Issuer may generate the Authentication Code
as follows:<vspace blankLines="1" />AUTHCODE = passwordLen ||
identifier || password || checksum<vspace blankLines="1" /></t>
<t>where<vspace blankLines="1" /> <list hangIndent="10"
style="hanging">
<t hangText="passwordLen">: 1 digit indicating the 'password'
length. The maximum length of the password is 10. A passwordLen
value '0' indicates a password of 10 digits.<vspace
blankLines="1" /></t>
<t hangText="identifier">: A globally unique identifier of the
user’s order for token provisioning. The length of the
identifier may be fixed e.g. 10 digits or variable e.g. 1 to 20
digits. The identifier may be generated as a sequence
number.<vspace blankLines="1" /></t>
<t hangText="password">: 6 to 10 digits. The password should be
generated by the system as a random number to make the AUTHCODE
more difficult to guess.<vspace blankLines="1" /></t>
<t hangText="checksum">: 1 digit calculated from the remaining
digits in the code.</t>
</list></t>
<t>The Authentication Data, AUTHDATA, may be derived from the
AUTHCODE and other information as follows:<vspace
blankLines="1" /></t>
<t>MAC = DSKPP-PRF-AES(K_AUTHCODE, AUTHCODE->Identifier || URL_S
|| [R_S], 16)<vspace blankLines="1" /></t>
<t>where <vspace blankLines="1" /><list>
<t>Refer to <xref target="DSKPP-PRF"></xref> for a description
of DSKPP-PRF in general and <xref
target="Section-PRFRealizations"></xref> for a description of
DSKPP-PRF-AES.<vspace blankLines="1" /></t>
<t>In four-pass DSKPP, the cryptographic module uses the client
nonce R_C, the server nonce R_S, and the server URL URL_S to
calculate the MAC. In two-pass DSKPP, the cryptographic module
does not have access to the server nonce R_S therefore only the
client nonce R_C is used in combination with the server URL
URL_S to produce the MAC.<vspace blankLines="1" /></t>
<t>The K_AUTHCODE MAY be derived from AUTHCODE>password as
follows:<list>
<t>K_AUTHCODE = truncate( Hash( Hash(...n times...(
AUTHCODE->password ||R_C||[K]) ) ) )</t>
</list><vspace blankLines="1" />where <vspace
blankLines="1" /><list>
<t>K is optional and MAY be one of the following:<vspace
blankLines="1" /><list hangIndent="10">
<t>K_CLIENT: The device public key when a device
certificate is available and used for key transport in
2-pass<vspace blankLines="1" /></t>
<t>K_SHARED: The shared key between the Client and the
Server when it is used for key wrap in two-pass or for
R_C protection in four-pass<vspace blankLines="1" /></t>
<t>K_DERIVED: when a passphrase derived key is used for
key wrap in two-pass.<vspace blankLines="1" /></t>
</list></t>
<t>'truncate()' returns the first 16 bytes from the result
of the last hash iteration, and n is the number of hash
iterations. n may be any number between 10 and 1000.</t>
</list></t>
</list></t>
<t>Notes:<list style="format %d">
<t>Authentication data MAY be omitted if client certificate
authentication has been provided by the transport channel such
as TLS.<vspace blankLines="1" /></t>
<t>When an issuer delegates symmetric key provisioning to a
third party provisioning service provider, both client
authentication and issuer authentication are required by the
provisioning server. Client authentication to the issuer MAY be
in-band or out-of-band as described above. The issuer acts as a
proxy for the provisioning server. The issuer authenticates to
the provisioning service provider either using a certificate or
a pre-established secret key.</t>
</list></t>
</section>
</section>
<section title="Client Authentication Examples">
<section title="Example Using a MAC from an Authentication Code">
<figure>
<preamble></preamble>
<artwork><![CDATA[ <AuthenticationData>
<ClientID>31300257</ClientID>
<AuthenticationCodeMac>
<IterationCount>512</IterationCount>
<Mac>4bRJf9xXd3KchKoTenHJiw==</Mac>
</AuthenticationCodeMac>
</AuthenticationData>]]></artwork>
<postamble></postamble>
</figure>
</section>
<section title="Example Using a Device Certificate">
<figure>
<preamble></preamble>
<artwork><![CDATA[ <AuthenticationData>
<DigitalSignature>
<ds:SignedInfo>
<ds:CanonicalizationMethod
Algorithm="http://www.w3.org/TR/2001/REC-xml-c14n-20010315" />
<ds:SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#rsa-sha1"/>
<ds:Reference URI="#Nonce">
<ds:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/>
<ds:DigestValue></ds:DigestValue>
</ds:Reference>
</ds:SignedInfo>
<ds:SignatureValue></ds:SignatureValue>
<ds:KeyInfo>
<ds:X509Data>
<ds:X509Certificate>miib</ds:X509Certificate>
</ds:X509Data>
</ds:KeyInfo>
<ds:Object Id="Nonce">xwQzwEl0CjPAiQeDxwRJdQ==</ds:Object>
</DigitalSignature>]]></artwork>
<postamble></postamble>
</figure>
</section>
</section>
</section>
<section title="Four-Pass Protocol">
<t>In this section, example messages are used to describe parameters,
encoding and semantics in a 4-pass DSKPP exchanges. The examples are
written using XML. While they are syntactically correct, MAC and cipher
values are fictitious.</t>
<section title="XML Basics">
<t>The DSKPP XML schema can be found in <xref
target="Section-Schema"></xref>. Some DSKPP elements rely on the
parties being able to compare received values with stored values.
Unless otherwise noted, all elements in this document that have the
XML Schema "xs:string" type, or a type derived from it, MUST be
compared using an exact binary comparison. In particular, DSKPP
implementations MUST NOT depend on case-insensitive string
comparisons, normalization or trimming of white space, or conversion
of locale-specific formats such as numbers.</t>
<t>Implementations that compare values that are represented using
different character encodings MUST use a comparison method that
returns the same result as converting both values to the Unicode
character encoding, Normalization Form C <xref
target="UNICODE"></xref>, and then performing an exact binary
comparison.</t>
<t>No collation or sorting order for attributes or element values is
defined. Therefore, DSKPP implementations MUST NOT depend on specific
sorting orders for values.</t>
</section>
<section title="Round-Trip #1: <KeyProvClientHello> and <KeyProvServerHello>">
<t></t>
<section title="Examples">
<t></t>
<section title="Example Without a Preceding Trigger">
<figure>
<preamble></preamble>
<artwork><![CDATA[<?xml version="1.0" encoding="UTF-8"?>
<dskpp:KeyProvClientHello Version="1.0"
xmlns:dskpp="urn:ietf:params:xml:ns:keyprov:1.0:protocol"
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:1.0:container"
xmlns:ds="http://www.w3.org/2000/09/xmldsig#"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="urn:ietf:params:xml:ns:keyprov:1.0:protocol
keyprov-dskpp-1.0.xsd">
<DeviceIdentifierData>
<DeviceId>
<pskc:Manufacturer>ManufacturerABC</pskc:Manufacturer>
<pskc:SerialNo>XL0000000001234</pskc:SerialNo>
<pskc:Model>U2</pskc:Model>
</DeviceId>
</DeviceIdentifierData>
<SupportedKeyTypes>
<Algorithm>urn:ietf:params:xml:schema:keyprov:otpalg#HOTP</Algorithm>
<Algorithm>
http://www.rsa.com/rsalabs/otps/schemas/2005/09/otps-wst#SecurID-AES
</Algorithm>
</SupportedKeyTypes>
<SupportedEncryptionAlgorithms>
<Algorithm>http://www.w3.org/2001/05/xmlenc#rsa_1_5</Algorithm>
<Algorithm>
urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes
</Algorithm>
</SupportedEncryptionAlgorithms>
<SupportedMacAlgorithms>
<Algorithm>
urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes
</Algorithm>
</SupportedMacAlgorithms>
<SupportedProtocolVariants><FourPass/></SupportedProtocolVariants>
<SupportedKeyContainers>
<KeyContainerFormat>
urn:ietf:params:xml:schema:keyprov:container#KeyContainer
</KeyContainerFormat>
</SupportedKeyContainers>
</dskpp:KeyProvClientHello>]]></artwork>
<postamble></postamble>
</figure>
<figure>
<preamble></preamble>
<artwork><![CDATA[<?xml version="1.0" encoding="UTF-8"?>
<dskpp:KeyProvServerHello Version="1.0" SessionID="4114" Status="Success"
xmlns:dskpp="urn:ietf:params:xml:ns:keyprov:1.0:protocol"
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:1.0:container"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:ds="http://www.w3.org/2000/09/xmldsig#"
xsi:schemaLocation="urn:ietf:params:xml:ns:keyprov:1.0:protocol
keyprov-dskpp-1.0.xsd">
<KeyType>
urn:ietf:params:xml:schema:keyprov:otpalg#SecurID-AES
</KeyType>
<EncryptionAlgorithm>
urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes
</EncryptionAlgorithm>
<MacAlgorithm>
urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes
</MacAlgorithm>
<EncryptionKey>
<ds:KeyName>KEY-1</ds:KeyName>
</EncryptionKey>
<KeyContainerFormat>
urn:ietf:params:xml:schema:keyprov:container#KeyContainer
</KeyContainerFormat>
<Payload>
<Nonce>qw2ewasde312asder394jw==</Nonce>
</Payload>
</dskpp:KeyProvServerHello>]]></artwork>
<postamble></postamble>
</figure>
</section>
<section title="Example Assuming a Preceding Trigger">
<figure>
<preamble></preamble>
<artwork><![CDATA[<?xml version="1.0" encoding="UTF-8"?>
<dskpp:KeyProvClientHello Version="1.0"
xmlns:dskpp="urn:ietf:params:xml:ns:keyprov:1.0:protocol"
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:1.0:container"
xmlns:ds="http://www.w3.org/2000/09/xmldsig#"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="urn:ietf:params:xml:ns:keyprov:1.0:protocol
keyprov-dskpp-1.0.xsd">
<DeviceIdentifierData>
<DeviceId>
<pskc:Manufacturer>ManufacturerABC</pskc:Manufacturer>
<pskc:SerialNo>XL0000000001234</pskc:SerialNo>
<pskc:Model>U2</pskc:Model>
</DeviceId>
</DeviceIdentifierData>
<KeyID>SE9UUDAwMDAwMDAx</KeyID>
<TriggerNonce>112dsdfwf312asder394jw==</TriggerNonce>
<SupportedKeyTypes>
<Algorithm>urn:ietf:params:xml:schema:keyprov:otpalg#HOTP</Algorithm>
<Algorithm>
http://www.rsa.com/rsalabs/otps/schemas/2005/09/otps-wst#SecurID-AES
</Algorithm>
</SupportedKeyTypes>
<SupportedEncryptionAlgorithms>
<Algorithm>http://www.w3.org/2001/05/xmlenc#rsa_1_5</Algorithm>
<Algorithm>
urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes
</Algorithm>
</SupportedEncryptionAlgorithms>
<SupportedMacAlgorithms>
<Algorithm>
urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes
</Algorithm>
</SupportedMacAlgorithms>
<SupportedProtocolVariants><FourPass/></SupportedProtocolVariants>
<SupportedKeyContainers>
<KeyContainerFormat>
urn:ietf:params:xml:schema:keyprov:container#KeyContainer
</KeyContainerFormat>
</SupportedKeyContainers>
</dskpp:KeyProvClientHello>]]></artwork>
<postamble></postamble>
</figure>
<figure>
<preamble></preamble>
<artwork><![CDATA[<?xml version="1.0" encoding="UTF-8"?>
<dskpp:KeyProvServerHello Version="1.0" SessionID="4114" Status="Success"
xmlns:dskpp="urn:ietf:params:xml:ns:keyprov:1.0:protocol"
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:1.0:container"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:ds="http://www.w3.org/2000/09/xmldsig#"
xsi:schemaLocation="urn:ietf:params:xml:ns:keyprov:1.0:protocol
keyprov-dskpp-1.0.xsd">
<KeyType>
http://www.rsa.com/rsalabs/otps/schemas/2005/09/otps-wst#SecurID-AES
</KeyType>
<EncryptionAlgorithm>
urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes
</EncryptionAlgorithm>
<MacAlgorithm>
urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes
</MacAlgorithm>
<EncryptionKey>
<ds:KeyName>KEY-1</ds:KeyName>
</EncryptionKey>
<KeyContainerFormat>
urn:ietf:params:xml:schema:keyprov:container#KeyContainer
</KeyContainerFormat>
<Payload>
<Nonce>qw2ewasde312asder394jw==</Nonce>
</Payload>
<Mac MacAlgorithm=
"urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes">
cXcycmFuZG9tMzEyYXNkZXIzOTRqdw==
</Mac>
</dskpp:KeyProvServerHello>]]></artwork>
<postamble></postamble>
</figure>
</section>
</section>
<section title="Components of the <KeyProvClientHello> Request">
<t>The components of this message have the following meaning:<list
style="symbols">
<t>Version: (attribute inherited from the AbstractRequestType
type) The highest version of this protocol the client supports.
Only version one ("1.0") is currently specified.</t>
<t><DeviceIdentifierData>: An identifier for the
cryptographic module as defined in <xref
target="Section-ClientAuthN"></xref> above. The identifier MUST
only be present if such shared secrets exist or if the
identifier was provided by the server in a
<KeyProvTrigger> element (see <xref
target="Section-InitDSKPP"></xref> below). In the latter case,
it MUST have the same value as the identifier provided in that
element.</t>
<t><KeyID>: An identifier for the key that will be
overwritten if the protocol run is successful. The identifier
MUST only be present if the key exists or if the identifier was
provided by the server in a <KeyProvTrigger> element, in
which case, it MUST have the same value as the identifier
provided in that element (see <xref
target="Section-Trigger">a</xref> and <xref
target="Section-InitDSKPP"></xref> below).</t>
<t><KeyProvClientNonce>: This is the nonce R, which, when
present, MUST be used by the server when calculating MAC values
(see below). It is RECOMMENDED that clients include this element
whenever the <KeyID> element is present.</t>
<t><TriggerNonce>: This OPTIONAL element MUST be present
if and only if the DSKPP run was initialized with a
<KeyProvTrigger> message (see <xref
target="Section-InitDSKPP"></xref> below), and MUST, in that
case, have the same value as the <TriggerNonce> child of
that message. A server using nonces in this way MUST verify that
the nonce is valid and that any device or key identifier values
provided in the <KeyProvTrigger> message match the
corresponding identifier values in the
<KeyProvClientHello> message.</t>
<t><SupportedKeyTypes>: A sequence of URIs indicating the
key types for which the cryptographic module is willing to
generate keys through DSKPP.</t>
<t><SupportedEncryptionAlgorithms>: A sequence of URIs
indicating the encryption algorithms supported by the
cryptographic module for the purposes of DSKPP. The DSKPP client
MAY indicate the same algorithm both as a supported key type and
as an encryption algorithm.</t>
<t><SupportedMacAlgorithms>: A sequence of URIs indicating
the MAC algorithms supported by the cryptographic module for the
purposes of DSKPP. The DSKPP client MAY indicate the same
algorithm both as an encryption algorithm and as a MAC algorithm
(e.g., urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes
defined in <xref target="Section-PRFRealizations"></xref>).</t>
<t><SupportedProtocolVariants>: This OPTIONAL element is
used by the DSKPP client to indicate support for four-pass or
two-pass DSKPP. If two-pass support is specified, then
<KeyProvClientNonce> MUST be set to nonce R in the
<KeyProvClientHello> message unless <TriggerNonce>
is already present.</t>
<t><SupportedKeyContainers>: This OPTIONAL element is a
sequence of URIs indicating the key container formats supported
by the DSKPP client. If this element is not provided, then the
DSKPP server MUST proceed with
"urn:ietf:params:xml:schema:keyprov:container#KeyContainer" (see
<xref target="PSKC"></xref>).</t>
<t><AuthenticationData>: This OPTIONAL element contains
data that the DSKPP client uses to authenticate the user or
device to the DSKPP server. The element is set as specified in
<xref target="Section-ClientAuthN"></xref>.</t>
<t><Extensions>: A sequence of extensions. One extension
is defined for this message in this version of DSKPP: the
ClientInfoType (see <xref
target="Section-ProtocolExts"></xref>).</t>
</list></t>
<section title="The DSKPP Client: The DeviceIdentifierDataType Type">
<t>The DeviceIdentifierDataType type is used to uniquely identify
the device that houses the cryptographic module, e.g., a mobile
phone. The device identifier allows the DSKPP server to find,
e.g., a pre-shared transport key for 2-pass DSKPP and/or the
correct shared secret for MAC'ing purposes. The default
DeviceIdentifierDataType is defined in <xref
target="PSKC"></xref>.</t>
</section>
<section title="Selecting a Protocol Variant: The ProtocolVariantsType Type">
<t>The ProtocolVariantsType type is OPTIONAL for a DSKPP client,
who MAY use it to indicate the number of passes of the DSKPP
protocol that it supports. The ProtocolVariantsType MAY be used to
indicate support for 4-pass or 2-pass DSKPP. Because 1-pass DSKPP
does not include a client request to the server, the
ProtocolVariantsType type MAY NOT be used to indicate support for
1-pass DSKPP. If the ProtocolVariantsType is not used, then the
DSKPP server will proceed with ordinary 4-pass DSKPP. However, it
does not support 4-pass DSKPP, then the server MUST find a
suitable two-pass variant or else the protocol run will fail.</t>
<t>The TwoPassSupportType type signals client support for the
2-pass version of DSKPP, informs the server of supported two-pass
variants, and provides OPTIONAL payload data to the DSKPP server.
The payload is sent in an opportunistic fashion, and MAY be
discarded by the DSKPP server if the server does not support the
two-pass variant the payload is associated with. The elements of
this type have the following meaning:<list style="symbols">
<t><SupportedKeyInitializationMethod>: A two-pass key
initialization method supported by the DSKPP client. Multiple
supported methods MAY be present, in which case they MUST be
listed in order of precedence.</t>
<t><Payload>: An OPTIONAL payload associated with each
supported key initialization method.</t>
</list>A DSKPP client that indicates support for two-pass DSKPP
MUST also include the nonce R in its <KeyProvClientHello>
message (this will enable the client to verify that the DSKPP
server it is communicating with is alive).</t>
</section>
<section title="Selecting a Key Container Format: The KeyContainersFormatType Type">
<t>The OPTIONAL KeyContainersFormatType type is a list of
type-value pairs that a DSKPP client or server MAY use to define
key container formats it supports. Key container formats are
identified through URIs, e.g., the PSKC KeyContainer URI
"urn:ietf:params:xml:schema:keyprov:container#KeyContainer" (see
<xref target="PSKC"></xref>).</t>
</section>
<section anchor="Section-AuthNData"
title="Selecting a Client and Server Authentication Mechanism: The AuthenticationDataType Type">
<t>The OPTIONAL AuthenticationDataType type is used by DSKPP
clients and server to carry authentication values in DSKPP
messages. The element MAY contain a device certificate or MAC
derived from an authentication code as follows:<list
style="format %c.">
<t>A DSKPP client MAY include a one-time use
AuthenticationCode that was given by the issuer to the user
for acquiring a symmetric key. An AuthenticationCode MAY or
MAY NOT contain alphanumeric characters in addition to numeric
digits depending on the device type and policy of the issuer.
For example, if the device is a mobile phone, a code that the
user enters on the keypad would typically be restricted to
numeric digits for ease of use. An authentication code MAY be
sent to the DSKPP server as MAC data calculated according to
section <xref target="Section-AuthCode"></xref>.</t>
<t>A DSKPP client MAY contain Authentication Data consisting
of signed data of client Nonce with a client certificate's
private key. A service provider may have a policy to issue
symmetric keys for a device only if it has a trusted device
certificate. An authentication code isn't required in this
case.</t>
<t>A DSKPP server MAY use the AuthenticationDataType element
AuthenticationCodeMac to carry a MAC for authenticating itself
to the client. For example, when a successful 1- or 2-pass
DSKPP protocol run will result in an existing key being
replaced, then the DSKPP server MUST include a MAC proving to
the DSKPP client that the server knows the value of the key it
is about to replace.</t>
</list></t>
<t>The element of the AuthenticationDataType type have the
following meaning:<list style="symbols">
<t><ClientID>: A requester's identifier. The value MAY
be a user ID, a device ID, or a keyID associated with the
requester's authentication value. When the authentication data
is based on a certificate, <ClientID> can be omitted, as
the certificate itself is typically sufficient to identify the
requester. Also, if a <KeyProvTrigger> message was
provided by the server to initiate the DSKPP protocol run,
<ClientID> can be omitted, as the DeviceID, KeyID,
and/or nonce provided in the <InitializationTriggerType>
element ought to be sufficient to identify the requester.</t>
<t><AuthenticationCodeMac>: An authentication MAC and
OPTIONAL additional information (e.g., MAC algorithm). The
value could be a one-time use value sent as a MAC value to the
DSKPP server; or, it could be a MAC value sent to the DSKPP
client. Refer to section <xref
target="Section-AuthCode"></xref> for calculation of MAC with
an authentication code.</t>
<t><DigitalSignature>: Client nonce R_C signed using the
device certificate and sent in KeyProvClientHello for two-pass
protocol or in KeyProvClientNonce for four-pass protocol.</t>
</list></t>
</section>
</section>
<section title="Components of the <KeyProvServerHello> Response">
<t>This message is the first message sent from the DSKPP server to
the DSKPP client (assuming a trigger message has not been sent to
initiate the protocol, in which case, this message is the second
message sent from the DSKPP server to the DSKPP client). It is sent
upon reception of a <KeyProvClientHello> message. The
components of this message have the following meaning:</t>
<t><list style="symbols">
<t>Version: (attribute inherited from the AbstractResponseType
type) The version selected by the DSKPP server. MAY be lower
than the version indicated by the DSKPP client, in which case,
local policy at the client MUST determine whether or not to
continue the session.</t>
<t>SessionID: (attribute inherited from the AbstractResponseType
type) An identifier for this session.</t>
<t>Status: (attribute inherited from the AbstractResponseType
type) Return code for the <KeyProvClientHello>. If Status
is not "Continue", only the Status and Version attributes will
be present; otherwise, all the other element MUST be present as
well.</t>
<t><KeyType>: The type of the key to be generated.</t>
<t><EncryptionAlgorithm>: The encryption algorithm to use
when protecting R_C.</t>
<t><MacAlgorithm>: The MAC algorithm to be used by the
DSKPP server.</t>
<t><EncryptionKey>: Information about the key to use when
encrypting R_C. It will either be the server's public key (the
<ds:KeyValue> alternative of ds:KeyInfoType) or an
identifier for a shared secret key (the <ds:KeyName>
alternative of ds:KeyInfoType).</t>
<t><KeyContainerFormat>: The key container format type to
be used by the DSKPP server. The default setting relies on the
KeyContainerType element defined in
"urn:ietf:params:xml:schema:keyprov:container" <xref
target="PSKC"></xref>.</t>
<t><Payload>: The actual payload. For this version of the
protocol, only one payload is defined: the pseudorandom string
R_S.</t>
<t><Extensions>: A list of server extensions. Two
extensions are defined for this message in this version of
DSKPP: the ClientInfoType and the ServerInfoType (see <xref
target="Section-ProtocolExts"></xref>).</t>
<t><Mac>: The MAC MUST be present if the DSKPP run will
result in the replacement of an existing symmetric key with a
new one (i.e., if the <KeyID> element was present in the
<ClientHello message). In this case, the DSKPP server MUST
prove to the cryptographic module that it is authorized to
replace it.</t>
</list><list>
<t>The DSKPP client MUST verify the MAC if the successful
execution of the protocol will result in the replacement of an
existing symmetric key with a newly generated one. The DSKPP
client MUST terminate the DSKPP session if the MAC does not
verify, and MUST delete any nonces, keys, and/or secrets
associated with the failed run of the DSKPP protocol.</t>
<t>The MacType's MacAlgorithm attribute MUST, when present,
identify the negotiated MAC algorithm.</t>
</list></t>
</section>
</section>
<section title="Round-Trip #2: <KeyProvClientNonce> and <KeyProvServerFinished>">
<t></t>
<section title="Examples">
<t></t>
<section title="Example Using Default Encryption">
<t>This message contains the nonce chosen by the cryptographic
module, R_C, encrypted by the specified encryption key and
encryption algorithm.</t>
<figure>
<preamble></preamble>
<artwork><![CDATA[<?xml version="1.0" encoding="UTF-8"?>
<dskpp:KeyProvClientNonce Version="1.0" SessionID="4114"
xmlns:dskpp="urn:ietf:params:xml:ns:keyprov:1.0:protocol"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="urn:ietf:params:xml:ns:keyprov:1.0:protocol
keyprov-dskpp-1.0.xsd">
<EncryptedNonce>VXENc+Um/9/NvmYKiHDLaErK0gk=</EncryptedNonce>
<AuthenticationData>
<ClientID>31300257</ClientID>
<AuthenticationCodeMac>
<IterationCount>512</IterationCount>
<Mac>4bRJf9xXd3KchKoTenHJiw==</Mac>
</AuthenticationCodeMac>
</AuthenticationData>
</dskpp:KeyProvClientNonce>]]></artwork>
<postamble></postamble>
</figure>
<figure>
<preamble></preamble>
<artwork><![CDATA[<?xml version="1.0" encoding="UTF-8"?>
<dskpp:KeyProvServerFinished Version="1.0" SessionID="4114" Status="Success"
xmlns:dskpp="urn:ietf:params:xml:ns:keyprov:1.0:protocol"
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:1.0:container"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="urn:ietf:params:xml:ns:keyprov:1.0:protocol
keyprov-dskpp-1.0.xsd">
<KeyContainer>
<KeyContainer Version="1.0">
<pskc:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#hmac-sha1"/>
<pskc:Device>
<pskc:Key
KeyAlgorithm=
"http://www.rsa.com/rsalabs/otps/schemas/2005/09/otps-wst#SecurID-AES"
KeyId="XL0000000001234">
<pskc:Issuer>CredentialIssuer</pskc:Issuer>
<pskc:Usage otp="true">
<pskc:ResponseFormat format="DECIMAL" length="6"/>
</pskc:Usage>
<pskc:FriendlyName>MyFirstToken</pskc:FriendlyName>
<pskc:Data Name="TIME">
<pskc:Value>AAAAADuaygA=</pskc:Value>
</pskc:Data>
<pskc:Expiry>10/30/2012</pskc:Expiry>
</pskc:Key>
</pskc:Device>
</KeyContainer>
</KeyContainer>
<Mac
MacAlgorithm="urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes">
miidfasde312asder394jw==
</Mac>
</dskpp:KeyProvServerFinished>]]></artwork>
<postamble></postamble>
</figure>
</section>
</section>
<section title="Components of a <KeyProvClientNonce> Request">
<t>The components of this message have the following meaning:</t>
<t><list style="symbols">
<t>Version: (inherited from the AbstractRequestType type) MUST
be the same version as in the <KeyProvServerHello>
message.</t>
<t><SessionID>: MUST have the same value as the SessionID
attribute in the received <KeyProvServerHello>
message.</t>
<t><EncryptedNonce>: The nonce generated and encrypted by
the cryptographic module. The encryption MUST be made using the
selected encryption algorithm and identified key, and as
specified in <xref target="DSKPP-PRF"></xref>.</t>
<t><AuthenticationData>: The authentication data value
MUST be set as specified in <xref
target="Section-ClientAuthN"></xref> and <xref
target="Section-AuthNData"></xref>.</t>
<t><Extensions>: A list of extensions. Two extensions are
defined for this message in this version of DSKPP: the
ClientInfoType and the ServerInfoType (see <xref
target="Section-ProtocolExts"></xref>)</t>
</list></t>
</section>
<section title="Components of a <KeyProvServerFinished> Response">
<t>This message is the last message of the DSKPP protocol run. In a
4-pass exchange, the DSKPP server sends this message in response to
a <KeyProvClientNonce> message, whereas in a 2-pass exchange,
the DSKPP server sends this message in response to a
<KeyProvClientHello> message. In a 1-pass exchange, the DSKPP
server sends only this message to the client. The components of this
message have the following meaning:</t>
<t><list style="symbols">
<t>Version: (inherited from the AbstractResponseType type) The
DSKPP version used in this session.</t>
<t>SessionID: (inherited from the AbstractResponseType type) The
previously established identifier for this session.</t>
<t>Status: (inherited from the AbstractResponseType type) Return
code for the <KeyProvServerFinished> message. If Status is
not "Success", only the Status, SessionID, and Version
attributes will be present (the presence of the SessionID
attribute is dependent on the type of reported error);
otherwise, all the other elements MUST be present as well. In
this latter case, the <KeyProvServerFinished> message can
be seen as a "Commit" message, instructing the cryptographic
module to store the generated key and associate the given key
identifier with this key.</t>
<t><KeyContainer>: The key container containing symmetric
key values (in the case of a 2- or 1-pass exchange) and
configuration data. The default container format is based on the
KeyContainerType type from PSKC, as defined in <xref
target="PSKC"></xref>.</t>
<t><Extensions>: A list of extensions chosen by the DSKPP
server. For this message, this version of DSKPP defines one
extension, the ClientInfoType (see <xref
target="Section-ProtocolExts"></xref>).</t>
<t><Mac>: To avoid a false "Commit" message causing the
cryptographic module to end up in an initialized state for which
the server does not know the stored key,
<KeyProvServerFinished> messages MUST always be
authenticated with a MAC. The MAC MUST be made using the already
established MAC algorithm.</t>
</list><list style="empty">
<t>When receiving a <KeyProvServerFinished> message with
Status="Success" for which the MAC verifies, the DSKPP client
MUST associate the generated key K_TOKEN with the provided key
identifier and store this data permanently. After this
operation, it MUST NOT be possible to overwrite the key unless
knowledge of an authorizing key is proven through a MAC on a
later <KeyProvServerHello> (and
<KeyProvServerFinished>) message.</t>
<t>The DSKPP client MUST verify the MAC. The DSKPP client MUST
terminate the DSKPP session if the MAC does not verify, and
MUST, in this case, also delete any nonces, keys, and/or secrets
associated with the failed run of the DSKPP protocol.</t>
<t>The MacType's MacAlgorithm attribute MUST, when present,
identify the negotiated MAC algorithm.</t>
</list></t>
</section>
</section>
<section title="DSKPP Server Results: The StatusCode Type">
<t>The StatusCode type enumerates all possible return codes. Upon
transmission or receipt of a message for which the Status attribute's
value is not "Success" or "Continue", the default behavior, unless
explicitly stated otherwise below, is that both the DSKPP server and
the DSKPP client MUST immediately terminate the DSKPP session. DSKPP
servers and DSKPP clients MUST delete any secret values generated as a
result of failed runs of the DSKPP protocol. Session identifiers MAY
be retained from successful or failed protocol runs for replay
detection purposes, but such retained identifiers MUST NOT be reused
for subsequent runs of the protocol.</t>
<t>When possible, the DSKPP client SHOULD present an appropriate error
message to the user.</t>
<t>These status codes are valid in all 4-Pass DSKPP Response messages
unless explicitly stated otherwise:<list style="symbols">
<t>"Continue" indicates that the DSKPP server is ready for a
subsequent request from the DSKPP client. It cannot be sent in the
server's final message.</t>
<t>"Success" indicates successful completion of the DSKPP session.
It can only be sent in the server's final message.</t>
<t>"Abort" indicates that the DSKPP server rejected the DSKPP
client's request for unspecified reasons.</t>
<t>"AccessDenied" indicates that the DSKPP client is not
authorized to contact this DSKPP server.</t>
<t>"MalformedRequest" indicates that the DSKPP server failed to
parse the DSKPP client's request.</t>
<t>"UnknownRequest" indicates that the DSKPP client made a request
that is unknown to the DSKPP server.</t>
<t>"UnknownCriticalExtension" indicates that a critical DSKPP
extension (see below) used by the DSKPP client was not supported
or recognized by the DSKPP server.</t>
<t>"UnsupportedVersion" indicates that the DSKPP client used a
DSKPP protocol version not supported by the DSKPP server. This
error is only valid in the DSKPP server's first response
message.</t>
<t>"NoSupportedKeyTypes" indicates that the DSKPP client only
suggested key types that are not supported by the DSKPP server.
This error is only valid in the DSKPP server's first response
message.</t>
<t>"NoSupportedEncryptionAlgorithms" indicates that the DSKPP
client only suggested encryption algorithms that are not supported
by the DSKPP server. This error is only valid in the DSKPP
server's first response message.</t>
<t>"NoSupportedMacAlgorithms" indicates that the DSKPP client only
suggested MAC algorithms that are not supported by the DSKPP
server. This error is only valid in the DSKPP server's first
response message.</t>
<t>"NoProtocolVariants" indicates that the DSKPP client only
suggested a protocol variant (either 2-pass or 4-pass) that is not
supported by the DSKPP server. This error is only valid in the
DSKPP server's first response messagei</t>
<t>"NoSupportedKeyContainers" indicates that the DSKPP client only
suggested key container formats that are not supported by the
DSKPP server. This error is only valid in the DSKPP server's first
response message.</t>
<t>"AuthenticationDataMissing" indicates that the DSKPP client
didn't provide authentication data that the DSKPP server
required.</t>
<t>"AuthenticationDataInvalid" indicates that the DSKPP client
supplied user or device authentication data that the DSKPP server
failed to validate.</t>
<t>"InitializationFailed" indicates that the DSKPP server could
not generate a valid key given the provided data. When this status
code is received, the DSKPP client SHOULD try to restart DSKPP, as
it is possible that a new run will succeed.</t>
<t>"ProvisioningPeriodExpired" indicates that the provisioning
period set by the DSKPP server has expired. When the status code
is received, the DSKPP client SHOULD report the key initialization
failure reason to the user and the user MUST register with the
DSKPP server to initialize a new key.</t>
</list></t>
</section>
</section>
<section title="Two-Pass Protocol">
<t>In this section, example messages are used to describe parameters,
encoding and semantics in a 2-pass DSKPP exchanges. The examples are
written using XML. While they are syntactically correct, MAC and cipher
values are fictitious.</t>
<section title="XML Basics">
<t>The DSKPP XML schema can be found in <xref
target="Section-Schema"></xref>. Some DSKPP elements rely on the
parties being able to compare received values with stored values.
Unless otherwise noted, all elements in this document that have the
XML Schema "xs:string" type, or a type derived from it, MUST be
compared using an exact binary comparison. In particular, DSKPP
implementations MUST NOT depend on case-insensitive string
comparisons, normalization or trimming of white space, or conversion
of locale-specific formats such as numbers.</t>
<t>Implementations that compare values that are represented using
different character encodings MUST use a comparison method that
returns the same result as converting both values to the Unicode
character encoding, Normalization Form C <xref
target="UNICODE"></xref>, and then performing an exact binary
comparison.</t>
<t>No collation or sorting order for attributes or element values is
defined. Therefore, DSKPP implementations MUST NOT depend on specific
sorting orders for values.</t>
</section>
<section title="Round-Trip #1: <KeyProvClientHello> and <KeyProvServerFinished>">
<t></t>
<section title="Examples">
<t></t>
<section anchor="Example-TwoPass-1"
title="Example Using the Key Transport Profile">
<t>The client indicates support all the Key Transport, Key Wrap,
and Passphrase-Based Key Wrap profiles (see <xref
target="Section-Profiles"></xref>):</t>
<figure>
<preamble></preamble>
<artwork><![CDATA[<?xml version="1.0" encoding="UTF-8"?>
<dskpp:KeyProvClientHello Version="1.0"
xmlns:dskpp="urn:ietf:params:xml:ns:keyprov:1.0:protocol"
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:1.0:container"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:ds="http://www.w3.org/2000/09/xmldsig#"
xsi:schemaLocation="urn:ietf:params:xml:ns:keyprov:1.0:protocol
keyprov-dskpp-1.0.xsd">
<DeviceIdentifierData>
<DeviceId>
<pskc:Manufacturer>ManufacturerABC</pskc:Manufacturer>
<pskc:SerialNo>XL0000000001234</pskc:SerialNo>
<pskc:Model>U2</pskc:Model>
</DeviceId>
</DeviceIdentifierData>
<ClientNonce>xwQzwEl0CjPAiQeDxwRJdQ==</ClientNonce>
<SupportedKeyTypes>
<Algorithm>urn:ietf:params:xml:schema:keyprov:otpalg#HOTP</Algorithm>
<Algorithm>
http://www.rsa.com/rsalabs/otps/schemas/2005/09/otps-wst#SecurID-AES
</Algorithm>
</SupportedKeyTypes>
<SupportedEncryptionAlgorithms>
<Algorithm>http://www.w3.org/2001/05/xmlenc#rsa_1_5</Algorithm>
<Algorithm>http://www.w3.org/2001/04/xmlenc#kw-aes128</Algorithm>
<Algorithm>urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes</Algorithm>
</SupportedEncryptionAlgorithms>
<SupportedMacAlgorithms>
<Algorithm>urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes</Algorithm>
</SupportedMacAlgorithms>
<SupportedProtocolVariants>
<TwoPass>
<SupportedKeyInitializationMethod>
urn:ietf:params:xml:schema:keyprov:protocol#wrap
</SupportedKeyInitializationMethod>
<Payload xsi:type="ds:KeyInfoType">
<ds:KeyName>Key_001</ds:KeyName>
</Payload>
<SupportedKeyInitializationMethod>
urn:ietf:params:xml:schema:keyprov:protocol#transport
</SupportedKeyInitializationMethod>
<SupportedKeyInitializationMethod>
urn:ietf:params:xml:schema:keyprov:protocol#passphrase-wrap
</SupportedKeyInitializationMethod>
<Payload xsi:type="ds:KeyInfoType">
<ds:X509Data>
<ds:X509Certificate>miib</ds:X509Certificate>
</ds:X509Data>
</Payload>
</TwoPass>
</SupportedProtocolVariants>
<SupportedKeyContainers>
<KeyContainerFormat>
urn:ietf:params:xml:schema:keyprov:container#KeyContainer
</KeyContainerFormat>
</SupportedKeyContainers>
<AuthenticationData>
<DigitalSignature>
<ds:SignedInfo>
<ds:CanonicalizationMethod
Algorithm="http://www.w3.org/TR/2001/REC-xml-c14n-20010315" />
<ds:SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#rsa-sha1"/>
<ds:Reference URI="#Nonce">
<ds:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/>
<ds:DigestValue></ds:DigestValue>
</ds:Reference>
</ds:SignedInfo>
<ds:SignatureValue></ds:SignatureValue>
<ds:KeyInfo>
<ds:X509Data>
<ds:X509Certificate>miib</ds:X509Certificate>
</ds:X509Data>
</ds:KeyInfo>
<ds:Object Id="Nonce">xwQzwEl0CjPAiQeDxwRJdQ==</ds:Object>
</DigitalSignature>
</AuthenticationData>
</dskpp:KeyProvClientHello>]]></artwork>
<postamble></postamble>
</figure>
<t>In this example, the server responds to the previous request
using the key transport profile.</t>
<figure>
<preamble></preamble>
<artwork><![CDATA[<?xml version="1.0" encoding="UTF-8"?>
<dskpp:KeyProvServerFinished Version="1.0" SessionID="4114" Status="Success"
xmlns:dskpp="urn:ietf:params:xml:ns:keyprov:1.0:protocol"
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:1.0:container"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:ds="http://www.w3.org/2000/09/xmldsig#"
xmlns:xenc="http://www.w3.org/2001/04/xmlenc#"
xsi:schemaLocation="urn:ietf:params:xml:ns:keyprov:1.0:protocol
keyprov-dskpp-1.0.xsd">
<KeyContainer>
<KeyContainer Version="1.0">
<pskc:EncryptionMethod
Algorithm="http://www.w3.org/2001/05/xmlenc#rsa_1_5">
<pskc:KeyInfo>
<ds:X509Data>
<ds:X509Certificate>miib</ds:X509Certificate>
</ds:X509Data>
</pskc:KeyInfo>
</pskc:EncryptionMethod>
<pskc:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#hmac-sha1"/>
<Device xmlns="urn:ietf:params:xml:ns:keyprov:1.0:container">
<Key KeyAlgorithm="urn:ietf:params:xml:schema:keyprov:otpalg#HOTP"
KeyId="SDU312345678">
<Issuer>CredentialIssuer</Issuer>
<Usage otp="true">
<ResponseFormat format="DECIMAL" length="6"/>
</Usage>
<FriendlyName>MyFirstToken</FriendlyName>
<Data Name="SECRET">
<Value>
7JHUyp3azOkqJENSsh6b2vxXzwGBYypzJxEr+ikQAa229KV/BgZhGA==
</Value>
<ValueDigest>
i8j+kpbfKQsSlwmJYS99lQ==
</ValueDigest>
</Data>
<Data Name="COUNTER">
<Value>AAAAAAAAAAA=</Value>
</Data>
<Expiry>10/30/2012</Expiry>
</Key>
</Device>
</KeyContainer>
</KeyContainer>
<Mac
MacAlgorithm="urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes">
miidfasde312asder394jw==
</Mac>
<AuthenticationData>
<AuthenticationCodeMac>
<Mac>4bRJf9xXd3KchKoTenHJiw==</Mac>
</AuthenticationCodeMac>
</AuthenticationData>
</dskpp:KeyProvServerFinished>]]></artwork>
<postamble></postamble>
</figure>
</section>
<section title="Example Using the Key Wrap Profile">
<t>The client sends a request that specifies a shared key to
protect the K_TOKEN, and the server responds using the Key Wrap
Profile. Authentication data in this example is basing on an
authentication code rather than a device certificate.</t>
<figure>
<preamble></preamble>
<artwork><![CDATA[<?xml version="1.0" encoding="UTF-8"?>
<dskpp:KeyProvClientHello Version="1.0"
xmlns:dskpp="urn:ietf:params:xml:ns:keyprov:1.0:protocol"
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:1.0:container"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:ds="http://www.w3.org/2000/09/xmldsig#"
xmlns:pkcs-5="http://www.rsasecurity.com/rsalabs/pkcs/schemas/pkcs-5v2-0#"
xsi:schemaLocation="urn:ietf:params:xml:ns:keyprov:1.0:protocol
keyprov-dskpp-1.0.xsd">
<DeviceIdentifierData>
<DeviceId>
<pskc:Manufacturer>ManufacturerABC</pskc:Manufacturer>
<pskc:SerialNo>XL0000000001234</pskc:SerialNo>
<pskc:Model>U2</pskc:Model>
</DeviceId>
</DeviceIdentifierData>
<ClientNonce>xwQzwEl0CjPAiQeDxwRJdQ==</ClientNonce>
<SupportedKeyTypes>
<Algorithm>urn:ietf:params:xml:schema:keyprov:otpalg#HOTP</Algorithm>
<Algorithm>
http://www.rsa.com/rsalabs/otps/schemas/2005/09/otps-wst#SecurID-AES
</Algorithm>
</SupportedKeyTypes>
<SupportedEncryptionAlgorithms>
<Algorithm>http://www.w3.org/2001/05/xmlenc#rsa_1_5</Algorithm>
<Algorithm>http://www.w3.org/2001/04/xmlenc#kw-aes128</Algorithm>
<Algorithm>
http://www.rsasecurity.com/rsalabs/pkcs/schemas/pkcs-5#pbes2
</Algorithm>
<Algorithm>
urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes
</Algorithm>
</SupportedEncryptionAlgorithms>
<SupportedMacAlgorithms>
<Algorithm>
urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes
</Algorithm>
</SupportedMacAlgorithms>
<SupportedProtocolVariants>
<TwoPass>
<SupportedKeyInitializationMethod>
urn:ietf:params:xml:schema:keyprov:protocol#wrap
</SupportedKeyInitializationMethod>
<Payload xsi:type="ds:KeyInfoType">
<ds:KeyName>Key_001</ds:KeyName>
</Payload>
</TwoPass>
</SupportedProtocolVariants>
<SupportedKeyContainers>
<KeyContainerFormat>
urn:ietf:params:xml:schema:keyprov:container#KeyContainer
</KeyContainerFormat>
</SupportedKeyContainers>
<AuthenticationData>
<ClientID>31300257</ClientID>
<AuthenticationCodeMac>
<IterationCount>512</IterationCount>
<Mac>4bRJf9xXd3KchKoTenHJiw==</Mac>
</AuthenticationCodeMac>
</AuthenticationData>
</dskpp:KeyProvClientHello>]]></artwork>
<postamble></postamble>
</figure>
<t>In this example, the server responds to the previous request
using the key wrap profile.</t>
<figure>
<preamble></preamble>
<artwork><![CDATA[<?xml version="1.0" encoding="UTF-8"?>
<dskpp:KeyProvServerFinished Version="1.0" Status="Success"
xmlns:dskpp="urn:ietf:params:xml:ns:keyprov:1.0:protocol"
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:1.0:container"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:ds="http://www.w3.org/2000/09/xmldsig#"
xmlns:xenc="http://www.w3.org/2001/04/xmlenc#"
xsi:schemaLocation="urn:ietf:params:xml:ns:keyprov:1.0:protocol
keyprov-dskpp-1.0.xsd">
<KeyContainer>
<ServerID>https://www.somedskppservice.com/</ServerID>
<KeyContainer Version="1.0">
<EncryptionMethod Algorithm="http://www.w3.org/2001/04/xmlenc#kw-aes128"
xmlns="urn:ietf:params:xml:ns:keyprov:1.0:container">
<KeyInfo>
<ds:KeyName>Key-001</ds:KeyName>
</KeyInfo>
</EncryptionMethod>
<pskc:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#hmac-sha1"/>
<Device xmlns="urn:ietf:params:xml:ns:keyprov:1.0:container">
<Key KeyAlgorithm="urn:ietf:params:xml:schema:keyprov:otpalg#HOTP"
KeyId="SDU312345678">
<Issuer>CredentialIssuer</Issuer>
<Usage otp="true">
<ResponseFormat format="DECIMAL" length="6"/>
</Usage>
<FriendlyName>MyFirstToken</FriendlyName>
<Data Name="SECRET">
<Value>
JSPUyp3azOkqJENSsh6b2hdXz1WBYypzJxEr+ikQAa22M6V/BgZhRg==
</Value>
<ValueDigest>
i8j+kpbfKQsSlwmJYS99lQ==
</ValueDigest>
</Data>
<Data Name="COUNTER">
<Value>AAAAAAAAAAA=</Value>
</Data>
<Expiry>10/30/2012</Expiry>
</Key>
</Device>
</KeyContainer>
</KeyContainer>
<Mac MacAlgorithm="urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes">
miidfasde312asder394jw==
</Mac>
<AuthenticationData>
<AuthenticationCodeMac>
<Mac>4bRJf9xXd3KchKoTenHJiw==</Mac>
</AuthenticationCodeMac>
</AuthenticationData>
</dskpp:KeyProvServerFinished>]]></artwork>
<postamble></postamble>
</figure>
</section>
<section title="Example Using the Passphrase-Based Key Wrap Profile">
<t>The client sends a request similar to that in <xref
target="Example-TwoPass-1"></xref> with authentication data basing
on an authentication code, and the server responds using the
Passphrase-Based Key Wrap Profile. The authentication data is set
in clear text when it is sent over a secure transport channel such
as TLS.</t>
<figure>
<preamble></preamble>
<artwork><![CDATA[<?xml version="1.0" encoding="UTF-8"?>
<dskpp:KeyProvClientHello Version="1.0"
xmlns:dskpp="urn:ietf:params:xml:ns:keyprov:1.0:protocol"
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:1.0:container"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:ds="http://www.w3.org/2000/09/xmldsig#"
xmlns:pkcs-5="http://www.rsasecurity.com/rsalabs/pkcs/schemas/pkcs-5v2-0#"
xsi:schemaLocation="urn:ietf:params:xml:ns:keyprov:1.0:protocol
keyprov-dskpp-1.0.xsd">
<DeviceIdentifierData>
<DeviceId>
<pskc:Manufacturer>ManufacturerABC</pskc:Manufacturer>
<pskc:SerialNo>XL0000000001234</pskc:SerialNo>
<pskc:Model>U2</pskc:Model>
</DeviceId>
</DeviceIdentifierData>
<ClientNonce>xwQzwEl0CjPAiQeDxwRJdQ==</ClientNonce>
<SupportedKeyTypes>
<Algorithm>urn:ietf:params:xml:schema:keyprov:otpalg#HOTP</Algorithm>
<Algorithm>
http://www.rsa.com/rsalabs/otps/schemas/2005/09/otps-wst#SecurID-AES
</Algorithm>
</SupportedKeyTypes>
<SupportedEncryptionAlgorithms>
<Algorithm>http://www.w3.org/2001/05/xmlenc#rsa_1_5</Algorithm>
<Algorithm>http://www.w3.org/2001/04/xmlenc#kw-aes128</Algorithm>
<Algorithm>
http://www.rsasecurity.com/rsalabs/pkcs/schemas/pkcs-5#pbes2
</Algorithm>
<Algorithm>
urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes
</Algorithm>
</SupportedEncryptionAlgorithms>
<SupportedMacAlgorithms>
<Algorithm>
urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes
</Algorithm>
</SupportedMacAlgorithms>
<SupportedProtocolVariants>
<TwoPass>
<SupportedKeyInitializationMethod>
urn:ietf:params:xml:schema:keyprov:protocol#wrap
</SupportedKeyInitializationMethod>
<Payload xsi:type="ds:KeyInfoType">
<ds:KeyName>Key_001</ds:KeyName>
</Payload>
<SupportedKeyInitializationMethod>
urn:ietf:params:xml:schema:keyprov:protocol#passphrase-wrap
</SupportedKeyInitializationMethod>
</TwoPass>
</SupportedProtocolVariants>
<SupportedKeyContainers>
<KeyContainerFormat>
urn:ietf:params:xml:schema:keyprov:container#KeyContainer
</KeyContainerFormat>
</SupportedKeyContainers>
<AuthenticationData>
<ClientID>31300257</ClientID>
<AuthenticationCodeMac>
<IterationCount>512</IterationCount>
<Mac>4bRJf9xXd3KchKoTenHJiw==</Mac>
</AuthenticationCodeMac>
</AuthenticationData>
</dskpp:KeyProvClientHello>]]></artwork>
<postamble></postamble>
</figure>
<t>In this example, the server responds to the previous request
using the Passphrase-Based Key Wrap Profile.</t>
<figure>
<preamble></preamble>
<artwork><![CDATA[<?xml version="1.0" encoding="UTF-8"?>
<dskpp:KeyProvServerFinished Version="1.0" SessionID="4114" Status="Success"
xmlns:dskpp="urn:ietf:params:xml:ns:keyprov:1.0:protocol"
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:1.0:container"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:ds="http://www.w3.org/2000/09/xmldsig#"
xmlns:xenc="http://www.w3.org/2001/04/xmlenc#"
xsi:schemaLocation="urn:ietf:params:xml:ns:keyprov:1.0:protocol
keyprov-dskpp-1.0.xsd">
<KeyContainer>
<KeyContainer Version="1.0">
<EncryptionMethod
Algorithm="http://www.rsasecurity.com/rsalabs/pkcs/schemas/pkcs-5#pbes2"
xmlns="urn:ietf:params:xml:ns:keyprov:1.0:container">
<PBEEncryptionParam
EncryptionAlgorithm="http://www.w3.org/2001/04/xmlenc#kw-aes128-cbc">
<PBESalt>y6TzckeLRQw=</PBESalt>
<PBEIterationCount>1024</PBEIterationCount>
</PBEEncryptionParam>
<IV>c2FtcGxlaXY=</IV>
</EncryptionMethod>
<pskc:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#hmac-sha1"/>
<Device xmlns="urn:ietf:params:xml:ns:keyprov:1.0:container">
<Key KeyAlgorithm="urn:ietf:params:xml:schema:keyprov:otpalg#HOTP"
KeyId="SDU312345678">
<Issuer>CredentialIssuer</Issuer>
<Usage otp="true">
<ResponseFormat format="DECIMAL" length="6"/>
</Usage>
<FriendlyName>MyFirstToken</FriendlyName>
<Data Name="SECRET">
<Value>
JSPUyp3azOkqJENSsh6b2hdXz1WBYypzJxEr+ikQAa22M6V/BgZhRg==
</Value>
<ValueDigest>
i8j+kpbfKQsSlwmJYS99lQ==
</ValueDigest>
</Data>
<Data Name="COUNTER">
<Value>AAAAAAAAAAA=</Value>
</Data>
<Expiry>10/30/2012</Expiry>
</Key>
</Device>
</KeyContainer>
</KeyContainer>
<Mac MacAlgorithm="urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes">
miidfasde312asder394jw==
</Mac>
<AuthenticationData>
<AuthenticationCodeMac>
<Mac>4bRJf9xXd3KchKoTenHJiw==</Mac>
</AuthenticationCodeMac>
</AuthenticationData>
</dskpp:KeyProvServerFinished>]]></artwork>
<postamble></postamble>
</figure>
</section>
</section>
<section title="Components of the <KeyProvClientHello> Request">
<t>The components of this message have the following meaning:<list
style="symbols">
<t>Version: (attribute inherited from the AbstractRequestType
type) The highest version of this protocol the client supports.
Only version one ("1.0") is currently specified.</t>
<t><DeviceIdentifierData>: An identifier for the
cryptographic module as defined in <xref
target="Section-ClientAuthN"></xref> above. The identifier MUST
only be present if such shared secrets exist or if the
identifier was provided by the server in a
<KeyProvTrigger> element (see <xref
target="Section-InitDSKPP"></xref> below). In the latter case,
it MUST have the same value as the identifier provided in that
element.</t>
<t><KeyID>: An identifier for the key that will be
overwritten if the protocol run is successful. The identifier
MUST only be present if the key exists or the identifier was
provided by the server in a <KeyProvTrigger> element (see
<xref target="Section-InitDSKPP"></xref> below). In the latter
case, it MUST have the same value as the identifier provided in
that element.</t>
<t><KeyProvClientNonce>: This is the nonce R, which, when
present, MUST be used by the server when calculating MAC values
(see below). It is RECOMMENDED that clients include this element
whenever the <KeyID> element is present.</t>
<t><TriggerNonce>: This OPTIONAL element MUST be present
if and only if the DSKPP run was initialized with a
<KeyProvTrigger> message (see <xref
target="Section-InitDSKPP"></xref> below), and MUST, in that
case, have the same value as the <TriggerNonce> child of
that message. A server using nonces in this way MUST verify that
the nonce is valid and that any device or key identifier values
provided in the <KeyProvTrigger> message match the
corresponding identifier values in the
<KeyProvClientHello> message.</t>
<t><SupportedKeyTypes>: A sequence of URIs indicating the
key types for which the cryptographic module is willing to
generate keys through DSKPP.</t>
<t><SupportedEncryptionAlgorithms>: A sequence of URIs
indicating the encryption algorithms supported by the
cryptographic module for the purposes of DSKPP. The DSKPP client
MAY indicate the same algorithm both as a supported key type and
as an encryption algorithm.</t>
<t><SupportedMacAlgorithms>: A sequence of URIs indicating
the MAC algorithms supported by the cryptographic module for the
purposes of DSKPP. The DSKPP client MAY indicate the same
algorithm both as an encryption algorithm and as a MAC algorithm
(e.g., urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes
defined in <xref target="Section-PRFRealizations"></xref>).</t>
<t><SupportedProtocolVariants>: This OPTIONAL element is
used by the DSKPP client to indicate support for four-pass or
two-pass DSKPP. If two-pass support is specified, then
<KeyProvClientNonce> MUST be set to nonce R in the
<KeyProvClientHello> message unless <TriggerNonce>
is already present.</t>
<t><SupportedKeyContainers>: This OPTIONAL element is a
sequence of URIs indicating the key container formats supported
by the DSKPP client. If this element is not provided, then the
DSKPP server MUST proceed with
"urn:ietf:params:xml:schema:keyprov:container#KeyContainer" (see
<xref target="PSKC"></xref>.</t>
<t><AuthenticationData>: This OPTIONAL element contains
data that the DSKPP client uses to authenticate the user or
device to the DSKPP server. The element is set as specified in
<xref target="Section-ClientAuthN"></xref>.</t>
<t><Extensions>: A sequence of extensions. One extension
is defined for this message in this version of DSKPP: the
ClientInfoType (see <xref
target="Section-ProtocolExts"></xref>).</t>
</list></t>
</section>
<section title="Components of a <KeyProvServerFinished> Response">
<t>This message is the last message of the DSKPP protocol run. In a
4-pass exchange, the DSKPP server sends this message in response to
a <KeyProvClientNonce> message, whereas in a 2-pass exchange,
the DSKPP server sends this message in response to a
<KeyProvClientHello> message. In a 1-pass exchange, the DSKPP
server sends only this message to the client. The components of this
message have the following meaning:</t>
<t><list style="symbols">
<t>Version: (inherited from the AbstractResponseType type) The
DSKPP version used in this session.</t>
<t>SessionID: (inherited from the AbstractResponseType type) The
previously established identifier for this session.</t>
<t>Status: (inherited from the AbstractResponseType type) Return
code for the <KeyProvServerFinished> message. If Status is
not "Success", only the Status, SessionID, and Version
attributes will be present (the presence of the SessionID
attribute is dependent on the type of reported error);
otherwise, all the other elements MUST be present as well. In
this latter case, the <KeyProvServerFinished> message can
be seen as a "Commit" message, instructing the cryptographic
module to store the generated key and associate the given key
identifier with this key.</t>
<t><KeyContainer>: The key container containing symmetric
key values (in the case of a 2- or 1-pass exchange) and
configuration data. The default container format is based on the
KeyContainerType type from PSKC, as defined in <xref
target="PSKC"></xref>.</t>
<t><Extensions>: A list of extensions chosen by the DSKPP
server. For this message, this version of DSKPP defines one
extension, the ClientInfoType (see <xref
target="Section-ProtocolExts"></xref>).</t>
<t><Mac>: To avoid a false "Commit" message causing the
cryptographic module to end up in an initialized state for which
the server does not know the stored key,
<KeyProvServerFinished> messages MUST always be
authenticated with a MAC. The MAC MUST be made using the already
established MAC algorithm.</t>
<t><AuthenticationData>: This OPTIONAL element contains
data that allows the DSKPP client to authenticate the DSKPP
server. The MAC value is calculated with K_MAC' as specified in
<xref target="Subsecton-TwoPass-ServerAuth"></xref>.</t>
</list><list style="empty">
<t>When receiving a <KeyProvServerFinished> message with
Status="Success" for which the MAC verifies, the DSKPP client
MUST associate the generated key K_TOKEN with the provided key
identifier and store this data permanently. After this
operation, it MUST not be possible to overwrite the key unless
knowledge of an authorizing key is proven through a MAC on a
later <KeyProvServerHello> (and
<KeyProvServerFinished>) message.</t>
<t>The DSKPP client MUST verify the MAC. The DSKPP client MUST
terminate the DSKPP session if the MAC does not verify, and
MUST, in this case, also delete any nonces, keys, and/or secrets
associated with the failed run of the DSKPP protocol.</t>
<t>The MacType's MacAlgorithm attribute MUST, when present,
identify the negotiated MAC algorithm.</t>
</list></t>
</section>
</section>
<section title="DSKPP Server Results: The StatusCode Type">
<t>The StatusCode type enumerates all possible return codes. Upon
transmission or receipt of a message for which the Status attribute's
value is not "Success" or "Continue", the default behavior, unless
explicitly stated otherwise below, is that both the DSKPP server and
the DSKPP client MUST immediately terminate the DSKPP session. DSKPP
servers and DSKPP clients MUST delete any secret values generated as a
result of failed runs of the DSKPP protocol. Session identifiers MAY
be retained from successful or failed protocol runs for replay
detection purposes, but such retained identifiers MUST not be reused
for subsequent runs of the protocol.</t>
<t>When possible, the DSKPP client SHOULD present an appropriate error
message to the user.</t>
<t>These status codes are valid in all DSKPP Response messages unless
explicitly stated otherwise:<list style="symbols">
<t>"Continue" indicates that the DSKPP server is ready for a
subsequent request from the DSKPP client. It cannot be sent in the
server's final message.</t>
<t>"Success" indicates successful completion of the DSKPP session.
It can only be sent in the server's final message.</t>
<t>"Abort" indicates that the DSKPP server rejected the DSKPP
client's request for unspecified reasons.</t>
<t>"AccessDenied" indicates that the DSKPP client is not
authorized to contact this DSKPP server.</t>
<t>"MalformedRequest" indicates that the DSKPP server failed to
parse the DSKPP client's request.</t>
<t>"UnknownRequest" indicates that the DSKPP client made a request
that is unknown to the DSKPP server.</t>
<t>"UnknownCriticalExtension" indicates that a critical DSKPP
extension (see below) used by the DSKPP client was not supported
or recognized by the DSKPP server.</t>
<t>"UnsupportedVersion" indicates that the DSKPP client used a
DSKPP protocol version not supported by the DSKPP server. This
error is only valid in the DSKPP server's first response
message.</t>
<t>"NoSupportedKeyTypes" indicates that the DSKPP client only
suggested key types that are not supported by the DSKPP server.
This error is only valid in the DSKPP server's first response
message.</t>
<t>"NoSupportedEncryptionAlgorithms" indicates that the DSKPP
client only suggested encryption algorithms that are not supported
by the DSKPP server. This error is only valid in the DSKPP
server's first response message. Note that the error will only
occur if the DSKPP server does not support any of the DSKPP
client's suggested encryption algorithms.</t>
<t>"NoSupportedMacAlgorithms" indicates that the DSKPP client only
suggested MAC algorithms that are not supported by the DSKPP
server. This error is only valid in the DSKPP server's first
response message. Note that the error will only occur if the DSKPP
server does not support any of the DSKPP client's suggested MAC
algorithms.</t>
<t>"NoProtocolVariants" indicates that the DSKPP client only
suggested a protocol variant (either 2-pass or 4-pass) that is not
supported by the DSKPP server. This error is only valid in the
DSKPP server's first response message. Note that the error will
only occur if the DSKPP server does not support any of the DSKPP
client's suggested protocol variants.</t>
<t>"NoSupportedKeyContainers" indicates that the DSKPP client only
suggested key container formats that are not supported by the
DSKPP server. This error is only valid in the DSKPP server's first
response message. Note that the error will only occur if the DSKPP
server does not support any of the DSKPP client's suggested key
container formats.</t>
<t>"AuthenticationDataMissing" indicates that the DSKPP client
didn't provide authentication data that the DSKPP server
required.</t>
<t>"AuthenticationDataInvalid" indicates that the DSKPP client
supplied user or device authentication data that the DSKPP server
failed to validate.</t>
<t>"InitializationFailed" indicates that the DSKPP server could
not generate a valid key given the provided data. When this status
code is received, the DSKPP client SHOULD try to restart DSKPP, as
it is possible that a new run will succeed.</t>
<t>"ProvisioningPeriodExpired" indicates that the provisioning
period set by the DSKPP server has expired. When the status code
is received, the DSKPP client SHOULD report the key initialization
failure reason to the user and the user MUST register with the
DSKPP server to initialize a new key.</t>
</list></t>
</section>
</section>
<section title="One-Pass Protocol">
<t>In this section, example messages are used to describe parameters,
encoding and semantics in a 1-pass DSKPP protocol. The examples are
written using XML. While they are syntactically correct, MAC and cipher
values are fictitious.</t>
<section title="XML Basics">
<t>The DSKPP XML schema can be found in <xref
target="Section-Schema"></xref>. Some DSKPP elements rely on the
parties being able to compare received values with stored values.
Unless otherwise noted, all elements in this document that have the
XML Schema "xs:string" type, or a type derived from it, MUST be
compared using an exact binary comparison. In particular, DSKPP
implementations MUST NOT depend on case-insensitive string
comparisons, normalization or trimming of white space, or conversion
of locale-specific formats such as numbers.</t>
<t>Implementations that compare values that are represented using
different character encodings MUST use a comparison method that
returns the same result as converting both values to the Unicode
character encoding, Normalization Form C <xref
target="UNICODE"></xref>, and then performing an exact binary
comparison.</t>
<t>No collation or sorting order for attributes or element values is
defined. Therefore, DSKPP implementations MUST NOT depend on specific
sorting orders for values.</t>
</section>
<section title="Server to Client Only: <KeyProvServerFinished>">
<t></t>
<section title="Example">
<t>The Server sends a provisioned key to a client with prior
knowledge about the client's capabilities:</t>
<figure>
<preamble></preamble>
<artwork><![CDATA[<?xml version="1.0" encoding="UTF-8"?>
<dskpp:KeyProvServerFinished Version="1.0" SessionID="4114" Status="Success"
xmlns:dskpp="urn:ietf:params:xml:ns:keyprov:1.0:protocol"
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:1.0:container"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:ds="http://www.w3.org/2000/09/xmldsig#"
xmlns:xenc="http://www.w3.org/2001/04/xmlenc#"
xsi:schemaLocation="urn:ietf:params:xml:ns:keyprov:1.0:protocol
keyprov-dskpp-1.0.xsd">
<KeyContainer>
<KeyContainer Version="1.0">
<pskc:EncryptionMethod
Algorithm="http://www.w3.org/2001/05/xmlenc#rsa_1_5">
<pskc:KeyInfo>
<ds:X509Data>
<ds:X509Certificate>miib</ds:X509Certificate>
</ds:X509Data>
</pskc:KeyInfo>
</pskc:EncryptionMethod>
<pskc:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#hmac-sha1"/>
<Device xmlns="urn:ietf:params:xml:ns:keyprov:1.0:container">
<Key KeyAlgorithm="urn:ietf:params:xml:schema:keyprov:otpalg#HOTP"
KeyId="SDU312345678">
<Issuer>CredentialIssuer</Issuer>
<Usage otp="true">
<ResponseFormat format="DECIMAL" length="6"/>
</Usage>
<FriendlyName>MyFirstToken</FriendlyName>
<Data Name="SECRET">
<Value>
7JHUyp3azOkqJENSsh6b2vxXzwGBYypzJxEr+ikQAa229KV/BgZhGA==
</Value>
<ValueDigest>
i8j+kpbfKQsSlwmJYS99lQ==
</ValueDigest>
</Data>
<Data Name="COUNTER">
<Value>AAAAAAAAAAA=</Value>
</Data>
<Expiry>10/30/2009</Expiry>
</Key>
</Device>
</KeyContainer>
</KeyContainer>
<Mac MacAlgorithm="urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes">
miidfasde312asder394jw==
</Mac>
<AuthenticationData>
<AuthenticationCodeMac>
<Mac>4bRJf9xXd3KchKoTenHJiw==</Mac>
</AuthenticationCodeMac>
</AuthenticationData>
</dskpp:KeyProvServerFinished>]]></artwork>
<postamble></postamble>
</figure>
</section>
<section title="Components of a <KeyProvServerFinished> Response">
<t>This message is the last message of the DSKPP protocol run. In a
4-pass exchange, the DSKPP server sends this message in response to
a <KeyProvClientNonce> message, whereas in a 2-pass exchange,
the DSKPP server sends this message in response to a
<KeyProvClientHello> message. In a 1-pass exchange, the DSKPP
server sends only this message to the client. The components of this
message have the following meaning:</t>
<t><list style="symbols">
<t>Version: (inherited from the AbstractResponseType type) The
DSKPP version used in this session.</t>
<t>SessionID: (inherited from the AbstractResponseType type) The
previously established identifier for this session.</t>
<t>Status: (inherited from the AbstractResponseType type) Return
code for the <KeyProvServerFinished> message. If Status is
not "Success", only the Status, SessionID, and Version
attributes will be present (the presence of the SessionID
attribute is dependent on the type of reported error);
otherwise, all the other elements MUST be present as well. In
this latter case, the <KeyProvServerFinished> message can
be seen as a "Commit" message, instructing the cryptographic
module to store the generated key and associate the given key
identifier with this key.</t>
<t><KeyContainer>: The key container containing symmetric
key values (in the case of a 2- or 1-pass exchange) and
configuration data. The default container format is based on the
KeyContainerType type from PSKC, as defined in <xref
target="PSKC"></xref>.</t>
<t><Extensions>: A list of extensions chosen by the DSKPP
server. For this message, this version of DSKPP defines one
extension, the ClientInfoType (see <xref
target="Section-ProtocolExts"></xref>).</t>
<t><Mac>: To avoid a false "Commit" message causing the
cryptographic module to end up in an initialized state for which
the server does not know the stored key,
<KeyProvServerFinished> messages MUST always be
authenticated with a MAC. The MAC MUST be made using the already
established MAC algorithm.</t>
<t><AuthenticationData>: This OPTIONAL element contains
data that allows the DSKPP client to authenticate the DSKPP
server. The MAC value is calculated with K_MAC' as specified in
<xref target="Subsecton-OnePass-ServerAuth"></xref>.</t>
</list><list style="empty">
<t>When receiving a <KeyProvServerFinished> message with
Status="Success" for which the MAC verifies, the DSKPP client
MUST associate the generated key K_TOKEN with the provided key
identifier and store this data permanently. After this
operation, it MUST not be possible to overwrite the key unless
knowledge of an authorizing key is proven through a MAC on a
later <KeyProvServerHello> (and
<KeyProvServerFinished>) message.</t>
<t>The DSKPP client MUST verify the MAC. The DSKPP client MUST
terminate the DSKPP session if the MAC does not verify, and
MUST, in this case, also delete any nonces, keys, and/or secrets
associated with the failed run of the DSKPP protocol.</t>
<t>The MacType's MacAlgorithm attribute MUST, when present,
identify the negotiated MAC algorithm.</t>
</list></t>
</section>
</section>
</section>
<section anchor="Section-Trigger" title="Trigger">
<t>In this section, an example is used to describe parameters, encoding
and semantics in a DSKPP Trigger message. The example is written using
XML.</t>
<section title="XML Basics">
<t>The DSKPP XML schema can be found in <xref
target="Section-Schema"></xref>. Some DSKPP elements rely on the
parties being able to compare received values with stored values.
Unless otherwise noted, all elements in this document that have the
XML Schema "xs:string" type, or a type derived from it, MUST be
compared using an exact binary comparison. In particular, DSKPP
implementations MUST NOT depend on case-insensitive string
comparisons, normalization or trimming of white space, or conversion
of locale-specific formats such as numbers.</t>
<t>Implementations that compare values that are represented using
different character encodings MUST use a comparison method that
returns the same result as converting both values to the Unicode
character encoding, Normalization Form C <xref
target="UNICODE"></xref>, and then performing an exact binary
comparison.</t>
<t>No collation or sorting order for attributes or element values is
defined. Therefore, DSKPP implementations MUST NOT depend on specific
sorting orders for values.</t>
</section>
<section title="Example">
<t></t>
<figure>
<preamble></preamble>
<artwork><![CDATA[
<dskpp:KeyProvTrigger Version="1.0"
xmlns:dskpp="urn:ietf:params:xml:ns:keyprov:1.0:protocol"
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:1.0:container"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="urn:ietf:params:xml:ns:keyprov:1.0:protocol
keyprov-dskpp-1.0.xsd">
<InitializationTrigger>
<DeviceIdentifierData>
<DeviceId>
<pskc:Manufacturer>ManufacturerABC</pskc:Manufacturer>
<pskc:SerialNo>XL0000000001234</pskc:SerialNo>
<pskc:Model>U2</pskc:Model>
</DeviceId>
</DeviceIdentifierData>
<KeyID>SE9UUDAwMDAwMDAx</KeyID>
<TokenPlatformInfo KeyLocation="Hardware" AlgorithmLocation="Software"/>
<TriggerNonce>112dsdfwf312asder394jw==</TriggerNonce>
<DSKPPServerUrl>https://www.somekeyprovservice.com/</DSKPPServerUrl>
</InitializationTrigger>
</dskpp:KeyProvTrigger>]]></artwork>
<postamble></postamble>
</figure>
</section>
<section title="Components of the <KeyProvTrigger> Message">
<t>The DSKPP server MAY initialize the DSKPP protocol by sending a
<KeyProvTrigger> message. This message MAY, e.g., be sent in
response to a user requesting key initialization in a browsing
session.</t>
<t>The <KeyProvTrigger> element is intended for the DSKPP client
and MAY inform the DSKPP client about the identifier for the device
that houses the cryptographic module to be initialized, and optionally
of the identifier for the key on that module. The latter would apply
to key renewal. The trigger always contains a nonce to allow the DSKPP
server to couple the trigger with a later DSKPP
<KeyProvClientHello> request. Finally, the trigger MAY contain a
URL to use when contacting the DSKPP server. The <xs:any>
elements are for future extensibility. Any provided
<DeviceIdentifierData> or <KeyID> values MUST be used by
the DSKPP client in the subsequent <KeyProvClientHello> request.
The OPTIONAL <TokenPlatformInfo> element informs the DSKPP
client about the characteristics of the intended cryptographic module
platform, and applies in the public-key variant of DSKPP in situations
when the client potentially needs to decide which one of several
modules to initialize.</t>
</section>
</section>
<!-- ////////////////////////////////////////////////////////////////////////////////// -->
<section anchor="Section-ProtocolExts" title="Extensibility">
<section title="The ClientInfoType Type">
<t>present in a <KeyProvClientHello> or a
<KeyProvClientNonce> message, the OPTIONAL ClientInfoType
extension contains DSKPP client-specific information. DSKPP servers
MUST support this extension. DSKPP servers MUST NOT attempt to
interpret the data it carries and, if received, MUST include it
unmodified in the current protocol run's next server response. Servers
need not retain the ClientInfoType's data after that response has been
generated.</t>
</section>
<section title="The ServerInfoType Type">
<t>When present, the OPTIONAL ServerInfoType extension contains DSKPP
server-specific information. This extension is only valid in
<KeyProvServerHello> messages for which Status = "Continue".
DSKPP clients MUST support this extension. DSKPP clients MUST NOT
attempt to interpret the data it carries and, if received, MUST
include it unmodified in the current protocol run's next client
request (i.e., the <KeyProvClientNonce> message). DSKPP clients
need not retain the ServerInfoType's data after that request has been
generated. This extension MAY be used, e.g., for state management in
the DSKPP server.</t>
</section>
<section title="The KeyInitializationDataType Type">
<t>This extension is used for 2- and 1-pass DSKPP exchange; it carries
an identifier for the selected key initialization method as well as
key initialization method-dependent payload data.</t>
<t>Servers MAY include this extension in a
<KeyProvServerFinished> message that is being sent in response
to a received <KeyProvClientHello> message if and only if that
<KeyProvClientHello> message selected TwoPassSupport as the
ProtocolVariantType and the client indicated support for the selected
key initialization method. Servers MUST include this extension in a
<KeyProvServerFinished> message that is sent as part of a 1-pass
DSKPP.</t>
<t>The elements of this type have the following meaning:</t>
<t><list style="symbols">
<t><KeyInitializationMethod>: A two-pass key initialization
method supported by the DSKPP client.</t>
<t><Payload>: A payload associated with the key
initialization method. Since the syntax is a shorthand for
<xs:element name="Payload" type="xs:anyType"/>, any
well-formed payloads can be carried in this element.</t>
</list></t>
</section>
</section>
<section anchor="Section-Profiles"
title="Key Initialization Profiles of Two- and One-Pass DSKPP">
<section title="Introduction">
<t>This appendix introduces three profiles of DSKPP for key
initialization. They MAY all be used for two- as well as one-pass
initialization of cryptographic modules. Further profiles MAY be
defined by external entities or through the IETF process.</t>
</section>
<section title="Key Transport Profile">
<section title="Introduction">
<t>This profile initializes the cryptographic module with a
symmetric key, K_TOKEN, through key transport and key derivation.
The key transport is carried out using a public key, K_CLIENT, whose
private key part resides in the cryptographic module as the
transport key. A key K from which two keys, K_TOKEN and K_MAC are
derived MUST be transported.</t>
</section>
<section title="Identification">
<t>This profile MUST be identified with the following URN:</t>
<t>urn:ietf:params:xml:schema:keyprov:protocol#transport</t>
</section>
<section title="Payloads">
<t>In the two-pass version of DSKPP, the client MUST send a payload
associated with this key initialization method. The payload MUST be
of type ds:KeyInfoType (<xref target="XMLDSIG"></xref>), and only
those choices of the ds:KeyInfoType that identify a public key are
allowed. The ds:X509Certificate option of the ds:X509Data
alternative is RECOMMENDED when the public key corresponding to the
private key on the cryptographic module has been certified.</t>
<t>The server payload associated with this key initialization method
MUST be of type xenc:EncryptedKeyType (<xref
target="XMLENC"></xref>), and only those encryption methods
utilizing a public key that are supported by the DSKPP client (as
indicated in the <SupportedEncryptionAlgorithms> element of
the <KeyProvClientHello> message in the case of 2-pass DSKPP,
or as otherwise known in the case of 1-pass DSKPP) are allowed as
values for the <xenc:EncryptionMethod> element. Further, in
the case of 2-pass DSKPP, the <ds:KeyInfo> element MUST
contain the same value (i.e. identify the same public key) as the
<Payload> of the corresponding supported key initialization
method in the <KeyProvClientHello> message that triggered the
response. The <CarriedKeyName> element MAY be present, but
MUST, when present, contain the same value as the <KeyID>
element of the <KeyProvServerFinished> message. The Type
attribute of the xenc:EncryptedKeyType MUST be present and MUST
identify the type of the wrapped key. The type MUST be one of the
types supported by the DSKPP client (as reported in the
<SupportedKeyTypes> of the preceding
<KeyProvClientHello> message in the case of 2-pass DSKPP, or
as otherwise known in the case of 1-pass DSKPP). The transported key
MUST consist of two parts of equal length. The first half
constitutes K_MAC and the second half constitutes K_TOKEN. The
length of K_TOKEN (and hence also the length of K_MAC) is determined
by the type of K_TOKEN.</t>
<t>DSKPP servers and cryptographic modules supporting this profile
MUST support the http://www.w3.org/2001/04/xmlenc#rsa-1_5
key-wrapping mechanism defined in <xref target="XMLENC"></xref>.</t>
<t>When this profile is used, the MacAlgorithm attribute of the
<Mac> element of the <KeyProvServerFinished> message
MUST be present and MUST identify the selected MAC algorithm. The
selected MAC algorithm MUST be one of the MAC algorithms supported
by the DSKPP client (as indicated in the
<SupportedMacAlgorithms> element of the
<KeyProvClientHello> message in the case of 2-pass DSKPP, or
as otherwise known in the case of 1-pass DSKPP). The MAC MUST be
calculated as described in <xref target="Subsecton-TwoPass"></xref>
for Two-Pass DSKPP and <xref target="Subsection-OnePass"></xref> for
One-Pass DSKPP.</t>
<t>In addition, DSKPP servers MUST include the
AuthenticationDataType element in their
<KeyProvServerFinished> messages whenever a successful
protocol run will result in an existing K_TOKEN being replaced.</t>
</section>
</section>
<section title="Key Wrap Profile">
<section title="Introduction">
<t>This profile initializes the cryptographic module with a
symmetric key, K_TOKEN, through key wrap and key derivation. The key
wrap MUST be carried out using a (symmetric) key-wrapping key,
K_SHARED, known in advance by both the cryptographic module and the
DSKPP server. A key K from which two keys, K_TOKEN and K_MAC are
derived MUST be wrapped.</t>
</section>
<section title="Identification">
<t>This profile MUST be identified with the following URI:</t>
<t>urn:ietf:params:xml:schema:keyprov:protocol#wrap</t>
</section>
<section title="Payloads">
<t>In the 2-pass version of DSKPP, the client MUST send a payload
associated with this key initialization method. The payload MUST be
of type ds:KeyInfoType (<xref target="XMLDSIG"></xref>), and only
those choices of the ds:KeyInfoType that identify a symmetric key
are allowed. The ds:KeyName alternative is RECOMMENDED.</t>
<t>The server payload associated with this key initialization method
MUST be of type xenc:EncryptedKeyType (<xref
target="XMLENC"></xref>), and only those encryption methods
utilizing a symmetric key that are supported by the DSKPP client (as
indicated in the <SupportedEncryptionAlgorithms> element of
the <KeyProvClientHello> message in the case of 2-pass DSKPP,
or as otherwise known in the case of 1-pass DSKPP) are allowed as
values for the <xenc:EncryptionMethod> element. Further, in
the case of 2-pass DSKPP, the <ds:KeyInfo> element MUST
contain the same value (i.e. identify the same symmetric key) as the
<Payload> of the corresponding supported key initialization
method in the <KeyProvClientHello> message that triggered the
response. The <CarriedKeyName> element MAY be present, and
MUST, when present, contain the same value as the <KeyID>
element of the <KeyProvServerFinished> message. The Type
attribute of the xenc:EncryptedKeyType MUST be present and MUST
identify the type of the wrapped key. The type MUST be one of the
types supported by the DSKPP client (as reported in the
<SupportedKeyTypes> of the preceding
<KeyProvClientHello> message in the case of 2-pass DSKPP, or
as otherwise known in the case of 1-pass DSKPP). The wrapped key
MUST consist of two parts of equal length. The first half
constitutes K_MAC and the second half constitutes K_TOKEN. The
length of K_TOKEN (and hence also the length of K_MAC) is determined
by the type of K_TOKEN.</t>
<t>DSKPP servers and cryptographic modules supporting this profile
MUST support the http://www.w3.org/2001/04/xmlenc#kw-aes128
key-wrapping mechanism defined in <xref target="XMLENC"></xref>.</t>
<t>When this profile is used, the MacAlgorithm attribute of the
<Mac> element of the <KeyProvServerFinished> message
MUST be present and MUST identify the selected MAC algorithm. The
selected MAC algorithm MUST be one of the MAC algorithms supported
by the DSKPP client (as indicated in the
<SupportedMacAlgorithms> element of the
<KeyProvClientHello> message in the case of 2-pass DSKPP, or
as otherwise known in the case of 1-pass DSKPP). The MAC MUST be
calculated as described in <xref
target="Subsecton-TwoPass"></xref>.</t>
<t>In addition, DSKPP servers MUST include the
AuthenticationDataType element in their
<KeyProvServerFinished> messages whenever a successful
protocol run will result in an existing K_TOKEN being replaced.</t>
</section>
</section>
<section title="Passphrase-Based Key Wrap Profile">
<section title="Introduction">
<t>This profile is a variation of the key wrap profile. It
initializes the cryptographic module with a symmetric key, K_TOKEN,
through key wrap and key derivation, using a passphrase-derived
key-wrapping key, K_DERIVED. The passphrase is known in advance by
both the device user and the DSKPP server. To preserve the property
of not exposing K_TOKEN to any other entity than the DSKPP server
and the cryptographic module itself, the method SHOULD be employed
only when the device contains facilities (e.g. a keypad) for direct
entry of the passphrase. A key K from which two keys, K_TOKEN and
K_MAC are derived MUST be wrapped.</t>
</section>
<section title="Identification">
<t>This profile MUST be identified with the following URI:</t>
<t>urn:ietf:params:xml:schema:keyprov:protocol#passphrase-wrap</t>
</section>
<section title="Payloads">
<t>In the 2-pass version of DSKPP, the client MUST send a payload
associated with this key initialization method. The payload MUST be
of type ds:KeyInfoType (<xref target="XMLDSIG"></xref>). The
ds:KeyName option MUST be used and the key name MUST identify the
passphrase that will be used by the server to generate the
key-wrapping key. As an example, the identifier could be a user
identifier or a registration identifier issued by the server to the
user during a session preceding the DSKPP protocol run.</t>
<t>The server payload associated with this key initialization method
MUST be of type xenc:EncryptedKeyType (<xref
target="XMLENC"></xref>), and only those encryption methods
utilizing a passphrase to derive the key-wrapping key that are
supported by the DSKPP client (as indicated in the
<SupportedEncryptionAlgorithms> element of the
<KeyProvClientHello> message in the case of 2-pass DSKPP, or
as otherwise known in the case of 1-pass DSKPP) are allowed as
values for the <xenc:EncryptionMethod> element. Further, in
the case of 2-pass DSKPP, the <ds:KeyInfo> element MUST
contain the same value (i.e. identify the same passphrase) as the
<Payload> of the corresponding supported key initialization
method in the <KeyProvClientHello> message that triggered the
response. The <CarriedKeyName> element MAY be present, and
MUST, when present, contain the same value as the <KeyID>
element of the <KeyProvServerFinished> message. The Type
attribute of the xenc:EncryptedKeyType MUST be present and MUST
identify the type of the wrapped key. The type MUST be one of the
types supported by the DSKPP client (as reported in the
<SupportedKeyTypes> of the preceding
<KeyProvClientHello> message in the case of 2-pass DSKPP, or
as otherwise known in the case of 1-pass DSKPP). The wrapped key
MUST consist of two parts of equal length. The first half
constitutes K_MAC and the second half constitutes K_TOKEN. The
length of K_TOKEN (and hence also the length of K_MAC) is determined
by the type of K_TOKEN.</t>
<t>DSKPP servers and cryptographic modules supporting this profile
MUST support the PBES2 password based encryption scheme defined in
<xref target="PKCS-5"></xref> (and identified as
http://www.rsasecurity.com/rsalabs/pkcs/schemas/pkcs-5#pbes2 in
<xref target="PKCS-5-XML"></xref>), the PBKDF2 passphrase-based key
derivation function also defined in <xref target="PKCS-5"></xref>
(and identified as
http://www.rsasecurity.com/rsalabs/pkcs/schemas/pkcs-5#pbkdf2 in
<xref target="PKCS-5-XML"></xref>), and the
http://www.w3.org/2001/04/xmlenc#kw-aes128 key-wrapping mechanism
defined in <xref target="XMLENC"></xref>.</t>
<t>When this profile is used, the MacAlgorithm attribute of the
<Mac> element of the <KeyProvServerFinished> message
MUST be present and MUST identify the selected MAC algorithm. The
selected MAC algorithm MUST be one of the MAC algorithms supported
by the DSKPP client (as indicated in the
<SupportedMacAlgorithms> element of the
<KeyProvClientHello> message in the case of 2-pass DSKPP, or
as otherwise known in the case of 1-pass DSKPP). The MAC MUST be
calculated as described in <xref
target="Subsecton-TwoPass"></xref>.</t>
<t>In addition, DSKPP servers MUST include the
AuthenticationDataType element in their
<KeyProvServerFinished> messages whenever a successful
protocol run will result in an existing K_TOKEN being replaced.</t>
</section>
</section>
</section>
<section anchor="Section-Bindings" title="Protocol Bindings">
<section title="General Requirements">
<t>DSKPP assumes a reliable transport.</t>
</section>
<section title="HTTP/1.1 Binding for DSKPP">
<section title="Introduction">
<t>This section presents a binding of the previous messages to
HTTP/1.1 <xref target="RFC2616"></xref>. Note that the HTTP client
normally will be different from the DSKPP client, i.e., the HTTP
client will only exist to "proxy" DSKPP messages from the DSKPP
client to the DSKPP server. Likewise, on the HTTP server side, the
DSKPP server MAY receive DSKPP PDUs from a "front-end" HTTP
server.</t>
</section>
<section anchor="Subsection-ContentType"
title="Identification of DSKPP Messages">
<t>The MIME-type for all DSKPP messages MUST be</t>
<t>application/vnd.ietf.keyprov.dskpp+xml</t>
</section>
<section title="HTTP Headers">
<t>HTTP proxies MUST NOT cache responses carrying DSKPP messages.
For this reason, the following holds:<list style="symbols">
<t>When using HTTP/1.1, requesters SHOULD:<list>
<t>Include a Cache-Control header field set to "no-cache,
no-store".</t>
<t>Include a Pragma header field set to "no-cache".</t>
</list></t>
<t>When using HTTP/1.1, responders SHOULD:<list>
<t>Include a Cache-Control header field set to "no-cache,
no-must-revalidate, private".</t>
<t>Include a Pragma header field set to "no-cache".</t>
<t>NOT include a Validator, such as a Last-Modified or ETag
header.</t>
</list></t>
</list>There are no other restrictions on HTTP headers, besides
the requirement to set the Content-Type header value according to
<xref target="Subsection-ContentType"></xref>.</t>
</section>
<section title="HTTP Operations">
<t>Persistent connections as defined in HTTP/1.1 are assumed but not
required. DSKPP requests are mapped to HTTP POST operations. DSKPP
responses are mapped to HTTP responses.</t>
</section>
<section title="HTTP Status Codes">
<t>A DSKPP HTTP responder that refuses to perform a message exchange
with a DSKPP HTTP requester SHOULD return a 403 (Forbidden)
response. In this case, the content of the HTTP body is not
significant. In the case of an HTTP error while processing a DSKPP
request, the HTTP server MUST return a 500 (Internal Server Error)
response. This type of error SHOULD be returned for HTTP-related
errors detected before control is passed to the DSKPP processor, or
when the DSKPP processor reports an internal error (for example, the
DSKPP XML namespace is incorrect, or the DSKPP schema cannot be
located). If the type of a DSKPP request cannot be determined, the
DSKPP responder MUST return a 400 (Bad request) response.</t>
<t>In these cases (i.e., when the HTTP response code is 4xx or 5xx),
the content of the HTTP body is not significant.</t>
<t>Redirection status codes (3xx) apply as usual.</t>
<t>Whenever the HTTP POST is successfully invoked, the DSKPP HTTP
responder MUST use the 200 status code and provide a suitable DSKPP
message (possibly with DSKPP error information included) in the HTTP
body.</t>
</section>
<section title="HTTP Authentication">
<t>No support for HTTP/1.1 authentication is assumed.</t>
</section>
<section anchor="Section-InitDSKPP" title="Initialization of DSKPP">
<t>The DSKPP server MAY initialize the DSKPP protocol by sending an
HTTP response with Content-Type set according to <xref
target="Subsection-ContentType"></xref> and response code set to 200
(OK). This message MAY, e.g., be sent in response to a user
requesting key initialization in a browsing session. The
initialization message MAY carry data in its body. If this is the
case, the data MUST be a valid instance of a <KeyProvTrigger>
element.</t>
</section>
<section title="Example Messages">
<t hangText=""><list counter="Examples" hangIndent="0"
style="format %c.">
<t>Initialization from DSKPP server:</t>
</list><list hangIndent="4" style="empty">
<t hangText="">HTTP/1.1 200 OK<vspace
blankLines="1" />Cache-Control: no-store<vspace
blankLines="0" />Content-Type:
application/vnd.ietf.keyprov.dskpp+xml<vspace
blankLines="0" />Content-Length: <some value><vspace
blankLines="1" />DSKPP initialization data in XML form...</t>
</list></t>
<t><list counter="Examples" hangIndent="0" style="format %c.">
<t>Initial request from DSKPP client:</t>
</list><list hangIndent="4" style="empty">
<t>POST http://example.com/cgi-bin/DSKPP-server HTTP/1.1<vspace
blankLines="0" />Cache-Control: no-store<vspace
blankLines="0" />Pragma: no-cache<vspace blankLines="0" />Host:
example.com<vspace blankLines="0" />Content-Type:
application/vnd.ietf.keyprov.dskpp+xml<vspace
blankLines="0" />Content-Length: <some value><vspace
blankLines="1" />DSKPP data in XML form (supported version,
supported algorithms...)</t>
</list></t>
<t hangText=""><list counter="Examples" hangIndent="0"
style="format %c.">
<t>Initial response from DSKPP server:</t>
</list><list hangIndent="4" style="empty">
<t hangText="">HTTP/1.1 200 OK<vspace
blankLines="1" />Cache-Control: no-store<vspace
blankLines="0" />Content-Type:
application/vnd.ietf.keyprov.dskpp+xml<vspace
blankLines="0" />Content-Length: <some value><vspace
blankLines="1" />DSKPP data in XML form (server random nonce,
server public key, ...)</t>
</list></t>
</section>
</section>
</section>
<!-- ////////////////////////////////////////////////////////////////////////////////// -->
<section anchor="Section-Schema" title="DSKPP Schema">
<figure>
<preamble></preamble>
<artwork><![CDATA[
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema
xmlns:dskpp="urn:ietf:params:xml:ns:keyprov:1.0:protocol"
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:1.0:container"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:ds="http://www.w3.org/2000/09/xmldsig#"
targetNamespace="urn:ietf:params:xml:ns:keyprov:1.0:protocol"
elementFormDefault="unqualified" attributeFormDefault="unqualified"
version="1.0">
<xs:import namespace="http://www.w3.org/2000/09/xmldsig#"
schemaLocation="http://www.w3.org/TR/2002/REC-xmldsig-core-20020212/xmldsig-core-schema.xsd"/>
<xs:import namespace="urn:ietf:params:xml:ns:keyprov:1.0:container"
schemaLocation="keyprov-pskc-1.0.xsd"/>
<!-- Basic types -->
<xs:complexType name="AbstractRequestType" abstract="true">
<xs:attribute name="Version" type="dskpp:VersionType" use="required"/>
</xs:complexType>
<xs:complexType name="AbstractResponseType" abstract="true">
<xs:attribute name="Version" type="dskpp:VersionType" use="required"/>
<xs:attribute name="SessionID" type="dskpp:IdentifierType"/>
<xs:attribute name="Status" type="dskpp:StatusCode" use="required"/>
</xs:complexType>
<xs:simpleType name="VersionType">
<xs:restriction base="xs:string">
<xs:pattern value="\d{1,2}\.\d{1,3}"/>
</xs:restriction>
</xs:simpleType>
<xs:simpleType name="IdentifierType">
<xs:restriction base="xs:string">
<xs:maxLength value="128"/>
</xs:restriction>
</xs:simpleType>
<xs:simpleType name="StatusCode">
<xs:restriction base="xs:string">
<xs:enumeration value="Continue"/>
<xs:enumeration value="Success"/>
<xs:enumeration value="Abort"/>
<xs:enumeration value="AccessDenied"/>
<xs:enumeration value="MalformedRequest"/>
<xs:enumeration value="UnknownRequest"/>
<xs:enumeration value="UnknownCriticalExtension"/>
<xs:enumeration value="UnsupportedVersion"/>
<xs:enumeration value="NoSupportedKeyTypes"/>
<xs:enumeration value="NoSupportedEncryptionAlgorithms"/>
<xs:enumeration value="NoSupportedMacAlgorithms"/>
<xs:enumeration value="NoProtocolVariants"/>
<xs:enumeration value="NoSupportedKeyContainers"/>
<xs:enumeration value="AuthenticationDataMissing"/>
<xs:enumeration value="AuthenticationDataInvalid"/>
<xs:enumeration value="InitializationFailed"/>
</xs:restriction>
</xs:simpleType>
<xs:complexType name="DeviceIdentifierDataType">
<xs:choice>
<xs:element name="DeviceId" type="pskc:DeviceIdType"/>
<xs:any namespace="##other" processContents="strict"/>
</xs:choice>
</xs:complexType>
<xs:simpleType name="PlatformType">
<xs:restriction base="xs:string">
<xs:enumeration value="Hardware"/>
<xs:enumeration value="Software"/>
<xs:enumeration value="Unspecified"/>
</xs:restriction>
</xs:simpleType>
<xs:complexType name="TokenPlatformInfoType">
<xs:attribute name="KeyLocation" type="dskpp:PlatformType"/>
<xs:attribute name="AlgorithmLocation" type="dskpp:PlatformType"/>
</xs:complexType>
<xs:simpleType name="NonceType">
<xs:restriction base="xs:base64Binary">
<xs:minLength value="16"/>
</xs:restriction>
</xs:simpleType>
<xs:complexType name="AlgorithmsType">
<xs:sequence maxOccurs="unbounded">
<xs:element name="Algorithm" type="dskpp:AlgorithmType"/>
</xs:sequence>
</xs:complexType>
<xs:simpleType name="AlgorithmType">
<xs:restriction base="xs:anyURI"/>
</xs:simpleType>
<xs:complexType name="ProtocolVariantsType">
<xs:sequence>
<xs:element name="FourPass" minOccurs="0"/>
<xs:element name="TwoPass" type="dskpp:TwoPassSupportType"
minOccurs="0"/>
<xs:element name="OnePass" minOccurs="0"/>
</xs:sequence>
</xs:complexType>
<xs:complexType name="TwoPassSupportType">
<xs:sequence maxOccurs="unbounded">
<xs:element name="SupportedKeyInitializationMethod"
type="xs:anyURI"/>
<xs:element name="Payload" minOccurs="0"/>
</xs:sequence>
</xs:complexType>
<xs:complexType name="KeyContainersFormatType">
<xs:sequence maxOccurs="unbounded">
<xs:element name="KeyContainerFormat"
type="dskpp:KeyContainerFormatType"/>
</xs:sequence>
</xs:complexType>
<xs:simpleType name="KeyContainerFormatType">
<xs:restriction base="xs:anyURI"/>
</xs:simpleType>
<xs:complexType name="AuthenticationDataType">
<xs:annotation>
<xs:documentation xml:lang="en">
Authentication data can consist of either authentication code
for authenticating a user of the protocol, or an X.509 Certificate for
authenticating a device. When a device certificate is used over a
transport layer that is not secure, the Signature is calculated over
a nonce value specified in ds:Signature/Object. When used in
conjunction with the KeyProvServerFinished PDU, it contains a MAC
authenticating the DSKPP server to the client.
</xs:documentation>
</xs:annotation>
<xs:sequence>
<xs:element name="ClientID" type="dskpp:IdentifierType"
minOccurs="0"/>
<xs:choice minOccurs="0">
<xs:element name="AuthenticationCodeMac"
type="dskpp:AuthenticationCodeMacType"/>
<xs:element name="DigitalSignature"
type="ds:SignatureType"/>
</xs:choice>
</xs:sequence>
</xs:complexType>
<xs:complexType name="AuthenticationCodeMacType">
<xs:annotation>
<xs:documentation xml:lang="en">
An authentication MAC calculated from an authentication code and
optionally server information as well as nonce value if they are
available.
</xs:documentation>
</xs:annotation>
<xs:sequence>
<xs:element name="Nonce" type="dskpp:NonceType" minOccurs="0"/>
<xs:element name="IterationCount" type="xs:int" minOccurs="0"/>
<xs:element name="Mac" type="dskpp:MacType"/>
</xs:sequence>
</xs:complexType>
<xs:complexType name="MacType">
<xs:simpleContent>
<xs:extension base="xs:base64Binary">
<xs:attribute name="MacAlgorithm" type="xs:anyURI"/>
</xs:extension>
</xs:simpleContent>
</xs:complexType>
<xs:complexType name="KeyContainerType">
<xs:sequence>
<xs:element name="ServerID" type="xs:anyURI" minOccurs="0"/>
<xs:choice>
<xs:element name="KeyContainer" type="pskc:KeyContainerType"/>
<xs:any namespace="##other" processContents="strict"/>
</xs:choice>
</xs:sequence>
</xs:complexType>
<xs:complexType name="InitializationTriggerType">
<xs:sequence>
<xs:element name="DeviceIdentifierData"
type="dskpp:DeviceIdentifierDataType" minOccurs="0"/>
<xs:element name="KeyID" type="xs:base64Binary" minOccurs="0"/>
<xs:element name="TokenPlatformInfo"
type="dskpp:TokenPlatformInfoType" minOccurs="0"/>
<xs:element name="TriggerNonce" type="dskpp:NonceType"/>
<xs:element name="DSKPPServerUrl" type="xs:anyURI" minOccurs="0"/>
<xs:any namespace="##other" processContents="strict"
minOccurs="0"/>
</xs:sequence>
</xs:complexType>
<!-- Extension types -->
<xs:complexType name="ExtensionsType">
<xs:sequence maxOccurs="unbounded">
<xs:element name="Extension" type="dskpp:AbstractExtensionType"/>
</xs:sequence>
</xs:complexType>
<xs:complexType name="AbstractExtensionType" abstract="true">
<xs:attribute name="Critical" type="xs:boolean"/>
</xs:complexType>
<xs:complexType name="ClientInfoType">
<xs:complexContent>
<xs:extension base="dskpp:AbstractExtensionType">
<xs:sequence>
<xs:element name="Data"
type="xs:base64Binary"/>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:complexType name="ServerInfoType">
<xs:complexContent>
<xs:extension base="dskpp:AbstractExtensionType">
<xs:sequence>
<xs:element name="Data"
type="xs:base64Binary"/>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:complexType name="PayloadType">
<xs:choice>
<xs:element name="Nonce" type="dskpp:NonceType"/>
<xs:any namespace="##other" processContents="strict"/>
</xs:choice>
</xs:complexType>
<xs:complexType name="KeyInitializationDataType">
<xs:annotation>
<xs:documentation xml:lang="en">
This extension is only valid in KeyProvServerFinished PDUs. It
contains key initialization data and its presence results in a
two-pass (or one-pass, if no KeyProvClientHello was sent) DSKPP
exchange.
</xs:documentation>
</xs:annotation>
<xs:complexContent>
<xs:extension base="dskpp:AbstractExtensionType">
<xs:sequence>
<xs:element name="KeyInitializationMethod" type="xs:anyURI"/>
<xs:element name="Payload" type="dskpp:PayloadType"/>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<!-- DSKPP PDUs -->
<xs:element name="KeyProvTrigger" type="dskpp:KeyProvTriggerType"/>
<xs:complexType name="KeyProvTriggerType">
<xs:annotation>
<xs:documentation xml:lang="en">
Message used to trigger the device to initiate a
DSKPP protocol run.
</xs:documentation>
</xs:annotation>
<xs:sequence>
<xs:choice>
<xs:element name="InitializationTrigger"
type="dskpp:InitializationTriggerType"/>
<xs:any namespace="##other" processContents="strict"/>
</xs:choice>
</xs:sequence>
<xs:attribute name="Version" type="dskpp:VersionType"/>
</xs:complexType>
<!-- KeyProvClientHello PDU -->
<xs:element name="KeyProvClientHello" type="dskpp:KeyProvClientHelloPDU"/>
<xs:complexType name="KeyProvClientHelloPDU">
<xs:annotation>
<xs:documentation xml:lang="en">
Message sent from DSKPP client to DSKPP server to initiate a
DSKPP session.
</xs:documentation>
</xs:annotation>
<xs:complexContent>
<xs:extension base="dskpp:AbstractRequestType">
<xs:sequence>
<xs:element name="DeviceIdentifierData"
type="dskpp:DeviceIdentifierDataType" minOccurs="0"/>
<xs:element name="KeyID" type="xs:base64Binary"
minOccurs="0"/>
<xs:element name="ClientNonce" type="dskpp:NonceType"
minOccurs="0"/>
<xs:element name="TriggerNonce" type="dskpp:NonceType"
minOccurs="0"/>
<xs:element name="SupportedKeyTypes"
type="dskpp:AlgorithmsType"/>
<xs:element name="SupportedEncryptionAlgorithms"
type="dskpp:AlgorithmsType"/>
<xs:element name="SupportedMacAlgorithms"
type="dskpp:AlgorithmsType"/>
<xs:element name="SupportedProtocolVariants"
type="dskpp:ProtocolVariantsType" minOccurs="0"/>
<xs:element name="SupportedKeyContainers"
type="dskpp:KeyContainersFormatType" minOccurs="0"/>
<xs:element name="AuthenticationData"
type="dskpp:AuthenticationDataType" minOccurs="0"/>
<xs:element name="Extensions" type="dskpp:ExtensionsType"
minOccurs="0"/>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<!-- KeyProvServerHello PDU -->
<xs:element name="KeyProvServerHello" type="dskpp:KeyProvServerHelloPDU"/>
<xs:complexType name="KeyProvServerHelloPDU">
<xs:annotation>
<xs:documentation xml:lang="en">
Message sent from DSKPP server to DSKPP client
in response to a received KeyProvClientHello PDU.
</xs:documentation>
</xs:annotation>
<xs:complexContent>
<xs:extension base="dskpp:AbstractResponseType">
<xs:sequence minOccurs="0">
<xs:element name="KeyType"
type="dskpp:AlgorithmType"/>
<xs:element name="EncryptionAlgorithm"
type="dskpp:AlgorithmType"/>
<xs:element name="MacAlgorithm"
type="dskpp:AlgorithmType"/>
<xs:element name="EncryptionKey"
type="ds:KeyInfoType"/>
<xs:element name="KeyContainerFormat"
type="dskpp:KeyContainerFormatType"/>
<xs:element name="Payload"
type="dskpp:PayloadType"/>
<xs:element name="Extensions"
type="dskpp:ExtensionsType" minOccurs="0"/>
<xs:element name="Mac" type="dskpp:MacType"
minOccurs="0"/>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<!-- KeyProvClientNonce PDU -->
<xs:element name="KeyProvClientNonce" type="dskpp:KeyProvClientNoncePDU"/>
<xs:complexType name="KeyProvClientNoncePDU">
<xs:annotation>
<xs:documentation xml:lang="en">
Second message sent from DSKPP client to
DSKPP server in a DSKPP session.
</xs:documentation>
</xs:annotation>
<xs:complexContent>
<xs:extension base="dskpp:AbstractRequestType">
<xs:sequence>
<xs:element name="EncryptedNonce"
type="xs:base64Binary"/>
<xs:element name="AuthenticationData"
type="dskpp:AuthenticationDataType" minOccurs="0"/>
<xs:element name="Extensions"
type="dskpp:ExtensionsType" minOccurs="0"/>
</xs:sequence>
<xs:attribute name="SessionID" type="dskpp:IdentifierType"
use="required"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<!-- KeyProvServerFinished PDU -->
<xs:element name="KeyProvServerFinished" type="dskpp:KeyProvServerFinishedPDU"/>
<xs:complexType name="KeyProvServerFinishedPDU">
<xs:annotation>
<xs:documentation xml:lang="en">
Final message sent from DSKPP server to DSKPP client in a DSKPP
session. A MAC value serves for key confirmation, and optional
AuthenticationData servers for server authentication.
</xs:documentation>
</xs:annotation>
<xs:complexContent>
<xs:extension base="dskpp:AbstractResponseType">
<xs:sequence minOccurs="0">
<xs:element name="KeyContainer"
type="dskpp:KeyContainerType"/>
<xs:element name="Extensions"
type="dskpp:ExtensionsType" minOccurs="0"/>
<xs:element name="Mac"
type="dskpp:MacType"/>
<xs:element name="AuthenticationData"
type="dskpp:AuthenticationDataType" minOccurs="0"/>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
</xs:schema>
]]></artwork>
<postamble></postamble>
</figure>
</section>
<!-- ////////////////////////////////////////////////////////////////////////////////// -->
<!-- ////////////////////////////////////////////////////////////////////////////////// -->
<section anchor="Section-Security" title="Security Considerations">
<section title="General">
<t>DSKPP is designed to protect generated key material from exposure.
No other entities than the DSKPP server and the cryptographic module
will have access to a generated K_TOKEN if the cryptographic
algorithms used are of sufficient strength and, on the DSKPP client
side, generation and encryption of R_C and generation of K_TOKEN take
place as specified in the cryptographic module. This applies even if
malicious software is present in the DSKPP client. However, as
discussed in the following, DSKPP does not protect against certain
other threats resulting from man-in-the-middle attacks and other forms
of attacks. DSKPP SHOULD, therefore, be run over a transport providing
privacy and integrity, such as HTTP over Transport Layer Security
(TLS) with a suitable ciphersuite, when such threats are a concern.
Note that TLS ciphersuites with anonymous key exchanges are not
suitable in those situations.</t>
</section>
<section title="Active Attacks">
<section title="Introduction">
<t>An active attacker MAY attempt to modify, delete, insert, replay,
or reorder messages for a variety of purposes including service
denial and compromise of generated key material. <xref
target="Subsection-Messages"></xref> through <xref
target="Subsection-MITM"></xref>.</t>
</section>
<section anchor="Subsection-Messages" title="Message Modifications">
<t>Modifications to a <DSKPPTrigger> message will either cause
denial-of-service (modifications of any of the identifiers or the
nonce) or will cause the DSKPP client to contact the wrong DSKPP
server. The latter is in effect a man-in-the-middle attack and is
discussed further in <xref target="Subsection-MITM"></xref>.</t>
<t>An attacker may modify a <KeyProvClientHello> message. This
means that the attacker could indicate a different key or device
than the one intended by the DSKPP client, and could also suggest
other cryptographic algorithms than the ones preferred by the DSKPP
client, e.g., cryptographically weaker ones. The attacker could also
suggest earlier versions of the DSKPP protocol, in case these
versions have been shown to have vulnerabilities. These
modifications could lead to an attacker succeeding in initializing
or modifying another cryptographic module than the one intended
(i.e., the server assigning the generated key to the wrong module),
or gaining access to a generated key through the use of weak
cryptographic algorithms or protocol versions. DSKPP implementations
MAY protect against the latter by having strict policies about what
versions and algorithms they support and accept. The former threat
(assignment of a generated key to the wrong module) is not possible
when the shared-key variant of DSKPP is employed (assuming existing
shared keys are unique per cryptographic module), but is possible in
the public-key variant. Therefore, DSKPP servers MUST NOT accept
unilaterally provided device identifiers in the public-key variant.
This is also indicated in the protocol description. In the
shared-key variant, however, an attacker may be able to provide the
wrong identifier (possibly also leading to the incorrect user being
associated with the generated key) if the attacker has real-time
access to the cryptographic module with the identified key. In other
words, the generated key is associated with the correct
cryptographic module but the module is associated with the incorrect
user. See further <xref target="Subsection-Interactions"></xref> for
a discussion of this threat and possible countermeasures.</t>
<t>An attacker may also modify a <KeyProvServerHello> message.
This means that the attacker could indicate different key types,
algorithms, or protocol versions than the legitimate server would,
e.g., cryptographically weaker ones. The attacker may also provide a
different nonce than the one sent by the legitimate server. Clients
MAY protect against the former through strict adherence to policies
regarding permissible algorithms and protocol versions. The latter
(wrong nonce) will not constitute a security problem, as a generated
key will not match the key generated on the legitimate server. Also,
whenever the DSKPP run would result in the replacement of an
existing key, the <Mac> element protects against modifications
of R_S.</t>
<t>Modifications of <KeyProvClientNonce> messages are also
possible. If an attacker modifies the SessionID attribute, then, in
effect, a switch to another session will occur at the server,
assuming the new SessionID is valid at that time on the server. It
still will not allow the attacker to learn a generated K_TOKEN since
R_C has been wrapped for the legitimate server. Modifications of the
<EncryptedNonce> element, e.g., replacing it with a value for
which the attacker knows an underlying R'C, will not result in the
client changing its pre-DSKPP state, since the server will be unable
to provide a valid MAC in its final message to the client. The
server MAY, however, end up storing K'TOKEN rather than K_TOKEN. If
the cryptographic module has been associated with a particular user,
then this could constitute a security problem. For a further
discussion about this threat, and a possible countermeasure, see
<xref target="Subsection-Interactions"></xref> below. Note that use
of Secure Socket Layer (SSL) or TLS does not protect against this
attack if the attacker has access to the DSKPP client (e.g., through
malicious software, "trojans").</t>
<t>Finally, attackers may also modify the
<KeyProvServerFinished> message. Replacing the <Mac>
element will only result in denial-of-service. Replacement of any
other element may cause the DSKPP client to associate, e.g., the
wrong service with the generated key. DSKPP SHOULD be run over a
transport providing privacy and integrity when this is a
concern.</t>
</section>
<section title="Message Deletion">
<t>Message deletion will not cause any other harm than
denial-of-service, since a cryptographic module MUST NOT change its
state (i.e., "commit" to a generated key) until it receives the
final message from the DSKPP server and successfully has processed
that message, including validation of its MAC. A deleted
<KeyProvServerFinished> message will not cause the server to
end up in an inconsistent state vis-a-vis the cryptographic module
if the server implements the suggestions in <xref
target="Subsection-Interactions"></xref>.</t>
</section>
<section title="Message Insertion">
<t>An active attacker may initiate a DSKPP run at any time, and
suggest any device identifier. DSKPP server implementations MAY
receive some protection against inadvertently initializing a key or
inadvertently replacing an existing key or assigning a key to a
cryptographic module by initializing the DSKPP run by use of the
<KeyProvTrigger>. The <TriggerNonce> element allows the
server to associate a DSKPP protocol run with, e.g., an earlier
user-authenticated session. The security of this method, therefore,
depends on the ability to protect the <TriggerNonce> element
in the DSKPP initialization message. If an eavesdropper is able to
capture this message, he may race the legitimate user for a key
initialization. DSKPP over a transport providing privacy and
integrity, coupled with the recommendations in <xref
target="Subsection-Interactions"></xref>, is RECOMMENDED when this
is a concern.</t>
<t>Insertion of other messages into an existing protocol run is seen
as equivalent to modification of legitimately sent messages.</t>
</section>
<section title="Message Replay">
<t>During 4-pass DSKPP, attempts to replay a previously recorded
DSKPP message will be detected, as the use of nonces ensures that
both parties are live. For example, a DSKPP client knows that a
server it is communicating with is "live" since the server MUST
create a MAC on information sent by the client.</t>
<t>The same is true for 2-pass DSKPP thanks to the requirement that
the client sends R in the <KeyProvClientHello> message and
that the server includes R in the MAC computation.</t>
<t>In 1-pass DSKPP clients that record the latest I used by a
particular server (as identified by ID_S) will be able to detect
replays.</t>
</section>
<section title="Message Reordering">
<t>An attacker may attempt to re-order 4-pass DSKPP messages but
this will be detected, as each message is of a unique type. Note:
Message re-ordering attacks cannot occur in 2- and 1-pass DSKPP
since each party sends at most one message each.</t>
</section>
<section anchor="Subsection-MITM" title="Man-in-the-Middle">
<t>In addition to other active attacks, an attacker posing as a man
in the middle may be able to provide his own public key to the DSKPP
client. This threat and countermeasures to it are discussed in <xref
target="Subsection-FourPassUsage"></xref>. An attacker posing as a
man-in-the-middle may also be acting as a proxy and, hence, may not
interfere with DSKPP runs but still learn valuable information; see
<xref target="Subsection-Passive"></xref>.</t>
</section>
</section>
<section anchor="Subsection-Passive" title="Passive Attacks">
<t>Passive attackers may eavesdrop on DSKPP runs to learn information
that later on may be used to impersonate users, mount active attacks,
etc.</t>
<t>If DSKPP is not run over a transport providing privacy, a passive
attacker may learn:<list hangIndent="0" style="symbols">
<t>What cryptographic modules a particular user is in possession
of;</t>
<t>The identifiers of keys on those cryptographic modules and
other attributes pertaining to those keys, e.g., the lifetime of
the keys; and</t>
<t>DSKPP versions and cryptographic algorithms supported by a
particular DSKPP client or server.</t>
</list>Whenever the above is a concern, DSKPP SHOULD be run over a
transport providing privacy. If man-in-the-middle attacks for the
purposes described above are a concern, the transport SHOULD also
offer server-side authentication.</t>
</section>
<section title="Cryptographic Attacks">
<t>An attacker with unlimited access to an initialized cryptographic
module may use the module as an "oracle" to pre-compute values that
later on may be used to impersonate the DSKPP server. <xref
target="Subsection-Enc"></xref> and <xref
target="Section-Protocol"></xref> contain discussions of this threat
and steps RECOMMENDED to protect against it.</t>
</section>
<section anchor="Subsection-Interactions"
title="Attacks on the Interaction between DSKPP and User Authentication">
<t>If keys generated in DSKPP will be associated with a particular
user at the DSKPP server (or a server trusted by, and communicating
with the DSKPP server), then in order to protect against threats where
an attacker replaces a client-provided encrypted R_C with his own R'C
(regardless of whether the public-key variant or the shared-secret
variant of DSKPP is employed to encrypt the client nonce), the server
SHOULD not commit to associate a generated K_TOKEN with the given
cryptographic module until the user simultaneously has proven both
possession of the device that hosts the cryptographic module
containing K_TOKEN and some out-of-band provided authenticating
information (e.g., a temporary password). For example, if the
cryptographic module is a one-time password token, the user could be
required to authenticate with both a one-time password generated by
the cryptographic module and an out-of-band provided temporary PIN in
order to have the server "commit" to the generated OTP value for the
given user. Preferably, the user SHOULD perform this operation from
another host than the one used to initialize keys on the cryptographic
module, in order to minimize the risk of malicious software on the
client interfering with the process.</t>
<t>Note: This scenario, wherein the attacker replaces a
client-provided R_C with his own R'C, does not apply to 2- and 1-pass
DSKPP as the client does not provide any entropy to K_TOKEN. The
attack as such (and its countermeasures) still applies to 2- and
1-pass DSKPP, however, as it essentially is a man-in-the-middle
attack.</t>
<t>Another threat arises when an attacker is able to trick a user to
authenticate to the attacker rather than to the legitimate service
before the DSKPP protocol run. If successful, the attacker will then
be able to impersonate the user towards the legitimate service, and
subsequently receive a valid DSKPP trigger. If the public-key variant
of DSKPP is used, this may result in the attacker being able to (after
a successful DSKPP protocol run) impersonate the user. Ordinary
precautions MUST, therefore, be in place to ensure that users
authenticate only to legitimate services.</t>
</section>
<section title="Additional Considerations Specific to 2- and 1-pass DSKPP">
<section title="Client Contributions to K_TOKEN Entropy">
<t>In 4-pass DSKPP, both the client and the server provide
randomizing material to K_TOKEN , in a manner that allows both
parties to verify that they did contribute to the resulting key. In
the 1- and 2-pass DSKPP versions defined herein, only the server
contributes to the entropy of K_TOKEN. This means that a broken or
compromised (pseudo-)random number generator in the server may cause
more damage than it would in the 4-pass variant. Server
implementations SHOULD therefore take extreme care to ensure that
this situation does not occur.</t>
</section>
<section title="Key Confirmation">
<t>4-pass DSKPP servers provide key confirmation through the MAC on
R_C in the <KeyProvServerFinished> message. In the 1- and
2-pass DSKPP variants described herein, key confirmation is provided
by the MAC including I (in the 1-pass case) or R (2-pass case),
using K_MAC.</t>
</section>
<section anchor="Subsection-ServerAuth" title="Server Authentication">
<t>DSKPP servers MUST authenticate themselves whenever a successful
DSKPP 1- or 2-pass protocol run would result in an existing K_TOKEN
being replaced by a K_TOKEN', or else a denial-of-service attack
where an unauthorized DSKPP server replaces a K_TOKEN with another
key would be possible. In 1- and 2-pass DSKPP, servers authenticate
by including the AuthenticationDataType extension containing a MAC
as described in <xref target="Subsecton-TwoPass"></xref> for
Two-Pass DSKPP and <xref target="Subsection-OnePass"></xref> for
One-Pass DSKPP.</t>
</section>
<section title="Client Authentication">
<t>A DSKPP server MUST authenticate a client to ensure that K_TOKEN
is delivered to the intended device. The following measures SHOULD
be considered:<list style="symbols">
<t>When a device certificate is used for client authentication,
the DSKPP server SHOULD follow standard certificate verification
processes to ensure that it is a trusted device.</t>
<t>When an Authentication Code is used for client
authentication, a password dictionary attack on the
authentication data is possible.</t>
<t>The length of the Authentication Code when used over a
non-secure channel SHOULD be longer than what is used over a
secure channel. When a device, e.g., some mobile phones with
small screens, cannot handle a long Authentication Code in a
user-friendly manner, DSKPP SHOULD rely on a secure channel for
communication.</t>
<t>In the case that a non-secure channel has to be used, the
Authentication Code SHOULD be sent to the server MAC's as
specified in <xref target="Section-ClientAuthN"></xref>. The
Authentication Code and nonce value MUST be strong enough to
prevent offline brute-force recovery of the Authentication Code
from the HMAC data. Given that the nonce value is sent in
plaintext format over a non-secure transport, the cryptographic
strength of the AuthenticationData depends more on the quality
of the AuthenticationCode.</t>
<t>When the AuthenticationCode is sent from the DSKPP server to
the device in a DSKPP initialization trigger message, an
eavesdropper may be able to capture this message and race the
legitimate user for a key initialization. To prevent this, the
transport layer used to send the DSKPP trigger MUST provide
privacy and integrity e.g. secure browser session.</t>
</list></t>
</section>
<section title="Key Protection in the Passphrase Profile">
<t>The passphrase-based key wrap profile uses the PBKDF2 function
from <xref target="PKCS-5"></xref> to generate an encryption key
from a passphrase and salt string. The derived key, K_DERIVED is
used by the server to encrypt K_TOKEN and by the cryptographic
module to decrypt the newly delivered K_TOKEN. It is important to
note that passphrase-based encryption is generally limited in the
security that it provides despite the use of salt and iteration
count in PBKDF2 to increase the complexity of attack.
Implementations SHOULD therefore take additional measures to
strengthen the security of the passphrase-based key wrap profile.
The following measures SHOULD be considered where applicable:</t>
<t><list style="symbols">
<t>The passphrase SHOULD be selected well, and usage guidelines
such as the ones in <xref target="NIST-PWD"></xref> SHOULD be
taken into account.</t>
<t>A different passphrase SHOULD be used for every key
initialization wherever possible (the use of a global passphrase
for a batch of cryptographic modules SHOULD be avoided, for
example). One way to achieve this is to use randomly-generated
passphrases.</t>
<t>The passphrase SHOULD be protected well if stored on the
server and/or on the cryptographic module and SHOULD be
delivered to the device's user using secure methods.</t>
<t>User pre-authentication SHOULD be implemented to ensure that
K_TOKEN is not delivered to a rogue recipient.</t>
<t>The iteration count in PBKDF2 SHOULD be high to impose more
work for an attacker using brute-force methods (see <xref
target="PKCS-5"></xref> for recommendations). However, it MUST
be noted that the higher the count, the more work is required on
the legitimate cryptographic module to decrypt the newly
delivered K_TOKEN. Servers MAY use relatively low iteration
counts to accommodate devices with limited processing power such
as some PDA and cell phones when other security measures are
implemented and the security of the passphrase-based key wrap
method is not weakened.</t>
<t>Transport level security (e.g. TLS) SHOULD be used where
possible to protect a 2-pass or 1-pass protocol run. Transport
level security provides a second layer of protection for the
newly generated K_TOKEN.</t>
</list></t>
</section>
</section>
</section>
<section title="Internationalization Considerations">
<t>The DSKPP protocol is mostly meant for machine-to-machine
communications; as such, most of its elements are tokens not meant for
direct human consumption. If these tokens are presented to the end user,
some localization may need to occur. DSKPP exchanges information using
XML. All XML processors are required to understand UTF-8 and UTF-16
encoding, and therefore all DSKPP clients and servers MUST understand
UTF-8 and UTF-16 encoded XML. Additionally, DSKPP servers and clients
MUST NOT encode XML with encodings other than UTF-8 or UTF-16.</t>
</section>
<section title="IANA Considerations">
<t>This document calls for registration of new URNs within the IETF
sub-namespace per RFC3553 <xref target="RFC3553"></xref>. The following
URNs are RECOMMENDED:<list style="symbols">
<t>DSKPP XML schema:
"urn:ietf:params:xml:schema:keyprov:protocol"</t>
<t>DSKPP XML namespace:
"urn:ietf:params:xml:ns:keyprov:protocol"</t>
</list></t>
</section>
<!-- ////////////////////////////////////////////////////////////////////////////////// -->
<section anchor="Section-IPR" title="Intellectual Property Considerations">
<t>RSA and RSA Security are registered trademarks or trademarks of RSA
Security Inc. in the United States and/or other countries. The names of
other products and services mentioned may be the trademarks of their
respective owners.</t>
</section>
<!-- ////////////////////////////////////////////////////////////////////////////////// -->
<section title="Contributors">
<t>This work is based on information contained in <xref
target="RFC4758"></xref>, authored by Magnus Nystrom, with enhancements
(esp. Client Authentication, and support for multiple key container
formats) from an individual Internet-Draft co-authored by Mingliang Pei
and Salah Machani.</t>
<t>We would like to thank Shuh Chang for contributing the DSKPP object
model, and Philip Hoyer for his work in aligning DSKPP and PSKC
schemas.</t>
<t>We would also like to thank Hannes Tschofenig for his draft reviews,
feedback, and text contributions.</t>
</section>
<section anchor="Section-Acknowledgements" title="Acknowledgements">
<t>We would like to thank the following for detailed review of previous
DSKPP document versions:<vspace blankLines="1" /><list style="symbols">
<t>Dr. Ulrike Meyer (Review June 2007)<vspace blankLines="1" /></t>
<t>Niklas Neumann (Review June 2007)<vspace blankLines="1" /></t>
<t>Shuh Chang (Review June 2007)<vspace blankLines="1" /></t>
<t>Hannes Tschofenig (Review June 2007 and again in August
2007)<vspace blankLines="1" /></t>
<t>Sean Turner (Review August 2007)<vspace blankLines="1" /></t>
<t>John Linn (Review August 2007)<vspace blankLines="1" /></t>
<t>Philip Hoyer (Review September 2007)</t>
</list></t>
<t>We would also like to thank the following for their input to selected
design aspects of the DSKPP protocol:<vspace blankLines="1" /><list
style="symbols">
<t>Anders Rundgren (Key Container Format and Client Authentication
Data)<vspace blankLines="1" /></t>
<t>Hannes Tschofenig (HTTP Binding)<vspace blankLines="1" /></t>
<t>Phillip Hallam-Baker (Registry for Algorithms)</t>
</list></t>
<t>Finally, we would like to thank Robert Griffin for opening
communication channels for us with the IEEE P1619.3 Key Management
Group, and facilitating our groups in staying informed of potential
areas (esp. key provisioning and global key identifiers of
collaboration) of collaboration.</t>
</section>
<!-- ////////////////////////////////////////////////////////////////////////////////// -->
</middle>
<back>
<references title="Normative references">
<reference anchor="UNICODE"
target="http://www.unicode.org/unicode/reports/tr15/tr15-21.html">
<front>
<title>Unicode Normalization Forms</title>
<author initials="M." surname="Davis">
<organization>UNICODE Consortium</organization>
</author>
<author initials="M." surname="Duerst">
<organization>UNICODE Consortium</organization>
<address>
<postal>
<street></street>
<city></city>
<region></region>
<code></code>
<country></country>
</postal>
<phone></phone>
<facsimile></facsimile>
<email></email>
<uri></uri>
</address>
</author>
<date month="March" year="2001" />
</front>
</reference>
<reference anchor="XMLENC"
target="http://www.w3.org/TR/2002/REC-xmldsig-core-20020212/">
<front>
<title>XML Encryption Syntax and Processing</title>
<author>
<organization>W3C</organization>
</author>
<date month="December" year="2002" />
</front>
<seriesInfo name="W3C" value="Recommendation" />
</reference>
<reference anchor="XMLDSIG"
target="http://www.w3.org/TR/2002/REC-xmldsig-core-20020212/">
<front>
<title>XML Signature Syntax and Processing</title>
<author>
<organization>W3C</organization>
</author>
<date month="February" year="2002" />
</front>
<seriesInfo name="W3C" value="Recommendation" />
</reference>
</references>
<references title="Informative references">
<reference anchor="CT-KIP-P11"
target="http://www.rsasecurity.com/rsalabs/pkcs/">
<front>
<title>PKCS #11 Mechanisms for the Cryptographic Token Key
Initialization Protocol</title>
<author>
<organization>RSA Laboratories</organization>
</author>
<date month="December" year="2005" />
</front>
<seriesInfo name="PKCS" value="#11 Version 2.20 Amd.2" />
</reference>
<reference anchor="FAQ">
<front>
<title>Frequently Asked Questions About Today's Cryptography</title>
<author>
<organization>RSA Laboratories</organization>
</author>
<date month="" year="2000" />
</front>
<seriesInfo name="" value="Version 4.1" />
</reference>
<reference anchor="FIPS180-SHA"
target="http://csrc.nist.gov/publications/fips/fips180-2/fips180-2withchangenotice.pdf">
<front>
<title>Secure Hash Standard</title>
<author>
<organization>National Institute of Standards and
Technology</organization>
</author>
<date month="February" year="2004" />
</front>
<seriesInfo name="FIPS" value="180-2" />
</reference>
<reference anchor="FIPS197-AES"
target="http://csrc.nist.gov/publications/fips/fips197/fips-197.pdf">
<front>
<title>Specification for the Advanced Encryption Standard
(AES)</title>
<author>
<organization>National Institute of Standards and
Technology</organization>
</author>
<date month="November" year="2001" />
</front>
<seriesInfo name="FIPS" value="197" />
</reference>
<reference anchor="FSE2003"
target="http://crypt.cis.ibaraki.ac.jp/omac/docs/omac.pdf">
<front>
<title>OMAC: One-Key CBC MAC. In Fast Software Encryption</title>
<author initials="T." surname="Iwata">
<organization></organization>
</author>
<author initials="K." surname="Kurosawa">
<organization></organization>
<address>
<postal>
<street></street>
<city></city>
<region></region>
<code></code>
<country></country>
</postal>
<phone></phone>
<facsimile></facsimile>
<email></email>
<uri></uri>
</address>
</author>
<date year="2003" />
</front>
<seriesInfo name="FSE" value="2003" />
<seriesInfo name="Springer-Verlag" value="" />
</reference>
<reference anchor="NIST-PWD"
target="http://www.itl.nist.gov/fipspubs/fip112.htm">
<front>
<title>Password Usage</title>
<author>
<organization>National Institute of Standards and
Technology</organization>
</author>
<date month="May" year="1985" />
</front>
<seriesInfo name="FIPS" value="112" />
</reference>
<reference anchor="OATH" target="http://www.openauthentication.org">
<front>
<title>Initiative for Open AuTHentication</title>
<author>
<organization></organization>
</author>
<date year="2005" />
</front>
</reference>
<reference anchor="PSKC"
target="http://www.ietf.org/internet-drafts/draft-hoyer-keyprov-portable-symmetric-key-container-00.txt">
<front>
<title>Portable Symmetric Key Container</title>
<author fullname="">
<organization></organization>
</author>
<date year="2005" />
</front>
</reference>
<reference anchor="PKCS-1"
target="http://www.rsasecurity.com/rsalabs/pkcs/">
<front>
<title>RSA Cryptography Standard</title>
<author>
<organization>RSA Laboratories</organization>
</author>
<date month="June" year="2002" />
</front>
<seriesInfo name="PKCS" value="#1 Version 2.1" />
</reference>
<reference anchor="PKCS-5"
target="http://www.rsasecurity.com/rsalabs/pkcs/">
<front>
<title>Password-Based Cryptography Standard</title>
<author>
<organization>RSA Laboratories</organization>
</author>
<date month="March" year="1999" />
</front>
<seriesInfo name="PKCS" value="#5 Version 2.0" />
</reference>
<reference anchor="PKCS-5-XML"
target="http://www.rsasecurity.com/rsalabs/pkcs/">
<front>
<title>XML Schema for PKCS #5 Version 2.0</title>
<author>
<organization>RSA Laboratories</organization>
</author>
<date month="October" year="2006" />
</front>
<seriesInfo name="PKCS" value="#5 Version 2.0 Amd.1 (FINAL DRAFT)" />
</reference>
<reference anchor="PKCS-11"
target="http://www.rsasecurity.com/rsalabs/pkcs/">
<front>
<title>Cryptographic Token Interface Standard</title>
<author>
<organization>RSA Laboratories</organization>
</author>
<date month="June" year="2004" />
</front>
<seriesInfo name="PKCS" value="#11 Version 2.20" />
</reference>
<reference anchor="PKCS-12"
target="ftp://ftp.rsasecurity.com/pub/pkcs/pkcs-12/pkcs-12v1.pdf">
<front>
<title>Personal Information Exchange Syntax Standard</title>
<author fullname="">
<organization></organization>
</author>
<date year="2005" />
</front>
<seriesInfo name="PKCS" value="#12 Version 1.0" />
</reference>
<reference anchor="RFC2104">
<front>
<title>HMAC: Keyed-Hashing for Message Authentication</title>
<author initials="H." surname="Krawzcyk">
<organization></organization>
</author>
<author initials="M." surname="Bellare">
<organization></organization>
<address>
<postal>
<street></street>
<city></city>
<region></region>
<code></code>
<country></country>
</postal>
<phone></phone>
<facsimile></facsimile>
<email></email>
<uri></uri>
</address>
</author>
<author initials="R." surname="Canetti">
<organization></organization>
<address>
<postal>
<street></street>
<city></city>
<region></region>
<code></code>
<country></country>
</postal>
<phone></phone>
<facsimile></facsimile>
<email></email>
<uri></uri>
</address>
</author>
<date month="February" year="1997" />
</front>
<seriesInfo name="RFC" value="2104" />
</reference>
<reference anchor="RFC2119" target="http://www.ietf.org/rfc/rfc2119.txt">
<front>
<title>Key words for use in RFCs to Indicate Requirement
Levels</title>
<author fullname="">
<organization></organization>
</author>
<date month="March" year="1997" />
</front>
<seriesInfo name="BCP" value="14" />
<seriesInfo name="RFC" value="2119" />
</reference>
<reference anchor="RFC2616" target="http://www.ietf.org/rfc/rfc2616.txt">
<front>
<title>Hypertext Transfer Protocol -- HTTP/1.1</title>
<author initials="R." surname="Fielding">
<organization></organization>
</author>
<author initials="J." surname="Gettys">
<organization></organization>
<address>
<postal>
<street></street>
<city></city>
<region></region>
<code></code>
<country></country>
</postal>
<phone></phone>
<facsimile></facsimile>
<email></email>
<uri></uri>
</address>
</author>
<author initials="J." surname="Mogul">
<organization></organization>
<address>
<postal>
<street></street>
<city></city>
<region></region>
<code></code>
<country></country>
</postal>
<phone></phone>
<facsimile></facsimile>
<email></email>
<uri></uri>
</address>
</author>
<author initials="H." surname="Frystyk">
<organization></organization>
<address>
<postal>
<street></street>
<city></city>
<region></region>
<code></code>
<country></country>
</postal>
<phone></phone>
<facsimile></facsimile>
<email></email>
<uri></uri>
</address>
</author>
<author initials="L." surname="Masinter">
<organization></organization>
<address>
<postal>
<street></street>
<city></city>
<region></region>
<code></code>
<country></country>
</postal>
<phone></phone>
<facsimile></facsimile>
<email></email>
<uri></uri>
</address>
</author>
<author initials="P." surname="Leach">
<organization></organization>
<address>
<postal>
<street></street>
<city></city>
<region></region>
<code></code>
<country></country>
</postal>
<phone></phone>
<facsimile></facsimile>
<email></email>
<uri></uri>
</address>
</author>
<author initials="T." surname="Berners-Lee">
<organization></organization>
<address>
<postal>
<street></street>
<city></city>
<region></region>
<code></code>
<country></country>
</postal>
<phone></phone>
<facsimile></facsimile>
<email></email>
<uri></uri>
</address>
</author>
<date month="June" year="1999" />
</front>
<seriesInfo name="RFC" value="2616" />
</reference>
<reference anchor="RFC3280">
<front>
<title>Internet X.509 Public Key Infrastructure Certificate and
Certificate Revocation List (CRL) Profile</title>
<author initials="R." surname="Housley">
<organization>VeriSign</organization>
</author>
<author initials="W." surname="Polk">
<organization>Adobe Systems</organization>
<address>
<postal>
<street></street>
<city></city>
<region></region>
<code></code>
<country></country>
</postal>
<phone></phone>
<facsimile></facsimile>
<email></email>
<uri></uri>
</address>
</author>
<author initials="W." surname="Ford">
<organization>Qualcomm</organization>
<address>
<postal>
<street></street>
<city></city>
<region></region>
<code></code>
<country></country>
</postal>
<phone></phone>
<facsimile></facsimile>
<email></email>
<uri></uri>
</address>
</author>
<author initials="D." surname="Solo">
<organization>Nine by Nine</organization>
<address>
<postal>
<street></street>
<city></city>
<region></region>
<code></code>
<country></country>
</postal>
<phone></phone>
<facsimile></facsimile>
<email></email>
<uri></uri>
</address>
</author>
<date month="April" year="2002" />
</front>
<seriesInfo name="RFC" value="3280" />
</reference>
<reference anchor="RFC3553">
<front>
<title>An IETF URN Sub-namespace for Registered Protocol
Parameters</title>
<author initials="M." surname="Mealling">
<organization>VeriSign</organization>
</author>
<author initials="L." surname="Masinter">
<organization>Adobe Systems</organization>
<address>
<postal>
<street></street>
<city></city>
<region></region>
<code></code>
<country></country>
</postal>
<phone></phone>
<facsimile></facsimile>
<email></email>
<uri></uri>
</address>
</author>
<author initials="T." surname="Hardie">
<organization>Qualcomm</organization>
<address>
<postal>
<street></street>
<city></city>
<region></region>
<code></code>
<country></country>
</postal>
<phone></phone>
<facsimile></facsimile>
<email></email>
<uri></uri>
</address>
</author>
<author initials="G." surname="Klyne">
<organization>Nine by Nine</organization>
<address>
<postal>
<street></street>
<city></city>
<region></region>
<code></code>
<country></country>
</postal>
<phone></phone>
<facsimile></facsimile>
<email></email>
<uri></uri>
</address>
</author>
<date month="June" year="2003" />
</front>
<seriesInfo name="RFC" value="3553" />
<seriesInfo name="BCP" value="73" />
</reference>
<reference anchor="RFC4758" target="http://www.ietf.org/rfc/rfc4758.txt">
<front>
<title>Cryptographic Token Key Initialization Protocol
(CT-KIP)</title>
<author fullname="Magnus Nystrom">
<organization>RSA, The Security Division of EMC</organization>
</author>
<date month="November" year="2006" />
</front>
</reference>
</references>
<section anchor="Section-Integration" title="Integration with PKCS #11">
<t>A DSKPP client that needs to communicate with a connected
cryptographic module to perform a DSKPP exchange MAY use PKCS #11 <xref
target="PKCS-11"></xref>as a programming interface.</t>
<section title="The 4-pass Variant">
<t>When performing 4-pass DSKPP with a cryptographic module using the
PKCS #11 programming interface, the procedure described in <xref
target="CT-KIP-P11"></xref>, Appendix B, is RECOMMENDED.</t>
</section>
<section title="The 2-pass Variant">
<t>A suggested procedure to perform 2-pass DSKPP with a cryptographic
module through the PKCS #11 interface using the mechanisms defined in
<xref target="CT-KIP-P11"></xref> is as follows:</t>
<t><list counter="2-pass" style="format %c.">
<t>On the client side, <list counter="1st" style="format %d.">
<t>The client selects a suitable slot and token (e.g. through
use of the <DeviceIdentifier> or the
<PlatformInfo> element of the DSKPP trigger
message).</t>
<t>A nonce R is generated, e.g. by calling C_SeedRandom and
C_GenerateRandom.</t>
<t>The client sends its first message to the server, including
the nonce R.</t>
</list></t>
<t>On the server side, <list counter="2nd" style="format %d.">
<t>A generic key K = K_TOKEN | K _MAC (where '|' denotes
concatenation) is generated, e.g. by calling C_GenerateKey
(using key type CKK_GENERIC_SECRET). The template for K MUST
allow it to be exported (but only in wrapped form, i.e.
CKA_SENSITIVE MUST be set to CK_TRUE and CKA_EXTRACTABLE MUST
also be set to CK_TRUE), and also to be used for further key
derivation. From K, a token key K_TOKEN of suitable type is
derived by calling C_DeriveKey using the PKCS #11 mechanism
CKM_EXTRACT_KEY_FROM_KEY and setting the CK_EXTRACT_PARAMS to
the first bit of the generic secret key (i.e. set to 0).
Likewise, a MAC key K_MAC is derived from K by calling
C_DeriveKey using the CKM_EXTRACT_KEY_FROM_KEY mechanism, this
time setting CK_EXTRACT_PARAMS to the length of K (in bits)
divided by two.</t>
<t>The server wraps K with either the token's public key
K_CLIENT, the shared secret key K_SHARED, or the derived
shared secret key K_DERIVED by using C_WrapKey. If use of the
DSKPP key wrap algorithm has been negotiated then the
CKM_KIP_WRAP mechanism MUST be used to wrap K. When calling
C_WrapKey, the hKey handle in the CK_KIP_PARAMS structure MUST
be set to NULL_PTR. The pSeed parameter in the CK_KIP_PARAMS
structure MUST point to the nonce R provided by the DSKPP
client, and the ulSeedLen parameter MUST indicate the length
of R. The hWrappingKey parameter in the call to C_WrapKey MUST
be set to refer to the wrapping key.</t>
<t>Next, the server needs to calculate a MAC using K_MAC. If
use of the DSKPP MAC algorithm has been negotiated, then the
MAC is calculated by calling C_SignInit with the CKM_KIP_MAC
mechanism followed by a call to C_Sign. In the call to
C_SignInit, K_MAC MUST be the signature key, the hKey
parameter in the CK_KIP_PARAMS structure MUST be set to
NULL_PTR, the pSeed parameter of the CT_KIP_PARAMS structure
MUST be set to NULL_PTR, and the ulSeedLen parameter MUST be
set to zero. In the call to C_Sign, the pData parameter MUST
be set to the concatenation of the string ID_S and the nonce
R, and the ulDataLen parameter MUST be set to the length of
the concatenated string. The desired length of the MAC MUST be
specified through the pulSignatureLen parameter and MUST be
set to the length of R.</t>
<t>If the server also needs to authenticate its message (due
to an existing K_TOKEN being replaced), the server MUST
calculate a second MAC. Again, if use of the DSKPP MAC
algorithm has been negotiated, then the MAC is calculated by
calling C_SignInit with the CKM_KIP_MAC mechanism followed by
a call to C_Sign. In this call to C_SignInit, the K_MAC
existing before this DSKPP protocol run MUST be the signature
key, the hKey parameter in the CK_KIP_PARAMS structure MUST be
set to NULL, the pSeed parameter of the CT_KIP_PARAMS
structure MUST be set to NULL_PTR, and the ulSeeidLen
parameter MUST be set to zero. In the call to C_Sign, the
pData parameter MUST be set to the concatenation of the string
ID_S and the nonce R, and the ulDataLen parameter MUST be set
to the length of concatenated string. The desired length of
the MAC MUST be specified through the pulSignatureLen
parameter and MUST be set to the length of R.</t>
<t>The server sends its message to the client, including the
wrapped key K, the MAC and possibly also the authenticating
MAC.</t>
</list></t>
<t>On the client side, <list counter="3rd" style="format %d.">
<t>The client calls C_UnwrapKey to receive a handle to K.
After this, the client calls C_DeriveKey twice: Once to derive
K_TOKEN and once to derive K_MAC. The client MUST use the same
mechanism (CKM_EXTRACT_KEY_FROM_KEY) and the same mechanism
parameters as used by the server above. When calling
C_UnwrapKey and C_DeriveKey, the pTemplate parameter MUST be
used to set additional key attributes in accordance with local
policy and as negotiated and expressed in the protocol. In
particular, the value of the <KeyID> element in the
server's response message MAY be used as CKA_ID for K_TOKEN.
The key K MUST be destroyed after deriving K_TOKEN and
K_MAC.</t>
<t>The MAC is verified in a reciprocal fashion as it was
generated by the server. If use of the CKM_KIP_MAC mechanism
has been negotiated, then in the call to C_VerifyInit, the
hKey parameter in the CK_KIP_PARAMS structure MUST be set to
NULL_PTR, the pSeed parameter MUST be set to NULL_PTR, and
ulSeedLen MUST be set to 0. The hKey parameter of C_VerifyInit
MUST refer to K_MAC. In the call to C_Verify, pData MUST be
set to the concatenation of the string ID_S and the nonce R,
and the ulDataLen parameter MUST be set to the length of the
concatenated string, pSignature to the MAC value received from
the server, and ulSignatureLen to the length of the MAC. If
the MAC does not verify the protocol session ends with a
failure. The token MUST be constructed to not "commit" to the
new K_TOKEN or the new K_MAC unless the MAC verifies.</t>
<t>If an authenticating MAC was received (REQUIRED if the new
K_TOKEN will replace an existing key on the token), then it is
verified in a similar vein but using the K_MAC associated with
this server and existing before the protocol run. Again, if
the MAC does not verify the protocol session ends with a
failure, and the token MUST be constructed no to "commit" to
the new K_TOKEN or the new K_MAC unless the MAC verifies.</t>
</list></t>
</list></t>
</section>
<section title="The 1-pass Variant">
<t>A suggested procedure to perform 1-pass DSKPP with a cryptographic
module through the PKCS #11 interface using the mechanisms defined in
<xref target="CT-KIP-P11"></xref> is as follows:</t>
<t><list counter="1-pass" style="format %c.">
<t>On the server side, <list counter="1-1" style="format %d.">
<t>A generic key K = K_TOKEN | K _MAC (where '|' denotes
concatenation) is generated, e.g. by calling C_GenerateKey
(using key type CKK_GENERIC_SECRET). The template for K MUST
allow it to be exported (but only in wrapped form, i.e.
CKA_SENSITIVE MUST be set to CK_TRUE and CKA_EXTRACTABLE MUST
also be set to CK_TRUE), and also to be used for further key
derivation. From K, a token key K_TOKEN of suitable type is
derived by calling C_DeriveKey using the PKCS #11 mechanism
CKM_EXTRACT_KEY_FROM_KEY and setting the CK_EXTRACT_PARAMS to
the first bit of the generic secret key (i.e. set to 0).
Likewise, a MAC key K_MAC is derived from K by calling
C_DeriveKey using the CKM_EXTRACT_KEY_FROM_KEY mechanism, this
time setting CK_EXTRACT_PARAMS to the length of K (in bits)
divided by two.</t>
<t>The server wraps K with either the token's public key,
K_CLIENT, the shared secret key, K_SHARED, or the derived
shared secret key, K_DERIVED by using C_WrapKey. If use of the
DSKPP key wrap algorithm has been negotiated, then the
CKM_KIP_WRAP mechanism MUST be used to wrap K. When calling
C_WrapKey, the hKey handle in the CK_KIP_PARAMS structure MUST
be set to NULL_PTR. The pSeed parameter in the CK_KIP_PARAMS
structure MUST point to the octet-string representation of an
integer I whose value MUST be incremented before each protocol
run, and the ulSeedLen parameter MUST indicate the length of
the octet-string representation of I. The hWrappingKey
parameter in the call to C_WrapKey MUST be set to refer to the
wrapping key.<vspace blankLines="1" /> Note: The
integer-to-octet string conversion MUST be made using the
I2OSP primitive from <xref target="PKCS-1"></xref>. There MUST
be no leading zeros.</t>
<t>For the server's message to the client, if use of the DSKPP
MAC algorithm has been negotiated, then the MAC is calculated
by calling C_SignInit with the CKM_KIP_MAC mechanism followed
by a call to C_Sign. In the call to C_SignInit, K_MAC MUST be
the signature key, the hKey parameter in the CK_KIP_PARAMS
structure MUST be set to NULL_PTR, the pSeed parameter of the
CT_KIP_PARAMS structure MUST be set to NULL_PTR, and the
ulSeedLen parameter MUST be set to zero. In the call to
C_Sign, the pData parameter MUST be set to the concatenation
of the string ID_S and the octet-string representation of the
integer I, and the ulDataLen parameter MUST be set to the
length of concatenated string. The desired length of the MAC
MUST be specified through the pulSignatureLen parameter as
usual, and MUST be equal to, or greater than, sixteen
(16).</t>
<t>If the server also needs to authenticate its message (due
to an existing K_TOKEN being replaced), the server calculates
a second MAC. If the DSKPP MAC mechanism is used, the server
does this by calling C_SignInit with the CKM_KIP_MAC mechanism
followed by a call to C_Sign. In the call to C_SignInit, the
K_MAC existing on the token before this protocol run MUST be
the signature key, the hKey parameter in the CK_KIP_PARAMS
structure MUST be set to NULL_PTR, the pSeed parameter of the
CT_KIP_PARAMS structure MUST be set to NULL_PTR, and the
ulSeedLen parameter MUST be set to zero. In the call to
C_Sign, the pData parameter MUST be set to the concatenation
of the string ID_S and the octet-string representation of the
integer I+1 (i.e. I MUST be incremented before each use), and
the ulDataLen parameter MUST be set to the length of the
concatenated string. The desired length of the MAC MUST be
specified through the pulSignatureLen parameter as usual, and
MUST be equal to, or greater than, sixteen (16).</t>
<t>The server sends its message to the client, including the
MAC and possibly also the authenticating MAC.</t>
</list></t>
<t>On the client side, <list counter="1-2" style="format %d.">
<t>The client calls C_UnwrapKey to receive a handle to K.
After this, the client calls C_DeriveKey twice: Once to derive
K_TOKEN and once to derive K_MAC. The client MUST use the same
mechanism (CKM_EXTRACT_KEY_FROM_KEY) and the same mechanism
parameters as used by the server above. When calling
C_UnwrapKey and C_DeriveKey, the pTemplate parameter MUST be
used to set additional key attributes in accordance with local
policy and as negotiated and expressed in the protocol. In
particular, the value of the <KeyID> element in the
server's response message MAY be used as CKA_ID for K_TOKEN.
The key K MUST be destroyed after deriving K_TOKEN and
K_MAC.</t>
<t>The MAC is verified in a reciprocal fashion as it was
generated by the server. If use of the CKM_KIP_MAC mechanism
has been negotiated, then in the call to C_VerifyInit, the
hKey parameter in the CK_KIP_PARAMS structure MUST be set to
NULL_PTR, the pSeed parameter MUST be set to NULL_PTR, and
ulSeedLen MUST be set to 0. The hKey parameter of C_VerifyInit
MUST refer to K_MAC. In the call to C_Verify, pData MUST be
set to the concatenation of the string ID_S and the
octet-string representation of the provided value for I, and
the ulDataLen parameter MUST be set to the length of the
concatenated string, pSignature to the MAC value received from
the server, and ulSignatureLen to the length of the MAC. If
the MAC does not verify or if the provided value of I is not
larger than any stored value I' for the identified server ID_S
the protocol session ends with a failure. The token MUST be
constructed to not "commit" to the new K_TOKEN or the new
K_MAC unless the MAC verifies. If the verification succeeds,
the token MUST store the provided value of I as a new I' for
ID_S.</t>
<t>If an authenticating MAC was received (REQUIRED if K_TOKEN
will replace an existing key on the token), it is verified in
a similar vein but using the K_MAC existing before the
protocol run. Again, if the MAC does not verify the protocol
session ends with a failure, and the token MUST be constructed
no to "commit" to the new K_TOKEN or the new K_MAC unless the
MAC verifies.</t>
</list></t>
</list></t>
</section>
</section>
<section anchor="Section-PRFRealizations"
title="Example of DSKPP-PRF Realizations">
<section title="Introduction">
<t>This example appendix defines DSKPP-PRF in terms of AES <xref
target="FIPS197-AES"></xref> and HMAC <xref
target="RFC2104"></xref>.</t>
</section>
<section title="DSKPP-PRF-AES">
<section title="Identification">
<t>For cryptographic modules supporting this realization of
DSKPP-PRF, the following URI MAY be used to identify this algorithm
in DSKPP:</t>
<t>urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-aes</t>
<t>When this URI is used to identify the encryption algorithm to
use, the method for encryption of R_C values described in <xref
target="Subsection-Enc"></xref> MUST be used.</t>
</section>
<section title="Definition">
<t>DSKPP-PRF-AES (k, s, dsLen)</t>
<t>Input:<list hangIndent="10" style="hanging">
<t hangText="k">Encryption key to use</t>
<t hangText="s">Octet string consisting of randomizing material.
The length of the string s is sLen.</t>
<t hangText="dsLen">Desired length of the output</t>
</list></t>
<t>Output:</t>
<t><list hangIndent="10" style="hanging">
<t hangText="DS">A pseudorandom string, dsLen-octets long</t>
</list></t>
<t>Steps:</t>
<t><list hangIndent="0" style="format %d.">
<t>Let bLen be the output block size of AES in octets:<vspace
blankLines="1" />bLen = (AES output block length in
octets)<vspace blankLines="0" />(normally, bLen = 16)</t>
<t>If dsLen > (2**32 - 1) * bLen, output "derived data too
long" and stop</t>
<t>Let n be the number of bLen-octet blocks in the output data,
rounding up, and let j be the number of octets in the last
block:<vspace blankLines="1" />n = ROUND( dsLen / bLen)<vspace
blankLines="0" />j = dsLen - (n - 1) * bLen</t>
<t>For each block of the pseudorandom string DS, apply the
function F defined below to the key k, the string s and the
block index to compute the block:<vspace blankLines="1" />B1 = F
(k, s, 1) ,<vspace blankLines="0" />B2 = F (k, s, 2) ,<vspace
blankLines="0" />...<vspace blankLines="0" />Bn = F (k, s,
n)</t>
</list>The function F is defined in terms of the OMAC1
construction from <xref target="FSE2003"></xref>, using AES as the
block cipher:<vspace blankLines="1" />F (k, s, i) = OMAC1-AES (k,
INT (i) || s)<vspace blankLines="1" />where INT (i) is a four-octet
encoding of the integer i, most significant octet first, and the
output length of OMAC1 is set to bLen.<vspace
blankLines="1" />Concatenate the blocks and extract the first dsLen
octets to product the desired data string DS:<vspace
blankLines="1" />DS = B1 || B2 || ... || Bn<0..j-1><vspace
blankLines="1" />Output the derived data DS.</t>
</section>
<section title="Example">
<t>If we assume that dsLen = 16, then:</t>
<t>n = 16 / 16 = 1</t>
<t>j = 16 - (1 - 1) * 16 = 16</t>
<t>DS = B1 = F (k, s, 1) = OMAC1-AES (k, INT (1) || s)</t>
</section>
</section>
<section title="DSKPP-PRF-SHA256">
<section title="Identification">
<t>For cryptographic modules supporting this realization of
DSKPP-PRF, the following URI MAY be used to identify this algorithm
in DSKPP:</t>
<t>urn:ietf:params:xml:schema:keyprov:protocol#dskpp-prf-sha256</t>
<t>When this URI is used to identify the encryption algorithm to
use, the method for encryption of R_C values described in <xref
target="Subsection-Enc"></xref> MUST be used.</t>
</section>
<section title="Definition">
<t>DSKPP-PRF-SHA256 (k, s, dsLen)</t>
<t>Input:<list hangIndent="10" style="hanging">
<t hangText="k">Encryption key to use</t>
<t hangText="s">Octet string consisting of randomizing material.
The length of the string s is sLen.</t>
<t hangText="dsLen">Desired length of the output</t>
</list></t>
<t>Output:</t>
<t><list hangIndent="10" style="hanging">
<t hangText="DS">A pseudorandom string, dsLen-octets long</t>
</list></t>
<t>Steps:</t>
<t><list hangIndent="0" style="format %d.">
<t>Let bLen be the output size of SHA-256 in octets of <xref
target="FIPS180-SHA"></xref> (no truncation is done on the HMAC
output):<vspace blankLines="1" />bLen = 32<vspace
blankLines="0" />(normally, bLen = 16)</t>
<t>If dsLen > (2**32 - 1) * bLen, output "derived data too
long" and stop</t>
<t>Let n be the number of bLen-octet blocks in the output data,
rounding up, and let j be the number of octets in the last
block:<vspace blankLines="1" />n = ROUND( dsLen / bLen)<vspace
blankLines="0" />j = dsLen - (n - 1) * bLen</t>
<t>For each block of the pseudorandom string DS, apply the
function F defined below to the key k, the string s and the
block index to compute the block:<vspace blankLines="1" />B1 = F
(k, s, 1) ,<vspace blankLines="0" />B2 = F (k, s, 2) ,<vspace
blankLines="0" />...<vspace blankLines="0" />Bn = F (k, s,
n)</t>
</list>The function F is defined in terms of the HMAC construction
from <xref target="RFC2104"></xref>, using SHA-256 as the digest
algorithm:<vspace blankLines="1" />F (k, s, i) = HMAC-SHA256 (k, INT
(i) || s)<vspace blankLines="1" />where INT (i) is a four-octet
encoding of the integer i, most significant octet first, and the
output length of HMAC is set to bLen.<vspace
blankLines="1" />Concatenate the blocks and extract the first dsLen
octets to product the desired data string DS:<vspace
blankLines="1" />DS = B1 || B2 || ... || Bn<0..j-1><vspace
blankLines="1" />Output the derived data DS.</t>
</section>
<section title="Example">
<t>If we assume that sLen = 256 (two 128-octet long values) and
dsLen = 16, then:</t>
<t>n = ROUND ( 16 / 32 ) = 1</t>
<t>j = 16 - (1 - 1) * 32 = 16</t>
<t>B1 = F (k, s, 1) = HMAC-SHA256 (k, INT (1) || s)</t>
<t>DS = B1<0 ... 15></t>
<t>That is, the result will be the first 16 octets of the HMAC
output.</t>
</section>
</section>
</section>
</back>
</rfc>| PAFTECH AB 2003-2026 | 2026-04-23 20:38:20 |