One document matched: draft-ietf-keyprov-dskpp-05.xml
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<!-- Copyright 2006 RSA Security Inc. All rights reserved. -->
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<rfc category="std" docName="draft-ietf-keyprov-dskpp-05.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>andrea.doherty@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>magnus.nystrom@rsa.com</email>
</address>
</author>
<date day="12" month="July" year="2008" />
<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>Two variations of the protocol support multiple usage scenarios. 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. The two-pass variant enables secure and
efficient download and installation of pre-generated symmetric keys to a
cryptographic module.</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 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">
<t>A symmetric key cryptographic module provides data authentication and
encryption services to software (or firmware) applications hosted on
hardware devices, such as personal computers, handheld mobile phones,
one-time password tokens, USB flash drives, tape drives, etc. Until
recently, provisioning symmetric keys to these modules has been labor
intensive, involving manual operations that are device-specific, and
inherently error-prone.</t>
<t>Fortunately, an increasing number of hardware devices enable
programmatic initialization of their applications. For example, a
U3-ready thumb drive lets users load and configure applications locally
through a USB port on their PC. Other hardware devices, such as Personal
Digital Assistant (PDA) phones, allow users to load and configure
applications over-the-air. Likewise, programmable cryptographic modules
enable key issuers to provision symmetric keys via the Internet, whether
over-the-wire or over-the-air.</t>
<t>This document describes the Dynamic Symmetric Key Provisioning
Protocol (DSKPP), which leverages these recent technological
developments. DSKPP provides an open and interoperable mechanism for
initializing and configuring symmetric keys to cryptographic modules
that are accessible over the Internet. The description is based on the
information contained in RFC4758, and contains specific enhancements,
such as User Authentication and support for the <xref
target="PSKC"></xref> format for transmission of keying material.</t>
<t>DSKPP is a client-server protocol with two variations. One variation
establishes a symmetric key by mutually authenticated key agreement. The
other variation relies on key distribution. In the former case, key
agreement enables two parties (a cryptographic module and key
provisioning server) to establish a symmetric cryptographic key using an
exchange of four messages, such that the key is not transported over the
Internet. In the latter case, key distribution enables a key
provisioning server to transport a symmetric key to a cryptographic
module over the Internet using an exchange of two messages. In either
case, DSKPP is flexible enough to be run with or without private-key
capability in the cryptographic module, and with or without an
established public-key infrastructure.</t>
<t>All DSKPP communications consist of pairs of messages: a request and
a response. Each pair is called an “exchange”, and each
message sent in an exchange is called a “pass”. Thus, an
implementation of DSKPP that relies on mutually authenticated key
agreement is called the “four-pass protocol”; an
implementation of DSKPP that relies on key distribution is called the
“two-pass protocol”.</t>
<t>DSKPP message flow always consists of a request followed by a
response. It is the responsibility of the client to ensure reliability.
If the response is not received with a timeout interval, the client
needs to retransmit the request (or abandon the connection). Number of
retries and lengths of timeouts are not covered in this document because
they do not affect interoperability.</t>
<section title="Usage Scenarios">
<t>DSKPP is expected to be used to provision symmetric keys to
cryptographic modules in a number of different scenarios, each with
its own special requirements.</t>
<section anchor="UC1" title="Single Key Request">
<t>The usual scenario is that a cryptographic module makes a request
for a symmetric key from a provisioning server that is located on
the local network or somewhere on the Internet. Depending upon the
deployment scenario, 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 need 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 the AES encryption algorithm.</t>
</section>
<section title="User Authentication">
<t>In some deployment scenarios, a key issuer may rely on a third
party provisioning service. In this case, the issuer directs
provisioning requests from the cryptographic module to the
provisioning service. As such, it is the responsibility of the
issuer to authenticate the user through some out-of-band means
before granting him rights to acquire keys. Once the issuer has
granted those rights, the issuer provides an authentication code to
the user and makes it available to the provisioning service, so that
the user can prove that he is authorized to acquire keys.</t>
</section>
<section title="Provisioning Time-Out Policy">
<t>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. The server will allow a key to be provisioned
to the cryptographic module hosted by the user's device when user
authentication is required only if the user inputs a valid
authentication code within the fixed time period established by the
issuer.</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 scenario 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 a device 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
scenario is the organization who recycles devices. In this case, a
key 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 usage scenario is essentially the same as the last
scenario wherein the same key ID is used for renewal.</t>
</section>
<section title="Pre-Shared Manufacturing 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-issued card manufacturer's
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 usage scenario are for the
protocol to be tunneled and the provisioning server to know the
correct pre-established manufacturer's key.</t>
</section>
<section title="End-to-End Protection of Key Material">
<t>In this scenario, transport layer security does not provide
end-to-end protection of keying material transported from the
provisioning server to the cryptographic module. For example, TLS
may terminate at an application hosted on a PC rather than at the
cryptographic module (i.e., the endpoint) located on a data storage
device. Mutually authenticated key agreement provides end-to-end
protection, which TLS cannot provide.</t>
</section>
</section>
<section title="Protocol 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. In this document,
the DSKPP server 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>. Conceptually, each entity is represented by
the definitions found in <xref
target="Subsection-Definitions"></xref>.</t>
<figure anchor="Objects" title="Object Model">
<artwork><![CDATA[----------- -------------
| User | | Device |
|---------|* owns *|-----------|
| UserID |--------->| DeviceID |
| ... | | ... |
----------- -------------
| 1
|
| contains
|
| *
V
--------------------------
|Cryptographic Module |
|------------------------|
|Crypto Module ID |
|Security Attribute List |
|... |
--------------------------
| 1
|
| contains
|
| *
V
-----------------------
|Key Package |
|---------------------|
|Key ID |
|Key Type |
|... |
-----------------------
]]></artwork>
</figure>
<t>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="Initiating DSKPP">
<t>To initiate DSKPP:<vspace blankLines="1" /><list hangIndent="4"
style="format %d.">
<t>A server may first send a DSKPP trigger message to a client
application (e.g., in response to a user browsing to a Web site
that requires a symmetric key for authentication), although this
step is optional.</t>
<t>A client application calls on the DSKPP client to send a
symmetric key request to a DSKPP server, thus beginning a DSKPP
protocol run.</t>
</list></t>
<t>One of the following actions may be used to contact a DSKPP
server:<vspace blankLines="1" /><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 or 2-pass protocol.</t>
</section>
<section title="Determining Which Protocol Variant to Use">
<t>The four-pass and two-pass protocols are appropriate in different
deployment scenarios, as described in the sub-sections below. The
biggest differentiator between the two is that the two-pass protocol
supports transport of an existing key to a cryptographic module, while
the four-pass involves key generation on-the-fly via key agreement. In
either case, both protocol variants support algorithm agility through
negotiation of encryption mechanisms and key types at the beginning of
each protocol run.</t>
<section title="Criteria for Using the Four-Pass Protocol">
<t>The four-pass protocol is needed under one or more of the
following conditions:<vspace blankLines="1" /><list style="symbols">
<t>Policy requires that both parties engaged in the protocol
jointly contribute entropy to the key. Enforcing this policy
mitigates the risk of exposing a key during the provisioning
process as the key is generated through mutual agreement without
being transferred over-the-air or over-the-wire. It also
mitigates risk of exposure after the key is provisioned, as the
key will be not be vulnerable to a single point of attack in the
system.</t>
<t>A cryptographic module does not have private-key
capabilities.</t>
<t>The cryptographic module is hosted by a device that was
neither pre-issued with a manufacturer's key or other form of
pre-shared key (as might be the case with a smart card or SIM
card) nor has a keypad that can be used for entering a
passphrase (such as present on a mobile phone).</t>
</list></t>
</section>
<section title="Criteria for Using the Two-Pass Protocol">
<t>The two-pass protocol is needed under one or more of the
following conditions:<vspace blankLines="1" /><list style="symbols">
<t>Pre-existing (i.e., legacy) keys must be provisioned via
transport to the cryptographic module.</t>
<t>The cryptographic module is hosted on a device that was
pre-issued with a manufacturer's key (such as may exist on a
smart card), or other form of pre-shared key (such as may exist
on a SIM-card), and is capable of performing private-key
operations.</t>
<t>The cryptographic module is hosted by a device that has a
built-in keypad with which a user may enter a passphrase, useful
for deriving a key wrapping key for distribution of keying
material.</t>
</list></t>
</section>
</section>
<section title="Presentation Syntax">
<t>This documents presents DSKPP message formats and data elements
using XML syntax. The main goal in using this syntax is to document
DSKPP. Application of the syntax beyond this goal is OPTIONAL.</t>
<section title="Versions">
<t>There is a provision made in the syntax for an explicit version
number. Only version "1.0" is currently specified.</t>
</section>
<section title="Namespaces">
<t>The XML namespace <xref target="XMLNS"></xref> URN that MUST be
used by implementations of this syntax is:</t>
<t>xmlns:dskpp="urn:ietf:params:xml:ns:keyprov:dskpp:1.0"</t>
<t>References to qualified elements in the DSKPP schema defined
herein use the prefix "dskpp".</t>
<t>This document relies on qualified elements already defined in the
Portable Symmetric Key Container <xref target="PSKC"></xref>
namespace, which is represented by the prefix "pskc" and declared
as:</t>
<t>xmlns:pskc="urn:ietf:params:xml:ns:keyprov:pskc:1.0"</t>
<t>Finally, the DSKPP syntax presented in this document relies on
algorithm identifiers defined in the XML Signature <xref
target="XMLDSIG"></xref> namespace:</t>
<t>xmlns:ds="http://www.w3.org/2000/09/xmldsig#"</t>
<t>References to algorithm identifiers in the XML Signature
namespace are represented by the prefix "ds".</t>
</section>
<section title="Identifiers">
<t>This document uses Uniform Resource Identifiers <xref
target="RFC2396"></xref> to identify resources, algorithms, and
semantics.</t>
</section>
</section>
</section>
<!-- ////////////////////////////////////////////////////////////////////////////////// -->
<section anchor="terms" title="Terminology">
<section title="Key Words">
<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>.</t>
</section>
<section anchor="Subsection-Definitions" title="Definitions">
<t>The definitions provided below are defined as used in this
document. The same terms may be defined differently in other
documents.</t>
<t><list hangIndent="4" style="hanging">
<t hangText="Authentication Code (AC):">Client Authentication Code
comprised of a string of numeric characters known to the device
and the server and containing an identifier and a password<vspace
blankLines="1" /></t>
<t hangText="Authentication Data (AD):">Client Authentication Data
that may be derived from the Authentication Code (AC)<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="CryptoModule ID:">A unique identifier for an instance
of the cryptographic module<vspace blankLines="1" /></t>
<t hangText="Device:">A physical piece of hardware, or a software
framework, that hosts symmetric key cryptographic modules<vspace
blankLines="1" /></t>
<t hangText="Device ID (DeviceID):">A unique identifier for the
device<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="DSKPP Server ID (ServerID):">The unique identifier of
a DSKPP server<vspace blankLines="1" /></t>
<t hangText="Issuer:">See "Key Issuer"<vspace
blankLines="1" /></t>
<t hangText="Key Issuer:">An organization that issues symmetric
keys to end-users<vspace blankLines="1" /></t>
<t hangText="Key Package (KP):">An object that encapsulates a
symmetric key and its configuration data<vspace
blankLines="1" /></t>
<t hangText="Key Package Header (KPH):">Information about the Key
Package, useful for two-pass DSKPP, e.g., the passing the ServerID
and the Key Protection Method<vspace blankLines="1" /></t>
<t hangText="Key ID (KeyID):">A unique identifier for the
symmetric key<vspace blankLines="1" /></t>
<t hangText="Key Protection Method (KPM):">The key transport
method used during two-pass DSKPP<vspace blankLines="1" /></t>
<t hangText="Key Protection Method List (KPML):">The list of key
protection methods supported by a cryptographic module<vspace
blankLines="1" /></t>
<t hangText="Key Provisioning Server:">A lifecycle management
system that provides a key issuer with the ability to provision
keys to cryptographic modules hosted on end-users' devices<vspace
blankLines="1" /></t>
<t hangText="Key Transport:">A key establishment procedure whereby
the DSKPP server selects and encrypts the keying material and then
sends the material to the DSKPP client <xref
target="NIST-SP800-57"></xref><vspace blankLines="1" /></t>
<t hangText="Key Transport Key:">The private key that resides on
the cryptographic module. This key is paired with the DSKPP
client's public key, which the DSKPP server uses to encrypt keying
material during key transport <xref
target="NIST-SP800-57"></xref><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>
<t hangText="Key Wrapping:">A method of encrypting keys for key
transport <xref target="NIST-SP800-57"></xref><vspace
blankLines="1" /></t>
<t hangText="Key Wrapping Key:">A symmetric key encrypting key
used for key wrapping <xref target="NIST-SP800-57"></xref><vspace
blankLines="1" /></t>
<t hangText="Keying Material:">The data necessary (e.g., keys and
key configuration data) necessary to establish and maintain
cryptographic keying relationships <xref
target="NIST-SP800-57"></xref><vspace blankLines="1" /></t>
<t hangText="Manufacturer's Key">A unique master key pre-issued to
a hardware device, e.g., a smart card, during the manufacturing
process. If present, this key may be used by a cryptographic
module to derive secret keys<vspace blankLines="1" /></t>
<t hangText="Provisioning Service:">See "Key Provisioning
Server"<vspace blankLines="1" /></t>
<t hangText="Security Attribute List (SAL):">A payload that
contains the DSKPP version, DSKPP variation (four- or two-pass),
key package formats, key types, and cryptographic algorithms that
the cryptographic module is capable of supporting<vspace
blankLines="1" /></t>
<t hangText="Security Context (SC):">A payload that contains the
DSKPP version, DSKPP variation (four- or two-pass), key package
format, key type, and cryptographic algorithms relevant to the
current protocol run<vspace blankLines="1" /></t>
<t hangText="User:">The person or client to whom devices are
issued<vspace blankLines="1" /></t>
<t hangText="User ID:">A unique identifier for the user or
client<vspace blankLines="1" /></t>
</list></t>
</section>
<section title="Notation">
<t><list hangIndent="18" 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="<XMLElement>">A typographical convention used
in the body of the text<vspace blankLines="1" /></t>
<t hangText="DSKPP-PRF(k,x,l)">A keyed pseudo-random function (see
<xref target="DSKPP-PRF"></xref>)<vspace blankLines="1" /></t>
<t hangText="E(k,m)">Encryption of m with the key k<vspace
blankLines="1" /></t>
<t hangText="K">Key used to encrypt R_C (either K_SERVER or
K_SHARED), or in MAC or DSKPP_PRF computations<vspace
blankLines="1" /></t>
<t hangText="K_AC">Secret key that is derived from the
Authentication Code and used for user authentication
purposes<vspace blankLines="1" /></t>
<t hangText="K_MAC">Secret key derived during a DSKPP exchange for
use with key confirmation<vspace blankLines="1" /></t>
<t hangText="K_MAC'">A second secret key used for server
authentication<vspace blankLines="1" /></t>
<t hangText="K_PROV">A provisioning master key from which two keys
are derived: K_TOKEN and K_MAC<vspace blankLines="1" /></t>
<t hangText="K_SERVER">Public key of the DSKPP server; used for
encrypting R_C in the four-pass protocol variant<vspace
blankLines="1" /></t>
<t hangText="K_SHARED">Secret key that is pre-shared between the
DSKPP client and the DSKPP server; used for encrypting R_C in the
four-pass protocol variant<vspace blankLines="1" /></t>
<t hangText="K_TOKEN">Secret key that is established in a
cryptographic module using DSKPP<vspace blankLines="1" /></t>
<t hangText="R">Pseudorandom value chosen by the DSKPP client and
used for MAC computations<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="R_TRIGGER">Pseudorandom value chosen by the DSKPP
server and used as input in a trigger message.<vspace
blankLines="1" /></t>
<t hangText="URL_S">DSKPP server address, as a URL<vspace
blankLines="1" /></t>
</list></t>
</section>
<section title="Abbreviations">
<t><list hangIndent="8" style="hanging">
<t hangText="AC">Authentication Code</t>
<t hangText="AD">Authentication Data</t>
<t hangText="DSKPP">Dynamic Symmetric Key Provisioning
Protocol</t>
<t hangText="HTTP">Hypertext Transfer Protocol</t>
<t hangText="KP">Key Package</t>
<t hangText="KPH">Key Package Header</t>
<t hangText="KPM">Key Protection Method</t>
<t hangText="KPML">Key Protection Method List</t>
<t hangText="MAC">Message Authentication Code</t>
<t hangText="PC">Personal Computer</t>
<t hangText="PDU">Protocol Data Unit</t>
<t hangText="PKCS">Public-Key Cryptography Standards</t>
<t hangText="PRF">Pseudo-Random Function</t>
<t hangText="PSKC">Portable Symmetric Key Container</t>
<t hangText="SAL">Security Attribute List (see <xref
target="Subsection-Definitions"></xref>)</t>
<t hangText="SC">Security Context (see <xref
target="Subsection-Definitions"></xref>)</t>
<t hangText="TLS">Transport Layer Security</t>
<t hangText="URL">Uniform Resource Locator</t>
<t hangText="USB">Universal Serial Bus</t>
<t hangText="XML">eXtensible Markup Language</t>
</list></t>
</section>
</section>
<!---->
<section anchor="Section-Protocol" title="DSKPP Protocol Details">
<t>DSKPP enables symmetric key provisioning between a DSKPP server and
DSKPP client. The DSKPP protocol supports the request and response
messages shown in <xref target="Figure-Overview"></xref>. These messages
are described below.</t>
<figure anchor="Figure-Overview"
title="The DSKPP protocol (with OPTIONAL preceding trigger)">
<artwork><![CDATA[+---------------+ +---------------+
| | | |
| DSKPP Client | | DSKPP Server |
| | | |
+---------------+ +---------------+
| |
| [ <--------- <KeyProvTrigger> --------- ] |
| |
| ------- <KeyProvClientHello> -------> |
| (Applicable to 4- and 2-pass) |
| |
| <------ <KeyProvServerHello> -------- |
| (Applicable to 4-pass only) |
| |
| ------- <KeyProvClientNonce> -------> |
| (Applicable to 4-pass only) |
| |
| <---- <KeyProvServerFinished> ------- |
| (Applicable to 4- and 2-pass) |
| |
]]></artwork>
</figure>
<t><list hangIndent="4" style="hanging">
<t hangText="[<KeyProvTrigger>]:">A DSKPP server may initiate
the DSKPP protocol by sending a <KeyProvTrigger> message. For
example, this message may be sent in response to a user requesting a
symmetric key in a browsing session. The trigger message always
contains a nonce to allow the server to couple the trigger with a
later <KeyProvClientHello> request.<vspace
blankLines="1" /></t>
<t hangText="<KeyProvClientHello>:">With this request, a DSKPP
client initiates contact with the DSKPP server, indicating which
protocol versions and variations (four-pass or two-pass), 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>
<t hangText="<KeyProvServerHello>:">Upon receiving a
<KeyProvClientHello> request, the DSKPP server uses the
<KeyProvServerHello> response to specify which protocol
version and variation, 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 variation, key type,
and cryptographic algorithms to pick is policy- and
implementation-dependent and therefore outside the scope of this
document.<vspace blankLines="1" />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).<vspace blankLines="1" />Optionally, the DSKPP
server may provide a MAC that the DSKPP client may use for server
authentication.<vspace blankLines="1" /></t>
<t hangText="<KeyProvClientNonce>:">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
user authentication data that the DSKPP server uses to verify
proof-of-possession of the device.<vspace blankLines="1" /></t>
<t hangText="<KeyProvServerFinished>:">The
<KeyProvServerFinished> response is a confirmation message
that includes a key package that holds configuration data, and may
also contain protected keying material (this depends on the protocol
variation, as discussed below).<vspace blankLines="1" />Optionally,
the DSKPP server may provide a MAC that the DSKPP client may use for
server authentication.</t>
</list></t>
<section anchor="Subsection-FourPassUsage"
title="Four-Pass Protocol Usage">
<t>This section describes the message flow and methods that comprise
the four-pass protocol variant.</t>
<section anchor="Subsection-4PassFlow" title="Message Flow">
<t>The four-pass protocol flow consists of two message
exchanges:</t>
<t><list style="format %d:">
<t>Pass 1 = <KeyProvClientHello>, Pass 2 =
<KeyProvServerHello></t>
<t>Pass 3 = <KeyProvClientNonce>, Pass 4 =
<KeyProvServerFinished></t>
</list></t>
<t>The first pair of messages negotiate cryptographic algorithms and
exchange nonces. The second pair of messages establishes a symmetric
key using mutually authenticated key agreement.</t>
<t>The DSKPP server MUST ensure that a generated key is associated
with the correct cryptographic module, and if applicable, the
correct user. To do this, the DSKPP server MAY couple an initial
user authentication to the DSKPP execution using one of the
mechanisms described in <xref
target="Section-ClientAuthN"></xref>.</t>
<t>The purpose and content of each message are described below,
including the optional <KeyProvTrigger>.</t>
<figure>
<preamble></preamble>
<artwork><![CDATA[ DSKPP Client DSKPP Server
------------ ------------
[<---] R_TRIGGER, [DeviceID],
[KeyID], [URL_S]
]]></artwork>
</figure>
<t>The DSKPP server optionally sends a <KeyProvTrigger>
message to the DSKPP client. The trigger message MUST contain a
nonce, R_TRIGGER, to allow the server to couple the trigger with a
later <KeyProvClientHello> request. <KeyProvTrigger> MAY
include a DeviceID to allow the client to select the device with
which it will communicate (for more information about device
identification, refer to <xref
target="Subsection-DeviceID"></xref>). In the case of key renewal,
<KeyProvTrigger> MAY include the identifier for the key,
KeyID, that is being replaced. Finally, the trigger MAY contain a
URL for the DSKPP client to use when contacting the DSKPP
server.</t>
<figure>
<preamble></preamble>
<artwork><![CDATA[ DSKPP Client DSKPP Server
------------ ------------
SAL, [R_TRIGGER],
[DeviceID], [KeyID] --->
]]></artwork>
</figure>
<t>The DSKPP client sends a <KeyProvClientHello> message to
the DSKPP server. This message MUST contain a Security Attribute
List (SAL), identifying which DSKPP versions, protocol variations
(in this case "four-pass"), key package formats, key types,
encryption and MAC algorithms that the client supports. In addition,
if a trigger message preceded <KeyProvClientHello>, then it
passes the parameters received in <KeyProvTrigger> back to the
DSKPP Server. In particular, it MUST include R_TRIGGER so that the
DSKPP server can associate the client with the trigger message, and
SHOULD include DeviceID and KeyID.</t>
<figure>
<preamble></preamble>
<artwork><![CDATA[ DSKPP Client DSKPP Server
------------ ------------
<--- SC, R_S, [K], [MAC]
]]></artwork>
</figure>
<t>The DSKPP server responds to the DSKPP client with a
<KeyProvServerHello> message, whose Status attribute is set to
a return code for <KeyProvClientHello>. If Status is not
"Continue", only the Status and Version attributes will be present,
and the DSKPP client MUST abort the protocol. If Status is set to
"Continue", then the message MUST include a Security Context (SC).
The DSKPP client will use the SC to select the DSKPP version and
variation (e.g., four-pass), type of key to generate, and
cryptographic algorithms that it will use for the remainder of the
protocol run. <KeyProvServerHello> MUST also include the
server's random nonce, R_S, whose length may depend on the selected
key type. In addition, the <KeyProvServerHello> message MAY
provide K, which represents its own public key (K_SERVER) or
information about a shared secret key (K_SHARED) to use for
encrypting the cryptographic module's random nonce (see description
of <KeyProvClientNonce> below). Optionally,
<KeyProvServerHello> MAY include a MAC that the DSKPP client
can use for server authentication in the case of key renewal (<xref
target="Subsection-4passAuthZ"></xref> describes how to calculate
the MAC).</t>
<figure>
<preamble></preamble>
<artwork><![CDATA[ DSKPP Client DSKPP Server
------------ ------------
E(K,R_C), [AD] --->
]]></artwork>
</figure>
<t>Based on the Security Context (SC) provided in the
<KeyProvServerHello> message, the cryptographic module
generates a random nonce, R_C. The length of the nonce R_C will
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.</t>
<t>Note: 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>.</t>
<t>Note: If successful execution of the protocol will result in the
replacement of an existing key with a newly generated one, the DSKPP
client MUST verify the MAC provided in the
<KeyProvServerHello> message. 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.</t>
<t>The DSKPP client MUST send the encrypted random nonce to the
DSKPP server in a <KeyProvClientNonce> message, and MAY
include client Authentication Data (AD), such as a MAC derived from
an authentication code and R_C (refer to <xref
target="Section-AuthCode"></xref>). Finally, the cryptographic
module calculates and stores a symmetric key, K_TOKEN, of the key
type specified in the SC received in <KeyProvServerHello>
(refer to <xref
target="Subsection-KeyGen"></xref>.<KeyProvServerFinished> for
a description of how K_TOKEN is generated).</t>
<figure>
<preamble></preamble>
<artwork><![CDATA[ DSKPP Client DSKPP Server
------------ ------------
<--- KP, MAC
]]></artwork>
</figure>
<t>If Authentication Data (AD) was received in the
<KeyProvClientNonce> message, then the DSKPP server MUST
authenticate the user in accordance with <xref
target="Section-AuthCode"></xref>. If authentication fails, then
DSKPP server MUST abort. Otherwise, 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 (refer
to <xref target="Subsection-KeyGen"></xref> for a description of how
K_TOKEN is generated). 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 MUST include
a Key Package (KP) 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
package format is based on the Portable Symmetric Key Container
(PSKC) defined in <xref target="PSKC"></xref>. Alternative formats
MAY include <xref target="SKPC-ASN.1"></xref>, PKCS#12 <xref
target="PKCS-12"></xref>, or PKCS#5 XML <xref
target="PKCS-5-XML"></xref> format. In addition to a Key Package,
<KeyProvServerFinished> MUST also include a MAC that the DSKPP
client will use to authenticate the message before committing
K_TOKEN.</t>
<t>After receiving a <KeyProvServerFinished> message with
Status = "Success", 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 protocol. If
<KeyProvServerFinished> has Status = "Success" and the MAC was
verified, then the DSKPP client MUST associate the provided key
package with the generated key K_TOKEN, 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>
</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 anchor="Subsection-FourPassDataFlow" 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. using a connection
independent from the one used for the key generation).</t>
</section>
<section anchor="Subsection-KeyGen"
title="Computing the Symmetric Key">
<t>In DSKPP, K_TOKEN and K_MAC 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. The input parameter
dsLen is set to the desired length of the key, K_PROV, whose first
half constitutes K_MAC and second half constitutes K_TOKEN. The
combined length is determined by the type of K_TOKEN and
K_MAC:</t>
<t>dsLen = (desired length of K_PROV, i.e., the combined length of
K_TOKEN and K_MAC)</t>
<t>K_PROV = DSKPP-PRF (R_C, "Key generation" || K || R_S,
dsLen)</t>
<t>Then K_TOKEN and K_MAC derived from K_PROV, where</t>
<t>K_PROV = K_MAC || K_TOKEN</t>
<t>When computing K_PROV, the derived keys, K_MAC and K_TOKEN, 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.</t>
</section>
</section>
<section anchor="Subsection-Enc"
title="Encryption of Pseudorandom Nonces Sent from the DSKPP Client">
<t>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>E(DS, R_C) = DS ^ R_C</t>
<t>The DSKPP server will then perform the reverse operation to
extract R_C from E(DS, R_C).</t>
</section>
<section title="MAC Calculations">
<section anchor="Subsection-4passAuthZ"
title="Server Authentication in the Case of Key Renewal">
<t>A MAC MUST be present in the <KeyProvServerHello> message
if the DSKPP run will result in the replacement of an existing key
with a new one, as proof that the DSKPP server is authenticated to
perform the action. 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' (i.e., the value
of the MAC key that existed before this protocol run). Note that
the implementation may specify K_MAC' to be the value of the
K_TOKEN that is being replaced, or a version of K_MAC from the
previous protocol run.</t>
<t>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>
<t>The MAC algorithm MUST be the same as the algorithm used for
key confirmation purposes.</t>
</section>
<section title="Key Confirmation">
<t>To avoid a false "Commit" message causing the cryptographic
module to end up in an initialized state in which the server does
not recognize the stored key, <KeyProvServerFinished>
messages MUST be authenticated with a MAC, calculated as
follows:</t>
<t>msg_hash = SHA-256(msg_1, ..., msg_n)</t>
<t>dsLen = len(msg_hash)</t>
<t>MAC = DSKPP-PRF (K_MAC, "MAC 2 computation" || msg_hash,
dsLen)</t>
<t>where</t>
<t><list hangIndent="12" style="hanging">
<t hangText="MAC">The MAC MUST be calculated using the already
established MAC algorithm and MUST be computed on the (ASCII)
string "MAC 2 computation" and msg_hash using the existing the
MAC key K_MAC.<vspace blankLines="1" /></t>
<t hangText="K_MAC">The key derived from K_PROV, as described
in <xref target="Subsection-KeyGen"></xref>. <vspace
blankLines="1" /></t>
<t hangText="msg_hash">The message hash, defined below, of
messages msg_1, ..., msg_n.</t>
</list></t>
<t>If DSKPP-PRF (defined in <xref target="DSKPP-PRF"></xref>) is
used as the MAC algorithm, then the input parameter s MUST consist
of the concatenation of the (ASCII) string "MAC 2 computation" and
msg_hash, and the parameter dsLen MUST be set to the length of
msg_hash.</t>
</section>
<section anchor="Subsection-MsgHashAlg"
title="Message Hash Algorithm">
<t>To compute a message hash for a MAC, given a sequence of DSKPP
messages msg_1, ..., msg_n, the following operations MUST be
carried out:<vspace blankLines="1" /><list hangIndent=""
style="format %c.">
<t>The sequence of messages contains all DSKPP Request and
Response messages up to but not including this message.<vspace
blankLines="0" /></t>
<t>Re-transmitted messages are removed from the sequence of
messages.<vspace blankLines="0" />Note: The resulting sequence
of messages MUST be an alternating sequence of DSKPP Request
and DSKPP Response messages<vspace blankLines="0" /></t>
<t>The contents of each message is concatenated
together.<vspace blankLines="0" /></t>
<t>The resulting string is hashed using SHA-256 in accordance
with <xref target="FIPS180-SHA"></xref>.</t>
</list></t>
</section>
</section>
</section>
<section anchor="Subsecton-TwoPass" title="Two-Pass Protocol Usage">
<t>This section describes the message flow and methods that comprise
the two-pass protocol variant. Two-pass DSKPP is essentially a
transport of keying material from the DSKPP server to the DSKPP
client. The keying material is contained in a package that is
formatted in such a way that ensures that the symmetric key that is
being established, K_TOKEN, is not exposed to any other entity than
the DSKPP server and the cryptographic module itself. To ensure the
keying material is adequately protected for all two-pass usage
scenarios, the key package format MUST support the following key
protection methods, as defined in <xref
target="Section-Profiles"></xref>:</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 the public
key of the DSKPP client, whose private key part resides in the
cryptographic module as the key 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 key
wrapping key, 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, known in advance by
both the cryptographic module and DSKPP server.</t>
</list></t>
<t>Key package formats that satisfy this criteria are <xref
target="PSKC"></xref> and <xref target="SKPC-ASN.1"></xref>.</t>
<section anchor="Subsection-2PassFlow" title="Message Flow">
<t>The two-pass protocol flow consists of one exchange:</t>
<t><list style="format %d:">
<t>Pass 1 = <KeyProvClientHello>, Pass 2 =
<KeyProvServerFinished></t>
</list></t>
<t>The client's initial <KeyProvClientHello> message is
directly followed by a <KeyProvServerFinished> message (unlike
the four-pass variant, there is no exchange of the
<KeyProvServerHello> and <KeyProvClientNonce> messages).
However, as the two-pass variation 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.</t>
<t>The DSKPP server MUST ensure that a generated key is associated
with the correct cryptographic module, and if applicable, the
correct user. To ensure that the key 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 as
described in <xref target="Section-ClientAuthN"></xref>.</t>
<t>The purpose and content of each message are described below,
including the optional <KeyProvTrigger>.</t>
<figure>
<preamble></preamble>
<artwork><![CDATA[ DSKPP Client DSKPP Server
------------ ------------
[<---] R_TRIGGER, [DeviceID],
[KeyID], [URL_S]
]]></artwork>
</figure>
<t>The DSKPP server optionally sends a <KeyProvTrigger>
message to the DSKPP client. The trigger message MUST contain a
nonce, R_TRIGGER, to allow the server to couple the trigger with a
later <KeyProvClientHello> request. <KeyProvTrigger> MAY
include a DeviceID to allow the client to select the device with
which it will communicate (for more information about device
identification, refer to <xref
target="Subsection-DeviceID"></xref>). In the case of key renewal,
<KeyProvTrigger> SHOULD include the identifier for the key,
KeyID, that is being replaced. Finally, the trigger MAY contain a
URL for the DSKPP client to use when contacting the DSKPP
server.</t>
<figure>
<preamble></preamble>
<artwork><![CDATA[ DSKPP Client DSKPP Server
------------ ------------
R_C, SAL, KPML, [AD],
[R_TRIGGER],
[DeviceID], [KeyID] --->
]]></artwork>
</figure>
<t>The DSKPP client sends a <KeyProvClientHello> message to
the DSKPP server. <KeyProvClientHello> MUST include client
nonce, R_C, and a Security Attribute List (SAL), identifying which
DSKPP versions, protocol variations (in this case "two-pass"), key
package formats, key types, encryption and MAC algorithms that the
client supports. Unlike 4-pass DSKPP, the 2-pass DSKPP client uses
the <KeyProvClientHello> message to declare the list of Key
Protection Methods (KPML) it supports, providing required payload
information in accordance with <xref
target="Section-Profiles"></xref>. Optionally, the message MAY
include client Authentication Data (AD), such as a MAC derived from
an authentication code and R_C (refer to <xref
target="Section-AuthCode"></xref>). In addition, if a trigger
message preceded <KeyProvClientHello>, then it passes the
parameters received in <KeyProvTrigger> back to the DSKPP
Server. In particular, it MUST include R_TRIGGER so that the DSKPP
server can associate the client with the trigger message, and SHOULD
include DeviceID and KeyID.</t>
<figure>
<preamble></preamble>
<artwork><![CDATA[ DSKPP Client DSKPP Server
------------ ------------
<--- KPH, KP, E(K,K_PROV),
MAC, AD
]]></artwork>
</figure>
<t>If Authentication Data (AD) was received, then the DSKPP server
MUST authenticate the user in accordance with <xref
target="Section-AuthCode"></xref>. If authentication fails, then
DSKPP server MUST abort. Otherwise, the DSKPP server generates a key
K_PROV from which two keys, K_TOKEN and K_MAC, are derived.
(Alternatively, the key K_PROV may have been pre-generated as
described in <xref target="UC1"></xref>. The DSKPP server selects a
Key Protection Method (KPM) and applies it to K_PROV in accordance
with <xref target="Section-Profiles"></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 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>. For two-pass DSKPP, the confirmation
message MUST include a Key Package Header (KPH) that contains the
DSKPP Server's ID and KPM. The ServerID is used for authentication
purposes, and the KPM informs the DSKPP client of the security
context in which it will operate. In addition to the KPH, the
confirmation message MUST include the Key Package (KP) that holds
the KeyID, K_PROV from which K_TOKEN and K_MAC are derived, and
additional configuration information. The default symmetric key
package format is based on the Portable Symmetric Key Container
(PSKC) defined in <xref target="PSKC"></xref>. Alternative formats
MAY include <xref target="SKPC-ASN.1"></xref>, PKCS#12 <xref
target="PKCS-12"></xref>, or PKCS#5 XML <xref
target="PKCS-5-XML"></xref>. Finally, <KeyProvServerFinished>
MUST include two MACs (MAC and AD) whose values are calculated with
contribution from the client nonce, R_C, provided in the
<ClientHello> message. The MAC values will allow the
cryptographic module to perform key confirmation and server
authentication before "committing" the key (see <xref
target="Subsection-MAC"></xref> for more information).</t>
<t>After receiving a <KeyProvServerFinished> message with
Status = "Success", the DSKPP client MUST verify both MAC values
(MAC and AD). The DSKPP client MUST terminate the DSKPP session if
either MAC does not verify, and MUST, in this case, also delete any
nonces, keys, and/or secrets associated with the failed run of the
protocol. If <KeyProvServerFinished> has Status = "Success"
and the MACs were verified, then the DSKPP client MUST extract the
key data from the provided key package, and store data locally.
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 <KeyProvServerFinished> message.</t>
</section>
<section anchor="Section-Profiles" title="Key Protection Profiles">
<t>This section introduces three profiles of two-pass DSKPP for key
protection. Further profiles MAY be defined by external entities or
through the IETF process.</t>
<section title="Key Transport Profile">
<t>This profile establishes a symmetric key, K_TOKEN, in the
cryptographic module using key transport and key derivation. Key
transport is carried out using a public key whose private key part
resides in the cryptographic module as the key transport key. A
provisioning master key, K_PROV, MUST be transported from the
DSKPP server to the client. From K_PROV, two keys are derived: the
symmetric key to be established, K_TOKEN, and a key used to
compute MACs, K_MAC.</t>
<t>This profile MUST be identified with the following URN:
urn:ietf:params:xml:schema:keyprov:dskpp#transport</t>
<t>In the two-pass version of DSKPP, the client MUST send a
payload associated with this key protection method. This payload
MUST be of type <ds:KeyInfoType> (<xref
target="XMLDSIG"></xref>), and only those choices of
<ds:KeyInfoType> that identify a public key are allowed
(i.e., <ds:KeyName>, <ds:KeyValue>,
<ds:X509Data>, or <ds:PGPData>). 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 protection 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) are allowed as values for the
<xenc:EncryptionMethod>. Further, in the case of 2-pass
DSKPP, <ds:KeyInfo> MUST contain the same value (i.e.
identify the same public key) as the <Payload> of the
corresponding supported key protection method in the
<KeyProvClientHello> message that triggered the response.
<xenc:CarriedKeyName> 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).
The transported key, K_PROV, 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).
The MAC MUST be calculated as described in <xref
target="Subsection-MAC"></xref> for two-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 title="Key Wrap Profile">
<t>This profile establishes a symmetric key, K_TOKEN, in the
cryptographic module through key wrap and key derivation. Key wrap
is carried out using a symmetric key wrapping key, known in
advance by both the cryptographic module and the DSKPP server. A
provisioning master key, K_PROV, MUST be transported from the
DSKPP server to the client. From K_PROV, two keys are derived: the
symmetric key to be established, K_TOKEN, and a key used to
compute MACs, K_MAC.</t>
<t>This profile MUST be identified with the following URI:
urn:ietf:params:xml:schema:keyprov:dskpp#wrap</t>
<t>In the 2-pass version of DSKPP, the client MUST send a payload
associated with this key protection method. This payload MUST be
of type <ds:KeyInfoType> (<xref target="XMLDSIG"></xref>),
and only those choices of <ds:KeyInfoType> that identify a
symmetric key are allowed (i.e., <ds:KeyName> and
<ds:KeyValue>). The <ds:KeyName> alternative is
RECOMMENDED.</t>
<t>The server payload associated with this key protection 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) are allowed as values for the
<xenc:EncryptionMethod>. Further, in the case of 2-pass
DSKPP, <ds:KeyInfo> MUST contain the same value (i.e.
identify the same symmetric key) as the <Payload> of the
corresponding supported key protection method in the
<KeyProvClientHello> message that triggered the response.
<xenc:CarriedKeyName> 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).
The wrapped key, K_PROV, 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).
The MAC MUST be calculated as described in <xref
target="Subsection-MAC"></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 title="Passphrase-Based Key Wrap Profile">
<t>This profile is a variation of the key wrap profile. It
establishes a symmetric key, K_TOKEN, in the cryptographic module
through key wrap and key derivation. Key wrap is carried out using
a passphrase-derived key wrapping key. The passphrase is known in
advance by both the user of the device 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 provisioning
master key, K_PROV, MUST be transported from the DSKPP server to
the client. From K_PROV, two keys are derived: the symmetric key
to be established, K_TOKEN, and a key used to compute MACs,
K_MAC.</t>
<t>This profile MUST be identified with the following URI:
urn:ietf:params:xml:schema:keyprov:dskpp#passphrase-wrap</t>
<t>In the 2-pass version of DSKPP, the client MUST send a payload
associated with this key protection method. This 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 protection 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)
are allowed as values for the <xenc:EncryptionMethod>.
Further, in the case of 2-pass DSKPP, <ds:KeyInfo> MUST
contain the same value (i.e. identify the same passphrase) as the
<Payload> of the corresponding supported key protection
method in the <KeyProvClientHello> message that triggered
the response. <xenc:CarriedKeyName> 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).
The wrapped key, K_PROV, 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).
The MAC MUST be calculated as described in <xref
target="Subsection-MAC"></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 anchor="Subsection-MAC" title="MAC Calculations">
<section title="Key Confirmation">
<t>The MAC value in the <KeyProvServerFinished> message MUST
be calculated as follows:</t>
<t>msg_hash = SHA-256(msg_1, ..., msg_n)</t>
<t>dsLen = len(msg_hash)</t>
<t>MAC = DSKPP-PRF (K_MAC, "MAC 1 computation" || msg_hash ||
ServerID, dsLen)</t>
<t>where</t>
<t><list hangIndent="12" style="hanging">
<t hangText="MAC">The MAC MUST be calculated using the already
established MAC algorithm and MUST be computed on the (ASCII)
string "MAC 1 computation", msg_hash, and ServerID using the
existing the MAC key K_MAC.<vspace blankLines="1" /></t>
<t hangText="K_MAC">The key, along with K_TOKEN, that is
derived from K_PROV which the DSKPP server MUST provide to the
cryptographic module.<vspace blankLines="1" /></t>
<t hangText="msg_hash">The message hash, defined in <xref
target="Subsection-MsgHashAlg"></xref>, of messages msg_1,
..., msg_n.<vspace blankLines="1" /></t>
<t hangText="ServerID">The identifier that the DSKPP server
MUST include in the <KeyPackage> element of
<KeyProvServerFinished>.</t>
</list></t>
<t>If DSKPP-PRF (defined in <xref target="DSKPP-PRF"></xref>) is
used as the MAC algorithm, then the input parameter s MUST consist
of the concatenation of the (ASCII) string "MAC 1 computation",
msg_hash, and ServerID, and the parameter dsLen MUST be set to the
length of msg_hash.</t>
</section>
<section anchor="Subsecton-TwoPass-ServerAuth"
title="Server Authentication in the Case of Key Renewal">
<t>A second MAC MUST be present in the
<KeyProvServerFinished> message as proof that the DSKPP
server is authorized to replace a key on the cryptographic module.
In 2-pass DSKPP, servers provide the second MAC in the
AuthenticationDataType element of <KeyProvServerFinished>.
The MAC value in the AuthenticationDataType element MUST be
computed on the (ASCII) string "MAC 2 computation", the server
identifier ServerID, and R, using a pre-existing MAC key K_MAC'
(the MAC key that existed before this protocol run). Note that the
implementation may specify K_MAC' to be the value of the K_TOKEN
that is being replaced, or a version of K_MAC from the previous
protocol run.</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 2 computation" ServerID, 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 2 computation" || ServerID || R,
dsLen)</t>
<t>The MAC algorithm MUST be the same as the algorithm used for
key confirmation purposes.</t>
</section>
</section>
</section>
<section anchor="Subsection-DeviceID" title="Device Identification">
<t>The DSKPP server MAY 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, in which case the DSKPP client MUST 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-ClientAuthN" title="User Authentication">
<t>The DSKPP server MUST ensure that a generated key is associated
with the correct cryptographic module, and if applicable, the correct
user. If the user has not been authenticated by some out-of-band
means, then the user SHOULD be authenticated within the DSKPP. When
relying on DSKPP for user authentication, the DSKPP server SHOULD
explicitly rely on client-provided Authentication Data (AD) to verify
that a legitimate user is behind the wheel. For a further discussion
of this, and threats related to man-in-the-middle attacks in this
context, see <xref target="Subsection-UserAuthN"></xref>.</t>
<section anchor="Section-AuthCode" title="Authentication Data">
<t>As described in the message flows above (see <xref
target="Subsection-4PassFlow"></xref> and <xref
target="Subsection-2PassFlow"></xref>), the DSKPP client MAY include
Authentication Data (AD) in its request(s). Note that AD MAY be
omitted if client certificate authentication has been provided by
the transport channel such as TLS. Nonetheless, when AD is provided,
the DSKPP server MUST verify the data before continuing with the
protocol run.</t>
<t>The data element that holds AD MUST include a Client ID and a
value derived from an Authentication Code (AC). The Client ID
represents a key request made by the user to the Provisioning
Server. AC is a one-time use value that is a (potentially low
entropy) shared secret between a user and the Provisioning Server.
This secret is made available to the client before the DSKPP message
exchange. Below are examples of how the DSKPP client may obtain the
AC:</t>
<t><list hangIndent="" style="format %c.">
<t>A key issuer may deliver an AC to the user or device in
response to a key request, which the user enters into an
application hosted on their device. For example, a user runs an
application that is resident on their device, e.g., a mobile
phone. The application cannot proceed without a new symmetric
key. The user is redirected to an issuer's Web site from where
the user requests a key. The issuer's Web application processes
the request, and returns an AC, which then appears on the user's
display. The user then invokes a symmetric key-based application
hosted on the device, which asks the user to input the AC using
a keypad. The application invokes the DSKPP client, providing it
with the AC.</t>
<t>The provisioning server may send a trigger message,
<KeyProvTrigger>, to the DSKPP client, which sets the
value of the trigger nonce, R_TRIGGER, to AC. 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>
</list></t>
<t>A description of the AC and how it is used to derive AD is
contained in the sub-sections below.</t>
</section>
<section title="Authentication Code Format">
<t>AC is encoded in Type-Length-Value (TLV) format. The format
consists of a minimum of two TLVs and a variable number of
additional TLVs, depending on implementation. See <xref
target="TLV"></xref> for TLV field layout.</t>
<t>A 1 byte type field identifies the specific TLV, and a 1 byte
length, in hexadecimal, indicates the length of the value field
contained in the TLV. A TLV MUST start on a 4 byte boundary. Pad
bytes MUST be placed at the end of the previous TLV in order to
align the next TLV. These pad bytes are not counted in the length
field of the TLV.</t>
<figure anchor="TLV" title="TLV Format">
<preamble></preamble>
<artwork><![CDATA[ 0 1 2
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Value[0] | ...Value[Length-1]
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+]]></artwork>
<postamble></postamble>
</figure>
<t>The TLV fields are defined as follows:</t>
<t><list hangIndent="26" style="hanging">
<t hangText="Type (1 byte)">The integer value identifying the
type of information contained in the value field.<vspace
blankLines="1" /></t>
<t hangText="Length (1 byte)">The length, in hexadecimal, of the
value field to follow.<vspace blankLines="1" /></t>
<t hangText="Value (variable length)">A variable-length
hexadecimal value containing the instance-specific information
for this TLV.<vspace blankLines="1" /></t>
</list><xref target="TLVtypes"></xref> summarizes the TLVs defined
in this document. Optional TLVs are allowed for vendor-specific
extensions with the constraint that the high bit MUST be set to
indicate a vendor-specific type. Other TLVs are left for later
revisions of this protocol.</t>
<figure anchor="TLVtypes" title="TLV Summary">
<preamble></preamble>
<artwork><![CDATA[+------+------------+-------------------------------------------+
| Type | TLV Name | Conformance | Example Usage |
+------+------------+-------------------------------------------+
| 1 | Client ID | Mandatory | { "AC00000A" } |
+------+------------+-------------+-----------------------------+
| 2 | Password | Mandatory | { "3582" } |
+------+------------+-------------+-----------------------------+
| 3 | Checksum | Optional | { 0x5F8D } |
+------+------------+-------------+-----------------------------+
]]></artwork>
<postamble></postamble>
</figure>
<section title="Client ID (MANDATORY)">
<t>The Client ID is a mandatory TLV that represents the
user’s key request. A summary of the Client ID TLV format is
given in <xref target="TLV-ClientID"></xref>. The fields are
transmitted from left to right.</t>
<figure anchor="TLV-ClientID" title="ClientID TLV Format">
<preamble></preamble>
<artwork><![CDATA[ 0 1 2
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 0x1 | Length | clientID ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+]]></artwork>
<postamble></postamble>
</figure>
<t>clientID is an ASCII string that identifies the key request.
The clientID MUST be HEX encoded.</t>
<t>For example, suppose clientID is set to "AC00000A", the
hexadecimal equivalent is 0x4143303030303041, resulting in a TLV
of {0x1, 0x8, 0x4143303030303041}.</t>
</section>
<section title="Password (MANDATORY)">
<t>The Password is a mandatory TLV the contains a one-time use
shared secret known by the user and the Provisioning Server. A
summary of the Password TLV format is given in <xref
target="TLV-Password"></xref>. The fields are transmitted from
left to right.</t>
<figure anchor="TLV-Password" title="Password TLV Format">
<preamble></preamble>
<artwork><![CDATA[ 0 1 2
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 0x2 | Length | password ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+]]></artwork>
<postamble></postamble>
</figure>
<t>Password is a unique value that SHOULD be a random string to
make AC more difficult to guess. The string MUST be UTF-8 encoded
in accordance with <xref target="RFC3629"></xref>.</t>
<t>For example, suppose password is set to "3582", then the TLV
would be {0x2, 0x4, UTF-8("3582")}.</t>
</section>
<section title="Checksum (OPTIONAL)">
<t>The Checksum is an OPTIONAL TLV, which is generated by the
issuing server and sent to the user as part of the AC. A summary
of the Checksum TLV format is given in <xref
target="TLV-Checksum"></xref>. The fields are transmitted from
left to right.</t>
<figure anchor="TLV-Checksum" title="Checksum TLV Format">
<preamble></preamble>
<artwork><![CDATA[ 0 1 2
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 0x3 | Length | checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+]]></artwork>
<postamble></postamble>
</figure>
<t>If included, the checksum MUST be computed using the CRC16
algorithm <xref target="ISO3309"></xref>. When the user enters the
AC, the typed password is verified with the checksum to ensure it
is correctly entered by the user.</t>
<t>For example, suppose the Password is set to "3582", then the
CRC16 calculation would generate a checksum of 0x5F8D, resulting
in TLV {0x3, 0x2, 0x5F8D}.</t>
</section>
</section>
<section anchor="Subsection-ADMAC"
title="Authentication Data Calculation">
<t>The Authentication Data consists of a Client ID (extracted from
the AC) and a value, which is derived from AC as follows (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):</t>
<t>MAC = DSKPP-PRF(K_AC, AC->clientID||URL_S||R_C||[R_S], 16)</t>
<t>In four-pass DSKPP, the cryptographic module uses R_C, R_S, and
URL_S to calculate the MAC, where URL_S is the URL the DSKPP client
uses when contacting the DSKPP server. In two-pass DSKPP, the
cryptographic module does not have access to R_S, therefore only R_C
is used in combination with URL_S to produce the MAC. In either
case, K_AC MUST be derived from AC>password as follows <xref
target="PKCS-5"></xref>:</t>
<t>K_AC = PBKDF2(AC->password, R_C || [K], iter_count, 16)</t>
<t>K is OPTIONAL only in four-pass where no K_SHARED is used. In all
other cases one of the following values for K MUST be used:<vspace
blankLines="1" /><list hangIndent="" style="format %c.">
<t>The public key of the DSKPP client, or the public key of the
device when a device certificate is available</t>
<t>The pre-shared key between the client and the server</t>
<t>A passphrase-derived key</t>
</list></t>
<t>The iteration count, iter_count, MUST be set to at least 100,000
except for case (b) and (c), above, in which case it MUST be set to
1.</t>
</section>
</section>
<section anchor="DSKPP-PRF"
title="The DSKPP One-Way Pseudorandom Function, DSKPP-PRF">
<section title="Introduction">
<t>All of the protocol variations 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></t>
<t>For the purposes of this document, the secret key k MUST be at
least 16 octets long.</t>
</section>
</section>
</section>
<section title="DSKPP Message Formats">
<t>The message formats from the DSKPP XML schema, found in <xref
target="Section-Schema"></xref>, are explained in this section. Examples
can be found in <xref target="Section-Examples"></xref>. The XML format
for DSKPP messages has been designed to be extensible. However, it is
possible that the use of extensions will harm interoperability;
therefore, any use of extensions SHOULD be carefully considered. For
example, if a particular implementation relies on the presence of a
proprietary extension, then it may not be able to interoperate with
independent implementations that have no knowledge of this
extension.</t>
<section title="General XML Schema Requirements">
<t>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 anchor="Section-Trigger"
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>
<figure>
<preamble></preamble>
<artwork><![CDATA[<xs:element name="KeyProvTrigger" type="dskpp:KeyProvTriggerType">
</xs:element>
<xs:complexType name="KeyProvTriggerType">
<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>
<xs:complexType name="InitializationTriggerType">
<xs:sequence>
<xs:element minOccurs="0" name="DeviceIdentifierData"
type="dskpp:DeviceIdentifierDataType" />
<xs:element minOccurs="0" name="KeyID" type="xs:base64Binary" />
<xs:element minOccurs="0" name="TokenPlatformInfo"
type="dskpp:TokenPlatformInfoType" />
<xs:element name="TriggerNonce" type="dskpp:NonceType" />
<xs:element minOccurs="0" name="ServerUrl" type="xs:anyURI" />
<xs:any minOccurs="0" namespace="##other"
processContents="strict" />
</xs:sequence>
</xs:complexType>
]]></artwork>
<postamble></postamble>
</figure>
<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 title="Components of the <KeyProvClientHello> Request">
<t>This message is the initial message sent from the DSKPP client to
the DSKPP server in both variations of the DSKPP.</t>
<figure>
<preamble></preamble>
<artwork><![CDATA[<xs:element name="KeyProvClientHello"
type="dskpp:KeyProvClientHelloPDU">
</xs:element>
<xs:complexType name="KeyProvClientHelloPDU">
<xs:complexContent mixed="false">
<xs:extension base="dskpp:AbstractRequestType">
<xs:sequence>
<xs:element minOccurs="0" name="DeviceIdentifierData"
type="dskpp:DeviceIdentifierDataType" />
<xs:element minOccurs="0" name="KeyID"
type="xs:base64Binary" />
<xs:element minOccurs="0" name="ClientNonce"
type="dskpp:NonceType" />
<xs:element minOccurs="0" name="TriggerNonce"
type="dskpp:NonceType" />
<xs:element name="SupportedKeyTypes"
type="dskpp:AlgorithmsType" />
<xs:element name="SupportedEncryptionAlgorithms"
type="dskpp:AlgorithmsType" />
<xs:element name="SupportedMacAlgorithms"
type="dskpp:AlgorithmsType" />
<xs:element minOccurs="0" name="SupportedProtocolVariants"
type="dskpp:ProtocolVariantsType" />
<xs:element minOccurs="0" name="SupportedKeyPackages"
type="dskpp:KeyPackagesFormatType" />
<xs:element minOccurs="0" name="AuthenticationData"
type="dskpp:AuthenticationDataType" />
<xs:element minOccurs="0" name="Extensions"
type="dskpp:ExtensionsType" />
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
]]></artwork>
<postamble></postamble>
</figure>
<t>The components of this message have the following meaning:</t>
<t><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>). 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>).</t>
<t><ClientNonce>: 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>), 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 container elements
that in turn contain URLs indicating the key types for which the
cryptographic module is willing to generate keys through
DSKPP.</t>
<t><SupportedEncryptionAlgorithms>: A sequence of container
elements that in turn contain URLs 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 container
elements that in turn contain URLs 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.,
http://www.ietf.org/keyprov/dskpp#dskpp-prf-aes, which is 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><SupportedKeyPackages>: This OPTIONAL element is a
sequence of container elements that in turn contain URLs
indicating the key package formats supported by the DSKPP client.
If this element is not provided, then the DSKPP server MUST
proceed with "http://www.ietf.org/keyprov/pskc#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>
<t>Some of the core elements of the message are described below.</t>
<section title="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 key 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>
<figure>
<preamble></preamble>
<artwork><![CDATA[<xs:complexType name="DeviceIdentifierDataType">
<xs:choice>
<xs:element name="DeviceId" type="pskc:DeviceIdType" />
<xs:any namespace="##other" processContents="strict" />
</xs:choice>
</xs:complexType>
]]></artwork>
<postamble></postamble>
</figure>
</section>
<section title="The ProtocolVariantsType Type">
<t>The ProtocolVariantsType is a complex type that is a sequence of
elements, each describing a DSKPP protocol variant. The DSKPP client
MAY use the ProtocolVariantsType to identify which protocol variants
it supports, i.e., by providing <SupportProtocolVariants>
within a <KeyProvClientHello> message.</t>
<t>Selecting the <FourPass> element signals client support for
4-pass DSKPP as described in <xref
target="Subsection-4PassFlow"></xref>.</t>
<t>Selecting the <TwoPass> element signals client support for
the 2-pass version of DSKPP as described in <xref
target="Subsection-2PassFlow"></xref>. The <TwoPass> element
is of type KeyProtectionDataType, which carries information that
informs the server of supported two-pass key protection methods as
described in <xref target="Section-Profiles"></xref>, 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 key protection method with which the
payload is associated.</t>
<t>If the DSKPP client does not include
<SupportedProtocolVariants> in the <KeyProvClientHello>
message, then the DSKPP server MUST proceed by using the 4-pass
DSKPP variant. If the DSKPP server does not support 4-pass DSKPP,
then the server MUST use the two-pass protocol variant. If it cannot
support the two-pass protocol variant, then the protocol run MUST
fail.</t>
<figure>
<preamble></preamble>
<artwork><![CDATA[ <xs:complexType name="ProtocolVariantsType">
<xs:sequence>
<xs:element name="FourPass" minOccurs="0" />
<xs:element name="TwoPass" type="dskpp:KeyProtectionDataType"
minOccurs="0"/>
</xs:sequence>
</xs:complexType>
<xs:complexType name="KeyProtectionDataType">
<xs:sequence maxOccurs="unbounded">
<xs:element name="SupportedKeyProtectionMethod" type="xs:anyURI"/>
<xs:element name="Payload" type="dskpp:PayloadType" minOccurs="0"/>
</xs:sequence>
</xs:complexType>
]]></artwork>
<postamble></postamble>
</figure>
<t>The elements of this type have the following meaning:</t>
<t><list style="symbols">
<t><SupportedKeyProtectionMethod>: A two-pass key
protection 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 protection method.</t>
</list></t>
<t>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="The KeyPackagesFormatType Type">
<t>The OPTIONAL KeyPackagesFormatType type is a list of type-value
pairs that a DSKPP client or server MAY use to define key package
formats it supports. Key package formats are identified through
URLs, e.g., the PSKC KeyContainer URL
"http://www.ietf.org/keyprov/pskc#KeyContainer" (see <xref
target="PSKC"></xref>).</t>
<figure>
<preamble></preamble>
<artwork><![CDATA[<xs:complexType name="KeyPackagesFormatType">
<xs:sequence maxOccurs="unbounded">
<xs:element name="KeyPackageFormat"
type="dskpp:KeyPackageFormatType"/>
</xs:sequence>
</xs:complexType>
<xs:simpleType name="KeyPackageFormatType">
<xs:restriction base="xs:anyURI" />
</xs:simpleType>
]]></artwork>
<postamble></postamble>
</figure>
</section>
<section anchor="Section-AuthNData"
title="The AuthenticationDataType Type">
<t>The OPTIONAL AuthenticationDataType type is used by DSKPP clients
to carry authentication values in DSKPP messages as described in
<xref target="Section-ClientAuthN"></xref>.</t>
<figure>
<preamble></preamble>
<artwork><![CDATA[<xs:complexType name="AuthenticationDataType">
<xs:sequence>
<xs:element name="ClientID"
type="dskpp:IdentifierType" />
<xs:element name="AuthenticationCodeMac"
type="dskpp:AuthenticationMacType" />
</xs:sequence>
</xs:complexType>
<xs:complexType name="AuthenticationMacType">
<xs:sequence>
<xs:element minOccurs="0" name="Nonce" type="dskpp:NonceType" />
<xs:element minOccurs="0" name="IterationCount" type="xs:int" />
<xs:element name="Mac" type="dskpp:MacType" />
</xs:sequence>
</xs:complexType>
]]></artwork>
<postamble></postamble>
</figure>
<t>The elements of the AuthenticationDataType type have the
following meaning:</t>
<t><list style="symbols">
<t><ClientID>: A requester's identifier of maximum length
128. The value MAY be a user ID, a device ID, or a keyID
associated with the requester's authentication value.</t>
<t><AuthenticationCodeMac>: An authentication MAC and
additional information (e.g., MAC algorithm), derived as
described in <xref target="Subsection-ADMAC"></xref>.</t>
</list></t>
</section>
</section>
<section title="Components of the <KeyProvServerHello> Response (Used Only in Four-Pass DSKPP)">
<t>In a four-pass exchange, 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.</t>
<figure>
<preamble></preamble>
<artwork><![CDATA[<xs:element name="KeyProvServerHello"
type="dskpp:KeyProvServerHelloPDU">
</xs:element>
<xs:complexType name="KeyProvServerHelloPDU">
<xs:complexContent mixed="false">
<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="KeyPackageFormat"
type="dskpp:KeyPackageFormatType" />
<xs:element name="Payload" type="dskpp:PayloadType" />
<xs:element minOccurs="0" name="Extensions"
type="dskpp:ExtensionsType" />
<xs:element minOccurs="0" name="Mac" type="dskpp:MacType" />
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
]]></artwork>
<postamble></postamble>
</figure>
<t>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. The SessionID has a maximum
length of 128.</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><KeyPackageFormat>: The key package format type to be
used by the DSKPP server. The default setting relies on the
KeyPackageType element defined in
"urn:ietf:params:xml:schema:keyprov:pskc" <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></t>
</section>
<section title="Components of a <KeyProvClientNonce> Request (Used Only in Four-Pass DSKPP)">
<t>In a four-pass DSKPP exchange, this message contains the nonce R_C
that was chosen by the cryptographic module, and encrypted by the
negotiated encryption key and encryption algorithm</t>
<figure>
<preamble></preamble>
<artwork><![CDATA[<xs:element name="KeyProvClientNonce"
type="dskpp:KeyProvClientNoncePDU">
</xs:element>
<xs:complexType name="KeyProvClientNoncePDU">
<xs:complexContent mixed="false">
<xs:extension base="dskpp:AbstractRequestType">
<xs:sequence>
<xs:element name="EncryptedNonce" type="xs:base64Binary" />
<xs:element minOccurs="0" name="AuthenticationData"
type="dskpp:AuthenticationDataType" />
<xs:element minOccurs="0" name="Extensions"
type="dskpp:ExtensionsType" />
</xs:sequence>
<xs:attribute name="SessionID" type="dskpp:IdentifierType"
use="required" />
</xs:extension>
</xs:complexContent>
</xs:complexType>
]]></artwork>
<postamble></postamble>
</figure>
<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>: (attribute inherited from the
AbstractResponseType type) MUST have the same value as the
SessionID attribute in the received <KeyProvServerHello>
message. SessionID has maximum length of 128.</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>: IThe 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.</t>
<figure>
<preamble></preamble>
<artwork><![CDATA[<xs:element name="KeyProvServerFinished"
type="dskpp:KeyProvServerFinishedPDU">
</xs:element>
<xs:complexType name="KeyProvServerFinishedPDU">
<xs:complexContent mixed="false">
<xs:extension base="dskpp:AbstractResponseType">
<xs:sequence minOccurs="0">
<xs:element name="KeyPackage"
type="dskpp:KeyPackageType" />
<xs:element minOccurs="0" name="Extensions"
type="dskpp:ExtensionsType" />
<xs:element name="Mac" type="dskpp:MacType" />
<xs:element minOccurs="0" name="AuthenticationData"
type="dskpp:AuthenticationMacType" />
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
]]></artwork>
<postamble></postamble>
</figure>
<t>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. The SessionID
is of maximum length 128.</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><KeyPackage>: The key package containing keying material
in accordance with four- and two-pass DSKPP usage (see <xref
target="Subsection-FourPassUsage"></xref> and <xref
target="Subsecton-TwoPass"></xref>). The default package 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 a
MAC value that the DSKPP server provides in a two-pass message
exchange as proof that the server is authorized to replace a key
on the cryptographic module. The MAC MUST be calculated as
specified in <xref
target="Subsecton-TwoPass-ServerAuth"></xref>.</t>
</list></t>
</section>
<section anchor="Subsection-StatusCodes" title="The StatusCode Type">
<t>The StatusCode type enumerates all possible return codes:</t>
<figure>
<preamble></preamble>
<artwork><![CDATA[<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="NoSupportedKeyPackages" />
<xs:enumeration value="AuthenticationDataMissing" />
<xs:enumeration value="AuthenticationDataInvalid" />
<xs:enumeration value="InitializationFailed" />
</xs:restriction>
</xs:simpleType>
]]></artwork>
<postamble></postamble>
</figure>
<t>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:</t>
<t><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 variation (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.</t>
<t>"NoSupportedKeyPackages" indicates that the DSKPP client only
suggested key package 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 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 reason for key
initialization failure to the user and the user MUST register with
the DSKPP server to initialize a new key.</t>
</list></t>
</section>
</section>
<!-- ////////////////////////////////////////////////////////////////////////////////// -->
<section anchor="Section-ProtocolExts" title="Protocol Extensions">
<section title="The ClientInfoType Type">
<t>Present in a <KeyProvClientHello> or a
<KeyProvClientNonce> message, the OPTIONAL ClientInfoType
extension contains DSKPP client-specific information that is custom to
an implementation. 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 that is custom to an implementation. 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>
<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.
The DSKPP server will be identified by a specific URL, which may be
pre-configured, or provided to the client during initialization.</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>In order to avoid caching of responses carrying DSKPP messages by
proxies, the following holds:</t>
<t><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".<vspace
blankLines="1" /></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></t>
<t>To handle content negotiation, HTTP requests MAY include an HTTP
Accept header field. This header field SHOULD have the value
application/vnd.ietf.keyprov.dskpp+xml as defined in <xref
target="Subsection-ContentType"></xref>. The Accept header MAY
include additional content types defined by future versions of this
protocol.</t>
<t>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 OPTIONAL. DSKPP
requests are mapped to HTTP requests with the POST method. DSKPP
responses are mapped to HTTP responses.</t>
<t>For the 4-pass DSKPP, messages within the protocol run are bound
together. In particular, <KeyProvServerHello> is bound to the
preceding <KeyProvClientHello> by being transmitted in the
corresponding HTTP response. <KeyProvServerHello> MUST have a
SessionID attribute, and the SessionID attribute of the subsequent
<KeyProvClientNonce> message MUST be identical.
<KeyProvServerFinished> is then once again bound to the rest
through HTTP (and possibly through a SessionID).</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 a request is received that is not a DSKPP client
message, 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>If a user requests key initialization in a browsing session, and
if that request has an appropriate Accept header (e.g., to a
specific DSKPP server URL), the DSKPP server MAY respond by sending
a DSKPP initialization message in an HTTP response with Content-Type
set according to <xref target="Subsection-ContentType"></xref> and
response code set to 200 (OK). The initialization message MAY carry
data in its body, such as the URL for the DSKPP client to use when
contacting the DSKPP server. If the message does carry data, the
data MUST be a valid instance of a <KeyProvTrigger>
element.</t>
<t>Note that if the user's request was directed to some other
resource, the DSKPP server MUST NOT respond by combining the DSKPP
content type with response code 200. In that case, the DSKPP server
SHOULD respond by sending a DSKPP initialization message in an HTTP
response with Content-Type set according to <xref
target="Subsection-ContentType"></xref> and response code set to 406
(Not Acceptable).</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="1" />Cache-Control: no-cache, no-store<vspace
blankLines="0" />Pragma: no-cache<vspace blankLines="0" />Host:
www.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-cache, no-must-revalidate,
private<vspace blankLines="0" />Pragma: no-cache<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>
<artwork><![CDATA[
<?xml version="1.0" encoding="utf-8"?>
<xs:schema
xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:dskpp="urn:ietf:params:xml:ns:keyprov:dskpp:1.0"
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:pskc:1.0"
xmlns:ds="http://www.w3.org/2000/09/xmldsig#"
targetNamespace="urn:ietf:params:xml:ns:keyprov:dskpp:1.0"
elementFormDefault="qualified" 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:pskc:1.0"
schemaLocation="keyprov-pskc-1.0.xsd"/>
<xs:complexType name="AbstractRequestType" abstract="true">
<xs:annotation>
<xs:documentation> Basic types </xs:documentation>
</xs:annotation>
<xs:attribute name="Version" type="dskpp:VersionType"
use="required"/>
</xs:complexType>
<xs:complexType name="AbstractResponseType" abstract="true">
<xs:annotation>
<xs:documentation> Basic types </xs:documentation>
</xs:annotation>
<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="NoSupportedKeyPackages" />
<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:KeyProtectionDataType"
minOccurs="0"/>
</xs:sequence>
</xs:complexType>
<xs:complexType name="KeyProtectionDataType">
<xs:annotation>
<xs:documentation xml:lang="en">
This element is only valid for two-pass DSKPP.
</xs:documentation>
</xs:annotation>
<xs:sequence maxOccurs="unbounded">
<xs:element name="SupportedKeyProtectionMethod" type="xs:anyURI"/>
<xs:element name="Payload" type="dskpp:PayloadType" minOccurs="0"/>
</xs:sequence>
</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="KeyPackagesFormatType">
<xs:sequence maxOccurs="unbounded">
<xs:element name="KeyPackageFormat"
type="dskpp:KeyPackageFormatType"/>
</xs:sequence>
</xs:complexType>
<xs:simpleType name="KeyPackageFormatType">
<xs:restriction base="xs:anyURI" />
</xs:simpleType>
<xs:complexType name="AuthenticationDataType">
<xs:annotation>
<xs:documentation xml:lang="en">
Authentication data contains a MAC.
</xs:documentation>
</xs:annotation>
<xs:sequence>
<xs:element name="ClientID"
type="dskpp:IdentifierType" />
<xs:element name="AuthenticationCodeMac"
type="dskpp:AuthenticationMacType" />
</xs:sequence>
</xs:complexType>
<xs:complexType name="AuthenticationMacType">
<xs:sequence>
<xs:element minOccurs="0" name="Nonce" type="dskpp:NonceType" />
<xs:element minOccurs="0" name="IterationCount" type="xs:int" />
<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="KeyPackageType">
<xs:sequence>
<xs:element minOccurs="0" name="ServerID" type="xs:anyURI" />
<xs:element minOccurs="0" name="KeyProtectionMethod"
type="xs:anyURI" />
<xs:choice>
<xs:element name="KeyPackage" type="pskc:KeyContainerType" />
<xs:any namespace="##other" processContents="strict" />
</xs:choice>
</xs:sequence>
</xs:complexType>
<xs:complexType name="InitializationTriggerType">
<xs:sequence>
<xs:element minOccurs="0" name="DeviceIdentifierData"
type="dskpp:DeviceIdentifierDataType" />
<xs:element minOccurs="0" name="KeyID" type="xs:base64Binary" />
<xs:element minOccurs="0" name="TokenPlatformInfo"
type="dskpp:TokenPlatformInfoType" />
<xs:element name="TriggerNonce" type="dskpp:NonceType" />
<xs:element minOccurs="0" name="ServerUrl" type="xs:anyURI" />
<xs:any minOccurs="0" namespace="##other"
processContents="strict" />
</xs:sequence>
</xs:complexType>
<xs:complexType name="ExtensionsType">
<xs:annotation>
<xs:documentation> Extension types </xs:documentation>
</xs:annotation>
<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 mixed="false">
<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 mixed="false">
<xs:extension base="dskpp:AbstractExtensionType">
<xs:sequence>
<xs:element name="Data" type="xs:base64Binary" />
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="KeyProvTrigger" type="dskpp:KeyProvTriggerType">
<xs:annotation>
<xs:documentation> DSKPP PDUs </xs:documentation>
</xs:annotation>
</xs:element>
<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>
<xs:element name="KeyProvClientHello"
type="dskpp:KeyProvClientHelloPDU">
<xs:annotation>
<xs:documentation> KeyProvClientHello PDU </xs:documentation>
</xs:annotation>
</xs:element>
<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 mixed="false">
<xs:extension base="dskpp:AbstractRequestType">
<xs:sequence>
<xs:element minOccurs="0" name="DeviceIdentifierData"
type="dskpp:DeviceIdentifierDataType" />
<xs:element minOccurs="0" name="KeyID"
type="xs:base64Binary" />
<xs:element minOccurs="0" name="ClientNonce"
type="dskpp:NonceType" />
<xs:element minOccurs="0" name="TriggerNonce"
type="dskpp:NonceType" />
<xs:element name="SupportedKeyTypes"
type="dskpp:AlgorithmsType" />
<xs:element name="SupportedEncryptionAlgorithms"
type="dskpp:AlgorithmsType" />
<xs:element name="SupportedMacAlgorithms"
type="dskpp:AlgorithmsType" />
<xs:element minOccurs="0" name="SupportedProtocolVariants"
type="dskpp:ProtocolVariantsType" />
<xs:element minOccurs="0" name="SupportedKeyPackages"
type="dskpp:KeyPackagesFormatType" />
<xs:element minOccurs="0" name="AuthenticationData"
type="dskpp:AuthenticationDataType" />
<xs:element minOccurs="0" name="Extensions"
type="dskpp:ExtensionsType" />
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="KeyProvServerHello"
type="dskpp:KeyProvServerHelloPDU">
<xs:annotation>
<xs:documentation> KeyProvServerHello PDU </xs:documentation>
</xs:annotation>
</xs:element>
<xs:complexType name="KeyProvServerHelloPDU">
<xs:annotation>
<xs:documentation xml:lang="en">
Response message sent from DSKPP server to DSKPP client
in four-pass DSKPP.
</xs:documentation>
</xs:annotation>
<xs:complexContent mixed="false">
<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="KeyPackageFormat"
type="dskpp:KeyPackageFormatType" />
<xs:element name="Payload" type="dskpp:PayloadType" />
<xs:element minOccurs="0" name="Extensions"
type="dskpp:ExtensionsType" />
<xs:element minOccurs="0" name="Mac" type="dskpp:MacType" />
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="KeyProvClientNonce"
type="dskpp:KeyProvClientNoncePDU">
<xs:annotation>
<xs:documentation> KeyProvClientNonce PDU </xs:documentation>
</xs:annotation>
</xs:element>
<xs:complexType name="KeyProvClientNoncePDU">
<xs:annotation>
<xs:documentation xml:lang="en">
Response message sent from DSKPP client to
DSKPP server in a four-pass DSKPP session.
</xs:documentation>
</xs:annotation>
<xs:complexContent mixed="false">
<xs:extension base="dskpp:AbstractRequestType">
<xs:sequence>
<xs:element name="EncryptedNonce" type="xs:base64Binary" />
<xs:element minOccurs="0" name="AuthenticationData"
type="dskpp:AuthenticationDataType" />
<xs:element minOccurs="0" name="Extensions"
type="dskpp:ExtensionsType" />
</xs:sequence>
<xs:attribute name="SessionID" type="dskpp:IdentifierType"
use="required" />
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:element name="KeyProvServerFinished"
type="dskpp:KeyProvServerFinishedPDU">
<xs:annotation>
<xs:documentation> KeyProvServerFinished PDU </xs:documentation>
</xs:annotation>
</xs:element>
<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 serves for server authentication.
</xs:documentation>
</xs:annotation>
<xs:complexContent mixed="false">
<xs:extension base="dskpp:AbstractResponseType">
<xs:sequence minOccurs="0">
<xs:element name="KeyPackage"
type="dskpp:KeyPackageType" />
<xs:element minOccurs="0" name="Extensions"
type="dskpp:ExtensionsType" />
<xs:element name="Mac" type="dskpp:MacType" />
<xs:element minOccurs="0" name="AuthenticationData"
type="dskpp:AuthenticationMacType" />
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
</xs:schema>
]]></artwork>
<postamble></postamble>
</figure>
</section>
<!-- ////////////////////////////////////////////////////////////////////////////////// -->
<!-- ////////////////////////////////////////////////////////////////////////////////// -->
<section title="Conformance Requirements">
<t>In order to assure that all implementations of DSKPP can
interoperate, the DSKPP server:</t>
<t><list style="format %c.">
<t>MUST implement the four-pass variation of the protocol (<xref
target="Subsection-FourPassUsage"></xref>)<vspace
blankLines="1" /></t>
<t>MUST implement the two-pass variation of the protocol (<xref
target="Subsecton-TwoPass"></xref>)<vspace blankLines="1" /></t>
<t>MUST support user authentication (<xref
target="Section-ClientAuthN"></xref>)<vspace blankLines="1" /></t>
<t>MUST support the following Key Derivation Functions:<list
style="symbols">
<t>DSKPP-PRF-AES DSKPP-PRF realization (<xref
target="Section-PRFRealizations"></xref>)</t>
<t>DSKPP-PRF-SHA256 DSKPP-PRF realization (<xref
target="Section-PRFRealizations"></xref>)<vspace
blankLines="1" /></t>
</list></t>
<t>MUST support the following Encryption mechanisms for protection
of the client nonce in the four-pass protocol:<list style="symbols">
<t>Mechanism described in <xref
target="Subsection-Enc"></xref><vspace blankLines="1" /></t>
</list></t>
<t>MUST support the following Encryption algorithms for symmetric
key operations, e.g., key wrap:<list style="symbols">
<t>AES-CBC-128 <xref target="FIPS197-AES"></xref><vspace
blankLines="1" /></t>
</list></t>
<t>MUST support the following Encryption algorithms for asymmetric
key operations, e.g., key transport:<list style="symbols">
<t>RSA Encryption Scheme <xref target="PKCS-1"></xref><vspace
blankLines="1" /></t>
</list></t>
<t>MUST support the following Integrity/KDF MAC functions:<list
style="symbols">
<t>HMAC-SHA256 <xref target="FIPS180-SHA"></xref></t>
<t>AES-CMAC-128 <xref target="FIPS197-AES"></xref><vspace
blankLines="1" /></t>
</list></t>
<t>MUST support the PSKC key package <xref target="PSKC"></xref>;
all three PSKC key protection profiles (Key Transport, Key Wrap, and
Passphrase-Based Key Wrap) MUST be implemented<vspace
blankLines="1" /></t>
<t>MAY support the ASN.1 key package as defined in <xref
target="SKPC-ASN.1"></xref></t>
</list></t>
<t>DSKPP clients need to support either the two-pass or the four-pass
variant of the protocol. DSKPP clients MUST fulfill all requirements
listed in item (c) - (j).</t>
<t>Of course, DSKPP is a security protocol, and one of its major
functions is to allow only authorized parties to successfully initialize
a cryptographic module with a new symmetric key. Therefore, a particular
implementation may be configured with any of a number of restrictions
concerning algorithms and trusted authorities that will prevent
universal interoperability.</t>
</section>
<section anchor="Section-Security" title="Security Considerations">
<section title="General">
<t>DSKPP is designed to protect generated keying 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 sub-sections, 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 keying 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 variation. Therefore, DSKPP servers MUST NOT accept
unilaterally provided device identifiers in the public-key
variation. This is also indicated in the protocol description. In
the shared-key variation, 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 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>
</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-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-FourPassDataFlow"></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></t>
<t>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 variation or the shared-secret
variation 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-pass DSKPP
as the client does not provide any entropy to K_TOKEN. The attack as
such (and its countermeasures) still applies to 2-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="Miscellaneous Considerations">
<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 2-pass DSKPP version 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 variation. 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 2-pass
DSKPP variation described herein, key confirmation is provided by
the MAC including R, using K_MAC.</t>
</section>
<section anchor="Subsection-ServerAuth" title="Server Authentication">
<t>DSKPP servers MUST authenticate themselves whenever a successful
DSKPP 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 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.</t>
</section>
<section anchor="Subsection-UserAuthN" title="User 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:</t>
<t><list style="symbols">
<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'd 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 Two-Pass DSKPP">
<t>Three key protection profiles are defined for the different
usages of 2-pass DSKPP, which MUST be supported by a key package
format, such as <xref target="PSKC"></xref> and <xref
target="SKPC-ASN.1"></xref>. Therefore, key protection in the
two-pass DSKPP is dependent upon the security of the key package
format selected for a protocol run. Some considerations for the
Passphrase profile follow.</t>
<t>The passphrase-based key wrap profile SHOULD depend upon the
PBKDF2 function from <xref target="PKCS-5"></xref> to generate an
encryption key from a passphrase and salt string. 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 per-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 two-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 requires several IANA registrations, detailed
below.</t>
<section title="URN Sub-Namespace Registration">
<t>This section registers a new XML namespace,
"urn:ietf:params:xml:ns:keyprov:dskpp:1.0" per the guidelines in <xref
target="RFC3688"></xref>:</t>
<t><list hangIndent="2" style="hanging">
<t hangText="URI:">urn:ietf:params:xml:ns:keyprov:dskpp:1.0</t>
<t hangText="Registrant Contact:">IETF, KEYPROV Working Group
(keyprov@ietf.org), Andrea Doherty (andrea.doherty@rsa.com)</t>
<t hangText="XML:"><vspace blankLines="0" /></t>
</list></t>
<figure>
<artwork><![CDATA[ BEGIN
<?xml version="1.0"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
<head>
<title>DSKPP Messsages</title>
</head>
<body>
<h1>Namespace for DSKPP Messages</h1>
<h2>urn:ietf:params:xml:ns:keyprov:dskpp:1.0</h2>
[NOTE TO IANA/RFC-EDITOR: Please replace XXXX below
with the RFC number for this specification.]
<p>See RFCXXXX</p>
</body>
</html>
END
]]></artwork>
</figure>
</section>
<section title="XML Schema Registration">
<t>This section registers an XML schema as per the guidelines in <xref
target="RFC3688"></xref>.</t>
<t><list style="hanging">
<t hangText="URI:">urn:ietf:params:xml:ns:keyprov:dskpp:1.0</t>
<t hangText="Registrant Contact:">IETF, KEYPROV Working Group
(keyprov@ietf.org), Andrea Doherty (andrea.doherty@rsa.com)</t>
<t hangText="Schema">The XML for this schema can be found as the
entirety of <xref target="Section-Schema"></xref> of this
document.</t>
</list></t>
</section>
<section title="MIME Media Type Registration">
<t>This section registers the "application/dskpp+xml" MIME type:</t>
<t><list counter="" hangIndent="2" style="hanging">
<t hangText="To:">ietf-types@iana.org</t>
<t hangText="Subject:">Registration of MIME media type
application/dskpp+xml</t>
<t hangText="MIME media type name:">application</t>
<t hangText="MIME subtype name:">dskpp+xml</t>
<t hangText="Required parameters:">(none)</t>
<t hangText="Optional parameters:">charset<vspace
blankLines="0" />Indicates the character encoding of enclosed XML.
Default is UTF-8.</t>
<t hangText="Encoding considerations:">Uses XML, which can employ
8-bit characters, depending on the character encoding used. See
<xref target="RFC3203"></xref>, Section 3.2.</t>
<t hangText="Security considerations:">This content type is
designed to carry protocol data related to key management.
Security mechanisms are built into the protocol to ensure that
various threats are dealt with.</t>
<t hangText="Interoperability considerations:">This content type
provides a basis for a protocol.</t>
<t hangText="Published specification:">RFC XXXX [NOTE TO
IANA/RFC-EDITOR: Please replace XXXX with the RFC number for this
specification.]</t>
<t hangText="Applications which use this media type:">Protocol for
key exchange.</t>
<t hangText="Additional information:"><vspace
blankLines="0" />Magic Number(s): (none)<vspace
blankLines="0" />File extension(s): .xmls<vspace
blankLines="0" />Macintosh File Type Code(s): (none)</t>
<t
hangText="Person & email address to contact for further information:"><vspace
blankLines="0" />Andrea Doherty (andrea.doherty@rsa.com)</t>
<t hangText="Intended usage:">LIMITED USE</t>
<t hangText="Author/Change controller:">The IETF</t>
<t hangText="Other information:">This media type is a
specialization of application/xml <xref target="RFC3203"></xref>,
and many of the considerations described there also apply to
application/dskpp+xml.</t>
</list></t>
</section>
<section title="Status Code Registry">
<t>This section registers status codes included in each DSKPP response
message. The status codes are defined in the schema in the
<StatusCode> type definition as described in the XML schema in
<xref target="Section-Schema"></xref>. The following summarizes the
registry:</t>
<t><list hangIndent="2" style="hanging">
<t hangText="Related Registry:"><vspace blankLines="0" />KEYPROV
DSKPP Registries, Status codes for DSKPP<vspace
blankLines="1" /></t>
<t hangText="Defining RFC:"><vspace blankLines="0" />RFC XXXX
[NOTE TO IANA/RFC-EDITOR: Please replace XXXX with the RFC number
for this specification.]<vspace blankLines="1" /></t>
<t hangText="Registration/Assignment Procedures:"><vspace
blankLines="0" />Following the policies outlined in <xref
target="RFC3575"></xref>, the IANA policy for assigning new values
for the status codes for DSKPP MUST be "Specification Required"
and their meanings MUST be documented in an RFC or in some other
permanent and readily available reference, in sufficient detail
that interoperability between independent implementations is
possible. No mechanism to mark entries as "deprecated" is
envisioned. It is possible to delete or update entries from the
registry.<vspace blankLines="1" /></t>
<t hangText="Registrant Contact:"><vspace blankLines="0" />IETF,
KEYPROV working group (keyprov@ietf.org),<vspace
blankLines="0" />Andrea Doherty (andrea.doherty@rsa.com)</t>
</list></t>
<t>This section pre-registers the initial status codes, as described
above in <xref target="Subsection-StatusCodes"></xref>, including
their textual description. The list in <xref
target="Subsection-StatusCodes"></xref>, starts with the StatusCode
"Continue" and ends with the StatusCode "InitializationFailed".</t>
</section>
</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 package
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 review of previous DSKPP
document versions:<vspace blankLines="1" /><list style="symbols">
<t>Dr. Ulrike Meyer (Review June 2007)<vspace blankLines="0" /></t>
<t>Niklas Neumann (Review June 2007)<vspace blankLines="0" /></t>
<t>Shuh Chang (Review June 2007)<vspace blankLines="0" /></t>
<t>Hannes Tschofenig (Review June 2007 and again in August
2007)<vspace blankLines="0" /></t>
<t>Sean Turner (Review August 2007)<vspace blankLines="0" /></t>
<t>John Linn (Review August 2007)<vspace blankLines="0" /></t>
<t>Philip Hoyer (Review September 2007)<vspace blankLines="0" /></t>
<t>Thomas Roessler (Review November 2007)<vspace
blankLines="0" /></t>
<t>Lakshminath Dondeti (Comments December 2007)<vspace
blankLines="0" /></t>
<t>Pasi Eronen (Comments December 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 Package Format and Client Authentication
Data)<vspace blankLines="0" /></t>
<t>Thomas Roessler (HTTP Binding)<vspace blankLines="0" /></t>
<t>Hannes Tschofenig (HTTP Binding)<vspace blankLines="0" /></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="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="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="RFC3629" target="http://www.ietf.org/rfc/rfc3629.txt">
<front>
<title>UTF-8, a transformation format of ISO10646</title>
<author fullname="">
<organization></organization>
</author>
<date month="November" year="2003" />
</front>
<seriesInfo name="STD" value="63" />
<seriesInfo name="RFC" value="3629" />
</reference>
<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="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>
<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>
</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="ISO3309">
<front>
<title>ISO Information Processing Systems - Data Communication -
High-Level Data Link Control Procedure - Frame Structure</title>
<author>
<organization></organization>
</author>
<date month="October" year="1984" />
</front>
<seriesInfo name="IS" value="3309, 3rd Edition" />
</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="NIST-SP800-38B"
target="http://csrc.nist.gov/publications/nistpubs/800-38B/SP_800-38B.pdf">
<front>
<title>Recommendations for Block Cipher Modes of Operation: The CMAC
Mode for Authentication</title>
<author initials="" surname="">
<organization>International Organization for
Standardization</organization>
</author>
<date month="May" year="2005" />
</front>
<seriesInfo name="NIST" value="SP800-38B" />
</reference>
<reference anchor="NIST-SP800-57"
target="http://csrc.nist.gov/publications/nistpubs/800-57/sp800-57-Part1-revised2_Mar08-2007.pdf">
<front>
<title>Recommendation for Key Management - Part I: General
(Revised)</title>
<author>
<organization>National Institute of Standards and
Technology</organization>
</author>
<date month="March" year="2007" />
</front>
<seriesInfo name="NIST" value="800-57" />
</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="PSKC"
target="http://www.ietf.org/internet-drafts/draft-hoyer-keyprov-portable-symmetric-key-container-03.txt">
<front>
<title>Portable Symmetric Key Container</title>
<author fullname="">
<organization></organization>
</author>
<date year="2008" />
</front>
</reference>
<reference anchor="RFC2104" target="http://www.ietf.org/rfc/rfc2104.txt">
<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="RFC2396" target="http://www.ietf.org/rfc/rfc2396.txt">
<front>
<title>Uniform Resource Identifiers (URI): Generic Syntax</title>
<author initials="T." surname="Berners-Lee">
<organization></organization>
</author>
<author initials="R." surname="Fielding">
<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>
<date month="August" year="1998" />
</front>
<seriesInfo name="RFC" value="2396" />
</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="RFC3203" target="http://www.ietf.org/rfc/rfc3203.txt">
<front>
<title>XML Media Types</title>
<author initials="M." surname="Murata">
<organization></organization>
</author>
<author initials="S." surname="St. Laurent">
<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="D." surname="Kohn">
<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="January" year="2001" />
</front>
<seriesInfo name="RFC" value="3203" />
</reference>
<reference anchor="RFC3280" target="http://www.ietf.org/rfc/rfc3280.txt">
<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="RFC3575" target="http://www.ietf.org/rfc/rfc3575.txt">
<front>
<title>IANA Considerations for RADIUS</title>
<author initials="B." surname="Aboba">
<organization>VeriSign</organization>
</author>
<date month="July" year="2003" />
</front>
<seriesInfo name="RFC" value="3575" />
</reference>
<reference anchor="RFC3688" target="http://www.ietf.org/rfc/rfc3688.txt">
<front>
<title>The IETF XML Registry</title>
<author initials="M." surname="Mealling">
<organization>VeriSign</organization>
</author>
<date month="January" year="2004" />
</front>
<seriesInfo name="RFC" value="3688" />
<seriesInfo name="BCP" value="81" />
</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>
<reference anchor="SKPC-ASN.1"
target="http://www.ietf.org/internet-drafts/draft-ietf-keyprov-symmetrickeyformat-01.txt">
<front>
<title>Symmetric Key Package Content Type</title>
<author>
<organization></organization>
</author>
<date year="2007" />
</front>
</reference>
<reference anchor="XMLNS"
target="http://www.w3.org/TR/1999/REC-xml-names-19990114 ">
<front>
<title>Namespaces in XML</title>
<author>
<organization>W3C</organization>
</author>
<date month="January" year="1999" />
</front>
<seriesInfo name="W3C" value="Recommendation" />
</reference>
</references>
<section anchor="Section-Examples" title="Examples">
<t>This appendix contains example messages that illustrate parameters,
encoding, and semantics in four-and two- pass DSKPP exchanges. The
examples are written using XML, and are syntactically correct. MAC and
cipher values are fictitious however.</t>
<section title="Trigger Message">
<figure>
<preamble></preamble>
<artwork><![CDATA[<?xml version="1.0" encoding="UTF-8"?>
<dskpp:KeyProvTrigger Version="1.0"
xmlns:dskpp="urn:ietf:params:xml:ns:keyprov:dskpp:1.0"
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:pskc:1.0">
<dskpp:InitializationTrigger>
<dskpp:DeviceIdentifierData>
<dskpp:DeviceId>
<pskc:Manufacturer>ManufacturerABC</pskc:Manufacturer>
<pskc:SerialNo>XL0000000001234</pskc:SerialNo>
<pskc:Model>U2</pskc:Model>
</dskpp:DeviceId>
</dskpp:DeviceIdentifierData>
<dskpp:KeyID>SE9UUDAwMDAwMDAx</dskpp:KeyID>
<dskpp:TokenPlatformInfo KeyLocation="Hardware"
AlgorithmLocation="Software"/>
<dskpp:TriggerNonce>112dsdfwf312asder394jw==</dskpp:TriggerNonce>
<dskpp:ServerUrl>https://www.somekeyprovservice.com/
</dskpp:ServerUrl>
</dskpp:InitializationTrigger>
</dskpp:KeyProvTrigger>
]]></artwork>
<postamble></postamble>
</figure>
</section>
<section title="Four-Pass Protocol">
<section title="<KeyProvClientHello> 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:dskpp:1.0"
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:pskc:1.0"
xmlns:ds="http://www.w3.org/2000/09/xmldsig#">
<dskpp:DeviceIdentifierData>
<dskpp:DeviceId>
<pskc:Manufacturer>ManufacturerABC</pskc:Manufacturer>
<pskc:SerialNo>XL0000000001234</pskc:SerialNo>
<pskc:Model>U2</pskc:Model>
</dskpp:DeviceId>
</dskpp:DeviceIdentifierData>
<dskpp:SupportedKeyTypes>
<dskpp:Algorithm>http://www.ietf.org/keyprov/pskc#hotp
</dskpp:Algorithm>
<dskpp:Algorithm>http://www.rsa.com/rsalabs/otps/schemas/2005/09/
otps-wst#SecurID-AES</dskpp:Algorithm>
</dskpp:SupportedKeyTypes>
<dskpp:SupportedEncryptionAlgorithms>
<dskpp:Algorithm>http://www.w3.org/2001/05/xmlenc#rsa_1_5
</dskpp:Algorithm>
<dskpp:Algorithm>http://www.ietf.org/keyprov/dskpp#dskpp-prf-aes
</dskpp:Algorithm>
</dskpp:SupportedEncryptionAlgorithms>
<dskpp:SupportedMacAlgorithms>
<dskpp:Algorithm>http://www.ietf.org/keyprov/dskpp#dskpp-prf-aes
</dskpp:Algorithm>
</dskpp:SupportedMacAlgorithms>
<dskpp:SupportedProtocolVariants><dskpp:FourPass/>
</dskpp:SupportedProtocolVariants>
<dskpp:SupportedKeyPackages>
<dskpp:KeyPackageFormat>
http://www.ietf.org/keyprov/pskc#KeyContainer
</dskpp:KeyPackageFormat>
</dskpp:SupportedKeyPackages>
</dskpp:KeyProvClientHello>
]]></artwork>
<postamble></postamble>
</figure>
</section>
<section title="<KeyProvClientHello> 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:dskpp:1.0"
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:pskc:1.0"
xmlns:ds="http://www.w3.org/2000/09/xmldsig#">
<dskpp:DeviceIdentifierData>
<dskpp:DeviceId>
<pskc:Manufacturer>ManufacturerABC</pskc:Manufacturer>
<pskc:SerialNo>XL0000000001234</pskc:SerialNo>
<pskc:Model>U2</pskc:Model>
</dskpp:DeviceId>
</dskpp:DeviceIdentifierData>
<dskpp:KeyID>SE9UUDAwMDAwMDAx</dskpp:KeyID>
<dskpp:TriggerNonce>112dsdfwf312asder394jw==</dskpp:TriggerNonce>
<dskpp:SupportedKeyTypes>
<dskpp:Algorithm>http://www.ietf.org/keyprov/pskc#hotp</dskpp:Algorithm>
<dskpp:Algorithm>http://www.rsa.com/rsalabs/otps/schemas/2005/09/
otps-wst#SecurID-AES</dskpp:Algorithm>
</dskpp:SupportedKeyTypes>
<dskpp:SupportedEncryptionAlgorithms>
<dskpp:Algorithm>http://www.w3.org/2001/05/xmlenc#rsa_1_5
</dskpp:Algorithm>
<dskpp:Algorithm>http://www.ietf.org/keyprov/dskpp#dskpp-prf-aes
</dskpp:Algorithm>
</dskpp:SupportedEncryptionAlgorithms>
<dskpp:SupportedMacAlgorithms>
<dskpp:Algorithm>http://www.ietf.org/keyprov/dskpp#dskpp-prf-aes
</dskpp:Algorithm>
</dskpp:SupportedMacAlgorithms>
<dskpp:SupportedProtocolVariants><dskpp:FourPass/>
</dskpp:SupportedProtocolVariants>
<dskpp:SupportedKeyPackages>
<dskpp:KeyPackageFormat>
http://www.ietf.org/keyprov/pskc#KeyContainer
</dskpp:KeyPackageFormat>
</dskpp:SupportedKeyPackages>
</dskpp:KeyProvClientHello>
]]></artwork>
<postamble></postamble>
</figure>
</section>
<section title="<KeyProvServerHello> Without a Preceding Trigger">
<figure>
<preamble></preamble>
<artwork><![CDATA[ <?xml version="1.0" encoding="UTF-8"?>
<dskpp:KeyProvServerHello Version="1.0" SessionID="4114" Status="Continue"
xmlns:dskpp="urn:ietf:params:xml:ns:keyprov:dskpp:1.0"
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:pskc:1.0"
xmlns:ds="http://www.w3.org/2000/09/xmldsig#">
<dskpp:KeyType>
http://www.rsa.com/rsalabs/otps/schemas/2005/09/otps-wst#SecurID-AES
</dskpp:KeyType>
<dskpp:EncryptionAlgorithm>
http://www.ietf.org/keyprov/dskpp#dskpp-prf-aes
</dskpp:EncryptionAlgorithm>
<dskpp:MacAlgorithm>
http://www.ietf.org/keyprov/dskpp#dskpp-prf-aes
</dskpp:MacAlgorithm>
<dskpp:EncryptionKey>
<ds:KeyName>KEY-1</ds:KeyName>
</dskpp:EncryptionKey>
<dskpp:KeyPackageFormat>
http://www.ietf.org/keyprov/pskc#KeyContainer
</dskpp:KeyPackageFormat>
<dskpp:Payload>
<dskpp:Nonce>qw2ewasde312asder394jw==</dskpp:Nonce>
</dskpp:Payload>
</dskpp:KeyProvServerHello>
]]></artwork>
<postamble></postamble>
</figure>
</section>
<section title="<KeyProvServerHello> Assuming a Preceding Trigger">
<figure>
<preamble></preamble>
<artwork><![CDATA[<?xml version="1.0" encoding="UTF-8"?>
<dskpp:KeyProvServerHello Version="1.0" SessionID="4114"
Status="Continue"
xmlns:dskpp="urn:ietf:params:xml:ns:keyprov:dskpp:1.0"
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:pskc:1.0"
xmlns:ds="http://www.w3.org/2000/09/xmldsig#">
<dskpp:KeyType>
urn:ietf:params:xml:schema:keyprov:otpalg#SecurID-AES
</dskpp:KeyType>
<dskpp:EncryptionAlgorithm>
http://www.ietf.org/keyprov/dskpp#dskpp-prf-aes
</dskpp:EncryptionAlgorithm>
<dskpp:MacAlgorithm>
http://www.ietf.org/keyprov/dskpp#dskpp-prf-aes
</dskpp:MacAlgorithm>
<dskpp:EncryptionKey>
<ds:KeyName>KEY-1</ds:KeyName>
</dskpp:EncryptionKey>
<dskpp:KeyPackageFormat>
http://www.ietf.org/keyprov/pskc#KeyContainer
</dskpp:KeyPackageFormat>
<dskpp:Payload>
<dskpp:Nonce>qw2ewasde312asder394jw==</dskpp:Nonce>
</dskpp:Payload>
<dskpp:Mac
MacAlgorithm="http://www.ietf.org/keyprov/dskpp#dskpp-prf-aes">
cXcycmFuZG9tMzEyYXNkZXIzOTRqdw==
</dskpp:Mac>
</dskpp:KeyProvServerHello>
]]></artwork>
<postamble></postamble>
</figure>
</section>
<section title="<KeyProvClientNonce> 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:dskpp:1.0">
<dskpp:EncryptedNonce>VXENc+Um/9/NvmYKiHDLaErK0gk=
</dskpp:EncryptedNonce>
<dskpp:AuthenticationData>
<dskpp:ClientID>31300257</dskpp:ClientID>
<dskpp:AuthenticationCodeMac>
<dskpp:IterationCount>512</dskpp:IterationCount>
<dskpp:Mac>4bRJf9xXd3KchKoTenHJiw==</dskpp:Mac>
</dskpp:AuthenticationCodeMac>
</dskpp:AuthenticationData>
</dskpp:KeyProvClientNonce>
]]></artwork>
<postamble></postamble>
</figure>
</section>
<section title="<KeyProvServerFinished> Using Default Encryption">
<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:dskpp:1.0"
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:pskc:1.0">
<dskpp:KeyPackage>
<dskpp:KeyPackage Version="1.0">
<pskc:MACAlgorithm>http://www.w3.org/2000/09/xmldsig#hmac-sha1
</pskc:MACAlgorithm>
<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>
<pskc:Time>
<pskc:PlainValue>0</pskc:PlainValue>
</pskc:Time>
</pskc:Data>
<pskc:ExpiryDate>2012-12-31T00:00:00</pskc:ExpiryDate>
</pskc:Key>
</pskc:Device>
</dskpp:KeyPackage>
</dskpp:KeyPackage>
<dskpp:Mac
MacAlgorithm="http://www.ietf.org/keyprov/dskpp#dskpp-prf-aes">
miidfasde312asder394jw==
</dskpp:Mac>
</dskpp:KeyProvServerFinished>
]]></artwork>
<postamble></postamble>
</figure>
</section>
</section>
<section title="Two-Pass Protocol">
<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:</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:dskpp:1.0"
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:pskc:1.0"
xmlns:ds="http://www.w3.org/2000/09/xmldsig#">
<dskpp:DeviceIdentifierData>
<dskpp:DeviceId>
<pskc:Manufacturer>ManufacturerABC</pskc:Manufacturer>
<pskc:SerialNo>XL0000000001234</pskc:SerialNo>
<pskc:Model>U2</pskc:Model>
</dskpp:DeviceId>
</dskpp:DeviceIdentifierData>
<dskpp:ClientNonce>xwQzwEl0CjPAiQeDxwRJdQ==</dskpp:ClientNonce>
<dskpp:SupportedKeyTypes>
<dskpp:Algorithm>http://www.ietf.org/keyprov/pskc#hotp
</dskpp:Algorithm>
<dskpp:Algorithm>
http://www.rsa.com/rsalabs/otps/schemas/2005/09/otps-wst#SecurID-AES
</dskpp:Algorithm>
</dskpp:SupportedKeyTypes>
<dskpp:SupportedEncryptionAlgorithms>
<dskpp:Algorithm>http://www.w3.org/2001/05/xmlenc#rsa_1_5
</dskpp:Algorithm>
<dskpp:Algorithm>http://www.w3.org/2001/04/xmlenc#kw-aes128
</dskpp:Algorithm>
<dskpp:Algorithm>http://www.ietf.org/keyprov/dskpp#dskpp-prf-aes
</dskpp:Algorithm>
</dskpp:SupportedEncryptionAlgorithms>
<dskpp:SupportedMacAlgorithms>
<dskpp:Algorithm>http://www.ietf.org/keyprov/dskpp#dskpp-prf-aes
</dskpp:Algorithm>
</dskpp:SupportedMacAlgorithms>
<dskpp:SupportedProtocolVariants>
<dskpp:TwoPass>
<dskpp:SupportedKeyProtectionMethod>
urn:ietf:params:xml:schema:keyprov:dskpp#wrap
</dskpp:SupportedKeyProtectionMethod>
<dskpp:Payload>
<ds:KeyInfo xsi:type="ds:KeyInfoType">
<ds:KeyName>Key_001</ds:KeyName>
</ds:KeyInfo>
</dskpp:Payload>
<dskpp:SupportedKeyProtectionMethod>
urn:ietf:params:xml:schema:keyprov:dskpp#transport
</dskpp:SupportedKeyProtectionMethod>
<dskpp:SupportedKeyProtectionMethod>
urn:ietf:params:xml:schema:keyprov:dskpp#passphrase-wrap
</dskpp:SupportedKeyProtectionMethod>
<dskpp:Payload>
<ds:KeyInfo xsi:type="ds:KeyInfoType">
<ds:X509Data>
<ds:X509Certificate>miib</ds:X509Certificate>
</ds:X509Data>
</ds:KeyInfo>
</dskpp:Payload>
</dskpp:TwoPass>
</dskpp:SupportedProtocolVariants>
<dskpp:SupportedKeyPackages>
<dskpp:KeyPackageFormat>
http://www.ietf.org/keyprov/pskc#KeyContainer
</dskpp:KeyPackageFormat>
</dskpp:SupportedKeyPackages>
<dskpp:AuthenticationData>
<dskpp:ClientID>31300257</dskpp:ClientID>
<dskpp:AuthenticationCodeMac>
<dskpp:IterationCount>512</dskpp:IterationCount>
<dskpp:Mac>4bRJf9xXd3KchKoTenHJiw==</dskpp:Mac>
</dskpp:AuthenticationCodeMac>
</dskpp: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:dskpp:1.0"
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:pskc:1.0"
xmlns:ds="http://www.w3.org/2000/09/xmldsig#"
xmlns:xenc="http://www.w3.org/2001/04/xmlenc#">
<dskpp:KeyPackage>
<dskpp:ServerID>https://www.somedskppservice.com/</dskpp:ServerID>
<dskpp:KeyProtectionMethod>
urn:ietf:params:xml:schema:keyprov:dskpp#transport
</dskpp:KeyProtectionMethod>
<dskpp:KeyPackage Version="1.0">
<pskc:EncryptionKey>
<ds:X509Data>
<ds:X509Certificate>miib</ds:X509Certificate>
</ds:X509Data>
</pskc:EncryptionKey>
<pskc:Device>
<pskc:DeviceInfo>
<pskc:Manufacturer>ACME</pskc:Manufacturer>
<pskc:SerialNo>0755225266</pskc:SerialNo>
</pskc:DeviceInfo>
<pskc:Key KeyAlgorithm="http://www.ietf.org/keyprov/pskc#hotp"
KeyId="0755225266">
<pskc:Issuer>AnIssuer</pskc:Issuer>
<pskc:Usage OTP="true">
<pskc:ResponseFormat Length="8" Format="DECIMAL"/>
</pskc:Usage>
<pskc:Data>
<pskc:Secret>
<pskc:EncryptedValue Id="ED">
<xenc:EncryptionMethod
Algorithm="http://www.w3.org/2001/04/xmlenc#rsa_1_5"/>
<xenc:CipherData>
<xenc:CipherValue>rf4dx3rvEPO0vKtKL14NbeVu8nk=
</xenc:CipherValue>
</xenc:CipherData>
</pskc:EncryptedValue>
</pskc:Secret>
<pskc:Counter>
<pskc:PlainValue>0</pskc:PlainValue>
</pskc:Counter>
</pskc:Data>
</pskc:Key>
</pskc:Device>
</dskpp:KeyPackage>
</dskpp:KeyPackage>
<dskpp:Mac
MacAlgorithm="http://www.ietf.org/keyprov/dskpp#dskpp-prf-aes">
miidfasde312asder394jw==
</dskpp:Mac>
<dskpp:AuthenticationData>
<dskpp:Mac>4bRJf9xXd3KchKoTenHJiw==</dskpp:Mac>
</dskpp: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 based 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:dskpp:1.0"
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:pskc:1.0"
xmlns:ds="http://www.w3.org/2000/09/xmldsig#"
xmlns:pkcs-5=
"http://www.rsasecurity.com/rsalabs/pkcs/schemas/pkcs-5v2-0#">
<dskpp:DeviceIdentifierData>
<dskpp:DeviceId>
<pskc:Manufacturer>ManufacturerABC</pskc:Manufacturer>
<pskc:SerialNo>XL0000000001234</pskc:SerialNo>
<pskc:Model>U2</pskc:Model>
</dskpp:DeviceId>
</dskpp:DeviceIdentifierData>
<dskpp:ClientNonce>xwQzwEl0CjPAiQeDxwRJdQ==</dskpp:ClientNonce>
<dskpp:SupportedKeyTypes>
<dskpp:Algorithm>http://www.ietf.org/keyprov/pskc#hotp
</dskpp:Algorithm>
<dskpp:Algorithm>http://www.rsa.com/rsalabs/otps/schemas/2005/09/
otps-wst#SecurID-AES</dskpp:Algorithm>
</dskpp:SupportedKeyTypes>
<dskpp:SupportedEncryptionAlgorithms>
<dskpp:Algorithm>http://www.w3.org/2001/05/xmlenc#rsa_1_5
</dskpp:Algorithm>
<dskpp:Algorithm>http://www.w3.org/2001/04/xmlenc#kw-aes128
</dskpp:Algorithm>
<dskpp:Algorithm>http://www.rsasecurity.com/rsalabs/pkcs/schemas/
pkcs-5#pbes2</dskpp:Algorithm>
<dskpp:Algorithm>http://www.ietf.org/keyprov/dskpp#dskpp-prf-aes
</dskpp:Algorithm>
</dskpp:SupportedEncryptionAlgorithms>
<dskpp:SupportedMacAlgorithms>
<dskpp:Algorithm>http://www.ietf.org/keyprov/dskpp#dskpp-prf-aes
</dskpp:Algorithm>
</dskpp:SupportedMacAlgorithms>
<dskpp:SupportedProtocolVariants>
<dskpp:TwoPass>
<dskpp:SupportedKeyProtectionMethod>
urn:ietf:params:xml:schema:keyprov:dskpp#wrap
</dskpp:SupportedKeyProtectionMethod>
<dskpp:Payload>
<ds:KeyInfo xsi:type="ds:KeyInfoType">
<ds:KeyName>Key_001</ds:KeyName>
</ds:KeyInfo>
</dskpp:Payload>
</dskpp:TwoPass>
</dskpp:SupportedProtocolVariants>
<dskpp:SupportedKeyPackages>
<dskpp:KeyPackageFormat>
http://www.ietf.org/keyprov/pskc#KeyContainer
</dskpp:KeyPackageFormat>
</dskpp:SupportedKeyPackages>
<dskpp:AuthenticationData>
<dskpp:ClientID>31300257</dskpp:ClientID>
<dskpp:AuthenticationCodeMac>
<dskpp:IterationCount>512</dskpp:IterationCount>
<dskpp:Mac>4bRJf9xXd3KchKoTenHJiw==</dskpp:Mac>
</dskpp:AuthenticationCodeMac>
</dskpp: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:dskpp:1.0"
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:pskc:1.0"
xmlns:ds="http://www.w3.org/2000/09/xmldsig#"
xmlns:xenc="http://www.w3.org/2001/04/xmlenc#">
<dskpp:KeyPackage>
<dskpp:ServerID>https://www.somedskppservice.com/</dskpp:ServerID>
<dskpp:KeyProtectionMethod>
urn:ietf:params:xml:schema:keyprov:dskpp#wrap
</dskpp:KeyProtectionMethod>
<dskpp:KeyPackage Version="1.0">
<pskc:EncryptionKey>
<ds:KeyName>PRE_SHARED_KEY</ds:KeyName>
</pskc:EncryptionKey>
<pskc:MACAlgorithm>http://www.w3.org/2000/09/xmldsig#hmac-sha1
</pskc:MACAlgorithm>
<pskc:Device>
<pskc:Key KeyAlgorithm="http://www.ietf.org/keyprov/pskc#hotp"
KeyId="312345678">
<pskc:Issuer>CredentialIssuer</pskc:Issuer>
<pskc:Usage OTP="true">
<pskc:ResponseFormat Format="DECIMAL" Length="6"/>
</pskc:Usage>
<pskc:FriendlyName>MyFirstToken</pskc:FriendlyName>
<pskc:Data>
<pskc:Secret>
<pskc:EncryptedValue>
<xenc:EncryptionMethod
Algorithm="http://www.w3.org/2001/04/xmlenc#aes256-cbc"/>
<xenc:CipherData>
<xenc:CipherValue>
kyzrWTJuhJKQHhZtf2CWbKC5H3LdfAPvKzHHQ8SdxyE=
</xenc:CipherValue>
</xenc:CipherData>
</pskc:EncryptedValue>
<pskc:ValueMAC>cwJI898rRpGBytTqCAsegaQqPZA=
</pskc:ValueMAC>
</pskc:Secret>
<pskc:Counter>
<pskc:PlainValue>1/pskc:PlainValue>
</pskc:Counter>
</pskc:Data>
<pskc:ExpiryDate>2012-12-31T00:00:00</pskc:ExpiryDate>
</pskc:Key>
</pskc:Device>
</dskpp:KeyPackage>
</dskpp:KeyPackage>
<dskpp:Mac
MacAlgorithm="http://www.ietf.org/keyprov/dskpp#dskpp-prf-aes">
miidfasde312asder394jw==
</dskpp:Mac>
<dskpp:AuthenticationData>
<dskpp:Mac>4bRJf9xXd3KchKoTenHJiw==</dskpp:Mac>
</dskpp: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 based 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:dskpp:1.0"
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:pskc:1.0"
xmlns:ds="http://www.w3.org/2000/09/xmldsig#"
xmlns:pkcs-5=
"http://www.rsasecurity.com/rsalabs/pkcs/schemas/pkcs-5v2-0#">
<dskpp:DeviceIdentifierData>
<dskpp:DeviceId>
<pskc:Manufacturer>ManufacturerABC</pskc:Manufacturer>
<pskc:SerialNo>XL0000000001234</pskc:SerialNo>
<pskc:Model>U2</pskc:Model>
</dskpp:DeviceId>
</dskpp:DeviceIdentifierData>
<dskpp:ClientNonce>xwQzwEl0CjPAiQeDxwRJdQ==</dskpp:ClientNonce>
<dskpp:SupportedKeyTypes>
<dskpp:Algorithm>http://www.ietf.org/keyprov/pskc#hotp
</dskpp:Algorithm>
<dskpp:Algorithm>
http://www.rsa.com/rsalabs/otps/schemas/2005/09/otps-wst#SecurID-AES
</dskpp:Algorithm>
</dskpp:SupportedKeyTypes>
<dskpp:SupportedEncryptionAlgorithms>
<dskpp:Algorithm>http://www.w3.org/2001/05/xmlenc#rsa_1_5
</dskpp:Algorithm>
<dskpp:Algorithm>http://www.w3.org/2001/04/xmlenc#kw-aes128
</dskpp:Algorithm>
<dskpp:Algorithm>
http://www.rsasecurity.com/rsalabs/pkcs/schemas/pkcs-5#pbes2
</dskpp:Algorithm>
<dskpp:Algorithm>
http://www.ietf.org/keyprov/dskpp#dskpp-prf-aes
</dskpp:Algorithm>
</dskpp:SupportedEncryptionAlgorithms>
<dskpp:SupportedMacAlgorithms>
<dskpp:Algorithm>
http://www.ietf.org/keyprov/dskpp#dskpp-prf-aes
</dskpp:Algorithm>
</dskpp:SupportedMacAlgorithms>
<dskpp:SupportedProtocolVariants>
<dskpp:TwoPass>
<dskpp:SupportedKeyProtectionMethod>
urn:ietf:params:xml:schema:keyprov:dskpp#wrap
</dskpp:SupportedKeyProtectionMethod>
<dskpp:Payload>
<ds:KeyInfo xsi:type="ds:KeyInfoType">
<ds:KeyName>Key_001</ds:KeyName>
</ds:KeyInfo>
</dskpp:Payload>
<dskpp:SupportedKeyProtectionMethod>
urn:ietf:params:xml:schema:keyprov:dskpp#passphrase-wrap
</dskpp:SupportedKeyProtectionMethod>
</dskpp:TwoPass>
</dskpp:SupportedProtocolVariants>
<dskpp:SupportedKeyPackages>
<dskpp:KeyPackageFormat>
http://www.ietf.org/keyprov/pskc#KeyContainer
</dskpp:KeyPackageFormat>
</dskpp:SupportedKeyPackages>
<dskpp:AuthenticationData>
<dskpp:ClientID>31300257</dskpp:ClientID>
<dskpp:AuthenticationCodeMac>
<dskpp:IterationCount>512</dskpp:IterationCount>
<dskpp:Mac>4bRJf9xXd3KchKoTenHJiw==</dskpp:Mac>
</dskpp:AuthenticationCodeMac>
</dskpp: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:dskpp:1.0"
xmlns:pskc="urn:ietf:params:xml:ns:keyprov:pskc:1.0"
xmlns:pkcs-5="http://www.rsasecurity.com/rsalabs/pkcs/schemas/pkcs-5v2-0#"
xmlns:ds="http://www.w3.org/2000/09/xmldsig#"
xmlns:xenc="http://www.w3.org/2001/04/xmlenc#">
<dskpp:KeyPackage>
<dskpp:ServerID>https://www.somedskppservice.com/</dskpp:ServerID>
<dskpp:KeyProtectionMethod>
urn:ietf:params:xml:schema:keyprov:dskpp#passphrase-wrap
</dskpp:KeyProtectionMethod>
<dskpp:KeyPackage Version="1.0">
<pskc:EncryptionKey>
<pskc:DerivedKey Id="#Passphrase1">
<pskc:CarriedKeyName>Passphrase1</pskc:CarriedKeyName>
<pskc:KeyDerivationMethod
Algorithm=
"http://www.rsasecurity.com/rsalabs/pkcs/schemas/pkcs-5#pbkdf2">
<pkcs-5:Parameters xsi:type="pkcs-5:PBKDF2ParameterType">
<Salt>
<Specified>Df3dRAhjGh8=</Specified>
</Salt>
<IterationCount>2000</IterationCount>
<KeyLength>16</KeyLength>
<PRF/>
</pkcs-5:Parameters>
</pskc:KeyDerivationMethod>
<xenc:ReferenceList>
<xenc:DataReference URI="#ED"/>
</xenc:ReferenceList>
</pskc:DerivedKey>
</pskc:EncryptionKey>
<pskc:Device>
<pskc:DeviceInfo>
<pskc:Manufacturer>Manufacturer</pskc:Manufacturer>
<pskc:SerialNo>0755225266</pskc:SerialNo>
</pskc:DeviceInfo>
<pskc:Key KeyAlgorithm="http://www.ietf.org/keyprov/pskc#hotp"
KeyId="0755225266">
<pskc:Issuer>AnIssuer</pskc:Issuer>
<pskc:Usage OTP="true">
<pskc:ResponseFormat Length="6" Format="DECIMAL"/>
</pskc:Usage>
<pskc:Data>
<pskc:Secret>
<pskc:EncryptedValue Id="ED">
<xenc:EncryptionMethod
Algorithm="http://www.w3.org/2001/04/xmlenc#kw-aes128"/>
<xenc:CipherData>
<xenc:CipherValue>rf4dx3rvEPO0vKtKL14NbeVu8nk=
</xenc:CipherValue>
</xenc:CipherData>
</pskc:EncryptedValue>
</pskc:Secret>
<pskc:Counter>
<pskc:PlainValue>0</pskc:PlainValue>
</pskc:Counter>
</pskc:Data>
</pskc:Key>
</pskc:Device>
</dskpp:KeyPackage>
</dskpp:KeyPackage>
<dskpp:Mac
MacAlgorithm="http://www.ietf.org/keyprov/dskpp#dskpp-prf-aes">
miidfasde312asder394jw==
</dskpp:Mac>
<dskpp:AuthenticationData>
<dskpp:Mac>4bRJf9xXd3KchKoTenHJiw==</dskpp:Mac>
</dskpp:AuthenticationData>
</dskpp:KeyProvServerFinished>
]]></artwork>
<postamble></postamble>
</figure>
</section>
</section>
</section>
<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_PROV = 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_PROV
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_PROV by calling
C_DeriveKey using the CKM_EXTRACT_KEY_FROM_KEY mechanism, this
time setting CK_EXTRACT_PARAMS to the length of K_PROV (in
bits) divided by two.</t>
<t>The server wraps K_PROV with either the public key of the
DSKPP client or device, the pre-shared secret key, or the
derived shared secret key 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 key 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 ServerID 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 implementation may specify K_MAC' to be the value of
the K_TOKEN that is being replaced, or a version of K_MAC from
the previous protocol run), 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 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 ServerID 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_TOKEN, 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_PROV 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 ServerID 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 (the
implementation may specify K_MAC' to be the value of the
K_TOKEN that is being replaced, or a version of K_MAC from the
previous 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 URL MAY be used to identify this algorithm
in DSKPP:</t>
<t>http://www.ietf.org/keyprov/dskpp#dskpp-prf-aes-128</t>
<t>When this URL 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:</t>
<t><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)<vspace
blankLines="1" /></t>
<t>If dsLen > (2**32 - 1) * bLen, output "derived data too
long" and stop<vspace blankLines="1" /></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 = CEILING( dsLen / bLen)<vspace
blankLines="0" />j = dsLen - (n - 1) * bLen<vspace
blankLines="1" /></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></t>
<t>The function F is defined in terms of the CMAC construction from
<xref target="NIST-SP800-38B"></xref>, using AES as the block
cipher:<vspace blankLines="1" />F (k, s, i) = CMAC-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 CMAC 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) = CMAC-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 URL MAY be used to identify this algorithm
in DSKPP:</t>
<t>http://www.ietf.org/keyprov/dskpp#dskpp-prf-sha256</t>
<t>When this URL 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:</t>
<t><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)<vspace
blankLines="1" /></t>
<t>If dsLen > (2**32 - 1) * bLen, output "derived data too
long" and stop<vspace blankLines="1" /></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 = CEILING( dsLen / bLen)<vspace
blankLines="0" />j = dsLen - (n - 1) * bLen<vspace
blankLines="1" /></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></t>
<t>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 = CEILING( 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 20:41:31 |