One document matched: draft-ietf-dhc-sedhcpv6-12.xml
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<rfc category="std" docName="draft-ietf-dhc-sedhcpv6-12" ipr="trust200902">
<front>
<title abbrev="SeDHCPv6">Secure DHCPv6</title>
<author fullname="Sheng Jiang" initials="S." surname="Jiang">
<organization>Huawei Technologies Co., Ltd</organization>
<address>
<postal>
<street>Q14, Huawei Campus, No.156 Beiqing Road</street>
<city>Hai-Dian District, Beijing, 100095</city>
<country>CN</country>
</postal>
<email>jiangsheng@huawei.com</email>
</address>
</author>
<author fullname="Lishan Li" initials="L." surname="Li">
<organization>Tsinghua University</organization>
<address>
<postal>
<street></street>
<city>Beijing</city>
<code>100084</code>
<country>P.R.China</country>
</postal>
<phone>+86-15201441862</phone>
<email>lilishan48@gmail.com</email>
</address>
</author>
<author fullname="Yong Cui" initials="Y." surname="Cui">
<organization>Tsinghua University</organization>
<address>
<postal>
<street></street>
<city>Beijing</city>
<code>100084</code>
<country>P.R.China</country>
</postal>
<phone>+86-10-6260-3059</phone>
<email>yong@csnet1.cs.tsinghua.edu.cn</email>
</address>
</author>
<author fullname="Tatuya Jinmei" initials="T." surname="Jinmei">
<organization>Infoblox Inc.</organization>
<address>
<postal>
<street>3111 Coronado Drive</street>
<city>Santa Clara</city>
<region>CA</region>
<country>US</country>
</postal>
<email>jinmei@wide.ad.jp</email>
</address>
</author>
<author fullname="Ted Lemon" initials="T." surname="Lemon">
<organization>Nominum, Inc.</organization>
<address>
<postal>
<street>2000 Seaport Blvd</street>
<city>Redwood City, CA</city>
<code>94063</code>
<country>USA</country>
</postal>
<phone>+1-650-381-6000</phone>
<email>Ted.Lemon@nominum.com</email>
</address>
</author>
<author fullname="Dacheng Zhang" initials="D." surname="Zhang">
<address>
<postal>
<street></street>
<city>Beijing</city>
<country>CN</country>
</postal>
<email>dacheng.zhang@gmail.com</email>
</address>
</author>
<date month="" year="2016" />
<area>Internet Area</area>
<workgroup>DHC Working Group</workgroup>
<keyword>Secure</keyword>
<keyword>DHCPv6</keyword>
<keyword>Public Key</keyword>
<abstract>
<t>The Dynamic Host Configuration Protocol for IPv6 (DHCPv6) enables
DHCPv6 servers to pass configuration parameters. It offers configuration
flexibility. If not secured, DHCPv6 is vulnerable to various attacks.
This document analyzes the security issues of DHCPv6 and specifies the
secure DHCPv6 mechanism for authentication and encryption of messages
between a DHCPv6 client and a DHCPv6 server.</t>
</abstract>
</front>
<middle>
<section title="Introduction">
<t>The Dynamic Host Configuration Protocol for IPv6 (DHCPv6, <xref
target="RFC3315"></xref>) enables DHCPv6 servers to pass configuration
parameters and offers configuration flexibility. If not being secured,
DHCPv6 is vulnerable to various attacks.</t>
<t>This document analyzes the security issues of DHCPv6 and
provides the following mechanisms for improving the security of DHCPv6
between the DHCPv6 client and the DHCPv6 server:<list style="symbols">
<t>the authentication of the DHCPv6 client and the DHCPv6 server to
defend against active attacks, such as spoofing attack.</t>
<t>the encryption between the DHCPv6 client and the DHCPv6 server in
order to protect the DHCPv6 from passive attacks, such as pervasive
monitoring.</t>
</list></t>
<t>Note: this secure mechanism in this document does not protect outer
options in Relay-Forward and Relay-Reply messages, either added by a
relay agent toward a server or added by a server toward a relay agent.
Communication between a server and a relay agent, and communications
between relay agents, may be secured through the use of IPsec, as
described in section 21.1 in <xref target="RFC3315"></xref>.</t>
<t>The security mechanism specified in this document achieves DHCPv6
authentication and encryption based on the sender's certificate.
We introduce two new DHCPv6 messages: Encrypted-Query message and
Encrypted-Response message and Four new DHCPv6 options: Certificate
option, Signature option, Timestamp option and Encrypted-message option
for DHCPv6 authentication and encryption. The Certificate option,
Signature option, Timestamp option are used for DHCPv6 client/server
authentication. The Encryption-Query message, Encryption-Response
message and Encrypted-message option are used for DHCPv6 encryption.
</t>
<!--
<t>The security mechanism specified in this document is based on DHCPv6
client/server's certificates with associated private keys. It also
integrates message signatures for the integrity
and timestamps for anti-replay. The sender authentication procedure
using certificates defined in this document depends on deployed Public
Key Infrastructure (PKI, <xref target="RFC5280"></xref>). However, the
deployment of PKI is out of the scope of this document.</t>
-->
</section>
<section title="Requirements Language and Terminology">
<t>The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in <xref
target="RFC2119"></xref> when they appear in ALL CAPS. When these words
are not in ALL CAPS (such as "should" or "Should"), they have their
usual English meanings, and are not to be interpreted as <xref
target="RFC2119"></xref> key words.</t>
</section>
<section title="Terminology">
<t>This section defines terminology specific to secure DHCPv6 used in
this document.</t>
<t><list hangIndent="16" style="hanging">
<t hangText="secure DHCPv6 client:">A node that initiates the DHCPv6
request on a link to obtain the DHCPv6 configuration parameters from
one or more DHCPv6 servers. The configuration process is authenticated
and encrypted using the defined mechanisms in this document.</t>
<t hangText="secure DHCPv6 server:">A node that responds to requests
from clients using the authentication and encryption mechanism
defined in this document.</t>
</list></t>
</section>
<section title="Security Issues of DHCPv6">
<t>DHCPv6 is a client/server protocol that provides managed
configuration of devices. It enables a DHCPv6 server to automatically
configure relevant network parameters on clients. The basic DHCPv6
specification <xref target="RFC3315"></xref> defines security
mechanisms, but they have some flaws and can be improved.</t>
<t>The basic DHCPv6 specifications can optionally authenticate the
origin of messages and validate the integrity of messages using an
authentication option with a symmetric key pair. <xref target="RFC3315"></xref>
relies on pre-established secret keys. For any kind of meaningful
security, each DHCPv6 client would need to be configured with its
own secret key; <xref target="RFC3315"></xref> provides no mechanism
for doing this.</t>
<!--
<t>For the keyed hash function, there are two key management mechanisms.
The first one is a key management done out of band, usually through some
manual process. The second approach is to use Public Key Infrastructure
(PKI).</t>
-->
<t>For the out of band approach, operators can set up a key database for
both servers and clients from which the client obtains a key before
running DHCPv6. Manual key distribution runs counter to the goal of
minimizing the configuration data needed at each host.</t>
<t><xref target="RFC3315"></xref> provides an additional mechanism for
preventing off-network timing attacks using the Reconfigure message: the
Reconfigure Key authentication method. However, this method protects only
the Reconfigure message. The key is transmitted in plaintext to the client
in earlier exchanges and so this method is vulnerable to active attacks.</t>
<t>In addition, the current DHCPv6 messages are still transmitted in
cleartext and the privacy information within the DHCPv6 message is not
protected from passive attack, such as pervasive monitoring. The IETF
has expressed strong agreement that pervasive monitoring is an attack
that needs to be mitigated where possible in <xref target="RFC7258"></xref>.
</t>
<t>In comparison, the security mechanisms defined in this document
provides for authentication and encryption based on the public
key certificates of the client and server. The DHCPv6 authentication can
protect DHCPv6 from active attacks, such as spoofing attack. And the
DHCPv6 encryption defends against passive attacks, such as pervasive
monitoring attack.</t>
</section>
<section title="Secure DHCPv6 Overview">
<section title="Solution Overview">
<t>This solution provides authentication and encryption mechanisms
based on the certificates of the DHCPv6 client and server. Before the
standard DHCPv6 configuration process, the Information-request and
Reply messages are exchanged to select the authenticated DHCPv6 server.
After mutual authentication between the DHCPv6 client and server, the
following DHCPv6 configuration process is encrypted to avoid the privacy
information disclosure. We introduce two new DHCPv6 messages: Encrypted-Query
message, Encrypted-Response message and four new DHCPv6 options:
Encrypted-message option, Certificate option, Signature option, Timestamp
option. Based on the new defined messages and options, the corresponding
authentication and encryption mechanisms are achieved.</t>
<t>The following figure illustrates secure DHCPv6 procedure. The
DHCPv6 client first sends Information-request message as per <xref target="RFC3315"></xref>.
The Information-request message is used to request the servers for the
servers' certificates information, without going through any address,
prefix or non-security option assignment process. The Information-request
contains no DHCPv6 options except ORO option to avoid client's privacy
information disclosure. When receiving the Information-request message,
the server sends the Reply message that contains the server's Certificate
option, Signature option, Timestamp option and Server Identifier option.
Upon the receipt of the Reply message, the DHCPv6 client verifies the
server's identity according to the contained options in the Reply message.
If there are multiple authenticated DHCPv6 server certs, the client selects
one authenticated DHCPv6 server for the following DHCPv6 configuration process.
If there are no authenticated DHCPv6 server cert or existing server certs
fails authentication, the client should retry a number of times. In this way,
it is difficult for a rogue server to beat out a busy "real" server. And then
the client takes some other alternative action depending on its local policy.</t>
<t>After the server's authentication, the first DHCPv6 message sent
from the client to the server, such as Solicit message, contains the client's
Certificate information for client authentication. The DHCPv6 client sends
the Encrypted-Query message to server, which carries the Encrypted-message
option and the Server Identifier option. The Encrypted-message option
contains the encrypted DHCPv6 message sent from the client to the server.
When the DHCPv6 server receives the Encrypted-Query message, it decrypts
the message using its private key. If the decrypted message contains the
client's Certificate option, the DHCPv6 server verifies the client's
identity according to the contained client certificate information.</t>
<t>After the client's authentication, the server sends the Encrypted-Response
message to the client, which contains the Encrypted-message option. The
Encrypted-message option contains the encrypted DHCPv6 message sent from
server to client, which is encrypted using the client's public key. If
the message fails client authentication, then the server sends the
corresponding error status code to the client. During the encrypted
DHCPv6 configuration process, the Timestamp option can be contained in
the encrypted DHCPv6 messages to defend against replay attacks.
</t>
<figure align="center" title="Secure DHCPv6 Procedure">
<artwork><![CDATA[
+-------------+ +-------------+
|DHCPv6 Client| |DHCPv6 Server|
+-------------+ +-------------+
| Information-request |
|----------------------------------------->|
| Option Request option |
| |
| Reply |
|<-----------------------------------------|
| Certificate option |
| Signature option |
| Timestamp option |
| Server Identifier option |
| |
| Encryption-Query |
|----------------------------------------->|
| Encrypted-message option |
| Server Identifier option |
| |
| Encryption-Response |
|<-----------------------------------------|
| Encrypted-message option |
| |
]]></artwork>
</figure>
<!--
<t>It is worth noticing that the signature on a Secure DHCPv6 message
can be expected to significantly increase the size of the message. One
example is normal DHCPv6 message length plus 1 KB for a X.509
certificate and signature and 256 byte for a signature. IPv6 fragments
<xref target="RFC2460"></xref> are highly possible. Hence, deployment of
Secure DHCPv6 should also consider the issues of IP fragment, PMTU,
etc. Also, if there are firewalls and relays between secure DHCPv6 clients
and secure DHCPv6 servers, it is RECOMMENDED that the firewalls and
relays are configured to pass ICMP Packet Too Big messages <xref target="RFC4443"></xref>.</t>
-->
</section>
<section title="New Components">
<t>The new components of the mechanism specified in this document are
as follows:</t>
<t><list style="symbols">
<t>Servers and clients that use certificates first generate a
public/private key pair and then obtain a certificate that signs
the public key. The Certificate option is defined to carry the
certificate of the sender.</t>
<t>A signature generated using the private key which is used by the
receiver to verify the integrity of the DHCPv6 messages and then
authentication of the client/server. Another option is defined
to carry the signature.</t>
<t>A timestamp that can be used to detect replayed packet. The
Timestamp option is defined to carry the current time of the
client/server. The secure DHCPv6 client/server need to meet some
accuracy requirements and be synced to global time, while the
timestamp checking mechanism allows a configurable time value
for clock drift. The real time provision is out of scope of
this document.
</t>
<t>The Encrypted-message option that contains the encrypted DHCPv6
message.</t>
<t>The Encrypted-Query message that is sent from the secure DHCPv6
client to the secure DHCPv6 server. The Encrypted-Query message
contains the Encrypted-message option and Server Identifier option.</t>
<t>The Encrypted-Response message that is sent from the secure DHCPv6
server to the secure DHCPv6 client. The Encrypted-Response message
contains the Encrypted-message option.</t>
</list></t>
</section>
<section title="Support for Algorithm Agility">
<t>In order to provide a means of addressing problems that may emerge
in the future with existing hash algorithms, as recommended in
<xref target="RFC4270"></xref>, this document provides a mechanism
for negotiating the use of more secure hashes in the future.</t>
<t>In addition to hash algorithm agility, this document also provides
a mechanism for signature algorithm and encryption algorithm agility.
</t>
<t>The support for algorithm agility in this document is mainly a
unilateral notification mechanism from sender to recipient. A
recipient MAY support various algorithms simultaneously among
different senders, and the different senders in a same administrative
domain may be allowed to use various algorithms simultaneously. It
is NOT RECOMMENDED that the same sender and recipient use various
algorithms in a single communication session.</t>
<t>If the server does not support the algorithm used by the client,
the server SHOULD reply with an AlgorithmNotSupported status code
(defined in <xref target="StatusCodes"></xref>) to the client.
Upon receiving this status code, the client MAY resend the message
protected with the mandatory algorithm.
</t>
</section>
<!--
<section title="Support for Algorithm Agility">
<t>Hash functions are used to provide message integrity checks. In
order to provide a means of addressing problems that may emerge in the
future with existing hash algorithms, as recommended in <xref
target="RFC4270"></xref>, this document provides a mechanism for
negotiating the use of more secure hashes in the future.</t>
<t>In addition to hash algorithm agility, this document also provides
a mechanism for signature algorithm agility.</t>
<t>The support for algorithm agility in this document is a unilateral
notification mechanism from a server to a client through the Reply
message. A client MAY support various algorithms among different servers
simultaneously. It is NOT RECOMMENDED that the same client and server use
various algorithms in a single communication session.</t>
<t>If the client does not support the hash and signature algorithms used by
the server, the Reply message SHOULD be dropped. If both hash and signature
algorithms are supported, the client then checks the authority of this
server. The client SHOULD also use the same algorithms in the subsequent
messages.</t>
depending on the local policy on the client, the client can choose
to drop the message, or skip the check;
</section>
<section title="Imposed Additional Constraints">
<t>The client/server that supports identity verification MAY
impose additional constraints for verification. For example, it
may impose limits on minimum and maximum key lengths.</t>
<t><list style="hanging">
<t hangText="Minbits">The minimum acceptable key length for public
keys. An upper limit MAY also be set for the amount of computation
needed when verifying packets that use these security
associations. The appropriate lengths SHOULD be set according to
the signature algorithm and also following prudent cryptographic
practice. For example, minimum length 1024 and upper limit 2048
may be used for RSA <xref target="RSA"></xref>.</t>
</list></t>
</section>
-->
<section title="Applicability">
<t>In principle, Secure DHCPv6 is applicable in any environment where
physical security on the link is not assured and attacks on DHCPv6
are a concern. In practice, however, it will rely on some
operational assumptions mainly regarding public key distribution
and management, until more lessons are learned and more experiences
are achieved.</t>
<t>One feasible environment in an early deployment stage would be
enterprise networks. In such networks the security policy tends to
be strict and it will be easier to manage client hosts. One
trivial deployment scenario is therefore to manually pre-configure
client with the trusted servers' public key and manually register
clients' public keys for the server. It may also be possible to
deploy an internal PKI to make this less reliant on manual
operations, although it is currently subject to future study
specifically how to integrate such a PKI into the DHCPv6 service
for the network.</t>
<t>Note that this deployment scenario based on manual operation is not
different very much from the existing, shared-secret based
authentication mechanisms defined in <xref target="RFC3315"></xref> in terms of
operational costs. However, Secure DHCPv6 is still securer than
the shared-secret mechanism in that even if clients' keys stored
for the server are stolen that does not mean an immediate threat as
these are public keys. In addition, if some kind of PKI is used
with Secure DHCPv6, even if the initial installation of the
certificates is done manually, it will help reduce operational
costs of revocation in case a private key (especially that of the
server) is compromised.</t>
<t>It is believed that Secure DHCPv6 could be more widely applicable
with integration of generic PKI so that it will be more easily
deployed. But such a deployment requires more general issues with
PKI deployment be addressed, and it is currently unknown whether we
can find practical deployment scenarios. It is subject to future
study and experiments, and out of scope of this document.</t>
</section>
</section>
<section title="DHCPv6 Client Behavior">
<t>For the secure DHCPv6 client, a certificate is needed for client
authentication. The client is pre-configured with a certificate and its
corresponding private key. If the client is pre-configured with public
key but not with a certificate, it can generate the self-signed
certificate for client authentication.</t>
<t>The secure DHCPv6 client sends Information-request message as per
<xref target="RFC3315"></xref>. The Information-request message is used
by the DHCPv6 client to request the server's identity verification information
without having addresses, prefixes or any non-security options assigned to
it. The Information-request message MUST NOT include any DHCPv6 options
except ORO option to minimize client's privacy information leakage. The
Option Request option in the Information-request message MUST contain the
option code of the Certificate option.</t>
<t>When receiving the Reply messages from DHCPv6 servers, a secure
DHCPv6 client discards any DHCPv6 messages that meet any of the
following conditions:<list style="symbols">
<t>the Signature option is missing,</t>
<t>multiple Signature options are present,</t>
<t>the Certificate option is missing.</t>
</list></t>
<t>And then the client first checks the support of the hash function,
signature algorithm and encryption algorithm that the server used. If
the check fails, the Reply message is dropped. If all the algorithms
are supported, the client then checks the authority of this server.
The client also uses the same algorithms in the return messages.</t>
<t>The client validates the certificates through the pre-configured local
trusted certificates list or other methods. A certificate that finds a
match in the local trust certificate list is treated as verified. If the
client want to check server's certificate to see whether it has been revoked,
the OCSP stapling can be used. The message transaction-id is used as
the identifier of the authenticated server's public key for encryption.
At this point, the client has either recognized the certificate of the
server, or decided to drop the message.
</t>
<t>The client MUST now authenticate the server by verifying the
signature and checking timestamp (see details in <xref
target="timestampCheck"></xref>), if there is a Timestamp option. The
order of two procedures is left as an implementation decision. It is
RECOMMENDED to check timestamp first, because signature verification is
much more computationally expensive.</t>
<t>The Signature field verification MUST show that the signature has
been calculated as specified in <xref target="SigOption"></xref>. Only
the messages that get through both the signature verification and
timestamp check (if there is a Timestamp option) are accepted. Reply
message that does not pass the above tests MUST be discarded.</t>
<t>If there are multiple authenticated DHCPv6 servers, the client
selects one DHCPv6 server for the following network parameters
configuration. The client can also choose other implementation
method depending on the client's local policy if the defined protocol can
also run normally. For example, the client can try multiple transactions
(each encrypted with different public key) at the "same" time. If there
are no authenticated DHCPv6 servers or existing servers failed authentication,
the client should retry a number of times. In this way, it is difficult
for the rogue server to beat out a busy "real" server. And then the client
takes some alternative action depending on its local policy, such as
attempting to use an unsecured DHCPv6 server. The client conducts
the server discovery process as per section 18.1.5 of <xref target="RFC3315"></xref>
to avoid the packet storm.
</t>
<t>Once the server has been authenticated, the DHCPv6 client sends the
Encrypted-Query message to the DHCPv6 server. The Encrypted-Query message
contains the Encrypted-message option, which MUST be constructed as
explained in <xref target="EncryMesOption"></xref>, and Server Identifier
option. The Encrypted-message option contains the DHCPv6 message that
is encrypted using the selected server's public key. The Server Identifier
option is externally visible to avoid decryption cost by those unselected
servers. </t>
<t>For the encrypted DHCPv6 message sent from the DHCPv6 client to the
DHCPv6 server, the first DHCPv6 message, such as Solicit message, MUST
contain the Certificate option, Signature option and Timestamp option
for client authentication. The Certificate option MUST be constructed as
explained in <xref target="CertOption"></xref>. In addition, one and
only one Signature option MUST be contained, which MUST be constructed
as explained in <xref target="SigOption"></xref>. One and only one
Timestamp option SHOULD be contained, which MUST be constructed as
explained in <xref target="TimeStampOption"></xref>. The Timestamp field
SHOULD be set to the current time, according to sender's real time
clock.</t>
<t>If the client has multiple certificates with different public/private
key pairs, the message transaction-id is used as the identifier of the
client's private key for decryption. In addition, the subsequent encrypted
DHCPv6 message can contain the Timestamp option to defend against replay
attack.</t>
<t>For the received Encrypted-Response message, the client extracts the
Encrypted-message option and decrypts it using its private key to obtain
the original DHCPv6 message. Then it handles the message as per <xref
target="RFC3315"></xref>. If the decrypted DHCPv6 message contains the
Timestamp option, the DHCPv6 client checks the timestamp according to
the rule defined in <xref target="timestampCheck"></xref>. The DHCPv6
message, which fails the timestamp check, MUST be discarded. If the
client fails to get the proper parameters from the chosen server, it
sends the Encrypted-Query message to another authenticated server for
parameters configuration until the client obtains the proper parameters.
</t>
<t>When the client receives a Reply message with an error status code,
the error status code indicates the failure reason on the server side.
According to the received status code, the client MAY take follow-up
action:</t>
<t><list style="symbols">
<t>Upon receiving an AlgorithmNotSupported error status code, the
client SHOULD resend the message protected with one of the
mandatory algorithms.</t>
<t>Upon receiving an AuthenticationFail error status code, the
client is not able to build up the secure communication with the
server. However, there may be other DHCPv6 servers available that
successfully complete authentication. The client MAY use the
AuthenticationFail as a hint and switch to other certificate if
it has another one; but otherwise treat the message containing the
status code as if it had not been received. But it SHOULD NOT retry
with the same certificate. However, if the client decides to retransmit
using the same certificate after receiving AuthenticationFail, it MUST
NOT retransmit immediately and MUST follow normal retransmission
routines defined in <xref target="RFC3315"></xref>.</t>
<t>Upon receiving a DecryptionFail error status code, the client MAY
resend the message following normal retransmission routines
defined in <xref target="RFC3315"></xref>.</t>
<t>Upon receiving a TimestampFail error status code, the client MAY
resend the message with an adjusted timestamp according to the
returned clock from the DHCPv6 server. The client SHOULD NOT
change its own clock, but only compute an offset for the
communication session.</t>
<t>Upon receiving a SignatureFail error status code, the client MAY
resend the message following normal retransmission routines defined
in <xref target="RFC3315"></xref>.</t>
</list></t>
</section>
<section title="DHCPv6 Server Behavior">
<t>For the secure DHCPv6 server, a certificate is needed for server
authentication. The server is pre-configured with a certificate and its
corresponding private key. If the server is pre-configured with public
key but not with a certificate, it can generate the self-signed certificate
for server authentication.</t>
<t>When the DHCPv6 server receives the Information-request message and
the contained Option Request option identifies the request is for the server
certificate information, it replies with a Reply message to the client.
The Reply message MUST contain the requested Certificate option, which
MUST be constructed as explained in <xref target="CertOption"></xref>,
and Server Identifier option. In addition, the Reply message MUST contain
one and only one Signature option, which MUST be constructed as explained
in <xref target="SigOption"></xref>. Besides, the Reply message SHOULD
contain one and only one Timestamp option, which MUST be constructed as
explained in <xref target="TimeStampOption"></xref>. The Timestamp field
SHOULD be set to the current time, according to server's real time clock.</t>
<t>Upon the receipt of Encrypted-Query message, the server checks the
Server Identifier option. It decrypts the Encrypted-message option using
its private key if it is the target server. The DHCPv6 server drops the
message that is not for it, thus not paying cost to decrypt messages not
for it.</t>
<t>If the decrypted message is a Solicit/Information-request message, the
secure DHCPv6 server discards the received message that meets any
of the following conditions:<list style="symbols">
<t>the Signature option is missing,</t>
<t>multiple Signature options are present,</t>
<t>the Certificate option is missing.</t>
</list></t>
<t>In such failure, the server replies with an UnspecFail (value 1,
<xref target="RFC3315"></xref>) error status code.</t>
<t>The server SHOULD first check the support of the hash function,
signature algorithm, encryption algorithm that the client used. If the
check fails, the server SHOULD reply with an AlgorithmNotSupported error
status code, defined in <xref target="StatusCodes"></xref>, back to the
client. If all the algorithms are supported, the server then checks the
authority of this client.</t>
<t>The server validates the client's public key through the local pre-configured
trusted public keys list. A public key that finds a match in the local trust
public keys list is treated as verified. The message that fails public key
validation MUST be dropped. In such failure, the DHCPv6 server replies with
an AuthenticationFail error status code, defined in <xref target="StatusCodes"></xref>,
back to the client. At this point, the server has either recognized the
authentication of the client, or decided to drop the message.</t>
<t>If the decrypted message contains the Timestamp option, the server
checks the timestamp according to the rule defined in <xref target="timestampCheck"></xref>.
If the timestamp check fails, a TimestampFail error status code, defined in
<xref target="StatusCodes"></xref>, should be sent back to the client.
Depending on server's local policy, the message without a Timestamp
option MAY be acceptable or rejected. If the server rejects such a
message, a TimestampFail error status code should be sent back to the
client. The Reply message that carries the TimestampFail error status
code carries a Timestamp option, which indicates the server's clock
for the client to use.</t>
<t>If the server does not send the Timestamp option, the client ignores
the timestamp check and verifies the signature. If there is a timestamp
option, the server MUST now authenticate the client by verifying the
signature and checking timestamp (see details in <xref
target="timestampCheck"></xref>). The order of two procedures is left as
an implementation decision. It is RECOMMENDED to check timestamp first,
because signature verification is much more computationally expensive.
Depending on server's local policy, the message without a Timestamp
option MAY be acceptable or rejected. If the server rejects such a
message, a TimestampFail error status code, defined in <xref
target="StatusCodes"></xref>, should be sent back to the client. The
reply message that carries the TimestampFail error status code SHOULD
carry a Timestamp option, which indicates the server's clock for the
client to use.</t>
<t>The Signature field verification MUST show that the signature has
been calculated as specified in <xref target="SigOption"></xref>. Only
the clients that get through both the signature verification and
timestamp check (if there is a Timestamp option) are accepted as
authenticated clients and continue to be handled their message as
defined in <xref target="RFC3315"></xref>. Clients that do not pass the
above tests MUST be treated as unauthenticated clients. The DHCPv6
server SHOULD reply a SignatureFail error status code, defined in <xref
target="StatusCodes"></xref>, for the signature verification failure; or
a TimestampFail error status code, defined in <xref
target="StatusCodes"></xref>, for the timestamp check failure, back to
the client.</t>
<t>Once the client has been authenticated, the DHCPv6 server sends the
Encrypted-response message to the DHCPv6 client. The Encrypted-response
message contains the Encrypted-message option, which MUST be constructed
as explained in <xref target="EncryMesOption"></xref>. The
Encrypted-message option contains the encrypted DHCPv6 message that is
encrypted using the authenticated client's public key. To provide the
replay protection, the Timestamp option can be contained in the encrypted
DHCPv6 message.</t>
</section>
<section title="Relay Agent Behavior">
<t>When a DHCPv6 relay agent receives an Encrypted-query or
Encrypted-response message, it may not recognize this message. The
unknown messages MUST be forwarded as described in <xref
target="RFC7283"></xref>.</t>
<t>When a DHCPv6 relay agent recognizes the Encrypted-query and
Encrypted-response messages, it forwards the message according to
section 20 of <xref target="RFC3315"></xref>. There is nothing more the
relay agents have to do, it neither needs to verify the messages from
client or server, nor add any secure DHCPv6 options. Actually, by
definition in this document, relay agents MUST NOT add any secure
DHCPv6 options.</t>
<t>Relay-forward and Relay-reply messages MUST NOT contain any
additional Certificate option or Timestamp option, aside from those
present in the innermost encapsulated messages from the client or
server.</t>
<t>Relay agent is RECOMMENDED to cache server announcements to form
the list of the available DHCPv6 server certs. If the relay agent
receives the Information-request message, then it replies with
a list of server certs available locally. In this way, the client
can be confident of a quick response, and therefore treat the lack
of a quick response as an indication that no authenticated DHCP servers
exist.</t>
</section>
<section title="Processing Rules">
<section anchor="timestampCheck" title="Timestamp Check">
<t>In order to check the Timestamp option, defined in <xref
target="TimeStampOption"></xref>, recipients SHOULD be configured with
an allowed timestamp Delta value, a "fuzz factor" for comparisons, and
an allowed clock drift parameter. The recommended default value for
the allowed Delta is 300 seconds (5 minutes); for fuzz factor 1
second; and for clock drift, 0.01 second.</t>
<t>Note: the Timestamp mechanism is based on the assumption that
communication peers have roughly synchronized clocks, within certain
allowed clock drift. So, an accurate clock is not necessary. If one has a
clock too far from the current time, the timestamp mechanism would not
work.</t>
<t>To facilitate timestamp checking, each recipient SHOULD store the
following information for each sender, from which at least one
accepted secure DHCPv6 message is successfully verified (for
timestamp check and signature verification):</t>
<t><list style="symbols">
<t>The receive time of the last received and accepted DHCPv6
message. This is called RDlast.</t>
<t>The timestamp in the last received and accepted DHCPv6 message.
This is called TSlast.</t>
</list>A verified (for timestamp check and signature verification)
secure DHCPv6 message initiates the update of the above variables
in the recipient's record.</t>
<t>Recipients MUST check the Timestamp field as follows:</t>
<t><list style="symbols">
<t>When a message is received from a new peer (i.e., one that is
not stored in the cache), the received timestamp, TSnew, is
checked, and the message is accepted if the timestamp is recent
enough to the reception time of the packet, RDnew:<list
style="empty">
<t>-Delta < (RDnew - TSnew) < +Delta</t>
</list><vspace blankLines="1" />After the signature verification
also succeeds, the RDnew and TSnew values SHOULD be stored in the
cache as RDlast and TSlast.</t>
<t>When a message is received from a known peer (i.e., one that
already has an entry in the cache), the timestamp is checked
against the previously received Secure DHCPv6 message:<list
style="empty">
<t>TSnew + fuzz > TSlast + (RDnew - RDlast) x (1 - drift) -
fuzz</t>
</list><vspace blankLines="1" />If this inequality does not hold
or RDnew < RDlast, the recipient SHOULD silently discard the
message. If, on the other hand, the inequality holds, the
recipient SHOULD process the message. <vspace
blankLines="1" />Moreover, if the above inequality holds and TSnew
> TSlast, the recipient SHOULD update RDlast and TSlast after
the signature verification also successes. Otherwise, the
recipient MUST NOT update RDlast or TSlast.</t>
</list>An implementation MAY use some mechanism such as a timestamp
cache to strengthen resistance to replay attacks. When there is a very
large number of nodes on the same link, or when a cache filling attack
is in progress, it is possible that the cache holding the most recent
timestamp per sender will become full. In this case, the node MUST
remove some entries from the cache or refuse some new requested
entries. The specific policy as to which entries are preferred over
others is left as an implementation decision.</t>
<t>An implementation MAY statefully record the latest timestamps from
senders. In such implementation, the timestamps MUST be strictly
monotonously increasing. This is reasonable given that DHCPv6 messages
are rarely misordered.</t>
</section>
</section>
<section title="Extensions for Secure DHCPv6">
<t>This section describes the extensions to DHCPv6. Four new DHCPv6
options, two new DHCPv6 messages and five new status codes are
defined.</t>
<section title="New DHCPv6 Options">
<section anchor="CertOption" title="Certificate Option">
<t>The Certificate option carries the certificate of the client/server.
The format of the Certificate option is described as follows:</t>
<t><figure align="center">
<artwork><![CDATA[ 0 1 2 3
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_CERTIFICATE | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| EA-id | |
+-+-+-+-+-+-+-+-+ .
. Certificate (variable length) .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_CERTIFICATE (TBA1).
option-len 1 + Length of certificate in octets.
EA-id Encryption Algorithm id. The encryption algorithm
is used for the encrypted DHCPv6 configuration
process. This design is adopted in order to provide
encryption algorithm agility. The value is from the
Encryption Algorithm for Secure DHCPv6 registry in
IANA. A registry of the initial assigned values
is defined in Section 12.
Certificate A variable-length field containing certificate. The
encoding of certificate and certificate data MUST
be in format as defined in Section 3.6, [RFC7296].
The support of X.509 certificate is mandatory.
]]></artwork>
</figure></t>
</section>
<section anchor="SigOption" title="Signature option">
<t>The Signature option allows a signature that is signed by the
private key to be attached to a DHCPv6 message. The Signature option
could be in any place within the DHCPv6 message while it is logically
created after the entire DHCPv6 header and options. It protects the
entire DHCPv6 header and options, including itself. The
format of the Signature option is described as follows:</t>
<t><figure align="center">
<artwork><![CDATA[ 0 1 2 3
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_SIGNATURE | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| HA-id | SA-id | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| |
. Signature (variable length) .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_SIGNATURE (TBA2).
option-len 2 + Length of Signature field in octets.
HA-id Hash Algorithm id. The hash algorithm is used for
computing the signature result. This design is
adopted in order to provide hash algorithm agility.
The value is from the Hash Algorithm for Secure
DHCPv6 registry in IANA. The support of SHA-256 is
mandatory. A registry of the initial assigned values
is defined in Section 12.
SA-id Signature Algorithm id. The signature algorithm is
used for computing the signature result. This
design is adopted in order to provide signature
algorithm agility. The value is from the Signature
Algorithm for Secure DHCPv6 registry in IANA. The
support of RSASSA-PKCS1-v1_5 is mandatory. A
registry of the initial assigned values is defined
in Section 12.
Signature A variable-length field containing a digital
signature. The signature value is computed with
the hash algorithm and the signature algorithm,
as described in HA-id and SA-id. The signature
constructed by using the sender's private key
protects the following sequence of octets:
1. The DHCPv6 message header.
2. All DHCPv6 options including the Signature
option (fill the Signature field with zeroes)
except for the Authentication Option.
The Signature field MUST be padded, with all 0, to
the next octet boundary if its size is not a
multiple of 8 bits. The padding length depends on
the signature algorithm, which is indicated in the
SA-id field.
]]></artwork>
</figure></t>
<t>Note: If Secure DHCPv6 is used, the DHCPv6 message is encrypted in a
way that the authentication mechanism defined in RFC3315 does not understand.
So the Authentication option SHOULD NOT be used if Secure DHCPv6 is
applied.</t>
<!--Note: if both signature and authentication option are
present, Signature option does not protect the Authentication
Option. It allows the Authentication Option to be created after
signature has been calculated and filled with the valid signature.
It is because both options need to apply hash algorithm to whole
message, so there must be a clear order and there can be only one
last-created option. In order to avoid update <xref target="RFC3315"></xref>
because of changing auth option, the authors choose not to include
authentication option in the signature.</t>
-->
</section>
<section anchor="TimeStampOption" title="Timestamp Option">
<t>The Timestamp option carries the current time on the sender. It
adds the anti-replay protection to the DHCPv6 messages. It is
optional.</t>
<t><figure>
<artwork><![CDATA[ 0 1 2 3
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_TIMESTAMP | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Timestamp (64-bit) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_TIMESTAMP (TBA3).
option-len 8, in octets.
Timestamp The current time of day (SeND-format timestamp
in UTC (Coordinated Universal Time). It can reduce
the danger of replay attacks. The timestamp data MUST
be in format as defined in Section 5.3.1, [RFC3971].
]]></artwork>
</figure></t>
</section>
<section anchor="EncryMesOption" title="Encrypted-message Option">
<t>The Encrypted-message option carries the encrypted DHCPv6 message
with the recipient's public key.</t>
<t>The format of the Encrypted-message option is:</t>
<figure align="center" anchor="option-dhcpv6-msg"
title="Encrypted-message Option Format">
<artwork><![CDATA[
0 1 2 3
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| option-code | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. encrypted DHCPv6 message .
. (variable) .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
</figure>
<t><list style="hanging">
<t hangText="option-code">OPTION_ENCRYPTED_MSG (TBA4).</t>
<t hangText="option-len">Length of the encrypted DHCPv6
message.</t>
<t hangText="encrypted DHCPv6 message">A variable length field
containing the encrypted DHCPv6 message sent by the client or
the server. In Encrypted-Query message, it contains encrypted
DHCPv6 message sent by a client. In Encrypted-response message,
it contains encrypted DHCPv6 message sent by a server.</t>
</list></t>
</section>
</section>
<section anchor="DHCPv6Messages" title="New DHCPv6 Messages">
<t>Two new DHCPv6 messages are defined to achieve the DHCPv6 encryption:
Encrypted-Query and Encrypted-Response. Both the DHCPv6 messages defined
in this document share the following format:</t>
<figure align="center" anchor="encrypted-query-format"
title="The format of Encrypted-Query and Encrypted-Response Messages">
<artwork><![CDATA[
0 1 2 3
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| msg-type | transaction-id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. options .
. (variable) .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
</figure>
<t><list hangIndent="16" style="hanging">
<t hangText="msg-type">Identifier of the message type. It can be either
Encrypted-Query (TBA5) or DHCPv6-Response (TBA6).</t>
<t hangText="transaction-id">The transaction ID for this message
exchange.</t>
<t hangText="options">The Encrypted-Query message MUST contain the
Server Identifier option and Encrypted-message option. The Encrypted-Response
message MUST contain the Encrypted-message option.</t>
</list></t>
</section>
<section anchor="StatusCodes" title="Status Codes">
<t>The following new status codes, see Section 5.4 of <xref
target="RFC3315"></xref> are defined. <list style="symbols">
<t>AlgorithmNotSupported (TBD7): indicates that the DHCPv6 server
does not support algorithms that sender used.</t>
<t>AuthenticationFail (TBD8): indicates that the message from the
DHCPv6 client fails authentication check.</t>
<t>TimestampFail (TBD9): indicates the message from DHCPv6 client
fails the timestamp check.</t>
<t>SignatureFail (TBD10): indicates the message from DHCPv6 client
fails the signature check.</t>
<t>DecryptionFail (TBD11): indicates the message from DHCPv6 client
fails the DHCPv6 message decryption.</t>
</list></t>
</section>
</section>
<section anchor="Security" title="Security Considerations">
<t>This document provides the authentication and encryption mechanisms
for DHCPv6.</t>
<t><xref target="RFC6273"></xref> has analyzed possible threats to the
hash algorithms used in SEND. Since Secure DHCPv6 defined in this
document uses the same hash algorithms in similar way to SEND, analysis
results could be applied as well: current attacks on hash functions do
not constitute any practical threat to the digital signatures used in
the signature algorithm in Secure DHCPv6.</t>
<t>A server, whose local policy accepts messages without a Timestamp
option, may have to face the risk of replay attacks.</t>
<t>A window of vulnerability for replay attacks exists until the
timestamp expires. Secure DHCPv6 nodes are protected against replay
attacks as long as they cache the state created by the message
containing the timestamp. The cached state allows the node to protect
itself against replayed messages. However, once the node flushes the
state for whatever reason, an attacker can re-create the state by
replaying an old message while the timestamp is still valid. In
addition, the effectiveness of timestamps is largely dependent upon the
accuracy of synchronization between communicating nodes. However, how
the two communicating nodes can be synchronized is out of scope of this
work.</t>
<t>Attacks against time synchronization protocols such as NTP <xref target="RFC5905"></xref>
may cause Secure DHCPv6 nodes to have an incorrect timestamp value. This
can be used to launch replay attacks, even outside the normal window of
vulnerability. To protect against these attacks, it is recommended that
Secure DHCPv6 nodes keep independently maintained clocks or apply
suitable security measures for the time synchronization protocols.</t>
<t>There are some mandatory algorithm for encryption algorithm in this
document. It may be at some point that the mandatory algorithm is no
longer safe to use.</t>
<t>If the client tries more than one cert for client authentication, the
server can easily get a client that implements this to enumerate its
entire cert list and probably learn a lot about a client that way.</t>
</section>
<section anchor="IANA" title="IANA Considerations">
<t>This document defines four new DHCPv6 <xref target="RFC3315"></xref>
options. The IANA is requested to assign values for these four options
from the DHCPv6 Option Codes table of the DHCPv6 Parameters registry
maintained in http://www.iana.org/assignments/dhcpv6-parameters. The
four options are:</t>
<t><list style="empty">
<t>The Certificate Option (TBA1), described in <xref
target="CertOption"></xref>.</t>
<t>The Signature Option (TBA2), described in <xref
target="SigOption"></xref>.</t>
<t>The Timestamp Option (TBA3),described in <xref
target="TimeStampOption"></xref>.</t>
<t>The Encrypted-message Option (TBA4), described in <xref
target="EncryMesOption"></xref>.</t>
</list></t>
<t>The IANA is also requested to assign value for these two messages
from the DHCPv6 Message Types table of the DHCPv6 Parameters registry
maintained in http://www.iana.org/assignments/dhcpv6-parameters. The two
messages are:</t>
<t><list style="empty">
<t>The Encrypted-Query Message (TBA5), described in <xref
target="DHCPv6Messages"></xref>.</t>
<t>The Encrypted-Response Message (TBA6), described in <xref
target="DHCPv6Messages"></xref>.</t>
</list></t>
<t>The IANA is also requested to add three new registry tables to the
DHCPv6 Parameters registry maintained in
http://www.iana.org/assignments/dhcpv6-parameters. The three tables are
the Hash Algorithm for Secure DHCPv6 table, the Signature Algorithm
for Secure DHCPv6 table and the Encryption Algorithm for Secure DHCPv6
table.</t>
<t>Initial values for these registries are given below. Future
assignments are to be made through Standards Action <xref
target="RFC5226"></xref>. Assignments for each registry consist of a
name, a value and a RFC number where the registry is defined.</t>
<t>Hash Algorithm for Secure DHCPv6. The values in this table are 8-bit
unsigned integers. The following initial values are assigned for Hash
Algorithm for Secure DHCPv6 in this document:</t>
<t><figure>
<artwork><![CDATA[ Name | Value | RFCs
-------------------+---------+--------------
SHA-256 | 0x01 | this document
SHA-512 | 0x02 | this document
]]></artwork>
</figure>Signature Algorithm for Secure DHCPv6. The values in this
table are 8-bit unsigned integers. The following initial values are
assigned for Signature Algorithm for Secure DHCPv6 in this document:</t>
<t><figure>
<artwork><![CDATA[ Name | Value | RFCs
-------------------+---------+--------------
RSASSA-PKCS1-v1_5 | 0x01 | this document
]]></artwork>
</figure>Encryption algorithm for Secure DHCPv6. The values in this table are
8-bit unsigned integers. The following initial values are assigned for
encryption algorithm for Secure DHCPv6 in this document:</t>
<t><figure>
<artwork><![CDATA[ Name | Value | RFCs
-------------------+---------+--------------
RSA | 0 | this document
]]></artwork>
</figure></t>
<t>IANA is requested to assign the following new DHCPv6 Status
Codes, defined in <xref target="StatusCodes"></xref>, in the DHCPv6
Parameters registry maintained in
http://www.iana.org/assignments/dhcpv6-parameters:</t>
<t><figure>
<artwork><![CDATA[ Code | Name | Reference
---------+-----------------------+--------------
TBD7 | AlgorithmNotSupported | this document
TBD8 | AuthenticationFail | this document
TBD9 | TimestampFail | this document
TBD10 | SignatureFail | this document
TBD11 | DecryptionFail | this document
]]></artwork>
</figure></t>
</section>
<section anchor="Acknowledgments" title="Acknowledgements">
<t>The authors would like to thank Tomek Mrugalski, Bernie Volz, Jianping
Wu, Randy Bush, Yiu Lee, Sean Shen, Ralph Droms, Jari Arkko, Sean
Turner, Stephen Farrell, Christian Huitema, Stephen Kent, Thomas Huth,
David Schumacher, Francis Dupont, Gang Chen, Suresh Krishnan, Fred
Templin, Robert Elz, Nico Williams, Erik Kline, Alan DeKok, Bernard
Aboba, Sam Hartman, Qi Sun, Zilong Liu and other members of the IETF
DHC working group for their valuable comments.</t>
<t>This document was produced using the xml2rfc tool <xref
target="RFC2629"></xref>.</t>
</section>
<section anchor="changes" title="Change log [RFC Editor: Please remove]">
<t>draft-ietf-dhc-sedhcpv6-12: Add the Signature option and timestamp
option during server/client authentication process. Add the hash
function and signature algorithm. Add the requirement: The Information-request
message cannot contain any other options except ORO option. Modify
the use of "SHOULD"; Delete the reference of RFC5280 and modify the
method of client/server cert verification; Add the relay agent cache
function for the quick response when there is no authenticated server.
2016-4-24.</t>
<t>draft-ietf-dhc-sedhcpv6-11: Delete the Signature option, because the
encrypted DHCPv6 message and the Information-request message (only contain
the Certificate option) don't need the Signature option for message
integrity check; Rewrite the "Applicability" section; Add the encryption
algorithm negotiation process; To support the encryption algorithm
negotiation, the Certificate option contains the EA-id(encryption
algorithm identifier) field; Reserve the Timestamp option to defend
against the replay attacks for encrypted DHCPv6 configuration process;
Modify the client behavior when there is no authenticated DHCPv6 server;
Add the DecryptionFail error code. 2016-3-9.</t>
<t>draft-ietf-dhc-sedhcpv6-10: merge DHCPv6 authentication and DHCPv6
encryption. The public key option is removed, because the device can
generate the self-signed certificate if it is pre-configured the public
key not the certificate. 2015-12-10.</t>
<t>draft-ietf-dhc-sedhcpv6-09: change some texts about the deployment
part.2015-12-10.</t>
<t>draft-ietf-dhc-sedhcpv6-08: clarified what the client and the server
should do if it receives a message using unsupported algorithm; refined
the error code treatment regarding to AuthenticationFail and
TimestampFail; added consideration on how to reduce the DoS attack when
using TOFU; other general editorial cleanups. 2015-06-10.</t>
<t>draft-ietf-dhc-sedhcpv6-07: removed the deployment consideration
section; instead, described more straightforward use cases with TOFU in
the overview section, and clarified how the public keys would be stored
at the recipient when TOFU is used. The overview section also clarified
the integration of PKI or other similar infrastructure is an open issue.
2015-03-23.</t>
<t>draft-ietf-dhc-sedhcpv6-06: remove the limitation that only clients
use PKI- certificates and only servers use public keys. The new text
would allow clients use public keys and servers use PKI-certificates.
2015-02-18.</t>
<t>draft-ietf-dhc-sedhcpv6-05: addressed comments from mail list that
responsed to the second WGLC. 2014-12-08.</t>
<t>draft-ietf-dhc-sedhcpv6-04: addressed comments from mail list. Making
timestamp an independent and optional option. Reduce the serverside
authentication to base on only client's certificate. Reduce the
clientside authentication to only Leaf of Faith base on server's public
key. 2014-09-26.</t>
<t>draft-ietf-dhc-sedhcpv6-03: addressed comments from WGLC. Added a new
section "Deployment Consideration". Corrected the Public Key Field in
the Public Key Option. Added consideration for large DHCPv6 message
transmission. Added TimestampFail error code. Refined the retransmission
rules on clients. 2014-06-18.</t>
<t>draft-ietf-dhc-sedhcpv6-02: addressed comments (applicability
statement, redesign the error codes and their logic) from IETF89 DHC WG
meeting and volunteer reviewers. 2014-04-14.</t>
<t>draft-ietf-dhc-sedhcpv6-01: addressed comments from IETF88 DHC WG
meeting. Moved Dacheng Zhang from acknowledgement to be co-author.
2014-02-14.</t>
<t>draft-ietf-dhc-sedhcpv6-00: adopted by DHC WG. 2013-11-19.</t>
<t>draft-jiang-dhc-sedhcpv6-02: removed protection between relay agent
and server due to complexity, following the comments from Ted Lemon,
Bernie Volz. 2013-10-16.</t>
<t>draft-jiang-dhc-sedhcpv6-01: update according to review comments from
Ted Lemon, Bernie Volz, Ralph Droms. Separated Public Key/Certificate
option into two options. Refined many detailed processes.
2013-10-08.</t>
<t>draft-jiang-dhc-sedhcpv6-00: original version, this draft is a
replacement of draft-ietf-dhc-secure-dhcpv6, which reached IESG and dead
because of consideration regarding to CGA. The authors followed the
suggestion from IESG making a general public key based mechanism.
2013-06-29.</t>
</section>
<section anchor="Issues" title="Open Issues [RFC Editor: Please remove]">
<t>this protocol changes DHCPv6 message exchanges quite substantially:
previously, the client first sends a Solicit message, gets possibly
multiple Advertise messages, chooses the server (= sender of one of
the Advertises) that would be best for the client, and then sends a
Request to that chosen server. Now the server selection is done at
the key exchange phase (the initial Information-request and Reply
exchange), and the Solicit can be sent only to a single server. If
the client doesn't like the Advertise it could restart the whole
process, but it will be more expensive, and there's no guarantee
that other servers can provide a better Advertise.</t>
<t>One might argue that it's okay as "secure DHCPv6" is an "optional"
extension. But, with keeping in mind that the current IETF trend is
to make everything privacy-aware (often by making everything
encrypted), I'd personally say we should consider it to be the
standard mode of DHCPv6 operation even if users can still disable
it. From this point of view, I think we should either<list style="symbols">
<t>A. make the server selection behavior more compatible with the
pre-encryption protocol, or</t>
<t>B. accept we give up the previous server selection feature for
privacy (after careful assessment of its effect and with clear wg
consensus), and explicitly note that. we might even have to
reflect that in rfc3315bis.</t>
</list></t>
</section>
</middle>
<back>
<references title="Normative References">
<?rfc include='reference.RFC.2119'?>
<?rfc include='reference.RFC.2460'?>
<?rfc include='reference.RFC.3315'?>
<?rfc include='reference.RFC.3971'?>
<?rfc include='reference.RFC.4443'?>
<?rfc include='reference.RFC.5905'?>
<?rfc include='reference.RFC.7296'?>
<?rfc include='reference.RFC.7283'?>
</references>
<references title="Informative References">
<reference anchor="RSA">
<front>
<title>RSA Encryption Standard, Version 2.1, PKCS 1</title>
<author fullname="">
<organization>RSA Laboratories</organization>
</author>
<date month="November" year="2002" />
</front>
</reference>
<?rfc include='reference.RFC.2629'?>
<?rfc include='reference.RFC.4270'?>
<?rfc include='reference.RFC.5226'?>
<?rfc include='reference.RFC.6273'?>
<?rfc include='reference.RFC.7258'?>
</references>
</back>
</rfc>
| PAFTECH AB 2003-2026 | 2026-04-24 03:18:56 |