draft-ietf-dhc-sedhcpv6-12.txt   draft-ietf-dhc-sedhcpv6-13.txt 
DHC Working Group S. Jiang DHC Working Group S. Jiang
Internet-Draft Huawei Technologies Co., Ltd Internet-Draft Huawei Technologies Co., Ltd
Intended status: Standards Track L. Li Intended status: Standards Track L. Li
Expires: October 26, 2016 Y. Cui Expires: January 9, 2017 Y. Cui
Tsinghua University Tsinghua University
T. Jinmei T. Jinmei
Infoblox Inc. Infoblox Inc.
T. Lemon T. Lemon
Nominum, Inc. Nominum, Inc.
D. Zhang D. Zhang
April 24, 2016 July 8, 2016
Secure DHCPv6 Secure DHCPv6
draft-ietf-dhc-sedhcpv6-12 draft-ietf-dhc-sedhcpv6-13
Abstract Abstract
The Dynamic Host Configuration Protocol for IPv6 (DHCPv6) enables DHCPv6 includes no deployable security mechanism that can protect
DHCPv6 servers to pass configuration parameters. It offers end-to-end communication between DHCP clients and servers. This memo
configuration flexibility. If not secured, DHCPv6 is vulnerable to describes a mechanism for using public key cryptography to provide
various attacks. This document analyzes the security issues of such security. The mechanism provides encryption in all cases, and
DHCPv6 and specifies the secure DHCPv6 mechanism for authentication can be used for authentication based either on pre-sharing of
and encryption of messages between a DHCPv6 client and a DHCPv6 authorized certificates, or else using trust-on-first-use.
server.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
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This Internet-Draft will expire on October 26, 2016. This Internet-Draft will expire on January 9, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the Copyright (c) 2016 IETF Trust and the persons identified as the
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Language and Terminology . . . . . . . . . . . . 3 2. Requirements Language and Terminology . . . . . . . . . . . . 3
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Security Issues of DHCPv6 . . . . . . . . . . . . . . . . . . 4 4. Security Issues of DHCPv6 . . . . . . . . . . . . . . . . . . 4
5. Secure DHCPv6 Overview . . . . . . . . . . . . . . . . . . . 5 5. Secure DHCPv6 Overview . . . . . . . . . . . . . . . . . . . 5
5.1. Solution Overview . . . . . . . . . . . . . . . . . . . . 5 5.1. Solution Overview . . . . . . . . . . . . . . . . . . . . 5
5.2. New Components . . . . . . . . . . . . . . . . . . . . . 7 5.2. New Components . . . . . . . . . . . . . . . . . . . . . 6
5.3. Support for Algorithm Agility . . . . . . . . . . . . . . 7 5.3. Support for Algorithm Agility . . . . . . . . . . . . . . 6
5.4. Applicability . . . . . . . . . . . . . . . . . . . . . . 8 5.4. Applicability . . . . . . . . . . . . . . . . . . . . . . 7
6. DHCPv6 Client Behavior . . . . . . . . . . . . . . . . . . . 9 6. DHCPv6 Client Behavior . . . . . . . . . . . . . . . . . . . 8
7. DHCPv6 Server Behavior . . . . . . . . . . . . . . . . . . . 12 7. DHCPv6 Server Behavior . . . . . . . . . . . . . . . . . . . 11
8. Relay Agent Behavior . . . . . . . . . . . . . . . . . . . . 14 8. Relay Agent Behavior . . . . . . . . . . . . . . . . . . . . 13
9. Processing Rules . . . . . . . . . . . . . . . . . . . . . . 14 9. Extensions for Secure DHCPv6 . . . . . . . . . . . . . . . . 14
9.1. Timestamp Check . . . . . . . . . . . . . . . . . . . . . 14 9.1. New DHCPv6 Options . . . . . . . . . . . . . . . . . . . 14
10. Extensions for Secure DHCPv6 . . . . . . . . . . . . . . . . 16 9.1.1. Certificate Option . . . . . . . . . . . . . . . . . 14
10.1. New DHCPv6 Options . . . . . . . . . . . . . . . . . . . 16 9.1.2. Signature option . . . . . . . . . . . . . . . . . . 15
10.1.1. Certificate Option . . . . . . . . . . . . . . . . . 16 9.1.3. Increasing-number Option . . . . . . . . . . . . . . 17
10.1.2. Signature option . . . . . . . . . . . . . . . . . . 17 9.1.4. Encrypted-message Option . . . . . . . . . . . . . . 17
10.1.3. Timestamp Option . . . . . . . . . . . . . . . . . . 18 9.2. New DHCPv6 Messages . . . . . . . . . . . . . . . . . . . 18
10.1.4. Encrypted-message Option . . . . . . . . . . . . . . 18 9.3. Status Codes . . . . . . . . . . . . . . . . . . . . . . 18
10.2. New DHCPv6 Messages . . . . . . . . . . . . . . . . . . 19 10. Security Considerations . . . . . . . . . . . . . . . . . . . 19
10.3. Status Codes . . . . . . . . . . . . . . . . . . . . . . 20 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19
11. Security Considerations . . . . . . . . . . . . . . . . . . . 20 12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 21
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21 13. Change log [RFC Editor: Please remove] . . . . . . . . . . . 21
13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 23 14. Open Issues [RFC Editor: Please remove] . . . . . . . . . . . 23
14. Change log [RFC Editor: Please remove] . . . . . . . . . . . 23 15. References . . . . . . . . . . . . . . . . . . . . . . . . . 23
15. Open Issues [RFC Editor: Please remove] . . . . . . . . . . . 25 15.1. Normative References . . . . . . . . . . . . . . . . . . 23
16. References . . . . . . . . . . . . . . . . . . . . . . . . . 25 15.2. Informative References . . . . . . . . . . . . . . . . . 25
16.1. Normative References . . . . . . . . . . . . . . . . . . 25 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 25
16.2. Informative References . . . . . . . . . . . . . . . . . 26
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 27
1. Introduction 1. Introduction
The Dynamic Host Configuration Protocol for IPv6 (DHCPv6, [RFC3315]) The Dynamic Host Configuration Protocol for IPv6 (DHCPv6, [RFC3315])
enables DHCPv6 servers to pass configuration parameters and offers allows DHCPv6 servers to flexibly provide addressing and other
configuration flexibility. If not being secured, DHCPv6 is configuration information relating to local network infrastructure to
vulnerable to various attacks. DHCP clients. The protocol provides no deployable security
mechanism, and consequently is vulnerable to various attacks.
This document analyzes the security issues of DHCPv6 and provides the This document provides a brief summary of the security
following mechanisms for improving the security of DHCPv6 between the vulnerabilities of the DHCPv6 protocol and then describes a new
DHCPv6 client and the DHCPv6 server: extension to the protocol that provides two additional types of
security:
o the authentication of the DHCPv6 client and the DHCPv6 server to o authentication of the DHCPv6 client and the DHCPv6 server to
defend against active attacks, such as spoofing attack. defend against active attacks, such as spoofing.
o the encryption between the DHCPv6 client and the DHCPv6 server in o encryption between the DHCPv6 client and the DHCPv6 server in
order to protect the DHCPv6 from passive attacks, such as order to protect the DHCPv6 from pervasive monitoring.
pervasive monitoring.
Note: this secure mechanism in this document does not protect outer The extension specified in this document applies only to end-to-end
options in Relay-Forward and Relay-Reply messages, either added by a communication between DHCP servers and clients. Options added by
relay agent toward a server or added by a server toward a relay relay agents in Relay-Forward messages, and options other than the
agent. Communication between a server and a relay agent, and client message in Relay-Reply messages sent by DHCP servers, are not
communications between relay agents, may be secured through the use protected. Such communications are already protected using the
of IPsec, as described in section 21.1 in [RFC3315]. mechanism described described in section 21.1 in [RFC3315].
The security mechanism specified in this document achieves DHCPv6 This extension introduces two new DHCPv6 messages: the Encrypted-
authentication and encryption based on the sender's certificate. We Query and the Encrypted-Response messages. It defines four new
introduce two new DHCPv6 messages: Encrypted-Query message and DHCPv6 options: the Certificate, the Signature, the Increasing-
Encrypted-Response message and Four new DHCPv6 options: Certificate number, and the Encrypted-message options. The Certificate,
option, Signature option, Timestamp option and Encrypted-message Signature, and Increasing-number options are used for authentication.
option for DHCPv6 authentication and encryption. The Certificate The Encryption-Query message, Encryption-Response message and
option, Signature option, Timestamp option are used for DHCPv6 Encrypted-message option are used for encryption.
client/server authentication. The Encryption-Query message,
Encryption-Response message and Encrypted-message option are used for
DHCPv6 encryption.
2. Requirements Language and Terminology 2. Requirements Language and Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119] when they document are to be interpreted as described in [RFC2119] when they
appear in ALL CAPS. When these words are not in ALL CAPS (such as appear in ALL CAPS. When these words are not in ALL CAPS (such as
"should" or "Should"), they have their usual English meanings, and "should" or "Should"), they have their usual English meanings, and
are not to be interpreted as [RFC2119] key words. are not to be interpreted as [RFC2119] key words.
3. Terminology 3. Terminology
This section defines terminology specific to secure DHCPv6 used in This section defines terminology specific to secure DHCPv6 used in
this document. this document.
secure DHCPv6 client: A node that initiates the DHCPv6 request on a secure DHCPv6 client: A node that initiates a DHCPv6 request on a
link to obtain the DHCPv6 configuration parameters link to obtain DHCPv6 configuration parameters from
from one or more DHCPv6 servers. The configuration one or more DHCPv6 servers using the encryption and
process is authenticated and encrypted using the optional authentication mechanisms defined in this
defined mechanisms in this document. document.
secure DHCPv6 server: A node that responds to requests from clients secure DHCPv6 server: A DHCPv6 server that implements the
using the authentication and encryption mechanism authentication and encryption mechanisms defined in
defined in this document. this document, and is configured to use them.
4. Security Issues of DHCPv6 4. Security Issues of DHCPv6
DHCPv6 is a client/server protocol that provides managed [RFC3315] defines an authentication mechanism with integrity
configuration of devices. It enables a DHCPv6 server to protection. This mechanism uses a symmetric key that is shared by
automatically configure relevant network parameters on clients. The the client and server for authentication. It does not provide any
basic DHCPv6 specification [RFC3315] defines security mechanisms, but key distribution mechanism.
they have some flaws and can be improved.
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. [RFC3315] 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; [RFC3315] provides no mechanism for doing this.
For the out of band approach, operators can set up a key database for For this approach, operators can set up a key database for both
both servers and clients from which the client obtains a key before servers and clients from which the client obtains a key before
running DHCPv6. Manual key distribution runs counter to the goal of running DHCPv6. However, manual key distribution runs counter to the
minimizing the configuration data needed at each host. goal of minimizing the configuration data needed at each host.
Consequently, there are no known deployments of this security
mechanism.
[RFC3315] provides an additional mechanism for preventing off-network [RFC3315] provides an additional mechanism for preventing off-network
timing attacks using the Reconfigure message: the Reconfigure Key timing attacks using the Reconfigure message: the Reconfigure Key
authentication method. However, this method protects only the authentication method. However, this method protects only the
Reconfigure message. The key is transmitted in plaintext to the Reconfigure message. The key is transmitted in plaintext to the
client in earlier exchanges and so this method is vulnerable to client in earlier exchanges and so this method is vulnerable to on-
active attacks. path active attacks.
In addition, the current DHCPv6 messages are still transmitted in Anonymity Profile for DHCP Clients [RFC7844] explains how to generate
cleartext and the privacy information within the DHCPv6 message is DHCPv4 or DHCPv6 requests that minimize the disclosure of identifying
not protected from passive attack, such as pervasive monitoring. The information. However, the anonymity profile limits the use of the
IETF has expressed strong agreement that pervasive monitoring is an certain options. It also cannot anticipate new options that may
attack that needs to be mitigated where possible in [RFC7258]. contain private information is defined. In addition, the anonymity
profile does not work in cases where the client wants to maintain
anonymity from eavesdroppers but must identify itself to the DHCP
server with which it intends to communicate.
In comparison, the security mechanisms defined in this document Privacy consideration for DHCPv6 [RFC7824] presents an analysis of
provides for authentication and encryption based on the public key the privacy issues associated with the use of DHCPv6 by Internet
certificates of the client and server. The DHCPv6 authentication can users. No solutions are presented.
protect DHCPv6 from active attacks, such as spoofing attack. And the
DHCPv6 encryption defends against passive attacks, such as pervasive
monitoring attack.
5. Secure DHCPv6 Overview 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 [RFC7258].
5.1. Solution Overview To better address the problem of passive monitoring and to achieve
authentication without requiring a symmetric key distribution
solution for DHCP, this document defines an asymmetric key
authentication and encryption mechanism. This protects against both
active attacks, such as spoofing, and passive attacks, such as
pervasive monitoring.
This solution provides authentication and encryption mechanisms based 5. Secure DHCPv6 Overview
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.
The following figure illustrates secure DHCPv6 procedure. The DHCPv6 5.1. Solution Overview
client first sends Information-request message as per [RFC3315]. 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.
After the server's authentication, the first DHCPv6 message sent from The following figure illustrated secure DHCPv6 procedure. Briefly,
the client to the server, such as Solicit message, contains the this extension establishes the server's identity with an anonymous
client's Certificate information for client authentication. The Information-Request exchange. Once the server's identity has been
DHCPv6 client sends the Encrypted-Query message to server, which established, the client may either choose to communicate with the
carries the Encrypted-message option and the Server Identifier server or not. Not communicating with an unknown server avoids
option. The Encrypted-message option contains the encrypted DHCPv6 revealing private information, but if there is no known server on a
message sent from the client to the server. When the DHCPv6 server particular link, the client will be unable to communicate with a DHCP
receives the Encrypted-Query message, it decrypts the message using server.
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.
After the client's authentication, the server sends the Encrypted- If the client chooses to communicate with a server, it uses the
Response message to the client, which contains the Encrypted-message Encrypted-Query message to encapsulate its communications to the DHCP
option. The Encrypted-message option contains the encrypted DHCPv6 server. The server responds with Encrypted-Response messages.
message sent from server to client, which is encrypted using the Normal DHCP messages are encapsulated in these two new messages using
client's public key. If the message fails client authentication, the new defined Encrypted-message option. Besides the Encrypted-
then the server sends the corresponding error status code to the message option, the Signature option is defined to verify the
client. During the encrypted DHCPv6 configuration process, the integrity of the DHCPv6 messages and then authentication of client
Timestamp option can be contained in the encrypted DHCPv6 messages to and server. The Increasing number is defined to detect replay
defend against replay attacks. attack.
+-------------+ +-------------+ +-------------+ +-------------+
|DHCPv6 Client| |DHCPv6 Server| |DHCPv6 Client| |DHCPv6 Server|
+-------------+ +-------------+ +-------------+ +-------------+
| Information-request | | Information-request |
|----------------------------------------->| |----------------------------------------->|
| Option Request option | | Option Request option |
| | | |
| Reply | | Reply |
|<-----------------------------------------| |<-----------------------------------------|
| Certificate option | | Certificate option |
| Signature option | | Signature option |
| Timestamp option | | Increasing-number option |
| Server Identifier option | | Server Identifier option |
| | | |
| Encryption-Query | | Encryption-Query |
|----------------------------------------->| |----------------------------------------->|
| Encrypted-message option | | Encrypted-message option |
| Server Identifier option | | Server Identifier option |
| | | |
| Encryption-Response | | Encryption-Response |
|<-----------------------------------------| |<-----------------------------------------|
| Encrypted-message option | | Encrypted-message option |
skipping to change at page 7, line 17 skipping to change at page 6, line 17
The new components of the mechanism specified in this document are as The new components of the mechanism specified in this document are as
follows: follows:
o Servers and clients that use certificates first generate a public/ o Servers and clients that use certificates first generate a public/
private key pair and then obtain a certificate that signs the private key pair and then obtain a certificate that signs the
public key. The Certificate option is defined to carry the public key. The Certificate option is defined to carry the
certificate of the sender. certificate of the sender.
o A signature generated using the private key which is used by the o A signature generated using the private key which is used by the
receiver to verify the integrity of the DHCPv6 messages and then receiver to verify the integrity of the DHCPv6 messages and then
authentication of the client/server. Another option is defined to authentication of the client/server. The Signature option is
carry the signature. defined to carry the signature.
o A timestamp that can be used to detect replayed packet. The o A Increasing-number that can be used to detect replayed packet.
Timestamp option is defined to carry the current time of the The Increasing-number option is defined to carry a strictly-
client/server. The secure DHCPv6 client/server need to meet some increasing serial number. Timestamp is one of the possible
accuracy requirements and be synced to global time, while the implementation choice.
timestamp checking mechanism allows a configurable time value for
clock drift. The real time provision is out of scope of this
document.
o The Encrypted-message option that contains the encrypted DHCPv6 o The Encrypted-message option that contains the encrypted DHCPv6
message. message.
o The Encrypted-Query message that is sent from the secure DHCPv6 o The Encrypted-Query message that is sent from the secure DHCPv6
client to the secure DHCPv6 server. The Encrypted-Query message client to the secure DHCPv6 server. The Encrypted-Query message
contains the Encrypted-message option and Server Identifier MUST contain the Encrypted-message option. In addition, the
option. Server Identifier option MUST be contained if it is contained in
the original DHCPv6 message. The Encrypted-Query message MUST NOT
contain other options except the Server Identifier option and
Encrypted-message option.
o The Encrypted-Response message that is sent from the secure DHCPv6 o The Encrypted-Response message that is sent from the secure DHCPv6
server to the secure DHCPv6 client. The Encrypted-Response server to the secure DHCPv6 client. The Encrypted-Response
message contains the Encrypted-message option. message contains the Encrypted-message option. The Encrypted-
Response message MUST NOT contain other options except Encrypted-
message option.
5.3. Support for Algorithm Agility 5.3. Support for Algorithm Agility
In order to provide a means of addressing problems that may emerge in In order to provide a means of addressing problems that may emerge
the future with existing hash algorithms, as recommended in with existing hash algorithms, signature algorithm and encryption
[RFC4270], this document provides a mechanism for negotiating the use algorithms in the future, this document provides a mechanism to
of more secure hashes in the future. support algotirhm agility. The support for algorithm agility in this
document is mainly a algorithm notification mechanism between the
In addition to hash algorithm agility, this document also provides a client and the server. The same client and server SHOULD use the
mechanism for signature algorithm and encryption algorithm agility. various algorithm in a single communication session.
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.
If the server does not support the algorithm used by the client, the If the server does not support the algorithm used by the client, the
server SHOULD reply with an AlgorithmNotSupported status code server SHOULD reply with an AlgorithmNotSupported status code
(defined in Section 10.3) to the client. Upon receiving this status (defined in Section 9.3) to the client. Upon receiving this status
code, the client MAY resend the message protected with the mandatory code, the client MAY resend the message protected with the mandatory
algorithm. algorithm.
5.4. Applicability 5.4. Applicability
In principle, Secure DHCPv6 is applicable in any environment where In principle, secure DHCPv6 is applicable in any environment where
physical security on the link is not assured and attacks on DHCPv6 physical security on the link is not assured and attacks on DHCPv6
are a concern. In practice, however, it will rely on some are a concern. In practice, however, authenticated and encrypted
operational assumptions mainly regarding public key distribution and DHCPv6 configuration will rely on some operational assumptions mainly
management, until more lessons are learned and more experiences are regarding public key distribution and management. In order to
achieved. achieve the more wide use of secure DHCPv6, opportunistic security
[RFC7435] can be applied for secure DHCPv6 deployment, which allows
DHCPv6 encryption in environments where support for authentication is
not available.
One feasible environment in an early deployment stage would be In some scenario where authentication is not available, secure DHCPv6
enterprise networks. In such networks the security policy tends to provides encryption without authentication to achieve the wide
be strict and it will be easier to manage client hosts. One trivial deployment of secure DHCPv6.
deployment scenario is therefore to manually pre-configure client
with the trusted servers' public key and manually register clients' Secure DHCPv6 provides authentication and encryption based either on
public keys for the server. It may also be possible to deploy an pre-sharing of authorized certificates, or else using trust-on-first-
internal PKI to make this less reliant on manual operations, although use. The One feasible environment in an early deployment stage would
it is currently subject to future study specifically how to integrate be enterprise networks. In such networks the security policy tends
such a PKI into the DHCPv6 service for the network. 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.
Note that this deployment scenario based on manual operation is not Note that this deployment scenario based on manual operation is not
different very much from the existing, shared-secret based different very much from the existing, shared-secret based
authentication mechanisms defined in [RFC3315] in terms of authentication mechanisms defined in [RFC3315] in terms of
operational costs. However, Secure DHCPv6 is still securer than the operational costs. However, Secure DHCPv6 is still securer than the
shared-secret mechanism in that even if clients' keys stored for 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 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 public keys. In addition, if some kind of PKI is used with Secure
DHCPv6, even if the initial installation of the certificates is done DHCPv6, even if the initial installation of the certificates is done
manually, it will help reduce operational costs of revocation in case manually, it will help reduce operational costs of revocation in case
skipping to change at page 9, line 33 skipping to change at page 8, line 37
When receiving the Reply messages from DHCPv6 servers, a secure When receiving the Reply messages from DHCPv6 servers, a secure
DHCPv6 client discards any DHCPv6 messages that meet any of the DHCPv6 client discards any DHCPv6 messages that meet any of the
following conditions: following conditions:
o the Signature option is missing, o the Signature option is missing,
o multiple Signature options are present, o multiple Signature options are present,
o the Certificate option is missing. o the Certificate option is missing.
And then the client first checks the support of the hash function, And then the client first checks the support of the hash algorithm,
signature algorithm and encryption algorithm that the server used. signature algorithm and encryption algorithm that the server used.
If the check fails, the Reply message is dropped. If all the If the check fails, the Reply message is dropped. If the hash
algorithms are supported, the client then checks the authority of algorithm field is zero, the signature algorithm and hash algorithm
this server. The client also uses the same algorithms in the return are not separated. The corresponding hash algorithm is fixed
messages. according the signature algorithm. 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.
The client validates the certificates through the pre-configured The client validates the certificates through the pre-configured
local trusted certificates list or other methods. A certificate that local trusted certificates list or other methods. A certificate that
finds a match in the local trust certificate list is treated as finds a match in the local trust certificates list is treated as
verified. If the client want to check server's certificate to see verified. The message transaction-id is used as the identifier of
whether it has been revoked, the OCSP stapling can be used. The the authenticated server's public key for further message encryption.
message transaction-id is used as the identifier of the authenticated
server's public key for encryption. At this point, the client has At this point, the client has either recognized the certificate of
either recognized the certificate of the server, or decided to drop the server, or decided to drop the message.
the message.
The client MUST now authenticate the server by verifying the The client MUST now authenticate the server by verifying the
signature and checking timestamp (see details in Section 9.1), if signature and checking increasing number, if there is a Increasing-
there is a Timestamp option. The order of two procedures is left as number option. The order of two procedures is left as an
an implementation decision. It is RECOMMENDED to check timestamp implementation decision. It is RECOMMENDED to check increasing
first, because signature verification is much more computationally number first, because signature verification is much more
expensive. computationally expensive. If the decrypted message contains the
Increasing-number option, the client checks it by comparing it with
the stored number on the client. The client has one stable stored
number for replay attack detection. The initial value of the stable
stored number is zero. If the contained number is higher than the
stored number, then the DHCPv6 message passes the increasing-number
check and the value of the stored number is changed into the value of
the Increasing-number option. If contained number is lower than the
stored number on the server, the server MUST drop the DHCPv6 message.
The Signature field verification MUST show that the signature has The Signature field verification MUST show that the signature has
been calculated as specified in Section 10.1.2. Only the messages been calculated as specified in Section 9.1.2. Only the messages
that get through both the signature verification and timestamp check that get through both the signature verification and increasing
(if there is a Timestamp option) are accepted. Reply message that number check (if there is a Increasing-number option) are accepted.
does not pass the above tests MUST be discarded. Reply message that does not pass the above tests MUST be discarded.
If there are multiple authenticated DHCPv6 servers, the client If there are multiple authenticated DHCPv6 certs, the client selects
selects one DHCPv6 server for the following network parameters one DHCPv6 cert for the following network parameters configuration.
configuration. The client can also choose other implementation The selected DHCPv6 cert may corresponds to multiple DHCPv6 servers.
method depending on the client's local policy if the defined protocol The client can also choose other implementation method depending on
can also run normally. For example, the client can try multiple the client's local policy if the defined protocol can also run
transactions (each encrypted with different public key) at the "same" normally. For example, the client can try multiple transactions
time. If there are no authenticated DHCPv6 servers or existing (each encrypted with different public key) at the "same" time.
servers failed authentication, the client should retry a number of
times. In this way, it is difficult for the rogue server to beat out If there are no authenticated DHCPv6 certs or existing servers fail
a busy "real" server. And then the client takes some alternative authentication, the client should retry a number of times. The
action depending on its local policy, such as attempting to use an client conducts the server discovery process as per section 18.1.5 of
unsecured DHCPv6 server. The client conducts the server discovery [RFC3315] to avoid the packet storm. In this way, it is difficult
process as per section 18.1.5 of [RFC3315] to avoid the packet storm. 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. In some
scenario, such as laptops in coffee room, clients are always not pre-
configured the sufficient information for server authentication and
can accept DHCPv6 encryption without DHCPv6 authentication. In such
scenario, if some DHCPv6 servers fail authentication because the
server's certificate is not in the trusted certs' list, and then the
client selects one DHCPv6 server and record the server's public key
for the future encrypted DHCPv6 configuration process.
Once the server has been authenticated, the DHCPv6 client sends the Once the server has been authenticated, the DHCPv6 client sends the
Encrypted-Query message to the DHCPv6 server. The Encrypted-Query Encrypted-Query message to the DHCPv6 server. The Encrypted-Query
message contains the Encrypted-message option, which MUST be message contains the Encrypted-message option, which MUST be
constructed as explained in Section 10.1.4, and Server Identifier constructed as explained in Section 9.1.4. In addition, the Server
option. The Encrypted-message option contains the DHCPv6 message Identifier option MUST be contained if it is in the original message
that is encrypted using the selected server's public key. The Server (i.e. Request, Renew, Decline, Release) to avoid the extra
Identifier option is externally visible to avoid decryption cost by decryption for the DHCPv6 servers not for it. The Encrypted-message
those unselected servers. option contains the DHCPv6 message that is encrypted using the public
key contained in the selected cert. The Server Identifier option is
externally visible to avoid decryption cost by those unselected
servers. The Encrypted-Query message MUST NOT contain other DHCPv6
option except the Server Identifier option and Encrypted-Message
option.
For the encrypted DHCPv6 message sent from the DHCPv6 client to the If the received Reply message indicates the request of the client's
DHCPv6 server, the first DHCPv6 message, such as Solicit message, certificate information through the Option Request option, the first
MUST contain the Certificate option, Signature option and Timestamp DHCPv6 message sent from the client to the server, such as Solicit
option for client authentication. The Certificate option MUST be message, MUST contain the Certificate option, Signature option and
constructed as explained in Section 10.1.1. In addition, one and Increasing-number option for client authentication. The encryption
only one Signature option MUST be contained, which MUST be text SHOULD be formatted as explain in [RFC5652]. The Certificate
constructed as explained in Section 10.1.2. One and only one option MUST be constructed as explained in Section 9.1.1. In
Timestamp option SHOULD be contained, which MUST be constructed as addition, one and only one Signature option MUST be contained, which
explained in Section 10.1.3. The Timestamp field SHOULD be set to MUST be constructed as explained in Section 9.1.2. One and only one
the current time, according to sender's real time clock. Increasing-number option SHOULD be contained, which MUST be
constructed as explained in Section 9.1.3.
If the client has multiple certificates with different public/private If the client has multiple certificates with different public/private
key pairs, the message transaction-id is used as the identifier of key pairs, the message transaction-id is used as the identifier of
the client's private key for decryption. In addition, the subsequent the client's private key for decryption. In addition, the subsequent
encrypted DHCPv6 message can contain the Timestamp option to defend encrypted DHCPv6 message can contain the Increasing-number option to
against replay attack. defend against replay attack.
For the received Encrypted-Response message, the client extracts the For the received Encrypted-Response message, the client MUST drop the
Encrypted-Response message if other DHCPv6 option except Encrypted-
message option is contained. Then, the client extracts the
Encrypted-message option and decrypts it using its private key to Encrypted-message option and decrypts it using its private key to
obtain the original DHCPv6 message. Then it handles the message as obtain the original DHCPv6 message. Then it handles the message as
per [RFC3315]. If the decrypted DHCPv6 message contains the per [RFC3315]. If the decrypted DHCPv6 message contains the
Timestamp option, the DHCPv6 client checks the timestamp according to Increasing-number option, the DHCPv6 client MUST drop the DHCPv6
the rule defined in Section 9.1. The DHCPv6 message, which fails the message with the lower number. If the client fails to get the proper
timestamp check, MUST be discarded. If the client fails to get the parameters from the chosen server, it sends the Encrypted-Query
proper parameters from the chosen server, it sends the Encrypted- message to another authenticated server for parameters configuration
Query message to another authenticated server for parameters until the client obtains the proper parameters.
configuration until the client obtains the proper parameters.
When the client receives a Reply message with an error status code, When the client receives a Reply message with an error status code,
the error status code indicates the failure reason on the server the error status code indicates the failure reason on the server
side. According to the received status code, the client MAY take side. According to the received status code, the client MAY take
follow-up action: follow-up action:
o Upon receiving an AlgorithmNotSupported error status code, the o Upon receiving an AlgorithmNotSupported error status code, the
client SHOULD resend the message protected with one of the client SHOULD resend the message protected with one of the
mandatory algorithms. mandatory algorithms.
skipping to change at page 11, line 43 skipping to change at page 11, line 25
status code as if it had not been received. But it SHOULD NOT status code as if it had not been received. But it SHOULD NOT
retry with the same certificate. However, if the client decides retry with the same certificate. However, if the client decides
to retransmit using the same certificate after receiving to retransmit using the same certificate after receiving
AuthenticationFail, it MUST NOT retransmit immediately and MUST AuthenticationFail, it MUST NOT retransmit immediately and MUST
follow normal retransmission routines defined in [RFC3315]. follow normal retransmission routines defined in [RFC3315].
o Upon receiving a DecryptionFail error status code, the client MAY o Upon receiving a DecryptionFail error status code, the client MAY
resend the message following normal retransmission routines resend the message following normal retransmission routines
defined in [RFC3315]. defined in [RFC3315].
o Upon receiving a TimestampFail error status code, the client MAY o Upon receiving a IncreasingnumFail error status code, the client
resend the message with an adjusted timestamp according to the MAY resend the message with an adjusted Increasing-number option
returned clock from the DHCPv6 server. The client SHOULD NOT according to the returned clock from the DHCPv6 server.
change its own clock, but only compute an offset for the
communication session.
o Upon receiving a SignatureFail error status code, the client MAY o Upon receiving a SignatureFail error status code, the client MAY
resend the message following normal retransmission routines resend the message following normal retransmission routines
defined in [RFC3315]. defined in [RFC3315].
7. DHCPv6 Server Behavior 7. DHCPv6 Server Behavior
For the secure DHCPv6 server, a certificate is needed for server For the secure DHCPv6 server, a certificate is needed for server
authentication. The server is pre-configured with a certificate and authentication. The server is pre-configured with a certificate and
its corresponding private key. If the server is pre-configured with its corresponding private key. If the server is pre-configured with
public key but not with a certificate, it can generate the self- public key but not with a certificate, it can generate the self-
signed certificate for server authentication. signed certificate for server authentication.
When the DHCPv6 server receives the Information-request message and When the DHCPv6 server receives the Information-request message and
the contained Option Request option identifies the request is for the the contained Option Request option identifies the request is for the
server certificate information, it replies with a Reply message to server certificate information, it replies with a Reply message to
the client. The Reply message MUST contain the requested Certificate the client. The Reply message MUST contain the requested Certificate
option, which MUST be constructed as explained in Section 10.1.1, and option, which MUST be constructed as explained in Section 9.1.1, and
Server Identifier option. In addition, the Reply message MUST Server Identifier option. In addition, the Reply message MUST
contain one and only one Signature option, which MUST be constructed contain one and only one Signature option, which MUST be constructed
as explained in Section 10.1.2. Besides, the Reply message SHOULD as explained in Section 9.1.2. Besides, the Reply message SHOULD
contain one and only one Timestamp option, which MUST be constructed contain one and only one Increasing-number option, which MUST be
as explained in Section 10.1.3. The Timestamp field SHOULD be set to constructed as explained in Section 9.1.3. In addition, if client
the current time, according to server's real time clock. authentication is needed, then the ORO option in the Reply message
contains the code of the certificate option to indicate the request
of the client certificate information.
Upon the receipt of Encrypted-Query message, the server checks the Upon the receipt of Encrypted-Query message, the server MUST drop the
Server Identifier option. It decrypts the Encrypted-message option message if the other DHCPv6 option except Server Identifier option
using its private key if it is the target server. The DHCPv6 server and Encrypted-message option is contained. Then, the server checks
drops the message that is not for it, thus not paying cost to decrypt the Server Identifier option if the Encrypted-Query message contains
messages not for it. the Server Identifier option. The DHCPv6 server drops the message
that is not for it, thus not paying cost to decrypt messages not for
it. It decrypts the Encrypted-message option using its private key
if it is the target server.
If the decrypted message is a Solicit/Information-request message, If the secure DHPCv6 need client authentication and decrypted message
the secure DHCPv6 server discards the received message that meets any is a Solicit/Information-request message which contains the
of the following conditions: information for client authentication, the secure DHCPv6 server
discards the received message that meets any of the following
conditions:
o the Signature option is missing, o the Signature option is missing,
o multiple Signature options are present, o multiple Signature options are present,
o the Certificate option is missing. o the Certificate option is missing.
In such failure, the server replies with an UnspecFail (value 1, In such failure, the server replies with an UnspecFail (value 1,
[RFC3315]) error status code. [RFC3315]) error status code.
The server SHOULD first check the support of the hash function, The server SHOULD first check the support of the hash function,
signature algorithm, encryption algorithm that the client used. If signature algorithm, encryption algorithm that the client used. If
the check fails, the server SHOULD reply with an the hash algorithm field is zero, then the signature algorithm and
AlgorithmNotSupported error status code, defined in Section 10.3, hash algorithm are not separated. The corresponding hash algorithm
back to the client. If all the algorithms are supported, the server is fixed according the signature algorithm. If the check fails, the
then checks the authority of this client. server SHOULD reply with an AlgorithmNotSupported error status code,
defined in Section 9.3, back to the client. If all the algorithms
The server validates the client's public key through the local pre- are supported, the server then checks the authority of this client.
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 Section 10.3, back to the client. At this
point, the server has either recognized the authentication of the
client, or decided to drop the message.
If the decrypted message contains the Timestamp option, the server The server validates the client's certificate through the local pre-
checks the timestamp according to the rule defined in Section 9.1. configured trusted certificates list. A certificate that finds a
If the timestamp check fails, a TimestampFail error status code, match in the local trust certificates list is treated as verified.
defined in Section 10.3, should be sent back to the client. The message that fails authentication validation MUST be dropped. In
Depending on server's local policy, the message without a Timestamp such failure, the DHCPv6 server replies with an AuthenticationFail
option MAY be acceptable or rejected. If the server rejects such a error status code, defined in Section 9.3, back to the client. At
message, a TimestampFail error status code should be sent back to the this point, the server has either recognized the authentication of
client. The Reply message that carries the TimestampFail error the client, or decided to drop the message.
status code carries a Timestamp option, which indicates the server's
clock for the client to use.
If the server does not send the Timestamp option, the client ignores If the decrypted message contains the Increasing-number option, the
the timestamp check and verifies the signature. If there is a server checks it by comparing it with the stored number on the
timestamp option, the server MUST now authenticate the client by server. The server has one stable stored number for replay attack
verifying the signature and checking timestamp (see details in detection. The initial value of the stable stored number is zero.
Section 9.1). The order of two procedures is left as an If the contained number is higher than the stored number, the value
implementation decision. It is RECOMMENDED to check timestamp first, of the stored number is changed into the value of the Increasing-
because signature verification is much more computationally number option. If contained number is lower than the stored number
expensive. Depending on server's local policy, the message without a on the server, the server MUST drop the DHCPv6 message and a
Timestamp option MAY be acceptable or rejected. If the server IncreasingnumFail error status code, defined in Section 9.3, should
rejects such a message, a TimestampFail error status code, defined in be sent back to the client. Depending on server's local policy, the
Section 10.3, should be sent back to the client. The reply message message without a Increasing-number option MAY be acceptable or
that carries the TimestampFail error status code SHOULD carry a rejected. If the server rejects such a message, a IncreasingnumFail
Timestamp option, which indicates the server's clock for the client error status code should be sent back to the client. The Reply
to use. message that carries the IncreasingnumFail error status code carries
a Increasing-number option, which indicates the server's storage
number for the client to use.
The Signature field verification MUST show that the signature has The Signature field verification MUST show that the signature has
been calculated as specified in Section 10.1.2. Only the clients been calculated as specified in Section 9.1.2. Only the clients that
that get through both the signature verification and timestamp check get through both the signature verification and increasing number
(if there is a Timestamp option) are accepted as authenticated check (if there is a Increasing-number option) are accepted as
clients and continue to be handled their message as defined in authenticated clients and continue to be handled their message as
[RFC3315]. Clients that do not pass the above tests MUST be treated defined in [RFC3315]. Clients that do not pass the above tests MUST
as unauthenticated clients. The DHCPv6 server SHOULD reply a be treated as unauthenticated clients. The DHCPv6 server SHOULD
SignatureFail error status code, defined in Section 10.3, for the reply a SignatureFail error status code, defined in Section 9.3, for
signature verification failure; or a TimestampFail error status code, the signature verification failure.
defined in Section 10.3, for the timestamp check failure, back to the
client.
Once the client has been authenticated, the DHCPv6 server sends the Once the client has been authenticated, the DHCPv6 server sends the
Encrypted-response message to the DHCPv6 client. The Encrypted- Encrypted-response message to the DHCPv6 client. The Encrypted-
response message contains the Encrypted-message option, which MUST be response message MUST only contain the Encrypted-message option,
constructed as explained in Section 10.1.4. The Encrypted-message which MUST be constructed as explained in Section 9.1.4. The
option contains the encrypted DHCPv6 message that is encrypted using encryption text SHOULD be formatted as explain in [RFC5652]. The
the authenticated client's public key. To provide the replay Encrypted-message option contains the encrypted DHCPv6 message that
protection, the Timestamp option can be contained in the encrypted is encrypted using the authenticated client's public key. To provide
DHCPv6 message. the replay protection, the Increasing-number option can be contained
in the encrypted DHCPv6 message.
8. Relay Agent Behavior 8. Relay Agent Behavior
When a DHCPv6 relay agent receives an Encrypted-query or Encrypted- When a DHCPv6 relay agent receives an Encrypted-query or Encrypted-
response message, it may not recognize this message. The unknown response message, it may not recognize this message. The unknown
messages MUST be forwarded as described in [RFC7283]. messages MUST be forwarded as described in [RFC7283].
When a DHCPv6 relay agent recognizes the Encrypted-query and When a DHCPv6 relay agent recognizes the Encrypted-query and
Encrypted-response messages, it forwards the message according to Encrypted-response messages, it forwards the message according to
section 20 of [RFC3315]. There is nothing more the relay agents have section 20 of [RFC3315]. There is nothing more the relay agents have
to do, it neither needs to verify the messages from client or server, to do, it neither needs to verify the messages from client or server,
nor add any secure DHCPv6 options. Actually, by definition in this nor add any secure DHCPv6 options. Actually, by definition in this
document, relay agents MUST NOT add any secure DHCPv6 options. document, relay agents MUST NOT add any secure DHCPv6 options.
Relay-forward and Relay-reply messages MUST NOT contain any Relay-forward and Relay-reply messages MUST NOT contain any
additional Certificate option or Timestamp option, aside from those additional Certificate option or Increasing-number option, aside from
present in the innermost encapsulated messages from the client or those present in the innermost encapsulated messages from the client
server. or server.
Relay agent is RECOMMENDED to cache server announcements to form the Relay agent is RECOMMENDED to cache server announcements to form the
list of the available DHCPv6 server certs. If the relay agent list of the available DHCPv6 server certs. If the relay agent
receives the Information-request message, then it replies with a list receives the Information-request message, then it replies with a list
of server certs available locally. In this way, the client can be of server certs available locally. In this way, the client can be
confident of a quick response, and therefore treat the lack of a confident of a quick response, and therefore treat the lack of a
quick response as an indication that no authenticated DHCP servers quick response as an indication that no authenticated DHCP servers
exist. exist.
9. Processing Rules 9. Extensions for Secure DHCPv6
9.1. Timestamp Check
In order to check the Timestamp option, defined in Section 10.1.3,
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.
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.
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):
o The receive time of the last received and accepted DHCPv6 message.
This is called RDlast.
o The timestamp in the last received and accepted DHCPv6 message.
This is called TSlast.
A verified (for timestamp check and signature verification) secure
DHCPv6 message initiates the update of the above variables in the
recipient's record.
Recipients MUST check the Timestamp field as follows:
o 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:
-Delta < (RDnew - TSnew) < +Delta
After the signature verification also succeeds, the RDnew and
TSnew values SHOULD be stored in the cache as RDlast and TSlast.
o 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:
TSnew + fuzz > TSlast + (RDnew - RDlast) x (1 - drift) - fuzz
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.
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.
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.
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.
10. Extensions for Secure DHCPv6
This section describes the extensions to DHCPv6. Four new DHCPv6 This section describes the extensions to DHCPv6. Four new DHCPv6
options, two new DHCPv6 messages and five new status codes are options, two new DHCPv6 messages and five new status codes are
defined. defined.
10.1. New DHCPv6 Options 9.1. New DHCPv6 Options
10.1.1. Certificate Option 9.1.1. Certificate Option
The Certificate option carries the certificate of the client/server. The Certificate option carries the certificate of the client/server.
The format of the Certificate option is described as follows: The format of the Certificate option is described as follows:
0 1 2 3 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 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 | | OPTION_CERTIFICATE | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| EA-id | | | EA-id | |
skipping to change at page 17, line 5 skipping to change at page 15, line 33
encryption algorithm agility. The value is from the encryption algorithm agility. The value is from the
Encryption Algorithm for Secure DHCPv6 registry in Encryption Algorithm for Secure DHCPv6 registry in
IANA. A registry of the initial assigned values IANA. A registry of the initial assigned values
is defined in Section 12. is defined in Section 12.
Certificate A variable-length field containing certificate. The Certificate A variable-length field containing certificate. The
encoding of certificate and certificate data MUST encoding of certificate and certificate data MUST
be in format as defined in Section 3.6, [RFC7296]. be in format as defined in Section 3.6, [RFC7296].
The support of X.509 certificate is mandatory. The support of X.509 certificate is mandatory.
10.1.2. Signature option 9.1.2. Signature option
The Signature option allows a signature that is signed by the private The Signature option allows a signature that is signed by the private
key to be attached to a DHCPv6 message. The Signature option could key to be attached to a DHCPv6 message. The Signature option could
be in any place within the DHCPv6 message while it is logically be in any place within the DHCPv6 message while it is logically
created after the entire DHCPv6 header and options. It protects the created after the entire DHCPv6 header and options. It protects the
entire DHCPv6 header and options, including itself. The format of entire DHCPv6 header and options, including itself. The format of
the Signature option is described as follows: the Signature option is described as follows:
0 1 2 3 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 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 | | OPTION_SIGNATURE | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| HA-id | SA-id | | | SA-id | HA-id | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| | | |
. Signature (variable length) . . Signature (variable length) .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_SIGNATURE (TBA2). option-code OPTION_SIGNATURE (TBA2).
option-len 2 + Length of Signature field in octets. 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 SA-id Signature Algorithm id. The signature algorithm is
used for computing the signature result. This used for computing the signature result. This
design is adopted in order to provide signature design is adopted in order to provide signature
algorithm agility. The value is from the Signature algorithm agility. The value is from the Signature
Algorithm for Secure DHCPv6 registry in IANA. The Algorithm for Secure DHCPv6 registry in IANA. The
support of RSASSA-PKCS1-v1_5 is mandatory. A support of RSASSA-PKCS1-v1_5 is mandatory. A
registry of the initial assigned values is defined registry of the initial assigned values is defined
in Section 12. in Section 12.
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. If the signature algorithm
and hash algorithm cannot be separated, the HA-id
field is zero. The hash algorithm is decided by the
corresponding signature algorithm.
Signature A variable-length field containing a digital Signature A variable-length field containing a digital
signature. The signature value is computed with signature. The signature value is computed with
the hash algorithm and the signature algorithm, the hash algorithm and the signature algorithm,
as described in HA-id and SA-id. The signature as described in HA-id and SA-id. The signature
constructed by using the sender's private key constructed by using the sender's private key
protects the following sequence of octets: protects the following sequence of octets:
1. The DHCPv6 message header. 1. The DHCPv6 message header.
2. All DHCPv6 options including the Signature 2. All DHCPv6 options including the Signature
option (fill the Signature field with zeroes) option (fill the Signature field with zeroes).
except for the Authentication Option.
The Signature field MUST be padded, with all 0, to The Signature field MUST be padded, with all 0, to
the next octet boundary if its size is not a the next octet boundary if its size is not a
multiple of 8 bits. The padding length depends on multiple of 8 bits. The padding length depends on
the signature algorithm, which is indicated in the the signature algorithm, which is indicated in the
SA-id field. SA-id field.
Note: If Secure DHCPv6 is used, the DHCPv6 message is encrypted in a Note: If Secure DHCPv6 is used, the DHCPv6 message is encrypted in a
way that the authentication mechanism defined in RFC3315 does not way that the authentication mechanism defined in RFC3315 does not
understand. So the Authentication option SHOULD NOT be used if understand. So the Authentication option SHOULD NOT be used if
Secure DHCPv6 is applied. Secure DHCPv6 is applied.
10.1.3. Timestamp Option 9.1.3. Increasing-number Option
The Timestamp option carries the current time on the sender. It adds The Increasing-number option carries the number which is higher than
the anti-replay protection to the DHCPv6 messages. It is optional. the local stored number on the client/server. It adds the anti-
replay protection to the DHCPv6 messages. It is optional.
0 1 2 3 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 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 | | OPTION_INCREASINGNUM | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| Timestamp (64-bit) | | InreasingNum (32-bit) |
| | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_TIMESTAMP (TBA3). -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_INCREASINGNUM (TBA3).
option-len 8, in octets. option-len 4, in octets.
Timestamp The current time of day (SeND-format timestamp IncreasingNum A number which is higher than the local stored number on the
in UTC (Coordinated Universal Time). It can reduce client/server for the replay attack detection.
the danger of replay attacks. The timestamp data MUST
be in format as defined in Section 5.3.1, [RFC3971].
10.1.4. Encrypted-message Option 9.1.4. Encrypted-message Option
The Encrypted-message option carries the encrypted DHCPv6 message The Encrypted-message option carries the encrypted DHCPv6 message
with the recipient's public key. with the recipient's public key.
The format of the Encrypted-message option is: The format of the Encrypted-message option is:
0 1 2 3 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 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 | | option-code | option-len |
skipping to change at page 19, line 28 skipping to change at page 18, line 8
option-code OPTION_ENCRYPTED_MSG (TBA4). option-code OPTION_ENCRYPTED_MSG (TBA4).
option-len Length of the encrypted DHCPv6 message. option-len Length of the encrypted DHCPv6 message.
encrypted DHCPv6 message A variable length field containing the encrypted DHCPv6 message A variable length field containing the
encrypted DHCPv6 message sent by the client or the server. In encrypted DHCPv6 message sent by the client or the server. In
Encrypted-Query message, it contains encrypted DHCPv6 message sent Encrypted-Query message, it contains encrypted DHCPv6 message sent
by a client. In Encrypted-response message, it contains encrypted by a client. In Encrypted-response message, it contains encrypted
DHCPv6 message sent by a server. DHCPv6 message sent by a server.
10.2. New DHCPv6 Messages 9.2. New DHCPv6 Messages
Two new DHCPv6 messages are defined to achieve the DHCPv6 encryption: Two new DHCPv6 messages are defined to achieve the DHCPv6 encryption:
Encrypted-Query and Encrypted-Response. Both the DHCPv6 messages Encrypted-Query and Encrypted-Response. Both the DHCPv6 messages
defined in this document share the following format: defined in this document share the following format:
0 1 2 3 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 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 | | msg-type | transaction-id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 20, line 5 skipping to change at page 18, line 33
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: The format of Encrypted-Query and Encrypted-Response Figure 2: The format of Encrypted-Query and Encrypted-Response
Messages Messages
msg-type Identifier of the message type. It can be either msg-type Identifier of the message type. It can be either
Encrypted-Query (TBA5) or DHCPv6-Response (TBA6). Encrypted-Query (TBA5) or DHCPv6-Response (TBA6).
transaction-id The transaction ID for this message exchange. transaction-id The transaction ID for this message exchange.
options The Encrypted-Query message MUST contain the Server options The Encrypted-Query message MUST only contain the
Identifier option and Encrypted-message option. The Server Identifier option or Encrypted-message option.
Encrypted-Response message MUST contain the The Encrypted-Response message MUST only contain the
Encrypted-message option. Encrypted-message option.
10.3. Status Codes 9.3. Status Codes
The following new status codes, see Section 5.4 of [RFC3315] are The following new status codes, see Section 5.4 of [RFC3315] are
defined. defined.
o AlgorithmNotSupported (TBD7): indicates that the DHCPv6 server o AlgorithmNotSupported (TBD7): indicates that the DHCPv6 server
does not support algorithms that sender used. does not support algorithms that sender used.
o AuthenticationFail (TBD8): indicates that the message from the o AuthenticationFail (TBD8): indicates that the message from the
DHCPv6 client fails authentication check. DHCPv6 client fails authentication check.
o TimestampFail (TBD9): indicates the message from DHCPv6 client o IncreasingnumFail (TBD9): indicates the message from DHCPv6 client
fails the timestamp check. fails the increasing number check.
o SignatureFail (TBD10): indicates the message from DHCPv6 client o SignatureFail (TBD10): indicates the message from DHCPv6 client
fails the signature check. fails the signature check.
o DecryptionFail (TBD11): indicates the message from DHCPv6 client o DecryptionFail (TBD11): indicates the message from DHCPv6 client
fails the DHCPv6 message decryption. fails the DHCPv6 message decryption.
11. Security Considerations 10. Security Considerations
This document provides the authentication and encryption mechanisms This document provides the authentication and encryption mechanisms
for DHCPv6. for DHCPv6.
[RFC6273] has analyzed possible threats to the hash algorithms used [RFC6273] has analyzed possible threats to the hash algorithms used
in SEND. Since Secure DHCPv6 defined in this document uses the same in SEND. Since Secure DHCPv6 defined in this document uses the same
hash algorithms in similar way to SEND, analysis results could be hash algorithms in similar way to SEND, analysis results could be
applied as well: current attacks on hash functions do not constitute applied as well: current attacks on hash functions do not constitute
any practical threat to the digital signatures used in the signature any practical threat to the digital signatures used in the signature
algorithm in Secure DHCPv6. algorithm in Secure DHCPv6.
A server, whose local policy accepts messages without a Timestamp A server, whose local policy accepts messages without a Increasing-
option, may have to face the risk of replay attacks. number option, may have to face the risk of replay attacks.
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.
Attacks against time synchronization protocols such as NTP [RFC5905]
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.
There are some mandatory algorithm for encryption algorithm in this There are some mandatory algorithm for encryption algorithm in this
document. It may be at some point that the mandatory algorithm is no document. It may be at some point that the mandatory algorithm is no
longer safe to use. longer safe to use.
If the client tries more than one cert for client authentication, the If the client tries more than one cert for client authentication, the
server can easily get a client that implements this to enumerate its 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. entire cert list and probably learn a lot about a client that way.
12. IANA Considerations 11. IANA Considerations
This document defines four new DHCPv6 [RFC3315] options. The IANA is This document defines four new DHCPv6 [RFC3315] options. The IANA is
requested to assign values for these four options from the DHCPv6 requested to assign values for these four options from the DHCPv6
Option Codes table of the DHCPv6 Parameters registry maintained in Option Codes table of the DHCPv6 Parameters registry maintained in
http://www.iana.org/assignments/dhcpv6-parameters. The four options http://www.iana.org/assignments/dhcpv6-parameters. The four options
are: are:
The Certificate Option (TBA1), described in Section 10.1.1. The Certificate Option (TBA1), described in Section 9.1.1.
The Signature Option (TBA2), described in Section 10.1.2. The Signature Option (TBA2), described in Section 9.1.2.
The Timestamp Option (TBA3),described in Section 10.1.3. The Increasing-number Option (TBA3),described in Section 9.1.3.
The Encrypted-message Option (TBA4), described in Section 10.1.4. The Encrypted-message Option (TBA4), described in Section 9.1.4.
The IANA is also requested to assign value for these two messages The IANA is also requested to assign value for these two messages
from the DHCPv6 Message Types table of the DHCPv6 Parameters registry from the DHCPv6 Message Types table of the DHCPv6 Parameters registry
maintained in http://www.iana.org/assignments/dhcpv6-parameters. The maintained in http://www.iana.org/assignments/dhcpv6-parameters. The
two messages are: two messages are:
The Encrypted-Query Message (TBA5), described in Section 10.2. The Encrypted-Query Message (TBA5), described in Section 9.2.
The Encrypted-Response Message (TBA6), described in Section 10.2. The Encrypted-Response Message (TBA6), described in Section 9.2.
The IANA is also requested to add three new registry tables to the The IANA is also requested to add three new registry tables to the
DHCPv6 Parameters registry maintained in DHCPv6 Parameters registry maintained in
http://www.iana.org/assignments/dhcpv6-parameters. The three tables http://www.iana.org/assignments/dhcpv6-parameters. The three tables
are the Hash Algorithm for Secure DHCPv6 table, the Signature are the Hash Algorithm for Secure DHCPv6 table, the Signature
Algorithm for Secure DHCPv6 table and the Encryption Algorithm for Algorithm for Secure DHCPv6 table and the Encryption Algorithm for
Secure DHCPv6 table. Secure DHCPv6 table.
Initial values for these registries are given below. Future Initial values for these registries are given below. Future
assignments are to be made through Standards Action [RFC5226]. assignments are to be made through Standards Action [RFC5226].
Assignments for each registry consist of a name, a value and a RFC Assignments for each registry consist of a name, a value and a RFC
number where the registry is defined. number where the registry is defined.
Hash Algorithm for Secure DHCPv6. The values in this table are 8-bit Hash Algorithm for Secure DHCPv6. The values in this table are 8-bit
unsigned integers. The following initial values are assigned for unsigned integers. The following initial values are assigned for
Hash Algorithm for Secure DHCPv6 in this document: Hash Algorithm for Secure DHCPv6 in this document:
Name | Value | RFCs Name | Value | RFCs
-------------------+---------+-------------- -------------------+---------+--------------
SigAlg-Combined | ox00 | this document
SHA-256 | 0x01 | this document SHA-256 | 0x01 | this document
SHA-512 | 0x02 | this document SHA-512 | 0x02 | this document
Signature Algorithm for Secure DHCPv6. The values in this table are Signature Algorithm for Secure DHCPv6. The values in this table are
8-bit unsigned integers. The following initial values are assigned 8-bit unsigned integers. The following initial values are assigned
for Signature Algorithm for Secure DHCPv6 in this document: for Signature Algorithm for Secure DHCPv6 in this document:
Name | Value | RFCs Name | Value | RFCs
-------------------+---------+-------------- -------------------+---------+--------------
RSASSA-PKCS1-v1_5 | 0x01 | this document RSASSA-PKCS1-v1_5 | 0x01 | this document
Encryption algorithm for Secure DHCPv6. The values in this table are Encryption algorithm for Secure DHCPv6. The values in this table are
8-bit unsigned integers. The following initial values are assigned 8-bit unsigned integers. The following initial values are assigned
for encryption algorithm for Secure DHCPv6 in this document: for encryption algorithm for Secure DHCPv6 in this document:
Name | Value | RFCs Name | Value | RFCs
-------------------+---------+-------------- -------------------+---------+--------------
RSA | 0 | this document RSA | 0x01 | this document
IANA is requested to assign the following new DHCPv6 Status Codes, IANA is requested to assign the following new DHCPv6 Status Codes,
defined in Section 10.3, in the DHCPv6 Parameters registry maintained defined in Section 9.3, in the DHCPv6 Parameters registry maintained
in http://www.iana.org/assignments/dhcpv6-parameters: in http://www.iana.org/assignments/dhcpv6-parameters:
Code | Name | Reference Code | Name | Reference
---------+-----------------------+-------------- ---------+-----------------------+--------------
TBD7 | AlgorithmNotSupported | this document TBD7 | AlgorithmNotSupported | this document
TBD8 | AuthenticationFail | this document TBD8 | AuthenticationFail | this document
TBD9 | TimestampFail | this document TBD9 | IncreasingnumFail | this document
TBD10 | SignatureFail | this document TBD10 | SignatureFail | this document
TBD11 | DecryptionFail | this document TBD11 | DecryptionFail | this document
13. Acknowledgements 12. Acknowledgements
The authors would like to thank Tomek Mrugalski, Bernie Volz, The authors would like to thank Tomek Mrugalski, Bernie Volz,
Jianping Wu, Randy Bush, Yiu Lee, Sean Shen, Ralph Droms, Jari Arkko, Jianping Wu, Randy Bush, Yiu Lee, Sean Shen, Ralph Droms, Jari Arkko,
Sean Turner, Stephen Farrell, Christian Huitema, Stephen Kent, Thomas Sean Turner, Stephen Farrell, Christian Huitema, Stephen Kent, Thomas
Huth, David Schumacher, Francis Dupont, Gang Chen, Suresh Krishnan, Huth, David Schumacher, Francis Dupont, Gang Chen, Suresh Krishnan,
Fred Templin, Robert Elz, Nico Williams, Erik Kline, Alan DeKok, Fred Templin, Robert Elz, Nico Williams, Erik Kline, Alan DeKok,
Bernard Aboba, Sam Hartman, Qi Sun, Zilong Liu and other members of Bernard Aboba, Sam Hartman, Qi Sun, Zilong Liu and other members of
the IETF DHC working group for their valuable comments. the IETF DHC working group for their valuable comments.
This document was produced using the xml2rfc tool [RFC2629]. This document was produced using the xml2rfc tool [RFC2629].
14. Change log [RFC Editor: Please remove] 13. Change log [RFC Editor: Please remove]
draft-ietf-dhc-sedhcpv6-13: Change the Timestamp option into
Increasing-number option and the corresponding check method; Delete
the OCSP stampling part for the certificate check; Add the scenario
where the hash and signature algorithms cannot be separated; Add the
comparison with RFC7824 and RFC7844; Add the encryption text format
and reference of RFC5652. Add the consideration of scenario where
multiple DHCPv6 servers share one common DHCPv6 server. Add the
statement that Encrypted-Query and Encrypted-Response messages can
only contain certain options: Server Identifier option and Encrypted-
message option. Add opportunistic security for deployment
consideration. Besides authentication+encyrption mode, encryption-
only mode is added.
draft-ietf-dhc-sedhcpv6-12: Add the Signature option and timestamp draft-ietf-dhc-sedhcpv6-12: Add the Signature option and timestamp
option during server/client authentication process. Add the hash option during server/client authentication process. Add the hash
function and signature algorithm. Add the requirement: The function and signature algorithm. Add the requirement: The
Information-request message cannot contain any other options except Information-request message cannot contain any other options except
ORO option. Modify the use of "SHOULD"; Delete the reference of ORO option. Modify the use of "SHOULD"; Delete the reference of
RFC5280 and modify the method of client/server cert verification; Add RFC5280 and modify the method of client/server cert verification; Add
the relay agent cache function for the quick response when there is the relay agent cache function for the quick response when there is
no authenticated server. 2016-4-24. no authenticated server. 2016-4-24.
skipping to change at page 25, line 8 skipping to change at page 23, line 30
Ted Lemon, Bernie Volz, Ralph Droms. Separated Public Key/ Ted Lemon, Bernie Volz, Ralph Droms. Separated Public Key/
Certificate option into two options. Refined many detailed Certificate option into two options. Refined many detailed
processes. 2013-10-08. processes. 2013-10-08.
draft-jiang-dhc-sedhcpv6-00: original version, this draft is a draft-jiang-dhc-sedhcpv6-00: original version, this draft is a
replacement of draft-ietf-dhc-secure-dhcpv6, which reached IESG and replacement of draft-ietf-dhc-secure-dhcpv6, which reached IESG and
dead because of consideration regarding to CGA. The authors followed dead because of consideration regarding to CGA. The authors followed
the suggestion from IESG making a general public key based mechanism. the suggestion from IESG making a general public key based mechanism.
2013-06-29. 2013-06-29.
15. Open Issues [RFC Editor: Please remove] 14. Open Issues [RFC Editor: Please remove]
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.
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
o A. make the server selection behavior more compatible with the The Reply message with the error status code may contain the client
pre-encryption protocol, or identifier option, then the client's privacy information may be
disclosed. The possible way is that we encrypts the Reply message.
But if the error is AlogorithmNotSupported, then the server cannot
encrypt the message with the algorithm used by client.
o B. accept we give up the previous server selection feature for We need to add some explanation on why TOFU is out of scope
privacy (after careful assessment of its effect and with clear wg currently. TOFU is tricky to get it right. If it is included, then
consensus), and explicitly note that. we might even have to operator may skip necessary setup for security. TOFU may be included
reflect that in rfc3315bis. in the future work.
16. References 15. References
16.1. Normative References 15.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>. <http://www.rfc-editor.org/info/rfc2119>.
[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460, (IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460,
December 1998, <http://www.rfc-editor.org/info/rfc2460>. December 1998, <http://www.rfc-editor.org/info/rfc2460>.
skipping to change at page 26, line 21 skipping to change at page 24, line 25
"SEcure Neighbor Discovery (SEND)", RFC 3971, "SEcure Neighbor Discovery (SEND)", RFC 3971,
DOI 10.17487/RFC3971, March 2005, DOI 10.17487/RFC3971, March 2005,
<http://www.rfc-editor.org/info/rfc3971>. <http://www.rfc-editor.org/info/rfc3971>.
[RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet [RFC4443] Conta, A., Deering, S., and M. Gupta, Ed., "Internet
Control Message Protocol (ICMPv6) for the Internet Control Message Protocol (ICMPv6) for the Internet
Protocol Version 6 (IPv6) Specification", RFC 4443, Protocol Version 6 (IPv6) Specification", RFC 4443,
DOI 10.17487/RFC4443, March 2006, DOI 10.17487/RFC4443, March 2006,
<http://www.rfc-editor.org/info/rfc4443>. <http://www.rfc-editor.org/info/rfc4443>.
[RFC5652] Housley, R., "Cryptographic Message Syntax (CMS)", STD 70,
RFC 5652, DOI 10.17487/RFC5652, September 2009,
<http://www.rfc-editor.org/info/rfc5652>.
[RFC5905] Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch, [RFC5905] Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch,
"Network Time Protocol Version 4: Protocol and Algorithms "Network Time Protocol Version 4: Protocol and Algorithms
Specification", RFC 5905, DOI 10.17487/RFC5905, June 2010, Specification", RFC 5905, DOI 10.17487/RFC5905, June 2010,
<http://www.rfc-editor.org/info/rfc5905>. <http://www.rfc-editor.org/info/rfc5905>.
[RFC7283] Cui, Y., Sun, Q., and T. Lemon, "Handling Unknown DHCPv6 [RFC7283] Cui, Y., Sun, Q., and T. Lemon, "Handling Unknown DHCPv6
Messages", RFC 7283, DOI 10.17487/RFC7283, July 2014, Messages", RFC 7283, DOI 10.17487/RFC7283, July 2014,
<http://www.rfc-editor.org/info/rfc7283>. <http://www.rfc-editor.org/info/rfc7283>.
[RFC7296] Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T. [RFC7296] Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T.
Kivinen, "Internet Key Exchange Protocol Version 2 Kivinen, "Internet Key Exchange Protocol Version 2
(IKEv2)", STD 79, RFC 7296, DOI 10.17487/RFC7296, October (IKEv2)", STD 79, RFC 7296, DOI 10.17487/RFC7296, October
2014, <http://www.rfc-editor.org/info/rfc7296>. 2014, <http://www.rfc-editor.org/info/rfc7296>.
16.2. Informative References [RFC7435] Dukhovni, V., "Opportunistic Security: Some Protection
Most of the Time", RFC 7435, DOI 10.17487/RFC7435,
December 2014, <http://www.rfc-editor.org/info/rfc7435>.
[RFC7824] Krishnan, S., Mrugalski, T., and S. Jiang, "Privacy
Considerations for DHCPv6", RFC 7824,
DOI 10.17487/RFC7824, May 2016,
<http://www.rfc-editor.org/info/rfc7824>.
[RFC7844] Huitema, C., Mrugalski, T., and S. Krishnan, "Anonymity
Profiles for DHCP Clients", RFC 7844,
DOI 10.17487/RFC7844, May 2016,
<http://www.rfc-editor.org/info/rfc7844>.
15.2. Informative References
[RFC2629] Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629, [RFC2629] Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629,
DOI 10.17487/RFC2629, June 1999, DOI 10.17487/RFC2629, June 1999,
<http://www.rfc-editor.org/info/rfc2629>. <http://www.rfc-editor.org/info/rfc2629>.
[RFC4270] Hoffman, P. and B. Schneier, "Attacks on Cryptographic
Hashes in Internet Protocols", RFC 4270,
DOI 10.17487/RFC4270, November 2005,
<http://www.rfc-editor.org/info/rfc4270>.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226, IANA Considerations Section in RFCs", BCP 26, RFC 5226,
DOI 10.17487/RFC5226, May 2008, DOI 10.17487/RFC5226, May 2008,
<http://www.rfc-editor.org/info/rfc5226>. <http://www.rfc-editor.org/info/rfc5226>.
[RFC6273] Kukec, A., Krishnan, S., and S. Jiang, "The Secure [RFC6273] Kukec, A., Krishnan, S., and S. Jiang, "The Secure
Neighbor Discovery (SEND) Hash Threat Analysis", RFC 6273, Neighbor Discovery (SEND) Hash Threat Analysis", RFC 6273,
DOI 10.17487/RFC6273, June 2011, DOI 10.17487/RFC6273, June 2011,
<http://www.rfc-editor.org/info/rfc6273>. <http://www.rfc-editor.org/info/rfc6273>.
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