draft-ietf-dhc-sedhcpv6-11.txt   draft-ietf-dhc-sedhcpv6-12.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: September 9, 2016 Y. Cui Expires: October 26, 2016 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
March 8, 2016 April 24, 2016
Secure DHCPv6 Secure DHCPv6
draft-ietf-dhc-sedhcpv6-11 draft-ietf-dhc-sedhcpv6-12
Abstract Abstract
The Dynamic Host Configuration Protocol for IPv6 (DHCPv6) enables The Dynamic Host Configuration Protocol for IPv6 (DHCPv6) enables
DHCPv6 servers to pass configuration parameters. It offers DHCPv6 servers to pass configuration parameters. It offers
configuration flexibility. If not secured, DHCPv6 is vulnerable to configuration flexibility. If not secured, DHCPv6 is vulnerable to
various attacks. This document analyzes the security issues of various attacks. This document analyzes the security issues of
DHCPv6 and specifies the secure DHCPv6 mechanism for authentication DHCPv6 and specifies the secure DHCPv6 mechanism for authentication
and encryption of messages between a DHCPv6 client and a DHCPv6 and encryption of messages between a DHCPv6 client and a DHCPv6
server. server.
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This Internet-Draft will expire on September 9, 2016. This Internet-Draft will expire on October 26, 2016.
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
document authors. All rights reserved. document authors. All rights reserved.
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements Language and Terminology . . . . . . . . . . . . 3 2. Requirements Language and Terminology . . . . . . . . . . . . 3
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
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 . . . . . . . . . . . . . . . . . . . . . 6 5.2. New Components . . . . . . . . . . . . . . . . . . . . . 7
5.3. Support for Algorithm Agility . . . . . . . . . . . . . . 7 5.3. Support for Algorithm Agility . . . . . . . . . . . . . . 7
5.4. Applicability . . . . . . . . . . . . . . . . . . . . . . 7 5.4. Applicability . . . . . . . . . . . . . . . . . . . . . . 8
6. DHCPv6 Client Behavior . . . . . . . . . . . . . . . . . . . 8 6. DHCPv6 Client Behavior . . . . . . . . . . . . . . . . . . . 9
7. DHCPv6 Server Behavior . . . . . . . . . . . . . . . . . . . 11 7. DHCPv6 Server Behavior . . . . . . . . . . . . . . . . . . . 12
8. Relay Agent Behavior . . . . . . . . . . . . . . . . . . . . 12 8. Relay Agent Behavior . . . . . . . . . . . . . . . . . . . . 14
9. Processing Rules . . . . . . . . . . . . . . . . . . . . . . 12 9. Processing Rules . . . . . . . . . . . . . . . . . . . . . . 14
9.1. Timestamp Check . . . . . . . . . . . . . . . . . . . . . 12 9.1. Timestamp Check . . . . . . . . . . . . . . . . . . . . . 14
10. Extensions for Secure DHCPv6 . . . . . . . . . . . . . . . . 14 10. Extensions for Secure DHCPv6 . . . . . . . . . . . . . . . . 16
10.1. New DHCPv6 Options . . . . . . . . . . . . . . . . . . . 14 10.1. New DHCPv6 Options . . . . . . . . . . . . . . . . . . . 16
10.1.1. Certificate Option . . . . . . . . . . . . . . . . . 14 10.1.1. Certificate Option . . . . . . . . . . . . . . . . . 16
10.1.2. Timestamp Option . . . . . . . . . . . . . . . . . . 15 10.1.2. Signature option . . . . . . . . . . . . . . . . . . 17
10.1.3. Encrypted-message Option . . . . . . . . . . . . . . 16 10.1.3. Timestamp Option . . . . . . . . . . . . . . . . . . 18
10.2. New DHCPv6 Messages . . . . . . . . . . . . . . . . . . 17 10.1.4. Encrypted-message Option . . . . . . . . . . . . . . 18
10.3. Status Codes . . . . . . . . . . . . . . . . . . . . . . 17 10.2. New DHCPv6 Messages . . . . . . . . . . . . . . . . . . 19
11. Security Considerations . . . . . . . . . . . . . . . . . . . 18 10.3. Status Codes . . . . . . . . . . . . . . . . . . . . . . 20
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18 11. Security Considerations . . . . . . . . . . . . . . . . . . . 20
13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 19 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21
14. Change log [RFC Editor: Please remove] . . . . . . . . . . . 20 13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 23
15. Open Issues [RFC Editor: Please remove] . . . . . . . . . . . 21 14. Change log [RFC Editor: Please remove] . . . . . . . . . . . 23
16. References . . . . . . . . . . . . . . . . . . . . . . . . . 22 15. Open Issues [RFC Editor: Please remove] . . . . . . . . . . . 25
16.1. Normative References . . . . . . . . . . . . . . . . . . 22 16. References . . . . . . . . . . . . . . . . . . . . . . . . . 25
16.2. Informative References . . . . . . . . . . . . . . . . . 23 16.1. Normative References . . . . . . . . . . . . . . . . . . 25
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23 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 enables DHCPv6 servers to pass configuration parameters and offers
configuration flexibility. If not being secured, DHCPv6 is configuration flexibility. If not being secured, DHCPv6 is
vulnerable to various attacks. vulnerable to various attacks.
This document analyzes the security issues of DHCPv6 and provides the This document analyzes the security issues of DHCPv6 and provides the
following mechanisms for improving the security of DHCPv6 between the following mechanisms for improving the security of DHCPv6 between the
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Note: this secure mechanism in this document does not protect outer Note: this secure mechanism in this document does not protect outer
options in Relay-Forward and Relay-Reply messages, either added by a 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 relay agent toward a server or added by a server toward a relay
agent. Communication between a server and a relay agent, and agent. Communication between a server and a relay agent, and
communications between relay agents, may be secured through the use communications between relay agents, may be secured through the use
of IPsec, as described in section 21.1 in [RFC3315]. of IPsec, as described in section 21.1 in [RFC3315].
The security mechanism specified in this document achieves DHCPv6 The security mechanism specified in this document achieves DHCPv6
authentication and encryption based on the sender's certificate. We authentication and encryption based on the sender's certificate. We
introduce two new DHCPv6 messages: Encrypted-Query message and introduce two new DHCPv6 messages: Encrypted-Query message and
Encrypted-Response message and three new DHCPv6 options: Certificate Encrypted-Response message and Four new DHCPv6 options: Certificate
option, Timestamp option and Encrypted-message option for DHCPv6 option, Signature option, Timestamp option and Encrypted-message
authentication and encryption. The Certificate option is used for option for DHCPv6 authentication and encryption. The Certificate
DHCPv6 authentication. The Encryption-Query message, Encryption- option, Signature option, Timestamp option are used for DHCPv6
Response message and Encrypted-message option are used for DHCPv6 client/server authentication. The Encryption-Query message,
encryption. The timestamp option is used to defend against replay Encryption-Response message and Encrypted-message option are used for
attack. 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.
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DHCPv6 encryption defends against passive attacks, such as pervasive DHCPv6 encryption defends against passive attacks, such as pervasive
monitoring attack. monitoring attack.
5. Secure DHCPv6 Overview 5. Secure DHCPv6 Overview
5.1. Solution Overview 5.1. Solution Overview
This solution provides authentication and encryption mechanisms based This solution provides authentication and encryption mechanisms based
on the certificates of the DHCPv6 client and server. Before the on the certificates of the DHCPv6 client and server. Before the
standard DHCPv6 configuration process, the Information-request and standard DHCPv6 configuration process, the Information-request and
Reply messages are exchanged to select one authenticated DHCPv6 Reply messages are exchanged to select the authenticated DHCPv6
server. After the mutual authentication between the DHCPv6 client server. After mutual authentication between the DHCPv6 client and
and server, the following DHCPv6 configuration process is encrypted server, the following DHCPv6 configuration process is encrypted to
to avoid the privacy information disclosure. We introduce two new avoid the privacy information disclosure. We introduce two new
DHCPv6 messages: Encrypted-Query message, Encrypted-Response message DHCPv6 messages: Encrypted-Query message, Encrypted-Response message
and three new DHCPv6 options: Encrypted-message option, Certificate and four new DHCPv6 options: Encrypted-message option, Certificate
option, Timestamp option. Based on the new defined messages and option, Signature option, Timestamp option. Based on the new defined
options, the corresponding authentication and encryption mechanisms messages and options, the corresponding authentication and encryption
are achieved. mechanisms are achieved.
The following figure illustrates secure DHCPv6 procedure. The DHCPv6 The following figure illustrates secure DHCPv6 procedure. The DHCPv6
client first sends an Information-request message to the standard client first sends Information-request message as per [RFC3315]. The
multicast address to all DHCPv6 servers. The Information-request Information-request message is used to request the servers for the
message is used to request the servers for the servers' certificates servers' certificates information, without going through any address,
information, without going through any address, prefix or non- prefix or non-security option assignment process. The Information-
security option assignment process. The Information-request is sent request contains no DHCPv6 options except ORO option to avoid
without any client's private information, such as Client Identifier client's privacy information disclosure. When receiving the
option or the Certificate option, to minimize client's privacy Information-request message, the server sends the Reply message that
information leakage. When receiving the Information-request message, contains the server's Certificate option, Signature option, Timestamp
the server sends the Reply message that contains the server's option and Server Identifier option. Upon the receipt of the Reply
Certificate option and Server Identifier option. Upon the receipt of message, the DHCPv6 client verifies the server's identity according
the Reply message, the DHCPv6 client verifies the server's identity to the contained options in the Reply message. If there are multiple
according to the contained certificate in the Reply message. If authenticated DHCPv6 server certs, the client selects one
there are multiple authenticated DHCPv6 servers, the client selects authenticated DHCPv6 server for the following DHCPv6 configuration
one authenticated DHCPv6 server for the following DHCPv6 process. If there are no authenticated DHCPv6 server cert or
configuration process. If there are no authenticated DHCPv6 servers existing server certs fails authentication, the client should retry a
or existing servers failed authentication, the client should retry a
number of times. In this way, it is difficult for a rogue server to 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 beat out a busy "real" server. And then the client takes some other
alternative action depending on its local policy. alternative action depending on its local policy.
After the server's authentication, the first DHCPv6 message sent from After the server's authentication, the first DHCPv6 message sent from
the client to the server, such as Solicit message, contains the the client to the server, such as Solicit message, contains the
client's Certificate information for client authentication. The client's Certificate information for client authentication. The
DHCPv6 client sends the Encrypted-Query message to server, which DHCPv6 client sends the Encrypted-Query message to server, which
carries the Encrypted-message option and the Server Identifier carries the Encrypted-message option and the Server Identifier
option. The Encrypted-message option contains the encrypted DHCPv6 option. The Encrypted-message option contains the encrypted DHCPv6
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Certificate option, the DHCPv6 server verifies the client's identity Certificate option, the DHCPv6 server verifies the client's identity
according to the contained client certificate information. according to the contained client certificate information.
After the client's authentication, the server sends the Encrypted- After the client's authentication, the server sends the Encrypted-
Response message to the client, which contains the Encrypted-message Response message to the client, which contains the Encrypted-message
option. The Encrypted-message option contains the encrypted DHCPv6 option. The Encrypted-message option contains the encrypted DHCPv6
message sent from server to client, which is encrypted using the message sent from server to client, which is encrypted using the
client's public key. If the message fails client authentication, client's public key. If the message fails client authentication,
then the server sends the corresponding error status code to the then the server sends the corresponding error status code to the
client. During the encrypted DHCPv6 configuration process, the client. During the encrypted DHCPv6 configuration process, the
timestamp option can be contained in the encrypted DHCPv6 messages to Timestamp option can be contained in the encrypted DHCPv6 messages to
defend against replay attacks. defend against replay attacks.
+-------------+ +-------------+ +-------------+ +-------------+
|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 |
| Timestamp 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 |
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5.2. New Components 5.2. New Components
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
receiver to verify the integrity of the DHCPv6 messages and then
authentication of the client/server. Another option is defined to
carry the signature.
o A timestamp that can be used to detect replayed packet. The o A timestamp that can be used to detect replayed packet. The
Timestamp option is defined to carry the current time of the Timestamp option is defined to carry the current time of the
client/server. The secure DHCPv6 client/server need to meet some client/server. The secure DHCPv6 client/server need to meet some
accuracy requirements and be synced to global time, while the accuracy requirements and be synced to global time, while the
timestamp checking mechanism allows a configurable time value for timestamp checking mechanism allows a configurable time value for
clock drift. The real time provision is out of scope of this clock drift. The real time provision is out of scope of this
document. document.
o The Encrypted-message option that contains the encrypted DHCPv6 o The Encrypted-message option that contains the encrypted DHCPv6
message. message.
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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 contains the Encrypted-message option and Server Identifier
option. 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.
5.3. Support for Algorithm Agility 5.3. Support for Algorithm Agility
Encryption algorithm is used for DHCPv6 encryption to defend against In order to provide a means of addressing problems that may emerge in
passive attack. In order to provide a means of addressing problems the future with existing hash algorithms, as recommended in
that may emerge in the future with existing encryption algorithms, [RFC4270], this document provides a mechanism for negotiating the use
this document provides a mechanism for negotiating the use of more of more secure hashes in the future.
encryption algorithms in the future.
In addition to hash algorithm agility, this document also provides a
mechanism for signature algorithm and encryption algorithm agility.
The support for algorithm agility in this document is mainly a The support for algorithm agility in this document is mainly a
unilateral notification mechanism from sender to recipient. A unilateral notification mechanism from sender to recipient. A
recipient MAY support various algorithms simultaneously among recipient MAY support various algorithms simultaneously among
different senders, and the different senders in a same administrative different senders, and the different senders in a same administrative
domain may be allowed to use various algorithms simultaneously. It domain may be allowed to use various algorithms simultaneously. It
is NOT RECOMMENDED that the same sender and recipient use various is NOT RECOMMENDED that the same sender and recipient use various
algorithms in a single communication session. 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 10.3) 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 (defined in Section 10.1.1). 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, it will rely on some
operational assumptions mainly regarding public key distribution and operational assumptions mainly regarding public key distribution and
management, until more lessons are learned and more experiences are management, until more lessons are learned and more experiences are
achieved. achieved.
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deployed. But such a deployment requires more general issues with deployed. But such a deployment requires more general issues with
PKI deployment be addressed, and it is currently unknown whether we PKI deployment be addressed, and it is currently unknown whether we
can find practical deployment scenarios. It is subject to future can find practical deployment scenarios. It is subject to future
study and experiments, and out of scope of this document. study and experiments, and out of scope of this document.
6. DHCPv6 Client Behavior 6. DHCPv6 Client Behavior
For the secure DHCPv6 client, a certificate is needed for client For the secure DHCPv6 client, a certificate is needed for client
authentication. The client is pre-configured with a certificate and authentication. The client is pre-configured with a certificate and
its corresponding private key. If the client is pre-configured with its corresponding private key. If the client is pre-configured with
public key not certificate, it can generate the self-signed public key but not with a certificate, it can generate the self-
certificate for client authentication. signed certificate for client authentication.
The secure DHCPv6 client multicasts the Information-request message The secure DHCPv6 client sends Information-request message as per
to the DHCPv6 servers. The Information-request message MUST NOT [RFC3315]. The Information-request message is used by the DHCPv6
include any option which may reveal the private information of the client to request the server's identity verification information
client, such as the Client Identifier option or the Certificate without having addresses, prefixes or any non-security options
option. The Information-request message is used by the DHCPv6 client assigned to it. The Information-request message MUST NOT include any
to request the server's identity verification information without DHCPv6 options except ORO option to minimize client's privacy
having addresses, prefixes or any non-security options assigned to information leakage. The Option Request option in the Information-
it. The Option Request option in the Information-request message request message MUST contain the option code of the Certificate
MUST contain the option code of the Certificate option. option.
When receiving the Reply messages from DHCPv6 servers, a secure When receiving the Reply messages from DHCPv6 servers, a secure
DHCPv6 client SHOULD discard any DHCPv6 messages when the Certificate DHCPv6 client discards any DHCPv6 messages that meet any of the
option or Server Identifier option is missing. And then the client following conditions:
SHOULD first check the support of the encryption algorithm that the
server used. If the check fails, the Reply message SHOULD be
dropped. If the encryption algorithm is supported, the client then
checks the authority of this server. The client SHOULD also use the
same algorithms in the return messages.
The client SHOULD validate the certificate according to the rules o the Signature option is missing,
defined in [RFC5280]. An implementation may create a local trust
certificate record for verified certificates in order to avoid o multiple Signature options are present,
repeated verification procedure in the future. A certificate that
o the Certificate option is missing.
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.
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 finds a match in the local trust certificate list is treated as
verified. The message transaction-id is used as the identifier of verified. If the client want to check server's certificate to see
the authenticated server's public key for encryption. At this point, whether it has been revoked, the OCSP stapling can be used. The
the client has either recognized the certificate of the server, or message transaction-id is used as the identifier of the authenticated
decided to drop the message. 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.
The client MUST now authenticate the server by verifying the
signature and checking timestamp (see details in Section 9.1), 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.
The Signature field verification MUST show that the signature has
been calculated as specified in Section 10.1.2. 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.
If there are multiple authenticated DHCPv6 servers, the client If there are multiple authenticated DHCPv6 servers, the client
selects one DHCPv6 server for the following network parameters selects one DHCPv6 server for the following network parameters
configuration. The client can also choose other implementation configuration. The client can also choose other implementation
method depending on the client's local policy if the defined protocol method depending on the client's local policy if the defined protocol
can also run normally. For example, the client can try multiple can also run normally. For example, the client can try multiple
transactions (each with different server) at the "same" time. If transactions (each encrypted with different public key) at the "same"
there are no authenticated DHCPv6 servers or existing servers failed time. If there are no authenticated DHCPv6 servers or existing
authentication, the client should retry a number of times. In this servers failed authentication, the client should retry a number of
way, it is difficult for the rogue server to beat out a busy "real" times. In this way, it is difficult for the rogue server to beat out
server. And then the client takes some alternative action depending a busy "real" server. And then the client takes some alternative
on its local policy, such as attempting to use an unsecured DHCPv6 action depending on its local policy, such as attempting to use an
server. The client conducts the server discovery process as per unsecured DHCPv6 server. The client conducts the server discovery
section 18.1.5 of [RFC3315] to avoid the packet storm. process as per section 18.1.5 of [RFC3315] to avoid the packet storm.
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 10.1.3, and Server Identifier constructed as explained in Section 10.1.4, and Server Identifier
option. The Encrypted-message option contains the DHCPv6 message option. The Encrypted-message option contains the DHCPv6 message
that is encrypted using the selected server's public key. The Server that is encrypted using the selected server's public key. The Server
Identifier option is externally visible to avoid decryption cost by Identifier option is externally visible to avoid decryption cost by
those unselected servers. those unselected servers.
For the encrypted DHCPv6 message sent from the DHCPv6 client to the For the encrypted DHCPv6 message sent from the DHCPv6 client to the
DHCPv6 server, the first DHCPv6 message, such as Solicit message, DHCPv6 server, the first DHCPv6 message, such as Solicit message,
MUST contain the Certificate option for client authentication. The MUST contain the Certificate option, Signature option and Timestamp
Certificate option MUST be constructed as explained in option for client authentication. The Certificate option MUST be
Section 10.1.1. If the client have multiple certificate with constructed as explained in Section 10.1.1. In addition, one and
different public/private key pairs, the message transaction-id is only one Signature option MUST be contained, which MUST be
used as the identifier of the client's private key for decryption. constructed as explained in Section 10.1.2. One and only one
In addition, the encrypted DHCPv6 message can contain the timestamp Timestamp option SHOULD be contained, which MUST be constructed as
option to defend against replay attacks. The timestamp option MUST explained in Section 10.1.3. The Timestamp field SHOULD be set to
be constructed as explained in Section 10.1.2. the current time, according to sender's real time clock.
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.
For the received Encrypted-Response message, the client extracts the For the received Encrypted-Response message, 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 Timestamp option, the DHCPv6 client checks the timestamp according to
the rule defined in Section 9.1. The DHCPv6 message, which fails the the rule defined in Section 9.1. The DHCPv6 message, which fails the
timestamp check, MUST be discarded. If the client fails to get the timestamp check, MUST be discarded. If the client fails to get the
proper parameters from the chosen server, it sends the Encrypted- proper parameters from the chosen server, it sends the Encrypted-
Query message to another authenticated server for parameters Query message to another authenticated server for parameters
configuration 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:
skipping to change at page 11, line 5 skipping to change at page 11, line 49
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 TimestampFail error status code, the client MAY
resend the message with an adjusted timestamp according to the resend the message with an adjusted timestamp according to the
returned clock from the DHCPv6 server. The client SHOULD NOT returned clock from the DHCPv6 server. The client SHOULD NOT
change its own clock, but only compute an offset for the change its own clock, but only compute an offset for the
communication session. communication session.
o Upon receiving a SignatureFail error status code, the client MAY
resend the message following normal retransmission routines
defined in [RFC3315].
7. DHCPv6 Server Behavior 7. DHCPv6 Server Behavior
For the secure DHCPv6 server, a certificate is need 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 not certificate, it can generate the self-signed public key but not with a certificate, it can generate the self-
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 10.1.1, and
Server Identifier option. Server Identifier option. In addition, the Reply message MUST
contain one and only one Signature option, which MUST be constructed
as explained in Section 10.1.2. Besides, the Reply message SHOULD
contain one and only one Timestamp option, which MUST be constructed
as explained in Section 10.1.3. The Timestamp field SHOULD be set to
the current time, according to server's real time clock.
Upon the receipt of Encrypted-Query message, the server checks the Upon the receipt of Encrypted-Query message, the server checks the
Server Identifier option. It decrypts the Encrypted-message option Server Identifier option. It decrypts the Encrypted-message option
using its private key if it is the target server. The DHCPv6 server 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 drops the message that is not for it, thus not paying cost to decrypt
messages not for it. messages not for it.
If the decrypted message is a Solicit/Information-request message, If the decrypted message is a Solicit/Information-request message,
the secure DHCPv6 server SHOULD discard the received message if the the secure DHCPv6 server discards the received message that meets any
Certificate option is missing. In such failure, the server SHOULD of the following conditions:
reply with an UnspecFail (value 1, [RFC3315]) error status code.
If a Certificate option is provided, the server SHOULD first check o the Signature option is missing,
the support of the encryption algorithm that the client used. If the
check fails, the server SHOULD reply with an AlgorithmNotSupported
error status code, defined in Section 10.3 back to the client. If
the encryption algorithm is supported, the server then checks the
authority of this client.
The server SHOULD validate the certificate according to the rules o multiple Signature options are present,
defined in [RFC5280]. An implementation may create a local trust
certificate record for verified certificates in order to avoid
repeated verification procedure in the future. A certificate that
finds a match in the local trust certificate list is treated as
verified. The message that fails certificate validation MUST be
dropped. In such failure, the DHCPv6 server SHOULD reply 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 o the Certificate option is missing.
In such failure, the server replies with an UnspecFail (value 1,
[RFC3315]) error status code.
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 Section 10.3,
back to the client. If all the algorithms are supported, the server
then checks the authority of this client.
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 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
checks the timestamp according to the rule defined in Section 9.1. checks the timestamp according to the rule defined in Section 9.1.
If the timestamp check fails, a TimestampFail error status code, If the timestamp check fails, a TimestampFail error status code,
defined in Section 10.3, should be sent back to the client. defined in Section 10.3, should be sent back to the client.
Depending on server's local policy, the message without a Timestamp Depending on server's local policy, the message without a Timestamp
option MAY be acceptable or rejected. If the server rejects such a option MAY be acceptable or rejected. If the server rejects such a
message, a TimestampFail error status code should be sent back to the message, a TimestampFail error status code should be sent back to the
client. The Reply message that carries the TimestampFail error client. The Reply message that carries the TimestampFail error
status code SHOULD carry a timestamp option, which indicates the status code carries a Timestamp option, which indicates the server's
server's clock for the client to use. clock for the client to use.
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
Section 9.1). 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
Section 10.3, 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.
The Signature field verification MUST show that the signature has
been calculated as specified in Section 10.1.2. 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
[RFC3315]. 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 Section 10.3, for the
signature verification failure; or a TimestampFail error status code,
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 contains the Encrypted-message option, which MUST be
constructed as explained in Section 10.1.3. The Encrypted-message constructed as explained in Section 10.1.4. The Encrypted-message
option contains the encrypted DHCPv6 message that is encrypted using option contains the encrypted DHCPv6 message that is encrypted using
the authenticated client's public key. To provide the replay the authenticated client's public key. To provide the replay
protection, the timestamp option can be contained in the encrypted protection, the Timestamp option can be contained in the encrypted
DHCPv6 message. 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 Timestamp option, aside from those
present in the innermost encapsulated messages from the client or present in the innermost encapsulated messages from the client or
server. server.
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.
9. Processing Rules 9. Processing Rules
9.1. Timestamp Check 9.1. Timestamp Check
In order to check the Timestamp option, defined in Section 10.1.2, In order to check the Timestamp option, defined in Section 10.1.3,
recipients SHOULD be configured with an allowed timestamp Delta recipients SHOULD be configured with an allowed timestamp Delta
value, a "fuzz factor" for comparisons, and an allowed clock drift value, a "fuzz factor" for comparisons, and an allowed clock drift
parameter. The recommended default value for the allowed Delta is parameter. The recommended default value for the allowed Delta is
300 seconds (5 minutes); for fuzz factor 1 second; and for clock 300 seconds (5 minutes); for fuzz factor 1 second; and for clock
drift, 0.01 second. drift, 0.01 second.
Note: the Timestamp mechanism is based on the assumption that Note: the Timestamp mechanism is based on the assumption that
communication peers have roughly synchronized clocks, within certain communication peers have roughly synchronized clocks, within certain
allowed clock drift. So, an accurate clock is not necessary. If one allowed clock drift. So, an accurate clock is not necessary. If one
has a clock too far from the current time, the timestamp mechanism has a clock too far from the current time, the timestamp mechanism
would not work. would not work.
To facilitate timestamp checking, each recipient SHOULD store the To facilitate timestamp checking, each recipient SHOULD store the
following information for each sender, from which at least one following information for each sender, from which at least one
accepted secure DHCPv6 message is successfully verified (for accepted secure DHCPv6 message is successfully verified (for
timestamp check): timestamp check and signature verification):
o The receive time of the last received and accepted DHCPv6 message. o The receive time of the last received and accepted DHCPv6 message.
This is called RDlast. This is called RDlast.
o The timestamp in the last received and accepted DHCPv6 message. o The timestamp in the last received and accepted DHCPv6 message.
This is called TSlast. This is called TSlast.
A verified (for timestamp check) secure DHCPv6 message initiates the A verified (for timestamp check and signature verification) secure
update of the above variables in the recipient's record. DHCPv6 message initiates the update of the above variables in the
recipient's record.
Recipients MUST check the Timestamp field as follows: Recipients MUST check the Timestamp field as follows:
o When a message is received from a new peer (i.e., one that is not 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, stored in the cache), the received timestamp, TSnew, is checked,
and the message is accepted if the timestamp is recent enough to and the message is accepted if the timestamp is recent enough to
the reception time of the packet, RDnew: the reception time of the packet, RDnew:
-Delta < (RDnew - TSnew) < +Delta -Delta < (RDnew - TSnew) < +Delta
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entries. The specific policy as to which entries are preferred over entries. The specific policy as to which entries are preferred over
others is left as an implementation decision. others is left as an implementation decision.
An implementation MAY statefully record the latest timestamps from An implementation MAY statefully record the latest timestamps from
senders. In such implementation, the timestamps MUST be strictly senders. In such implementation, the timestamps MUST be strictly
monotonously increasing. This is reasonable given that DHCPv6 monotonously increasing. This is reasonable given that DHCPv6
messages are rarely misordered. messages are rarely misordered.
10. Extensions for Secure DHCPv6 10. Extensions for Secure DHCPv6
This section describes the extensions to DHCPv6. Three new DHCPv6 This section describes the extensions to DHCPv6. Four new DHCPv6
options, two new DHCPv6 messages and four status codes are defined. options, two new DHCPv6 messages and five new status codes are
defined.
10.1. New DHCPv6 Options 10.1. New DHCPv6 Options
10.1.1. Certificate Option 10.1.1. 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
skipping to change at page 15, line 33 skipping to change at page 17, line 5
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. Timestamp Option 10.1.2. Signature option
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:
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.
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.
10.1.3. Timestamp Option
The Timestamp option carries the current time on the sender. It adds The Timestamp option carries the current time on the sender. It adds
the anti-replay protection to the DHCPv6 messages. It is optional. 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_TIMESTAMP | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| Timestamp (64-bit) | | Timestamp (64-bit) |
| | | |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_TIMESTAMP (TBA2). option-code OPTION_TIMESTAMP (TBA3).
option-len 8, in octets. option-len 8, in octets.
Timestamp The current time of day (SeND-format timestamp Timestamp The current time of day (SeND-format timestamp
in UTC (Coordinated Universal Time). It can reduce in UTC (Coordinated Universal Time). It can reduce
the danger of replay attacks. The timestamp data MUST the danger of replay attacks. The timestamp data MUST
be in format as defined in Section 5.3.1, [RFC3971]. be in format as defined in Section 5.3.1, [RFC3971].
10.1.3. Encrypted-message Option 10.1.4. 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
. encrypted DHCPv6 message . . encrypted DHCPv6 message .
. (variable) . . (variable) .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Encrypted-message Option Format Figure 1: Encrypted-message Option Format
option-code OPTION_ENCRYPTED_MSG (TBA3). 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 10.2. New DHCPv6 Messages
skipping to change at page 17, line 28 skipping to change at page 19, line 49
| | | |
. options . . options .
. (variable) . . (variable) .
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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 (TBA4) or DHCPv6-Response (TBA5). 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 contain the Server
Identifier option and Encrypted-message option. The Identifier option and Encrypted-message option. The
Encrypted-Response message MUST contain the Encrypted-Response message MUST contain the
Encrypted-message option. Encrypted-message option.
10.3. Status Codes 10.3. 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 (TBD6): 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 (TBD7): indicates that the DHCPv6 client fails o AuthenticationFail (TBD8): indicates that the message from the
authentication check. DHCPv6 client fails authentication check.
o TimestampFail (TBD8): indicates the message from DHCPv6 client o TimestampFail (TBD9): indicates the message from DHCPv6 client
fails the timestamp check. fails the timestamp check.
o DecryptionFail (TBD9): indicates the message from DHCPv6 client o SignatureFail (TBD10): indicates the message from DHCPv6 client
fails the signature check.
o DecryptionFail (TBD11): indicates the message from DHCPv6 client
fails the DHCPv6 message decryption. fails the DHCPv6 message decryption.
11. Security Considerations 11. 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
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.
A server, whose local policy accepts messages without a Timestamp A server, whose local policy accepts messages without a Timestamp
option, may have to face the risk of replay attacks. option, may have to face the risk of replay attacks.
A window of vulnerability for replay attacks exists until the A window of vulnerability for replay attacks exists until the
timestamp expires. Secure DHCPv6 nodes are protected against replay timestamp expires. Secure DHCPv6 nodes are protected against replay
attacks as long as they cache the state created by the message attacks as long as they cache the state created by the message
containing the timestamp. The cached state allows the node to containing the timestamp. The cached state allows the node to
protect itself against replayed messages. However, once the node protect itself against replayed messages. However, once the node
flushes the state for whatever reason, an attacker can re-create the flushes the state for whatever reason, an attacker can re-create the
state by replaying an old message while the timestamp is still valid. state by replaying an old message while the timestamp is still valid.
skipping to change at page 18, line 36 skipping to change at page 21, line 16
of scope of this work. of scope of this work.
Attacks against time synchronization protocols such as NTP [RFC5905] Attacks against time synchronization protocols such as NTP [RFC5905]
may cause Secure DHCPv6 nodes to have an incorrect timestamp value. may cause Secure DHCPv6 nodes to have an incorrect timestamp value.
This can be used to launch replay attacks, even outside the normal This can be used to launch replay attacks, even outside the normal
window of vulnerability. To protect against these attacks, it is window of vulnerability. To protect against these attacks, it is
recommended that Secure DHCPv6 nodes keep independently maintained recommended that Secure DHCPv6 nodes keep independently maintained
clocks or apply suitable security measures for the time clocks or apply suitable security measures for the time
synchronization protocols. synchronization protocols.
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.
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.
12. IANA Considerations 12. IANA Considerations
This document defines three new DHCPv6 [RFC3315] options. The IANA This document defines four new DHCPv6 [RFC3315] options. The IANA is
is requested to assign values for these three 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 three 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 10.1.1.
The Timestamp option (TBA2),described in Section 10.1.2. The Signature Option (TBA2), described in Section 10.1.2.
The Encrypted-message option (TBA3), described in Section 10.1.3. The Timestamp Option (TBA3),described in Section 10.1.3.
The Encrypted-message Option (TBA4), described in Section 10.1.4.
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 (TBA4), described in Section 10.2. The Encrypted-Query Message (TBA5), described in Section 10.2.
The Encrypted-Response message (TBA5), described in Section 10.2. The Encrypted-Response Message (TBA6), described in Section 10.2.
The IANA is also requested to add one 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 table is the http://www.iana.org/assignments/dhcpv6-parameters. The three tables
Encryption Algorithm for Secure DHCPv6 table. are the Hash Algorithm for Secure DHCPv6 table, the Signature
Algorithm for Secure DHCPv6 table and the Encryption Algorithm for
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
unsigned integers. The following initial values are assigned for
Hash Algorithm for Secure DHCPv6 in this document:
Name | Value | RFCs
-------------------+---------+--------------
SHA-256 | 0x01 | this document
SHA-512 | 0x02 | this document
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:
Name | Value | RFCs
-------------------+---------+--------------
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 | 0 | 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 10.3, 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
---------+-----------------------+-------------- ---------+-----------------------+--------------
TBD6 | AlgorithmNotSupported | this document TBD7 | AlgorithmNotSupported | this document
TBD7 | AuthenticationFail | this document TBD8 | AuthenticationFail | this document
TBD8 | TimestampFail | this document TBD9 | TimestampFail | this document
TBD9 | DecryptionFail | this document TBD10 | SignatureFail | this document
TBD11 | DecryptionFail | this document
13. Acknowledgements 13. 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] 14. Change log [RFC Editor: Please remove]
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.
draft-ietf-dhc-sedhcpv6-11: Delete the Signature option, because the draft-ietf-dhc-sedhcpv6-11: Delete the Signature option, because the
encrypted DHCPv6 message and the Information-request message (only encrypted DHCPv6 message and the Information-request message (only
contain the certificate option) don't need the signature option for contain the Certificate option) don't need the Signature option for
message integrity check; Rewrite the "Applicability" section; Add the message integrity check; Rewrite the "Applicability" section; Add the
encryption algorithm negotiation process; To support the encryption encryption algorithm negotiation process; To support the encryption
algorithm negotiation, the Certificate option contains the EA- algorithm negotiation, the Certificate option contains the EA-
id(encryption algorithm identifier) field; Reserve the timestamp id(encryption algorithm identifier) field; Reserve the Timestamp
option to defend against the replay attacks for encrypted DHCPv6 option to defend against the replay attacks for encrypted DHCPv6
configuration process; Modify the client behavior when there is no configuration process; Modify the client behavior when there is no
authenticated DHCPv6 server; Add the DecryptionFail error code. authenticated DHCPv6 server; Add the DecryptionFail error code.
2016-3-9. 2016-3-9.
draft-ietf-dhc-sedhcpv6-10: merge DHCPv6 authentication and DHCPv6 draft-ietf-dhc-sedhcpv6-10: merge DHCPv6 authentication and DHCPv6
encryption. The public key option is removed, because the device can encryption. The public key option is removed, because the device can
generate the self-signed certificate if it is pre-configured the generate the self-signed certificate if it is pre-configured the
public key not the certificate. 2015-12-10. public key not the certificate. 2015-12-10.
skipping to change at page 22, line 44 skipping to change at page 26, line 21
"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>.
[RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
Housley, R., and W. Polk, "Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation List
(CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008,
<http://www.rfc-editor.org/info/rfc5280>.
[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.
 End of changes. 69 change blocks. 
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