draft-ietf-dhc-sedhcpv6-13.txt   draft-ietf-dhc-sedhcpv6-14.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: January 9, 2017 Y. Cui Expires: April 11, 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
July 8, 2016 October 8, 2016
Secure DHCPv6 Secure DHCPv6
draft-ietf-dhc-sedhcpv6-13 draft-ietf-dhc-sedhcpv6-14
Abstract Abstract
DHCPv6 includes no deployable security mechanism that can protect DHCPv6 includes no deployable security mechanism that can protect
end-to-end communication between DHCP clients and servers. This memo end-to-end communication between DHCP clients and servers. This memo
describes a mechanism for using public key cryptography to provide describes a mechanism for using public key cryptography to provide
such security. The mechanism provides encryption in all cases, and such security. The mechanism provides encryption in all cases, and
can be used for authentication based either on pre-sharing of can be used for authentication based either on pre-sharing of
authorized certificates, or else using trust-on-first-use. authorized certificates.
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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and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 9, 2017. This Internet-Draft will expire on April 11, 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
document authors. All rights reserved. document authors. All rights reserved.
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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 . . . . . . . . . . . . . . . . . . . . . 6
5.3. Support for Algorithm Agility . . . . . . . . . . . . . . 6 5.3. Support for Algorithm Agility . . . . . . . . . . . . . . 7
5.4. Applicability . . . . . . . . . . . . . . . . . . . . . . 7 5.4. Caused change to RFC3315 . . . . . . . . . . . . . . . . 7
5.5. Applicability . . . . . . . . . . . . . . . . . . . . . . 8
6. DHCPv6 Client Behavior . . . . . . . . . . . . . . . . . . . 8 6. DHCPv6 Client Behavior . . . . . . . . . . . . . . . . . . . 8
7. DHCPv6 Server Behavior . . . . . . . . . . . . . . . . . . . 11 7. DHCPv6 Server Behavior . . . . . . . . . . . . . . . . . . . 12
8. Relay Agent Behavior . . . . . . . . . . . . . . . . . . . . 13 8. Relay Agent Behavior . . . . . . . . . . . . . . . . . . . . 14
9. Extensions for Secure DHCPv6 . . . . . . . . . . . . . . . . 14 9. Processing Rules . . . . . . . . . . . . . . . . . . . . . . 14
9.1. New DHCPv6 Options . . . . . . . . . . . . . . . . . . . 14 9.1. Increasing Number Check . . . . . . . . . . . . . . . . . 14
9.1.1. Certificate Option . . . . . . . . . . . . . . . . . 14 10. Extensions for Secure DHCPv6 . . . . . . . . . . . . . . . . 15
9.1.2. Signature option . . . . . . . . . . . . . . . . . . 15 10.1. New DHCPv6 Options . . . . . . . . . . . . . . . . . . . 15
9.1.3. Increasing-number Option . . . . . . . . . . . . . . 17 10.1.1. Certificate Option . . . . . . . . . . . . . . . . . 15
9.1.4. Encrypted-message Option . . . . . . . . . . . . . . 17 10.1.2. Signature option . . . . . . . . . . . . . . . . . . 16
9.2. New DHCPv6 Messages . . . . . . . . . . . . . . . . . . . 18 10.1.3. Increasing-number Option . . . . . . . . . . . . . . 18
9.3. Status Codes . . . . . . . . . . . . . . . . . . . . . . 18 10.1.4. Encrypted-message Option . . . . . . . . . . . . . . 18
10. Security Considerations . . . . . . . . . . . . . . . . . . . 19 10.2. New DHCPv6 Messages . . . . . . . . . . . . . . . . . . 19
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19 10.3. Status Codes . . . . . . . . . . . . . . . . . . . . . . 19
12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 21 11. Security Considerations . . . . . . . . . . . . . . . . . . . 20
13. Change log [RFC Editor: Please remove] . . . . . . . . . . . 21 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20
14. Open Issues [RFC Editor: Please remove] . . . . . . . . . . . 23 13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 22
15. References . . . . . . . . . . . . . . . . . . . . . . . . . 23 14. Change log [RFC Editor: Please remove] . . . . . . . . . . . 22
15.1. Normative References . . . . . . . . . . . . . . . . . . 23 15. References . . . . . . . . . . . . . . . . . . . . . . . . . 24
15.2. Informative References . . . . . . . . . . . . . . . . . 25 15.1. Normative References . . . . . . . . . . . . . . . . . . 24
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 25 15.2. Informative References . . . . . . . . . . . . . . . . . 26
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 26
1. Introduction 1. Introduction
The Dynamic Host Configuration Protocol for IPv6 (DHCPv6, [RFC3315]) The Dynamic Host Configuration Protocol for IPv6 (DHCPv6, [RFC3315])
allows DHCPv6 servers to flexibly provide addressing and other allows DHCPv6 servers to flexibly provide addressing and other
configuration information relating to local network infrastructure to configuration information relating to local network infrastructure to
DHCP clients. The protocol provides no deployable security DHCP clients. The protocol provides no deployable security
mechanism, and consequently is vulnerable to various attacks. mechanism, and consequently is vulnerable to various attacks.
This document provides a brief summary of the security This document provides a brief summary of the security
vulnerabilities of the DHCPv6 protocol and then describes a new vulnerabilities of the DHCPv6 protocol and then describes a new
extension to the protocol that provides two additional types of extension to the protocol that provides two additional types of
security: security:
o 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. defend against active attacks, such as spoofing.
o 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 pervasive monitoring. order to protect the DHCPv6 communication from pervasive
monitoring.
The extension specified in this document applies only to end-to-end The extension specified in this document applies only to end-to-end
communication between DHCP servers and clients. Options added by communication between DHCP servers and clients. Options added by
relay agents in Relay-Forward messages, and options other than the relay agents in Relay-Forward messages, and options other than the
client message in Relay-Reply messages sent by DHCP servers, are not client message in Relay-Reply messages sent by DHCP servers, are not
protected. Such communications are already protected using the protected. Such communications are already protected using the
mechanism described described in section 21.1 in [RFC3315]. mechanism described in section 21.1 in [RFC3315].
This extension introduces two new DHCPv6 messages: the Encrypted- This extension introduces two new DHCPv6 messages: the Encrypted-
Query and the Encrypted-Response messages. It defines four new Query and the Encrypted-Response messages. It defines four new
DHCPv6 options: the Certificate, the Signature, the Increasing- DHCPv6 options: the Certificate, the Signature, the Increasing-
number, and the Encrypted-message options. The Certificate, number, and the Encrypted-message options. The Certificate,
Signature, and Increasing-number options are used for authentication. Signature, and Increasing-number options are used for authentication.
The Encryption-Query message, Encryption-Response message and The Encryption-Query message, Encryption-Response message and
Encrypted-message option are used for encryption. Encrypted-message option are used for encryption.
2. Requirements Language and Terminology 2. Requirements Language and Terminology
skipping to change at page 5, line 25 skipping to change at page 5, line 36
particular link, the client will be unable to communicate with a DHCP particular link, the client will be unable to communicate with a DHCP
server. server.
If the client chooses to communicate with a server, it uses the If the client chooses to communicate with a server, it uses the
Encrypted-Query message to encapsulate its communications to the DHCP Encrypted-Query message to encapsulate its communications to the DHCP
server. The server responds with Encrypted-Response messages. server. The server responds with Encrypted-Response messages.
Normal DHCP messages are encapsulated in these two new messages using Normal DHCP messages are encapsulated in these two new messages using
the new defined Encrypted-message option. Besides the Encrypted- the new defined Encrypted-message option. Besides the Encrypted-
message option, the Signature option is defined to verify the message option, the Signature option is defined to verify the
integrity of the DHCPv6 messages and then authentication of client integrity of the DHCPv6 messages and then authentication of client
and server. The Increasing number is defined to detect replay and server. The Increasing number option is defined to detect replay
attack. attack.
+-------------+ +-------------+ +-------------+ +-------------+
|DHCPv6 Client| |DHCPv6 Server| |DHCPv6 Client| |DHCPv6 Server|
+-------------+ +-------------+ +-------------+ +-------------+
| Information-request | | Information-request |
|----------------------------------------->| |----------------------------------------->|
| Option Request option | | Option Request option |
| | | |
| Reply | | Reply |
skipping to change at page 6, line 21 skipping to change at page 6, line 47
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. The Signature option is authentication of the client/server. The Signature option is
defined to carry the signature. defined to carry the signature.
o A Increasing-number that can be used to detect replayed packet. o A Increasing-number that can be used to detect replayed packet.
The Increasing-number option is defined to carry a strictly- The Timestamp is one of the possible implementation choices. The
increasing serial number. Timestamp is one of the possible Increasing-number option is defined to carry a strictly-increasing
implementation choice. serial number.
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
MUST contain the Encrypted-message option. In addition, the MUST contain the Encrypted-message option. In addition, the
Server Identifier option MUST be contained if it is contained in Server Identifier option MUST be contained if it is contained in
the original DHCPv6 message. The Encrypted-Query message MUST NOT the original DHCPv6 message. The Encrypted-Query message MUST NOT
contain other options except the Server Identifier option and contain other options except the above options.
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. The Encrypted- message MUST contain the Encrypted-message option. The Encrypted-
Response message MUST NOT contain other options except Encrypted- Response message MUST NOT contain any other options except it.
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 order to provide a means of addressing problems that may emerge
with existing hash algorithms, signature algorithm and encryption with existing hash algorithms, signature algorithm and encryption
algorithms in the future, this document provides a mechanism to algorithms in the future, this document provides a mechanism to
support algotirhm agility. The support for algorithm agility in this support algorithm agility. The support for algorithm agility in this
document is mainly a algorithm notification mechanism between the document is mainly a algorithm notification mechanism between the
client and the server. The same client and server SHOULD use the client and the server. The same client and server SHOULD use the
various algorithm in a single communication session. same algorithm 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 9.3) 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. algorithm.
5.4. Applicability 5.4. Caused change to RFC3315
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). In addition, the Solicit and Rebind messages 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. For the privacy consideration, we have to give up the
previous server selection feature.
[RFC3315] provides an additional mechanism for preventing off-network
timing attacks using the Reconfigure message: the Reconfigure Key
authentication method. Secure DHCPv6 can protect the Reconfigure
message using the encryption method. So the Reconfigure Key
authentication method SHOULD NOT be used if Secure DHCPv6 is applied.
5.5. 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, authenticated and encrypted are a concern. In practice, however, authenticated and encrypted
DHCPv6 configuration will rely on some operational assumptions mainly DHCPv6 configuration will rely on some operational assumptions mainly
regarding public key distribution and management. In order to regarding public key distribution and management. In order to
achieve the more wide use of secure DHCPv6, opportunistic security achieve the more wide use of secure DHCPv6, opportunistic security
[RFC7435] can be applied for secure DHCPv6 deployment, which allows [RFC7435] can be applied to secure DHCPv6 deployment, which allows
DHCPv6 encryption in environments where support for authentication is DHCPv6 encryption in environments where support for authentication is
not available. not available.
In some scenario where authentication is not available, secure DHCPv6 Secure DHCPv6 can achieve authentication and encryption based on pre-
provides encryption without authentication to achieve the wide sharing of authorized certificates. The One feasible environment in
deployment of secure DHCPv6. an early deployment stage would be enterprise networks. In
enterprise networks, the client is manually pre-configured with the
Secure DHCPv6 provides authentication and encryption based either on trusted servers' public key and the server is also manually pre-
pre-sharing of authorized certificates, or else using trust-on-first- configured with the trusted clients' public keys. In some scenario,
use. The One feasible environment in an early deployment stage would such as coffee shop where the certificate cannot be validated and
be enterprise networks. In such networks the security policy tends don't want to be blocked from the Internet, then the DHCPv6
to be strict and it will be easier to manage client hosts. One configuration process can be encrypted without authentication.
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
a private key (especially that of the server) is compromised. a private key (especially that of the server) is compromised.
It is believed that Secure DHCPv6 could be more widely applicable
with integration of generic PKI so that it will be more easily
deployed. But such a deployment requires more general issues with
PKI deployment be addressed, and it is currently unknown whether we
can find practical deployment scenarios. It is subject to future
study and experiments, and out of scope of this document.
6. DHCPv6 Client Behavior 6. DHCPv6 Client Behavior
For the secure DHCPv6 client, a certificate is needed for client The secure DHCPv6 client is pre-configured with a certificate and its
authentication. The client is pre-configured with a certificate and corresponding private key for client authentication. If the client
its corresponding private key. If the client is pre-configured with is pre-configured with public key but not with a certificate, it can
public key but not with a certificate, it can generate the self- generate the self-signed certificate.
signed certificate for client authentication.
The secure DHCPv6 client sends Information-request message as per The secure DHCPv6 client sends Information-request message as per
[RFC3315]. The Information-request message is used by the DHCPv6 [RFC3315]. The Information-request message is used by the DHCPv6
client to request the server's identity verification information client to request the server's identity verification information
without having addresses, prefixes or any non-security options without having addresses, prefixes or any non-security options
assigned to it. The Information-request message MUST NOT include any assigned to it. The Information-request message MUST NOT include any
DHCPv6 options except ORO option to minimize client's privacy other DHCPv6 options except the ORO option to minimize client's
information leakage. The Option Request option in the Information- privacy information leakage. The Option Request option in the
request message MUST contain the option code of the Certificate Information-request message MUST contain the option code of the
option. Certificate option.
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 algorithm, 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
If the check fails, the Reply message is dropped. If the hash supports. If the check fails, the Reply message is dropped. If the
algorithm field is zero, the signature algorithm and hash algorithm hash algorithm field is zero, then it indicates that the hash
are not separated. The corresponding hash algorithm is fixed algorithm is fixed according to the corresponding signature
according the signature algorithm. If all the algorithms are algorithm. If all the algorithms are supported, then the client also
supported, the client then checks the authority of this server. The uses the same algorithms in the return messages.
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 certificates list is treated as
verified. The message transaction-id is used as the identifier of
the authenticated server's public key for further message encryption.
At this point, the client has either recognized the certificate of Then the client checks the authority of the server. The client
the server, or decided to drop the message. validates the certificates through the pre-configured local trusted
certificates list or other methods. A certificate that finds a match
in the local trust certificates list is treated as verified. The
message transaction-id is used as the identifier of the authenticated
server's public key for further message 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 The client MUST now authenticate the server by verifying the
signature and checking increasing number, if there is a Increasing- signature and checking increasing number, if there is a Increasing-
number option. The order of two procedures is left as an number option. The order of two procedures is left as an
implementation decision. It is RECOMMENDED to check increasing implementation decision. It is RECOMMENDED to check increasing
number first, because signature verification is much more number first, because signature verification is much more
computationally expensive. If the decrypted message contains the computationally expensive. If the decrypted message contains the
Increasing-number option, the client checks it by comparing it with Increasing-number option, the client checks it according to the rule
the stored number on the client. The client has one stable stored defined in Section 9.1. For the message without an Increasing-number
number for replay attack detection. The initial value of the stable option, according to the client's local policy, it MAY be acceptable
stored number is zero. If the contained number is higher than the or rejected. If the server rejects such a message, the increasing
stored number, then the DHCPv6 message passes the increasing-number number check fails.
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 9.1.2. Only the messages been calculated as specified in Section 10.1.2. Only the messages
that get through both the signature verification and increasing that get through both the signature verification and increasing
number check (if there is a Increasing-number option) are accepted. number check (if there is a Increasing-number option) are accepted.
Reply message that 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 certs, the client selects If there are multiple authenticated DHCPv6 certs, the client selects
one DHCPv6 cert for the following network parameters configuration. one DHCPv6 cert. 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. It should be noted that the selected certificate may
(each encrypted with different public key) at the "same" time. correspond to multiple DHCPv6 servers.
If there are no authenticated DHCPv6 certs or existing servers fail If there are no authenticated DHCPv6 certs or existing servers fail
authentication, the client should retry a number of times. The authentication, the client should retry a number of times. The
client conducts the server discovery process as per section 18.1.5 of client conducts the server discovery process as per section 18.1.5 of
[RFC3315] to avoid the packet storm. In this way, it is difficult [RFC3315] to avoid the packet storm. In this way, it is difficult
for the rogue server to beat out a busy "real" server. And then the for the rogue server to beat out a busy "real" server. And then the
client takes some alternative action depending on its local policy, client takes some alternative action depending on its local policy,
such as attempting to use an unsecured DHCPv6 server. In some such as attempting to use an unsecured DHCPv6 server.
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 9.1.4. In addition, the Server constructed as explained in Section 10.1.4. In addition, the Server
Identifier option MUST be contained if it is in the original message Identifier option MUST be included if it is in the original message
(i.e. Request, Renew, Decline, Release) to avoid the extra (i.e. Request, Renew, Decline, Release) to avoid the need for other
decryption for the DHCPv6 servers not for it. The Encrypted-message servers receiving the message to attempt to decrypt it. The
option contains the DHCPv6 message that is encrypted using the public Encrypted-message option contains the DHCPv6 message that is
key contained in the selected cert. The Server Identifier option is encrypted using the public key contained in the selected cert. The
externally visible to avoid decryption cost by those unselected Encrypted-Query message MUST NOT contain any other DHCPv6 option
servers. The Encrypted-Query message MUST NOT contain other DHCPv6 except the Server Identifier option and Encrypted-Message option.
option except the Server Identifier option and Encrypted-Message
option.
If the received Reply message indicates the request of the client's The first DHCPv6 message sent from the client to the server, such as
certificate information through the Option Request option, the first Solicit message, MUST contain the Certificate option, Signature
DHCPv6 message sent from the client to the server, such as Solicit option and Increasing-number option for client authentication. The
message, MUST contain the Certificate option, Signature option and encryption text SHOULD be formatted as explain in [RFC5652]. The
Increasing-number option for client authentication. The encryption Certificate option MUST be constructed as explained in
text SHOULD be formatted as explain in [RFC5652]. The Certificate Section 10.1.1. It should be noted that a client's certificate for
option MUST be constructed as explained in Section 9.1.1. In the mandatory algorithm MUST be contained to ensure that the Reply
addition, one and only one Signature option MUST be contained, which message with the error code can be encrypted using the mandatory
MUST be constructed as explained in Section 9.1.2. One and only one algorithm. In addition, one and only one Signature option MUST be
Increasing-number option SHOULD be contained, which MUST be contained, which MUST be constructed as explained in Section 10.1.2.
constructed as explained in Section 9.1.3. One and only one Increasing-number option SHOULD be contained, which
MUST be constructed as explained in Section 10.1.3.
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 also used as the identifier
the client's private key for decryption. In addition, the subsequent of the client's private key for decryption. In addition, the
encrypted DHCPv6 message can contain the Increasing-number option to subsequent encrypted DHCPv6 message can contain the Increasing-number
defend against replay attack. option to defend against replay attack.
For the received Encrypted-Response message, the client MUST drop the For the received Encrypted-Response message, the client MUST drop the
Encrypted-Response message if other DHCPv6 option except Encrypted- Encrypted-Response message if other DHCPv6 option except Encrypted-
message option is contained. Then, the client extracts the 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
Increasing-number option, the DHCPv6 client MUST drop the DHCPv6 Increasing-number option, the DHCPv6 client checks it according to
message with the lower number. If the client fails to get the proper the rule defined in Section 9.1. 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 decrypted message is Reply message with an error status
the error status code indicates the failure reason on the server code, the error status code indicates the failure reason on the
side. According to the received status code, the client MAY take server side. According to the received status code, the client MAY
follow-up action: take 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.
o Upon receiving an AuthenticationFail error status code, the client o Upon receiving an AuthenticationFail error status code, the client
is not able to build up the secure communication with the server. is not able to build up the secure communication with the server.
However, there may be other DHCPv6 servers available that However, there may be other DHCPv6 servers available that
successfully complete authentication. The client MAY use the successfully complete authentication. The client MAY use the
AuthenticationFail as a hint and switch to other certificate if it AuthenticationFail as a hint and switch to other certificate if it
skipping to change at page 11, line 25 skipping to change at page 11, line 42
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 IncreasingnumFail error status code, the client o Upon receiving a ReplayDetected error status code, the client MAY
MAY resend the message with an adjusted Increasing-number option resend the message with an adjusted Increasing-number option
according to the returned clock from the DHCPv6 server. according to the returned number from the DHCPv6 server.
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 The secure DHCPv6 server is pre-configured with a certificate and its
authentication. The server is pre-configured with a certificate and corresponding private key for server authentication. If the server
its corresponding private key. If the server is pre-configured with is pre-configured with public key but not with a certificate, it can
public key but not with a certificate, it can generate the self- generate the self-signed certificate.
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 9.1.1, and option, which MUST be constructed as explained in Section 10.1.1, 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 9.1.2. Besides, the Reply message SHOULD as explained in Section 10.1.2. Besides, the Reply message SHOULD
contain one and only one Increasing-number option, which MUST be contain one and only one Increasing-number option, which MUST be
constructed as explained in Section 9.1.3. In addition, if client constructed as explained in Section 10.1.3. In addition, if client
authentication is needed, then the ORO option in the Reply message authentication is needed, then the ORO option in the Reply message
contains the code of the certificate option to indicate the request contains the code of the certificate option to indicate the request
of the client certificate information. of the client certificate information.
Upon the receipt of Encrypted-Query message, the server MUST drop the Upon the receipt of Encrypted-Query message, the server MUST drop the
message if the other DHCPv6 option except Server Identifier option message if the other DHCPv6 option is contained except Server
and Encrypted-message option is contained. Then, the server checks Identifier option and Encrypted-message option. Then, the server
the Server Identifier option if the Encrypted-Query message contains checks the Server Identifier option if the Encrypted-Query message
the Server Identifier option. The DHCPv6 server drops the message contains it. The DHCPv6 server drops the message that is not for it,
that is not for it, thus not paying cost to decrypt messages not for thus not paying cost to decrypt messages. It decrypts the Encrypted-
it. It decrypts the Encrypted-message option using its private key message option using its private key if it is the target server. If
if it is the target server. the decryption fails, the server SHOULD send an encrypted Reply
message with a DecryptionFail error status code, defined in
Section 10.3, back to the client.
If the secure DHPCv6 need client authentication and decrypted message If secure DHCPv6 server needs client authentication and decrypted
is a Solicit/Information-request message which contains the message is a Solicit/Information-request message which contains the
information for client authentication, the secure DHCPv6 server information for client authentication, the secure DHCPv6 server
discards the received message that meets any of the following discards the received message that meets any of the following
conditions: 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 SHOULD send an encrypted Reply message
[RFC3315]) error status code. with an UnspecFail (value 1, [RFC3315]) error status code to the
client.
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 supports.
the hash algorithm field is zero, then the signature algorithm and If the hash algorithm field is zero, then the corresponding hash
hash algorithm are not separated. The corresponding hash algorithm algorithm is fixed according to the signature algorithm. If the
is fixed according the signature algorithm. If the check fails, the check fails, the server SHOULD reply with an AlgorithmNotSupported
server SHOULD reply with an AlgorithmNotSupported error status code, error status code, defined in Section 10.3, back to the client.
defined in Section 9.3, back to the client. If all the algorithms Because the server does not support the acknowledged algorithm, the
are supported, the server then checks the authority of this client. Reply message with the AlgorithmNotSupported error status code is
encrypted with the mandatory algorithm. If all the algorithms are
supported, the server then checks the authority of this client.
The server validates the client's certificate through the local pre- The server validates the client's certificate through the local pre-
configured trusted certificates list. A certificate that finds a configured trusted certificates list. A certificate that finds a
match in the local trust certificates list is treated as verified. match in the local trust certificates list is treated as verified.
The message that fails authentication validation MUST be dropped. In The message that fails authentication validation MUST be dropped. In
such failure, the DHCPv6 server replies with an AuthenticationFail such failure, the DHCPv6 server replies with an AuthenticationFail
error status code, defined in Section 9.3, back to the client. At error status code, defined in Section 10.3, back to the client. The
this point, the server has either recognized the authentication of Reply message with the AuthenticationFail error status code is also
the client, or decided to drop the message. encrypted. 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 Increasing-number option, the If the decrypted message contains the Increasing-number option, the
server checks it by comparing it with the stored number on the server checks it according to the rule defined in Section 9.1. If
server. The server has one stable stored number for replay attack the check fails, an encrypted Reply message with a ReplayDetected
detection. The initial value of the stable stored number is zero. error status code, defined in Section 10.3, should be sent back to
If the contained number is higher than the stored number, the value the client. In addition, a Increasing-number option is carried to
of the stored number is changed into the value of the Increasing- indicate the server's stored number for the client to use. According
number option. If contained number is lower than the stored number to the server's local policy, the message without an Increasing-
on the server, the server MUST drop the DHCPv6 message and a number option MAY be acceptable or rejected. If the server rejects
IncreasingnumFail error status code, defined in Section 9.3, should such a message, the server processes it as the increasing number
be sent back to the client. Depending on server's local policy, the check fails.
message without a Increasing-number option MAY be acceptable or
rejected. If the server rejects such a message, a IncreasingnumFail
error status code should be sent back to the client. The Reply
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 9.1.2. Only the clients that been calculated as specified in Section 10.1.2. If the signature
get through both the signature verification and increasing number check fails, the DHCPv6 server SHOULD send an encrypted Reply message
check (if there is a Increasing-number option) are accepted as with a SignatureFail error status code. Only the clients that get
through both the signature verification and increasing number check
(if there is a Increasing-number option) are accepted as
authenticated clients and continue to be handled their message as authenticated clients and continue to be handled their message as
defined in [RFC3315]. Clients that do not pass the above tests MUST defined in [RFC3315].
be treated as unauthenticated clients. The DHCPv6 server SHOULD
reply a SignatureFail error status code, defined in Section 9.3, for
the signature verification failure.
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 MUST only contain the Encrypted-message option, response message MUST only contain the Encrypted-message option,
which MUST be constructed as explained in Section 9.1.4. The which MUST be constructed as explained in Section 10.1.4. The
encryption text SHOULD be formatted as explain in [RFC5652]. The encryption text SHOULD be formatted as explain in [RFC5652]. The
Encrypted-message option contains the encrypted DHCPv6 message that Encrypted-message option contains the encrypted DHCPv6 message that
is encrypted using the authenticated client's public key. To provide is encrypted using the authenticated client's public key. To provide
the replay protection, the Increasing-number option can be contained the replay protection, the Increasing-number option can be contained
in the encrypted DHCPv6 message. 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
skipping to change at page 14, line 18 skipping to change at page 14, line 33
or 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. Extensions for Secure DHCPv6 9. Processing Rules
9.1. Increasing Number Check
In order to check the Increasing-number option, defined in
Section 10.1.3, the client/server has one stable stored number for
replay attack detection. The server should keep a record of the
increasing number forever. And the client keeps a record of the
increasing number during the transaction with the DHCPv6 server. In
addition, the client can forget the increasing number information
after the transaction is finished.
It is essential to remember that the increasing number is finite.
All arithmetic dealing with sequence numbers must be performed modulo
2^64. This unsigned arithmetic preserves the relationship of
sequence numbers as they cycle from 2^64 - 1 to 0 again.
In order to check the Increasing-number option, the following
comparison is needed. The symbol ">=" means "more or equal" (modulo
2^64).
NUM.STO = the stored number in the client/server
NUM.REC = the acknowledged number from the received message
The Increasing-number option in the received message passes the
increasing number check if it meets the following condition:
NUM.REC >= NUM.STO
And then, the value of NUM.STO is changed into the value of NUM.REC.
The increasing number check fails if NUM.REC is less than NUM.STO.
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.
9.1. New DHCPv6 Options 10.1. New DHCPv6 Options
9.1.1. Certificate Option 10.1.1. Certificate Option
The Certificate option carries the certificate of the client/server. The Certificate option carries the certificate(s) of the client/
The format of the Certificate option is described as follows: server. 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 | |
+-+-+-+-+-+-+-+-+ . +-+-+-+-+-+-+-+-+ .
. Certificate (variable length) . . Certificate (variable length) .
. . . .
skipping to change at page 15, line 28 skipping to change at page 16, line 28
option-len 1 + Length of certificate in octets. option-len 1 + Length of certificate in octets.
EA-id Encryption Algorithm id. The encryption algorithm EA-id Encryption Algorithm id. The encryption algorithm
is used for the encrypted DHCPv6 configuration is used for the encrypted DHCPv6 configuration
process. This design is adopted in order to provide process. This design is adopted in order to provide
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 certificates. 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.
9.1.2. Signature option 10.1.2. 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
skipping to change at page 17, line 5 skipping to change at page 18, line 5
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.
9.1.3. Increasing-number Option 10.1.3. Increasing-number Option
The Increasing-number option carries the number which is higher than The Increasing-number option carries the number which is higher than
the local stored number on the client/server. It adds the anti- the local stored number on the client/server. It adds the anti-
replay protection to the DHCPv6 messages. It is optional. 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_INCREASINGNUM | option-len | | OPTION_INCREASING_NUM | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| InreasingNum (32-bit) | | InreasingNum (64-bit) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_INCREASINGNUM (TBA3). option-code OPTION_INCREASING_NUM (TBA3).
option-len 4, in octets. option-len 8, in octets.
IncreasingNum A number which is higher than the local stored number on the IncreasingNum A number for the replay attack detection which is more
client/server for the replay attack detection. or equal compared with the local stored number.
9.1.4. 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 |
skipping to change at page 18, line 8 skipping to change at page 19, line 11
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.
9.2. New DHCPv6 Messages 10.2. 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 18, line 33 skipping to change at page 19, line 36
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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 only contain the options The Encrypted-Query message MUST contain the
Server Identifier option or Encrypted-message option. Encrypted-message option and MUST contain the Server
The Encrypted-Response message MUST only contain the Identifier option if the message in the Encrypted-
message option has a Server Identifier option. The
Encrypted-Response message MUST only contain the
Encrypted-message option. Encrypted-message option.
9.3. 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 (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 IncreasingnumFail (TBD9): indicates the message from DHCPv6 client o ReplayDetected (TBD9): indicates the message from DHCPv6 client
fails the increasing number 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.
10. 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 [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.
skipping to change at page 19, line 34 skipping to change at page 20, line 37
number option, may have to face the risk of replay attacks. number option, may have to face the risk of replay attacks.
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.
11. IANA Considerations 12. 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 9.1.1. The Certificate Option (TBA1), described in Section 10.1.1.
The Signature Option (TBA2), described in Section 9.1.2. The Signature Option (TBA2), described in Section 10.1.2.
The Increasing-number Option (TBA3),described in Section 9.1.3. The Increasing-number Option (TBA3),described in Section 10.1.3.
The Encrypted-message Option (TBA4), described in Section 9.1.4. 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 (TBA5), described in Section 9.2. The Encrypted-Query Message (TBA5), described in Section 10.2.
The Encrypted-Response Message (TBA6), described in Section 9.2. The Encrypted-Response Message (TBA6), described in Section 10.2.
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].
skipping to change at page 20, line 50 skipping to change at page 22, line 6
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 | 0x01 | 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 9.3, 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
---------+-----------------------+-------------- ---------+-----------------------+--------------
TBD7 | AlgorithmNotSupported | this document TBD7 | AlgorithmNotSupported | this document
TBD8 | AuthenticationFail | this document TBD8 | AuthenticationFail | this document
TBD9 | IncreasingnumFail | this document TBD9 | ReplayDetected | this document
TBD10 | SignatureFail | this document TBD10 | SignatureFail | this document
TBD11 | DecryptionFail | this document TBD11 | DecryptionFail | this document
12. 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].
13. Change log [RFC Editor: Please remove] 14. Change log [RFC Editor: Please remove]
draft-ietf-dhc-sedhcpv6-14: For the deployment part, Tofu is out of
scope and take Opportunistic security into consideration; Increasing
number option is changed into 64 bits; Increasing number check is a
separate section; IncreasingnumFail error status code is changed into
ReplayDetected error status code; Add the section of "caused change
to RFC3315";
draft-ietf-dhc-sedhcpv6-13: Change the Timestamp option into draft-ietf-dhc-sedhcpv6-13: Change the Timestamp option into
Increasing-number option and the corresponding check method; Delete Increasing-number option and the corresponding check method; Delete
the OCSP stampling part for the certificate check; Add the scenario the OCSP stampling part for the certificate check; Add the scenario
where the hash and signature algorithms cannot be separated; Add the where the hash and signature algorithms cannot be separated; Add the
comparison with RFC7824 and RFC7844; Add the encryption text format comparison with RFC7824 and RFC7844; Add the encryption text format
and reference of RFC5652. Add the consideration of scenario where and reference of RFC5652. Add the consideration of scenario where
multiple DHCPv6 servers share one common DHCPv6 server. Add the multiple DHCPv6 servers share one common DHCPv6 server. Add the
statement that Encrypted-Query and Encrypted-Response messages can statement that Encrypted-Query and Encrypted-Response messages can
only contain certain options: Server Identifier option and Encrypted- only contain certain options: Server Identifier option and Encrypted-
skipping to change at page 23, line 30 skipping to change at page 24, line 42
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.
14. Open Issues [RFC Editor: Please remove]
The Reply message with the error status code may contain the client
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.
We need to add some explanation on why TOFU is out of scope
currently. TOFU is tricky to get it right. If it is included, then
operator may skip necessary setup for security. TOFU may be included
in the future work.
15. References 15. References
15.1. 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
 End of changes. 78 change blocks. 
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