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Versions: (draft-jiang-dhc-sedhcpv6) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21

DHC Working Group                                               S. Jiang
Internet-Draft                              Huawei Technologies Co., Ltd
Intended status: Standards Track                                   L. Li
Expires: January 9, 2017                                          Y. Cui
                                                     Tsinghua University
                                                               T. Jinmei
                                                           Infoblox Inc.
                                                                T. Lemon
                                                           Nominum, Inc.
                                                                D. Zhang
                                                            July 8, 2016


                             Secure DHCPv6
                       draft-ietf-dhc-sedhcpv6-13

Abstract

   DHCPv6 includes no deployable security mechanism that can protect
   end-to-end communication between DHCP clients and servers.  This memo
   describes a mechanism for using public key cryptography to provide
   such security.  The mechanism provides encryption in all cases, and
   can be used for authentication based either on pre-sharing of
   authorized certificates, or else using trust-on-first-use.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on January 9, 2017.

Copyright Notice

   Copyright (c) 2016 IETF Trust and the persons identified as the
   document authors.  All rights reserved.





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   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Requirements Language and Terminology . . . . . . . . . . . .   3
   3.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Security Issues of DHCPv6 . . . . . . . . . . . . . . . . . .   4
   5.  Secure DHCPv6 Overview  . . . . . . . . . . . . . . . . . . .   5
     5.1.  Solution Overview . . . . . . . . . . . . . . . . . . . .   5
     5.2.  New Components  . . . . . . . . . . . . . . . . . . . . .   6
     5.3.  Support for Algorithm Agility . . . . . . . . . . . . . .   6
     5.4.  Applicability . . . . . . . . . . . . . . . . . . . . . .   7
   6.  DHCPv6 Client Behavior  . . . . . . . . . . . . . . . . . . .   8
   7.  DHCPv6 Server Behavior  . . . . . . . . . . . . . . . . . . .  11
   8.  Relay Agent Behavior  . . . . . . . . . . . . . . . . . . . .  13
   9.  Extensions for Secure DHCPv6  . . . . . . . . . . . . . . . .  14
     9.1.  New DHCPv6 Options  . . . . . . . . . . . . . . . . . . .  14
       9.1.1.  Certificate Option  . . . . . . . . . . . . . . . . .  14
       9.1.2.  Signature option  . . . . . . . . . . . . . . . . . .  15
       9.1.3.  Increasing-number Option  . . . . . . . . . . . . . .  17
       9.1.4.  Encrypted-message Option  . . . . . . . . . . . . . .  17
     9.2.  New DHCPv6 Messages . . . . . . . . . . . . . . . . . . .  18
     9.3.  Status Codes  . . . . . . . . . . . . . . . . . . . . . .  18
   10. Security Considerations . . . . . . . . . . . . . . . . . . .  19
   11. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  19
   12. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  21
   13. Change log [RFC Editor: Please remove]  . . . . . . . . . . .  21
   14. Open Issues [RFC Editor: Please remove] . . . . . . . . . . .  23
   15. References  . . . . . . . . . . . . . . . . . . . . . . . . .  23
     15.1.  Normative References . . . . . . . . . . . . . . . . . .  23
     15.2.  Informative References . . . . . . . . . . . . . . . . .  25
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  25

1.  Introduction

   The Dynamic Host Configuration Protocol for IPv6 (DHCPv6, [RFC3315])
   allows DHCPv6 servers to flexibly provide addressing and other
   configuration information relating to local network infrastructure to




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   DHCP clients.  The protocol provides no deployable security
   mechanism, and consequently is vulnerable to various attacks.

   This document provides a brief summary of the security
   vulnerabilities of the DHCPv6 protocol and then describes a new
   extension to the protocol that provides two additional types of
   security:

   o  authentication of the DHCPv6 client and the DHCPv6 server to
      defend against active attacks, such as spoofing.

   o  encryption between the DHCPv6 client and the DHCPv6 server in
      order to protect the DHCPv6 from pervasive monitoring.

   The extension specified in this document applies only to end-to-end
   communication between DHCP servers and clients.  Options added by
   relay agents in Relay-Forward messages, and options other than the
   client message in Relay-Reply messages sent by DHCP servers, are not
   protected.  Such communications are already protected using the
   mechanism described described in section 21.1 in [RFC3315].

   This extension introduces two new DHCPv6 messages: the Encrypted-
   Query and the Encrypted-Response messages.  It defines four new
   DHCPv6 options: the Certificate, the Signature, the Increasing-
   number, and the Encrypted-message options.  The Certificate,
   Signature, and Increasing-number options are used for authentication.
   The Encryption-Query message, Encryption-Response message and
   Encrypted-message option are used for encryption.

2.  Requirements Language and Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119] when they
   appear in ALL CAPS.  When these words are not in ALL CAPS (such as
   "should" or "Should"), they have their usual English meanings, and
   are not to be interpreted as [RFC2119] key words.

3.  Terminology

   This section defines terminology specific to secure DHCPv6 used in
   this document.

   secure DHCPv6 client:  A node that initiates a DHCPv6 request on a
                   link to obtain DHCPv6 configuration parameters from
                   one or more DHCPv6 servers using the encryption and
                   optional authentication mechanisms defined in this
                   document.



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   secure DHCPv6 server:  A DHCPv6 server that implements the
                   authentication and encryption mechanisms defined in
                   this document, and is configured to use them.

4.  Security Issues of DHCPv6

   [RFC3315] defines an authentication mechanism with integrity
   protection.  This mechanism uses a symmetric key that is shared by
   the client and server for authentication.  It does not provide any
   key distribution mechanism.

   For this approach, operators can set up a key database for both
   servers and clients from which the client obtains a key before
   running DHCPv6.  However, manual key distribution runs counter to the
   goal of minimizing the configuration data needed at each host.
   Consequently, there are no known deployments of this security
   mechanism.

   [RFC3315] provides an additional mechanism for preventing off-network
   timing attacks using the Reconfigure message: the Reconfigure Key
   authentication method.  However, this method protects only the
   Reconfigure message.  The key is transmitted in plaintext to the
   client in earlier exchanges and so this method is vulnerable to on-
   path active attacks.

   Anonymity Profile for DHCP Clients [RFC7844] explains how to generate
   DHCPv4 or DHCPv6 requests that minimize the disclosure of identifying
   information.  However, the anonymity profile limits the use of the
   certain options.  It also cannot anticipate new options that may
   contain private information is defined.  In addition, the anonymity
   profile does not work in cases where the client wants to maintain
   anonymity from eavesdroppers but must identify itself to the DHCP
   server with which it intends to communicate.

   Privacy consideration for DHCPv6 [RFC7824] presents an analysis of
   the privacy issues associated with the use of DHCPv6 by Internet
   users.  No solutions are presented.

   Current DHCPv6 messages are still transmitted in cleartext and the
   privacy information within the DHCPv6 message is not protected from
   passive attack, such as pervasive monitoring [RFC7258].

   To better address the problem of passive monitoring and to achieve
   authentication without requiring a symmetric key distribution
   solution for DHCP, this document defines an asymmetric key
   authentication and encryption mechanism.  This protects against both
   active attacks, such as spoofing, and passive attacks, such as
   pervasive monitoring.



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5.  Secure DHCPv6 Overview

5.1.  Solution Overview

   The following figure illustrated secure DHCPv6 procedure.  Briefly,
   this extension establishes the server's identity with an anonymous
   Information-Request exchange.  Once the server's identity has been
   established, the client may either choose to communicate with the
   server or not.  Not communicating with an unknown server avoids
   revealing private information, but if there is no known server on a
   particular link, the client will be unable to communicate with a DHCP
   server.

   If the client chooses to communicate with a server, it uses the
   Encrypted-Query message to encapsulate its communications to the DHCP
   server.  The server responds with Encrypted-Response messages.
   Normal DHCP messages are encapsulated in these two new messages using
   the new defined Encrypted-message option.  Besides the Encrypted-
   message option, the Signature option is defined to verify the
   integrity of the DHCPv6 messages and then authentication of client
   and server.  The Increasing number is defined to detect replay
   attack.

           +-------------+                           +-------------+
           |DHCPv6 Client|                           |DHCPv6 Server|
           +-------------+                           +-------------+
                  |            Information-request           |
                  |----------------------------------------->|
                  |           Option Request option          |
                  |                                          |
                  |                    Reply                 |
                  |<-----------------------------------------|
                  |             Certificate option           |
                  |             Signature option             |
                  |          Increasing-number option        |
                  |         Server Identifier option         |
                  |                                          |
                  |            Encryption-Query              |
                  |----------------------------------------->|
                  |          Encrypted-message option        |
                  |          Server Identifier option        |
                  |                                          |
                  |            Encryption-Response           |
                  |<-----------------------------------------|
                  |          Encrypted-message option        |
                  |                                          |

                          Secure DHCPv6 Procedure



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5.2.  New Components

   The new components of the mechanism specified in this document are as
   follows:

   o  Servers and clients that use certificates first generate a public/
      private key pair and then obtain a certificate that signs the
      public key.  The Certificate option is defined to carry the
      certificate of the sender.

   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.  The Signature option is
      defined to carry the signature.

   o  A Increasing-number that can be used to detect replayed packet.
      The Increasing-number option is defined to carry a strictly-
      increasing serial number.  Timestamp is one of the possible
      implementation choice.

   o  The Encrypted-message option that contains the encrypted DHCPv6
      message.

   o  The Encrypted-Query message that is sent from the secure DHCPv6
      client to the secure DHCPv6 server.  The Encrypted-Query message
      MUST contain the Encrypted-message option.  In addition, the
      Server Identifier option MUST be contained if it is contained in
      the original DHCPv6 message.  The Encrypted-Query message MUST NOT
      contain other options except the Server Identifier option and
      Encrypted-message option.

   o  The Encrypted-Response message that is sent from the secure DHCPv6
      server to the secure DHCPv6 client.  The Encrypted-Response
      message contains the Encrypted-message option.  The Encrypted-
      Response message MUST NOT contain other options except Encrypted-
      message option.

5.3.  Support for Algorithm Agility

   In order to provide a means of addressing problems that may emerge
   with existing hash algorithms, signature algorithm and encryption
   algorithms in the future, this document provides a mechanism to
   support algotirhm agility.  The support for algorithm agility in this
   document is mainly a algorithm notification mechanism between the
   client and the server.  The same client and server SHOULD use the
   various algorithm in a single communication session.





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   If the server does not support the algorithm used by the client, the
   server SHOULD reply with an AlgorithmNotSupported status code
   (defined in Section 9.3) to the client.  Upon receiving this status
   code, the client MAY resend the message protected with the mandatory
   algorithm.

5.4.  Applicability

   In principle, secure DHCPv6 is applicable in any environment where
   physical security on the link is not assured and attacks on DHCPv6
   are a concern.  In practice, however, authenticated and encrypted
   DHCPv6 configuration will rely on some operational assumptions mainly
   regarding public key distribution and management.  In order to
   achieve the more wide use of secure DHCPv6, opportunistic security
   [RFC7435] can be applied for secure DHCPv6 deployment, which allows
   DHCPv6 encryption in environments where support for authentication is
   not available.

   In some scenario where authentication is not available, secure DHCPv6
   provides encryption without authentication to achieve the wide
   deployment of secure DHCPv6.

   Secure DHCPv6 provides authentication and encryption based either on
   pre-sharing of authorized certificates, or else using trust-on-first-
   use.  The One feasible environment in an early deployment stage would
   be enterprise networks.  In such networks the security policy tends
   to be strict and it will be easier to manage client hosts.  One
   trivial deployment scenario is therefore to manually pre-configure
   client with the trusted servers' public key and manually register
   clients' public keys for the server.  It may also be possible to
   deploy an internal PKI to make this less reliant on manual
   operations, although it is currently subject to future study
   specifically how to integrate such a PKI into the DHCPv6 service for
   the network.

   Note that this deployment scenario based on manual operation is not
   different very much from the existing, shared-secret based
   authentication mechanisms defined in [RFC3315] in terms of
   operational costs.  However, Secure DHCPv6 is still securer than the
   shared-secret mechanism in that even if clients' keys stored for the
   server are stolen that does not mean an immediate threat as these are
   public keys.  In addition, if some kind of PKI is used with Secure
   DHCPv6, even if the initial installation of the certificates is done
   manually, it will help reduce operational costs of revocation in case
   a private key (especially that of the server) is compromised.

   It is believed that Secure DHCPv6 could be more widely applicable
   with integration of generic PKI so that it will be more easily



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   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

   For the secure DHCPv6 client, a certificate is needed for client
   authentication.  The client is pre-configured with a certificate and
   its corresponding private key.  If the client is pre-configured with
   public key but not with a certificate, it can generate the self-
   signed certificate for client authentication.

   The secure DHCPv6 client sends Information-request message as per
   [RFC3315].  The Information-request message is used by the DHCPv6
   client to request the server's identity verification information
   without having addresses, prefixes or any non-security options
   assigned to it.  The Information-request message MUST NOT include any
   DHCPv6 options except ORO option to minimize client's privacy
   information leakage.  The Option Request option in the Information-
   request message MUST contain the option code of the Certificate
   option.

   When receiving the Reply messages from DHCPv6 servers, a secure
   DHCPv6 client discards any DHCPv6 messages that meet any of the
   following conditions:

   o  the Signature option is missing,

   o  multiple Signature options are present,

   o  the Certificate option is missing.

   And then the client first checks the support of the hash algorithm,
   signature algorithm and encryption algorithm that the server used.
   If the check fails, the Reply message is dropped.  If the hash
   algorithm field is zero, the signature algorithm and hash algorithm
   are not separated.  The corresponding hash algorithm is fixed
   according the signature algorithm.  If all the algorithms are
   supported, the client then checks the authority of this server.  The
   client also uses the same algorithms in the return messages.

   The client validates the certificates through the pre-configured
   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.




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   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 increasing number, if there is a Increasing-
   number option.  The order of two procedures is left as an
   implementation decision.  It is RECOMMENDED to check increasing
   number first, because signature verification is much more
   computationally expensive.  If the decrypted message contains the
   Increasing-number option, the client checks it by comparing it with
   the stored number on the client.  The client has one stable stored
   number for replay attack detection.  The initial value of the stable
   stored number is zero.  If the contained number is higher than the
   stored number, then the DHCPv6 message passes the increasing-number
   check and the value of the stored number is changed into the value of
   the Increasing-number option.  If contained number is lower than the
   stored number on the server, the server MUST drop the DHCPv6 message.

   The Signature field verification MUST show that the signature has
   been calculated as specified in Section 9.1.2.  Only the messages
   that get through both the signature verification and increasing
   number check (if there is a Increasing-number option) are accepted.
   Reply message that does not pass the above tests MUST be discarded.

   If there are multiple authenticated DHCPv6 certs, the client selects
   one DHCPv6 cert for the following network parameters configuration.
   The selected DHCPv6 cert may corresponds to multiple DHCPv6 servers.
   The client can also choose other implementation method depending on
   the client's local policy if the defined protocol can also run
   normally.  For example, the client can try multiple transactions
   (each encrypted with different public key) at the "same" time.

   If there are no authenticated DHCPv6 certs or existing servers fail
   authentication, the client should retry a number of times.  The
   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
   for the rogue server to beat out a busy "real" server.  And then the
   client takes some alternative action depending on its local policy,
   such as attempting to use an unsecured DHCPv6 server.  In some
   scenario, such as laptops in coffee room, clients are always not pre-
   configured the sufficient information for server authentication and
   can accept DHCPv6 encryption without DHCPv6 authentication.  In such
   scenario, if some DHCPv6 servers fail authentication because the
   server's certificate is not in the trusted certs' list, and then the
   client selects one DHCPv6 server and record the server's public key
   for the future encrypted DHCPv6 configuration process.





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   Once the server has been authenticated, the DHCPv6 client sends the
   Encrypted-Query message to the DHCPv6 server.  The Encrypted-Query
   message contains the Encrypted-message option, which MUST be
   constructed as explained in Section 9.1.4.  In addition, the Server
   Identifier option MUST be contained if it is in the original message
   (i.e.  Request, Renew, Decline, Release) to avoid the extra
   decryption for the DHCPv6 servers not for it.  The Encrypted-message
   option contains the DHCPv6 message that is encrypted using the public
   key contained in the selected cert.  The Server Identifier option is
   externally visible to avoid decryption cost by those unselected
   servers.  The Encrypted-Query message MUST NOT contain other DHCPv6
   option except the Server Identifier option and Encrypted-Message
   option.

   If the received Reply message indicates the request of the client's
   certificate information through the Option Request option, the first
   DHCPv6 message sent from the client to the server, such as Solicit
   message, MUST contain the Certificate option, Signature option and
   Increasing-number option for client authentication.  The encryption
   text SHOULD be formatted as explain in [RFC5652].  The Certificate
   option MUST be constructed as explained in Section 9.1.1.  In
   addition, one and only one Signature option MUST be contained, which
   MUST be constructed as explained in Section 9.1.2.  One and only one
   Increasing-number option SHOULD be contained, which MUST be
   constructed as explained in Section 9.1.3.

   If the client has multiple certificates with different public/private
   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 Increasing-number option to
   defend against replay attack.

   For the received Encrypted-Response message, the client MUST drop the
   Encrypted-Response message if other DHCPv6 option except Encrypted-
   message option is contained.  Then, the client extracts the
   Encrypted-message option and decrypts it using its private key to
   obtain the original DHCPv6 message.  Then it handles the message as
   per [RFC3315].  If the decrypted DHCPv6 message contains the
   Increasing-number option, the DHCPv6 client MUST drop the DHCPv6
   message with the lower number.  If the client fails to get the proper
   parameters from the chosen server, it sends the Encrypted-Query
   message to another authenticated server for parameters configuration
   until the client obtains the proper parameters.

   When the client receives a Reply message with an error status code,
   the error status code indicates the failure reason on the server
   side.  According to the received status code, the client MAY take
   follow-up action:



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   o  Upon receiving an AlgorithmNotSupported error status code, the
      client SHOULD resend the message protected with one of the
      mandatory algorithms.

   o  Upon receiving an AuthenticationFail error status code, the client
      is not able to build up the secure communication with the server.
      However, there may be other DHCPv6 servers available that
      successfully complete authentication.  The client MAY use the
      AuthenticationFail as a hint and switch to other certificate if it
      has another one; but otherwise treat the message containing the
      status code as if it had not been received.  But it SHOULD NOT
      retry with the same certificate.  However, if the client decides
      to retransmit using the same certificate after receiving
      AuthenticationFail, it MUST NOT retransmit immediately and MUST
      follow normal retransmission routines defined in [RFC3315].

   o  Upon receiving a DecryptionFail error status code, the client MAY
      resend the message following normal retransmission routines
      defined in [RFC3315].

   o  Upon receiving a IncreasingnumFail error status code, the client
      MAY resend the message with an adjusted Increasing-number option
      according to the returned clock from the DHCPv6 server.

   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

   For the secure DHCPv6 server, a certificate is needed for server
   authentication.  The server is pre-configured with a certificate and
   its corresponding private key.  If the server is pre-configured with
   public key but not with a certificate, it can generate the self-
   signed certificate for server authentication.

   When the DHCPv6 server receives the Information-request message and
   the contained Option Request option identifies the request is for the
   server certificate information, it replies with a Reply message to
   the client.  The Reply message MUST contain the requested Certificate
   option, which MUST be constructed as explained in Section 9.1.1, and
   Server Identifier option.  In addition, the Reply message MUST
   contain one and only one Signature option, which MUST be constructed
   as explained in Section 9.1.2.  Besides, the Reply message SHOULD
   contain one and only one Increasing-number option, which MUST be
   constructed as explained in Section 9.1.3.  In addition, if client
   authentication is needed, then the ORO option in the Reply message




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   contains the code of the certificate option to indicate the request
   of the client certificate information.

   Upon the receipt of Encrypted-Query message, the server MUST drop the
   message if the other DHCPv6 option except Server Identifier option
   and Encrypted-message option is contained.  Then, the server checks
   the Server Identifier option if the Encrypted-Query message contains
   the Server Identifier option.  The DHCPv6 server drops the message
   that is not for it, thus not paying cost to decrypt messages not for
   it.  It decrypts the Encrypted-message option using its private key
   if it is the target server.

   If the secure DHPCv6 need client authentication and decrypted message
   is a Solicit/Information-request message which contains the
   information for client authentication, the secure DHCPv6 server
   discards the received message that meets any of the following
   conditions:

   o  the Signature option is missing,

   o  multiple Signature options are present,

   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 hash algorithm field is zero, then the signature algorithm and
   hash algorithm are not separated.  The corresponding hash algorithm
   is fixed according the signature algorithm.  If the check fails, the
   server SHOULD reply with an AlgorithmNotSupported error status code,
   defined in Section 9.3, 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 certificate through the local pre-
   configured trusted certificates list.  A certificate that finds a
   match in the local trust certificates list is treated as verified.
   The message that fails authentication validation MUST be dropped.  In
   such failure, the DHCPv6 server replies with an AuthenticationFail
   error status code, defined in Section 9.3, 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 Increasing-number option, the
   server checks it by comparing it with the stored number on the
   server.  The server has one stable stored number for replay attack



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   detection.  The initial value of the stable stored number is zero.
   If the contained number is higher than the stored number, 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 and a
   IncreasingnumFail error status code, defined in Section 9.3, should
   be sent back to the client.  Depending on server's local policy, the
   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
   been calculated as specified in Section 9.1.2.  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
   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 9.3, for
   the signature verification failure.

   Once the client has been authenticated, the DHCPv6 server sends the
   Encrypted-response message to the DHCPv6 client.  The Encrypted-
   response message MUST only contain the Encrypted-message option,
   which MUST be constructed as explained in Section 9.1.4.  The
   encryption text SHOULD be formatted as explain in [RFC5652].  The
   Encrypted-message option contains the encrypted DHCPv6 message that
   is encrypted using the authenticated client's public key.  To provide
   the replay protection, the Increasing-number option can be contained
   in the encrypted DHCPv6 message.

8.  Relay Agent Behavior

   When a DHCPv6 relay agent receives an Encrypted-query or Encrypted-
   response message, it may not recognize this message.  The unknown
   messages MUST be forwarded as described in [RFC7283].

   When a DHCPv6 relay agent recognizes the Encrypted-query and
   Encrypted-response messages, it forwards the message according to
   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,
   nor add any secure DHCPv6 options.  Actually, by definition in this
   document, relay agents MUST NOT add any secure DHCPv6 options.





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   Relay-forward and Relay-reply messages MUST NOT contain any
   additional Certificate option or Increasing-number option, aside from
   those present in the innermost encapsulated messages from the client
   or 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.  Extensions for Secure DHCPv6

   This section describes the extensions to DHCPv6.  Four new DHCPv6
   options, two new DHCPv6 messages and five new status codes are
   defined.

9.1.  New DHCPv6 Options

9.1.1.  Certificate Option

   The Certificate option carries the certificate of the client/server.
   The format of the Certificate option is described as follows:


























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    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      OPTION_CERTIFICATE       |         option-len            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     EA-id     |                                               |
   +-+-+-+-+-+-+-+-+                                               .
   .                  Certificate (variable length)                .
   .                                                               .
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   option-code    OPTION_CERTIFICATE (TBA1).

   option-len     1 + Length of certificate in octets.

   EA-id          Encryption Algorithm id. The encryption algorithm
                  is used for the encrypted DHCPv6 configuration
                  process. This design is adopted in order to provide
                  encryption algorithm agility. The value is from the
                  Encryption Algorithm for Secure DHCPv6 registry in
                  IANA. A registry of the initial assigned values
                  is defined in Section 12.

   Certificate    A variable-length field containing certificate. The
                  encoding of certificate and certificate data MUST
                  be in format as defined in Section 3.6, [RFC7296].
                  The support of X.509 certificate is mandatory.

9.1.2.  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             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     SA-id     |     HA-id     |                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               |
   |                                                               |
   .                    Signature (variable length)                .
   .                                                               .
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



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   option-code    OPTION_SIGNATURE (TBA2).

   option-len     2 + Length of Signature field in octets.

   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.

   HA-id          Hash Algorithm id. The hash algorithm is used for
                  computing the signature result. This design is
                  adopted in order to provide hash algorithm agility.
                  The value is from the Hash Algorithm for Secure
                  DHCPv6 registry in IANA. The support of SHA-256 is
                  mandatory. A registry of the initial assigned values
                  is defined in Section 12. If the signature algorithm
                  and hash algorithm cannot be separated, the HA-id
                  field is zero. The hash algorithm is decided by the
                  corresponding signature algorithm.

   Signature      A variable-length field containing a digital
                  signature. 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).

                  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.





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9.1.3.  Increasing-number Option

   The Increasing-number option carries the number which is higher than
   the local stored number on the client/server.  It adds the anti-
   replay protection to the DHCPv6 messages.  It is optional.

 0                   1                   2                   3
 0 1 2 3 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             |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                                                               |
|                  InreasingNum (32-bit)                        |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

option-code    OPTION_INCREASINGNUM (TBA3).

option-len     4, in octets.

IncreasingNum  A number which is higher than the local stored number on the
               client/server for the replay attack detection.

9.1.4.  Encrypted-message Option

   The Encrypted-message option carries the encrypted DHCPv6 message
   with the recipient's public key.

   The format of the Encrypted-message option is:

      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |          option-code          |           option-len          |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     .                  encrypted DHCPv6 message                     .
     .                       (variable)                              .
     .                                                               .
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                 Figure 1: Encrypted-message Option Format

   option-code  OPTION_ENCRYPTED_MSG (TBA4).

   option-len  Length of the encrypted DHCPv6 message.

   encrypted DHCPv6 message  A variable length field containing the
      encrypted DHCPv6 message sent by the client or the server.  In



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      Encrypted-Query message, it contains encrypted DHCPv6 message sent
      by a client.  In Encrypted-response message, it contains encrypted
      DHCPv6 message sent by a server.

9.2.  New DHCPv6 Messages

   Two new DHCPv6 messages are defined to achieve the DHCPv6 encryption:
   Encrypted-Query and Encrypted-Response.  Both the DHCPv6 messages
   defined in this document share the following format:

      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    msg-type   |               transaction-id                  |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     .                             options                           .
     .                           (variable)                          .
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Figure 2: The format of Encrypted-Query and Encrypted-Response
                                 Messages

   msg-type        Identifier of the message type.  It can be either
                   Encrypted-Query (TBA5) or DHCPv6-Response (TBA6).

   transaction-id  The transaction ID for this message exchange.

   options         The Encrypted-Query message MUST only contain the
                   Server Identifier option or Encrypted-message option.
                   The Encrypted-Response message MUST only contain the
                   Encrypted-message option.

9.3.  Status Codes

   The following new status codes, see Section 5.4 of [RFC3315] are
   defined.

   o  AlgorithmNotSupported (TBD7): indicates that the DHCPv6 server
      does not support algorithms that sender used.

   o  AuthenticationFail (TBD8): indicates that the message from the
      DHCPv6 client fails authentication check.

   o  IncreasingnumFail (TBD9): indicates the message from DHCPv6 client
      fails the increasing number check.




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   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.

10.  Security Considerations

   This document provides the authentication and encryption mechanisms
   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 Increasing-
   number option, may have to face the risk of replay attacks.

   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.

11.  IANA Considerations

   This document defines four new DHCPv6 [RFC3315] options.  The IANA is
   requested to assign values for these four options from the DHCPv6
   Option Codes table of the DHCPv6 Parameters registry maintained in
   http://www.iana.org/assignments/dhcpv6-parameters.  The four options
   are:

      The Certificate Option (TBA1), described in Section 9.1.1.

      The Signature Option (TBA2), described in Section 9.1.2.

      The Increasing-number Option (TBA3),described in Section 9.1.3.

      The Encrypted-message Option (TBA4), described in Section 9.1.4.

   The IANA is also requested to assign value for these two messages
   from the DHCPv6 Message Types table of the DHCPv6 Parameters registry




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   maintained in http://www.iana.org/assignments/dhcpv6-parameters.  The
   two messages are:

      The Encrypted-Query Message (TBA5), described in Section 9.2.

      The Encrypted-Response Message (TBA6), described in Section 9.2.

   The IANA is also requested to add three new registry tables to the
   DHCPv6 Parameters registry maintained in
   http://www.iana.org/assignments/dhcpv6-parameters.  The three tables
   are the Hash Algorithm for Secure DHCPv6 table, the Signature
   Algorithm for Secure DHCPv6 table and the Encryption Algorithm for
   Secure DHCPv6 table.

   Initial values for these registries are given below.  Future
   assignments are to be made through Standards Action [RFC5226].
   Assignments for each registry consist of a name, a value and a RFC
   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
      -------------------+---------+--------------
         SigAlg-Combined |   ox00  | this document
            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
   8-bit unsigned integers.  The following initial values are assigned
   for encryption algorithm for Secure DHCPv6 in this document:

             Name        |  Value  |  RFCs
      -------------------+---------+--------------
              RSA        |   0x01  | this document

   IANA is requested to assign the following new DHCPv6 Status Codes,
   defined in Section 9.3, in the DHCPv6 Parameters registry maintained
   in http://www.iana.org/assignments/dhcpv6-parameters:



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         Code  |           Name        |   Reference
      ---------+-----------------------+--------------
         TBD7  | AlgorithmNotSupported | this document
         TBD8  |   AuthenticationFail  | this document
         TBD9  |  IncreasingnumFail    | this document
         TBD10 |     SignatureFail     | this document
         TBD11 |    DecryptionFail     | this document

12.  Acknowledgements

   The authors would like to thank Tomek Mrugalski, Bernie Volz,
   Jianping Wu, Randy Bush, Yiu Lee, Sean Shen, Ralph Droms, Jari Arkko,
   Sean Turner, Stephen Farrell, Christian Huitema, Stephen Kent, Thomas
   Huth, David Schumacher, Francis Dupont, Gang Chen, Suresh Krishnan,
   Fred Templin, Robert Elz, Nico Williams, Erik Kline, Alan DeKok,
   Bernard Aboba, Sam Hartman, Qi Sun, Zilong Liu and other members of
   the IETF DHC working group for their valuable comments.

   This document was produced using the xml2rfc tool [RFC2629].

13.  Change log [RFC Editor: Please remove]

   draft-ietf-dhc-sedhcpv6-13: Change the Timestamp option into
   Increasing-number option and the corresponding check method; Delete
   the OCSP stampling part for the certificate check; Add the scenario
   where the hash and signature algorithms cannot be separated; Add the
   comparison with RFC7824 and RFC7844; Add the encryption text format
   and reference of RFC5652.  Add the consideration of scenario where
   multiple DHCPv6 servers share one common DHCPv6 server.  Add the
   statement that Encrypted-Query and Encrypted-Response messages can
   only contain certain options: Server Identifier option and Encrypted-
   message option.  Add opportunistic security for deployment
   consideration.  Besides authentication+encyrption mode, encryption-
   only mode is added.

   draft-ietf-dhc-sedhcpv6-12: Add the Signature option and timestamp
   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
   encrypted DHCPv6 message and the Information-request message (only
   contain the Certificate option) don't need the Signature option for
   message integrity check; Rewrite the "Applicability" section; Add the



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   encryption algorithm negotiation process; To support the encryption
   algorithm negotiation, the Certificate option contains the EA-
   id(encryption algorithm identifier) field; Reserve the Timestamp
   option to defend against the replay attacks for encrypted DHCPv6
   configuration process; Modify the client behavior when there is no
   authenticated DHCPv6 server; Add the DecryptionFail error code.
   2016-3-9.

   draft-ietf-dhc-sedhcpv6-10: merge DHCPv6 authentication and DHCPv6
   encryption.  The public key option is removed, because the device can
   generate the self-signed certificate if it is pre-configured the
   public key not the certificate. 2015-12-10.

   draft-ietf-dhc-sedhcpv6-09: change some texts about the deployment
   part.2015-12-10.

   draft-ietf-dhc-sedhcpv6-08: clarified what the client and the server
   should do if it receives a message using unsupported algorithm;
   refined the error code treatment regarding to AuthenticationFail and
   TimestampFail; added consideration on how to reduce the DoS attack
   when using TOFU; other general editorial cleanups. 2015-06-10.

   draft-ietf-dhc-sedhcpv6-07: removed the deployment consideration
   section; instead, described more straightforward use cases with TOFU
   in the overview section, and clarified how the public keys would be
   stored at the recipient when TOFU is used.  The overview section also
   clarified the integration of PKI or other similar infrastructure is
   an open issue.  2015-03-23.

   draft-ietf-dhc-sedhcpv6-06: remove the limitation that only clients
   use PKI- certificates and only servers use public keys.  The new text
   would allow clients use public keys and servers use PKI-certificates.
   2015-02-18.

   draft-ietf-dhc-sedhcpv6-05: addressed comments from mail list that
   responsed to the second WGLC. 2014-12-08.

   draft-ietf-dhc-sedhcpv6-04: addressed comments from mail list.
   Making timestamp an independent and optional option.  Reduce the
   serverside authentication to base on only client's certificate.
   Reduce the clientside authentication to only Leaf of Faith base on
   server's public key. 2014-09-26.

   draft-ietf-dhc-sedhcpv6-03: addressed comments from WGLC.  Added a
   new section "Deployment Consideration".  Corrected the Public Key
   Field in the Public Key Option.  Added consideration for large DHCPv6
   message transmission.  Added TimestampFail error code.  Refined the
   retransmission rules on clients. 2014-06-18.



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   draft-ietf-dhc-sedhcpv6-02: addressed comments (applicability
   statement, redesign the error codes and their logic) from IETF89 DHC
   WG meeting and volunteer reviewers. 2014-04-14.

   draft-ietf-dhc-sedhcpv6-01: addressed comments from IETF88 DHC WG
   meeting.  Moved Dacheng Zhang from acknowledgement to be co-author.
   2014-02-14.

   draft-ietf-dhc-sedhcpv6-00: adopted by DHC WG. 2013-11-19.

   draft-jiang-dhc-sedhcpv6-02: removed protection between relay agent
   and server due to complexity, following the comments from Ted Lemon,
   Bernie Volz. 2013-10-16.

   draft-jiang-dhc-sedhcpv6-01: update according to review comments from
   Ted Lemon, Bernie Volz, Ralph Droms.  Separated Public Key/
   Certificate option into two options.  Refined many detailed
   processes.  2013-10-08.

   draft-jiang-dhc-sedhcpv6-00: original version, this draft is a
   replacement of draft-ietf-dhc-secure-dhcpv6, which reached IESG and
   dead because of consideration regarding to CGA.  The authors followed
   the suggestion from IESG making a general public key based mechanism.
   2013-06-29.

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

15.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.





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   [RFC2460]  Deering, S. and R. Hinden, "Internet Protocol, Version 6
              (IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460,
              December 1998, <http://www.rfc-editor.org/info/rfc2460>.

   [RFC3315]  Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins,
              C., and M. Carney, "Dynamic Host Configuration Protocol
              for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July
              2003, <http://www.rfc-editor.org/info/rfc3315>.

   [RFC3971]  Arkko, J., Ed., Kempf, J., Zill, B., and P. Nikander,
              "SEcure Neighbor Discovery (SEND)", RFC 3971,
              DOI 10.17487/RFC3971, March 2005,
              <http://www.rfc-editor.org/info/rfc3971>.

   [RFC4443]  Conta, A., Deering, S., and M. Gupta, Ed., "Internet
              Control Message Protocol (ICMPv6) for the Internet
              Protocol Version 6 (IPv6) Specification", RFC 4443,
              DOI 10.17487/RFC4443, March 2006,
              <http://www.rfc-editor.org/info/rfc4443>.

   [RFC5652]  Housley, R., "Cryptographic Message Syntax (CMS)", STD 70,
              RFC 5652, DOI 10.17487/RFC5652, September 2009,
              <http://www.rfc-editor.org/info/rfc5652>.

   [RFC5905]  Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch,
              "Network Time Protocol Version 4: Protocol and Algorithms
              Specification", RFC 5905, DOI 10.17487/RFC5905, June 2010,
              <http://www.rfc-editor.org/info/rfc5905>.

   [RFC7283]  Cui, Y., Sun, Q., and T. Lemon, "Handling Unknown DHCPv6
              Messages", RFC 7283, DOI 10.17487/RFC7283, July 2014,
              <http://www.rfc-editor.org/info/rfc7283>.

   [RFC7296]  Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T.
              Kivinen, "Internet Key Exchange Protocol Version 2
              (IKEv2)", STD 79, RFC 7296, DOI 10.17487/RFC7296, October
              2014, <http://www.rfc-editor.org/info/rfc7296>.

   [RFC7435]  Dukhovni, V., "Opportunistic Security: Some Protection
              Most of the Time", RFC 7435, DOI 10.17487/RFC7435,
              December 2014, <http://www.rfc-editor.org/info/rfc7435>.

   [RFC7824]  Krishnan, S., Mrugalski, T., and S. Jiang, "Privacy
              Considerations for DHCPv6", RFC 7824,
              DOI 10.17487/RFC7824, May 2016,
              <http://www.rfc-editor.org/info/rfc7824>.





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   [RFC7844]  Huitema, C., Mrugalski, T., and S. Krishnan, "Anonymity
              Profiles for DHCP Clients", RFC 7844,
              DOI 10.17487/RFC7844, May 2016,
              <http://www.rfc-editor.org/info/rfc7844>.

15.2.  Informative References

   [RFC2629]  Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629,
              DOI 10.17487/RFC2629, June 1999,
              <http://www.rfc-editor.org/info/rfc2629>.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
              DOI 10.17487/RFC5226, May 2008,
              <http://www.rfc-editor.org/info/rfc5226>.

   [RFC6273]  Kukec, A., Krishnan, S., and S. Jiang, "The Secure
              Neighbor Discovery (SEND) Hash Threat Analysis", RFC 6273,
              DOI 10.17487/RFC6273, June 2011,
              <http://www.rfc-editor.org/info/rfc6273>.

   [RFC7258]  Farrell, S. and H. Tschofenig, "Pervasive Monitoring Is an
              Attack", BCP 188, RFC 7258, DOI 10.17487/RFC7258, May
              2014, <http://www.rfc-editor.org/info/rfc7258>.

   [RSA]      RSA Laboratories, "RSA Encryption Standard, Version 2.1,
              PKCS 1", November 2002.

Authors' Addresses

   Sheng Jiang
   Huawei Technologies Co., Ltd
   Q14, Huawei Campus, No.156 Beiqing Road
   Hai-Dian District, Beijing, 100095
   CN

   Email: jiangsheng@huawei.com


   Lishan Li
   Tsinghua University
   Beijing  100084
   P.R.China

   Phone: +86-15201441862
   Email: lilishan48@gmail.com





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Internet-Draft                  SeDHCPv6                       July 2016


   Yong Cui
   Tsinghua University
   Beijing  100084
   P.R.China

   Phone: +86-10-6260-3059
   Email: yong@csnet1.cs.tsinghua.edu.cn


   Tatuya Jinmei
   Infoblox Inc.
   3111 Coronado Drive
   Santa Clara, CA
   US

   Email: jinmei@wide.ad.jp


   Ted Lemon
   Nominum, Inc.
   2000 Seaport Blvd
   Redwood City, CA  94063
   USA

   Phone: +1-650-381-6000
   Email: Ted.Lemon@nominum.com


   Dacheng Zhang
   Beijing
   CN

   Email: dacheng.zhang@gmail.com


















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