DHC Working Group Sheng Jiang
Internet Draft Huawei Technologies Co., Ltd
Intended status: Standards Track Sean Shen
Expires: December 22, 2011 CNNIC
June 16, 2011
Secure DHCPv6 Using CGAs
draft-ietf-dhc-secure-dhcpv6-03.txt
Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that other
groups may also distribute working documents as Internet-Drafts.
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."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html
This Internet-Draft will expire on December 22, 2011.
Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved.
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.
Jiang & Shen Expires December 22, 2011 [Page 1]
Internet-Draft draft-ietf-dhc-secure-dhcpv6-03.txt June 2011
Abstract
The Dynamic Host Configuration Protocol for IPv6 (DHCPv6) enables
DHCP servers to pass configuration parameters. It offers
configuration flexibility. If not secured, DHCPv6 is vulnerable to
various attacks, particularly fake attack. This document analyzes the
security issues of DHCPv6 and specifies security mechanisms, mainly
using CGAs.
Table of Contents
1. Introduction ................................................ 3
2. Terminology ................................................. 3
3. Security Overview of DHCPv6 ................................. 3
4. Secure DHCPv6 Overview ...................................... 4
4.1. New Components ......................................... 5
4.2. Support for algorithm agility .......................... 6
5. Extension for Secure DHCPv6 ................................. 6
5.1. CGA Parameter Option ................................... 6
5.2. Signature Option ....................................... 7
5.3. DUID-SA Type .......................................... 10
6. Processing Rules and Behaviors ............................. 10
6.1. Processing Rules of Sender ............................ 10
6.2. Processing Rules of Receiver .......................... 11
6.3. Processing Rules of Relay Agent ....................... 12
7. Security Considerations .................................... 12
8. IANA Considerations ........................................ 13
9. Acknowledgments ............................................ 14
10. References ................................................ 15
10.1. Normative References ................................. 15
10.2. Informative References ............................... 15
Author's Addresses ............................................ 16
Jiang & Shen Expires December 22, 2011 [Page 2]
Internet-Draft draft-ietf-dhc-secure-dhcpv6-03.txt June 2011
1. Introduction
The Dynamic Host Configuration Protocol for IPv6 (DHCPv6 [RFC3315])
enables DHCP servers to pass configuration parameters. It offers
configuration flexibility. If not secured, DHCPv6 is vulnerable to
various attacks, particularly fake attack.
The requirements of using CGA to secure DHCPv6 have been introduced
in [I-D.draft-ietf-csi-dhcpv6-cga-ps]. This document analyzes the
security issues of DHCPv6 in more details. This document is aiming to
provide mechanisms for improving the security of DHCPv6, thus the
address of a DHCP message sender, which can be a DHCP server, a reply
agent or a client, is able to be verified by a receiver. It improves
communication security of DHCPv6 interaction. The security mechanisms
specified in this document is mainly based on the Cryptographically
Generated Addresses (CGA [RFC3972]).
Secure DHCPv6 is applicable in environments where physical security
on the link is not assured (such as over wireless) or where available
security mechanisms are not sufficient, and attacks on DHCPv6 are a
concern.
2. 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].
3. Security Overview of DHCPv6
DHCPv6 is a client/server protocol that provides managed and stateful
configuration of devices. It enables DHCPv6 server to auto-configure
relevant network parameters on clients through the DHCPv6 message
exchanging mechanisms. In the basic DHCPv6 specifications [RFC3315],
security of DHCPv6 message can be improved in a few aspects.
In the basic DHCPv6 specifications, regular IPv6 addresses are used.
It is possible for a malicious attacker to use a fake address to
spoof or launch an attack.
"One attack specific to a DHCP client is the establishment of a
malicious server with the intent of providing incorrect configuration
information to the client. The motivation for doing so may be to
mount a 'man in the middle' attack that causes the client to
communicate with a malicious server instead of a valid server for
some service such as DNS or NTP. The malicious server may also mount
a denial of service attack through mis-configuration of the client
Jiang & Shen Expires December 22, 2011 [Page 3]
Internet-Draft draft-ietf-dhc-secure-dhcpv6-03.txt June 2011
that causes all network communication from the client to fail."
[RFC3315]
"A DHCP client may also be subject to attack through the receipt of a
Reconfigure message from a malicious server that causes the client to
obtain incorrect configuration information from that server."
[RFC3315]
Fake servers can also provide clients with partially correct
information that allows the attacker to route traffic through certain
host where critical information can be collected. This becomes
important to detect and prevent when encrypted traffic is allowed to
pass through firewalls. Clients can be configured with bogus data, so
that they will assume that the network is down.
Once servers start updating DNS and other directory services,
attackers may spoof DHCP servers to register incorrect information in
those services.
Another possible attack is that attackers may be able to gain
unauthorized access to some resources, such as network access.
The basic DHCPv6 specifications achieve message origin authentication
and message integrity via an authentication option with a symmetric
key pair. For the key of the hash function, there are two key
management mechanisms. Firstly, the key management is out of band,
usually manual, i.e. operators set up key database for both server
and client before running DHCPv6. Usually multiple keys are deployed
once a time and key id is used to specify which key is used.
Secondly, a DHCPv6 server sends a reconfigure key to the client in
the initial exchange of DHCPv6 messages for future use, in this case
security is not guaranteed because this key is transmitted in
plaintext. In either way, the security of key itself is in question
mark.
Communication between a server and a relay agent, and communication
between relay agents, can be secured through the use of IPSec, as
described in section 21.1 in [RFC3315]. However, IPSec is quite
complicated. A simpler security mechanism may have better deploy
ability. Furthermore, the manual configuration and static keys are
potential issue makers. Relay agents MAY require other security
mechanisms besides IPSec.
4. Secure DHCPv6 Overview
To solve the abovementioned security issues, we introduce CGAs into
DHCPv6. CGAs are introduced in [RFC3972]. "CGAs are IPv6 addresses
for which the interface identifier is generated by computing a
cryptographic one-way hash function from a public key and auxiliary
parameters. The binding between the public key and the address can be
Jiang & Shen Expires December 22, 2011 [Page 4]
Internet-Draft draft-ietf-dhc-secure-dhcpv6-03.txt June 2011
verified by re-computing the hash value and by comparing the hash
with the interface identifier. Messages sent from an IPv6 address can
be protected by attaching the public key and auxiliary parameters and
by signing the message with the corresponding private key. The
protection works without a certification authority or any security
infrastructure."
In this document, a CGA option with an address ownership proof
mechanism and a signature option with a corresponding verification
mechanism are introduced. A DHCPv6 message (from either a server, a
relay agent or a client) with a CGA as source address, can carry the
CGA Parameters data structure and a digital signature. The receiver
of this DHCPv6 message can verify both the CGA and signature, then
process the payload of the DHCPv6 message only if the validation is
successful.
With them, the receiver of a DHCP message can verify the sender
address of the DHCP message, which improves communication security of
DHCP messages. By using the signature option, the verification of
data integrity and replay protections can also be achieved without
the authentication option.
This documentation focuses on using CGAs to secure the DHCPv6
protocol. It assumes the sender, which uses CGAs, has self-generated
or been configured CGAs. The CGA configuration in the DHCPv6 network
is out of scope and specified in
[I-D.draft-ietf-dhc-cga-config-dhcpv6].
In the relay scenarios, because relay agent restructures the DHCPv6
messages, a receiver would not find the sender's source CGA address
in the DHCPv6 message header. In the client-relay-server scenarios,
"the relay agent copies the source address from the header of the IP
datagram in which the message was received to the peer-address field
of the Relay-forward message" [RFC3315]. The receiver, a DHCPv6
server, can find the sender's source CGA address in the peer-address
field for CGA verification. In the server-relay-client scenarios, a
DHCP server knows a client is behind relay(s) if it receives a Relay-
forward DHCPv6 message. Then it will reply a Relay-reply message with
the server's source CGA address being carried in the server DUID,
which is in the payload. In this way, the receiver, a DHCPv6 client
can get the server's source CGA address for CGA verification. The
server DUID is also protected by CGA.
4.1. New Components
The components of the solution specified in this document are as
follows:
- CGAs are used to make sure that the sender of a DHCPv6 message
is the "owner" of the claimed address. A public-private key
Jiang & Shen Expires December 22, 2011 [Page 5]
Internet-Draft draft-ietf-dhc-secure-dhcpv6-03.txt June 2011
pair has been generated by a node itself before it can claim an
address. A new DHCPv6 option, the CGA Parameter Option, is used
to carry the public key and associated parameters.
- Public key signatures protect the integrity of the messages and
authenticate the identity of their sender. The authority of a
public key is established through the address ownership proof
mechanism, by using CGAs.
- Server Address type of DUID is used to carry server's source
address in the relay scenarios. The receiver gets the server's
source CGA address for CGA verification.
4.2. Support for algorithm agility
Hash functions are the fundamental of security mechanisms, including
CGAs in this document. "...they have two security properties: to be
one way and collision free." "The recent attacks have demonstrated
that one of those security properties is not true." [RFC4270]
Following the approach recommended by [RFC4270] and [NewHash], our
analysis shows none of these attacks are currently doable. However,
these attacks indicate the possibility of future real-world attacks.
Therefore, we have to take into account that future attacks will be
improved and provide a support for multiple hash algorithms. Our
mechanisms, in this document, support not only hash algorithm agility
but also signature algorithm agility.
The support for hash agility within CGAs has been defined in
[RFC4982]. The usage of CGAs in this document SHOULD also obey
[RFC4982], too.
5. Extensions for Secure DHCPv6
This section extends DHCPv6. Two new options and a new DUID type have
been defined. The new options MUST be supported, if the node has been
configured to use Secure DHCPv6. The new DUID type MUST be supported
in the relay scenarios.
5.1. CGA Parameter Option
The CGA option allows the verification of the sender's CGAs. The
format of the CGA option is described as follows:
Jiang & Shen Expires December 22, 2011 [Page 6]
Internet-Draft draft-ietf-dhc-secure-dhcpv6-03.txt June 2011
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_CGA_PARAMETER | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. CGA Parameters (variable length) .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_CGA_PARAMETER (TBA1).
option-len Length of CGA Parameters in octets.
CGA Parameters A variable-length field containing the CGA
Parameters data structure described in Section 4
of [RFC3972]. This specification requires that
the public key found from the CGA Parameters
field in the CGA option MUST be that referred by
the Key Hash field in the Signature option.
Packets received with two different keys MUST be
silently discarded. Note that a future extension
MAY provide a mechanism allowing the owner of an
address and the signer to be different parties.
5.2. Signature Option
The Signature option allows public key-based signatures to be
attached to a DHCPv6 message. The Signature option COULD be any place
within the DHCPv6 message. It protects all the DHCPv6 header and
options before it. Any options after the Signature option can be
processed, but it should be noticed that they are not protected by
this Signature option. The format of the Signature option is
described as follows:
Jiang & Shen Expires December 22, 2011 [Page 7]
Internet-Draft draft-ietf-dhc-secure-dhcpv6-03.txt June 2011
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_SIGNATURE | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| HA-id | SA-id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| HA-id-KH | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Timestamp (64-bit) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Key Hash (128-bit) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. Signature (variable length) .
. .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_SIGNATURE (TBA2).
option-len 32 + Length of signature field in octets.
HA-id Hash Algorithm id. The hash algorithm is used
for computing the signature result. RSA
signature [RSA] with SHA-1 [sha-1] is adopted.
In order to provide hash algorithm agility, SHA-
1 is assigned an initial value 0x0000 in this
document.
SA-id Signature Algorithm id. The signature algorithm
is used for computing the signature result. RSA
signature with RSASSA-PKCS1-v1_5 algorithm is
adopted. In order to provide algorithm agility,
RSASSA_PKCS1-v1_5 is assigned an initial value
0x0000 in this document.
HA-id-KH Hash Algorithm id for Key Hash. Hash algorithm
used for producing the Key Hash field in the
Signature option. SHA-1 is adopted. In order to
provide hash algorithm agility, SHA-1 is
assigned an initial value 0x0000 in this
document.
Jiang & Shen Expires December 22, 2011 [Page 8]
Internet-Draft draft-ietf-dhc-secure-dhcpv6-03.txt June 2011
Reserved A 16-bit field reserved for future use. The
value MUST be initialized to zero by the sender,
and MUST be ignored by the receiver.
Timestamp The current time of day (NTP-format timestamp
[RFC5905], a 64-bit unsigned fixed-point number,
in seconds relative to 0h on 1 January 1900.).
It can reduce the danger of replay attacks.
Key Hash A 128-bit field containing the most significant
(leftmost) 128 bits of a SHA-1 hash of the
public key used for constructing the signature.
The SHA-1 hash is taken over the presentation
used in the Public Key field of the CGA
Parameters data structure carried in the CGA
option. Its purpose is to associate the
signature to a particular key known by the
receiver. Such a key can either be stored in the
certificate cache of the receiver or be received
in the CGA option in the same message.
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
over the following sequence of octets:
1. The 128-bit CGA Message Type tag value for
Secure DHCPv6, 0x81be a1eb 0021 ce7e caa9 4090
0665 d2e0 02c2. (The tag value has been
generated randomly by the editor of this
specification.).
2. The 128-bit Source IPv6 Address.
3. The 128-bit Destination IPv6 Address.
4. The DHCPv6 message header.
5. All DHCPv6 options except for the Signature
option and the Authentication Option.
6. The content between the option-len field and
the signature field in this Signature option, in
the format described above.
Jiang & Shen Expires December 22, 2011 [Page 9]
Internet-Draft draft-ietf-dhc-secure-dhcpv6-03.txt June 2011
5.3. DUID-SA Type
Server Address Type DUID (DUID-SA) allows IP address of DHCPv6
servers can be carried in DHCPv6 message payload.
The following diagram illustrates the format of a DUID-SA:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TBA3 | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Server Address (128-bit) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type-code DUID-SA Type (TBA3)
Reserved A 16-bit field reserved for future use. The
value MUST be initialized to zero by the sender,
and MUST be ignored by the receiver.
Server Address The 128-bit IPv6 address of the DHCPv6 server.
In the secure DHCPv6 solution, the Server Address field of DUID-SA,
which is the IPv6 address of the DHCPv6 server, MUST be a CGA.
In the secure DHCPv6 solution, all the payloads, including DUID-SA,
are protected by signature option by the definition of section 5.1
and 5.2.
6. Processing Rules and Behaviors
6.1. Processing Rules of Sender
A DHCPv6 node, which could be a server, relay agent or client, can be
configured to send Secure DHCPv6 messages only if CGAs have been
configured on it.
The node MUST record the following configuration information:
CGA parameters Any information required to construct CGAs, as
described in [RFC3972].
Keypair A public-private key pair. The public key used
for constructing the signature MUST be the same
in CGA parameters.
Jiang & Shen Expires December 22, 2011 [Page 10]
Internet-Draft draft-ietf-dhc-secure-dhcpv6-03.txt June 2011
CGA flag A flag that indicates whether CGA is used or
not.
If a node has been configured to use Secure DHCPv6, the node MUST
send a DHCPv6 message using a CGA, which be constructed as specified
in Section 4 of [RFC3972], as the source address unless they are sent
with the unspecified source address. This DHCPv6 message MUST be
signed by the private key of the sender. In the message, both the CGA
option and the Signature option MUST be present. The CGA Parameter
field in the CGA option is filled according to the rules presented
above and in [RFC3972]. The public key in the field is taken from the
configuration used to generate the CGA, typically from a data
structure associated with the source address. The Signature option
MUST be constructed as explained in Section 5.2 and be the last
DHCPv6 option.
In relay scenario, a DHCPv6 server MUST include an OPTION_SERVERID
[RFC3315] in Relay-reply message and put its CGA in the Server
Address field of the DUID in the OPTION_SERVERID. The CGA of DHCPv6
server will not lose during relaying so that the client can verify
CGA address and signature.
6.2. Processing Rules of Receiver
The node that supports the verification of the Secure DHCPv6 messages
MUST record the following configuration information:
Minbits The minimum acceptable key length for public
keys used in the generation of CGAs. The default
SHOULD be 1024 bits. Implementations MAY also
set an upper limit for the amount of computation
needed when verifying packets that use these
security associations. Any implementation SHOULD
follow prudent cryptographic practice in
determining the appropriate key lengths.
On a node that has been configured to use Secure DHCPv6, DHCPv6
message without either the CGA option or the Signature option MUST be
treated as unsecured. Note the Secure DHCPv6 nodes MAY simply discard
the unsecured messages.
The receiving node MUST verify the source CGA address of the DHCPv6
message by using the public key of the DHCPv6 message sender, CGA
Parameters and the algorithm described in Section 5 of [RFC3972]. The
inputs to the algorithm are the source address, as used in IP header,
and the CGA Parameters field.
If the CGA verification is successful, the recipient proceeds with a
more time-consuming cryptographic check of the signature. Note that
Jiang & Shen Expires December 22, 2011 [Page 11]
Internet-Draft draft-ietf-dhc-secure-dhcpv6-03.txt June 2011
even if the CGA verification succeeds, no claims about the validity
of the use can be made until the signature has been checked.
The processing on the receiving node also includes the verification
on signed data by using the public key of the DHCPv6 message sender.
The receiving node MUST verify the Signature option as follows: the
Key Hash field MUST indicate the use of a known public key, either
one learned from a preceding CGA option in the same message, or one
known by other means. The signature field verification MUST show that
the signature has been calculated as specified in the previous
section.
Only the messages that get through both CGA and signature
verifications are accepted as secured DHCPv6 messages and continue to
be handled for their contained DHCPv6 options.
Messages that do not pass all the above tests MUST be silently
discarded if the host has been configured to accept only secured
DHCPv6 messages. The messages MAY be accepted if the host has been
configured to accept both secured and unsecured messages but MUST be
treated as an unsecured message. The receiver MAY also otherwise
silently discard packets.
In the relay scenarios, a DHCPv6 server obtains the CGA of a client
from the peer address field in the Relay-forward message. A DHCPv6
client obtains the CGA of a server from the Server Address field of
the DUID in the OPTION_SERVERID.
6.3. Processing Rules of Relay Agent
To support secure DHCPv6, Relay Agents follow the same processing
rules defined in [RFC3315].
By current definition: "The relay agent copies the source address
from the IP datagram in which the message was received from the
client into the peer-address field in the Relay-forward message". The
CGA of a client will not lose during relaying.
A relay will not change the OPTION_SERVERID when processing Relay-
reply message from a DHCPv6 server, CGA of the DHCPv6 server will not
lose.
7. Security Considerations
This document provides new security features to the DHCPv6 protocol.
Using CGA as source addresses of DHCPv6 servers, relays or, also in
DHCPv6 message exchanging provides the source address ownership
verification and data integrity protection.
Jiang & Shen Expires December 22, 2011 [Page 12]
Internet-Draft draft-ietf-dhc-secure-dhcpv6-03.txt June 2011
Without other pre-configured security mechanism, like pre-notified
DHCPv6 server address, using host-based CGA by DHCPv6 servers could
not prevent attacks claiming to be a DHCPv6 server. Furthermore, CGAs
of DHCPv6 servers may be pre-notified to hosts. Then, hosts may
decline the DHCPv6 messages from other servers, which may be fake
servers. But in this case the address will be fixed. It may increase
the vulnerability to, e.g., brute force attacks. The pre-notification
operation also needs to be protected, which is out of scope.
DHCPv6 nodes without CGAs or the DHCPv6 messages that use unspecific
addresses cannot be protected.
Downgrade attacks cannot be avoided if nodes are configured to accept
both secured and unsecured messages. A future specification MAY
provide a mechanism on how to treat unsecured DHCPv6 messages. One
simple solution MAY be that Secure DHCPv6 is mandated on all servers,
reply agents and clients if a certain link has been deployed Secure
DHCPv6.
As stated in CGA definition [RFC3972], link-local CGAs are more
vulnerable because the same prefix is used by all IPv6 nodes.
Therefore, when link-local CGAs are used by the DHCPv6 clients, it is
recommended to use a slightly higher Sec value. When higher Sec
values are used, the relative advantage of attacking link-local
addresses becomes insignificant.
Impacts of collision attacks on current uses of CGAs are analyzed in
[RFC4982]. The basic idea behind collision attacks, as described in
Section 4 of [RFC4270], is on the non-repudiation feature of hash
algorithms. However, CGAs do not provide non-repudiation features.
Therefore, as [RFC4982] points out CGA-based protocols, including
Secure DHCPv6 defined in this document, are not affected by collision
attacks on hash functions.
[RFC6273] has analyzed possible threats to the hash algorithms used
in SEND. Since the Secure DHCPv6 defined in this document uses the
same hash algorithms in similar way like SEND (except that Secure
DHCPv6 has not used PKIX Certificate), 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 RSA
signature in Secure. Attacks on CGAs, as described in [RFC4982], will
compromise the security of Secure DHCPv6 and they need to be
addressed by encoding the hash algorithm information into the CGA as
specified in [RFC4982].
8. IANA Considerations
This document defines two new DHCPv6 [RFC3315] options, which MUST be
assigned Option Type values within the option numbering space for
DHCPv6 messages:
Jiang & Shen Expires December 22, 2011 [Page 13]
Internet-Draft draft-ietf-dhc-secure-dhcpv6-03.txt June 2011
The CGA Parameter Option (TBA1), described in Section 5.1.
The Signature Option (TBA2), described in Section 5.2.
This document defines a new DHCPv6 DUID, which MUST be assigned DUID
Type values within the DHCPv6 DUID Type numbering space:
The DUID-SA (TBA3), described in Section 5.3.
This document defines three new registries that have been created and
are maintained by IANA. 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 id (HA-id). The values in this name space are 16-bit
unsigned integers. The following initial values are assigned for HA-
id in this document:
Name | Value | RFCs
-------------------+---------+------------
SHA-1 | 0x0000 | this document
Signature Algorithm id (SA-id). The values in this name space are 16-
bit unsigned integers. The following initial values are assigned for
SA-id in this document:
Name | Value | RFCs
-------------------+---------+------------
SHA-1 | 0x0000 | this document
Hash Algorithm id for Key Hash (HA-id-KH). The values in this name
space are 16-bit unsigned integers. The following initial values are
assigned for HA-id-KH in this document:
Name | Value | RFCs
-------------------+---------+------------
RSASSA-PKCS1-v1_5 | 0x0000 | this document
This document defines a new 128-bit value under the CGA Message Type
[RFC3972] namespace, 0x81be a1eb 0021 ce7e caa9 4090 0665 d2e0 02c2.
9. Acknowledgments
The authors would like to thank Bernie Volz, Ted Lemon, Ralph Dorms,
Jari Arkko, Sean Turner and other members of the IETF DHC & CSI
working groups for their valuable comments.
Jiang & Shen Expires December 22, 2011 [Page 14]
Internet-Draft draft-ietf-dhc-secure-dhcpv6-03.txt June 2011
10. References
10.1. Normative References
[RFC3315] R. Droms, et al., "Dynamic Host Configure Protocol for
IPv6", RFC3315, July 2003.
[RFC3972] T. Aura, "Cryptographically Generated Address", RFC3972,
March 2005.
[RFC4982] M. Bagnulo, J. Arkko, "Support for Multiple Hash Algorithms
in Cryptographically Generated Addresses (CGAs)", RFC4982,
July 2007.
[RFC5905] D. Mills, J. Martin, Ed., J. Burbank and W. Kasch, "Network
Time Protocol Version 4: Protocol and Algorithms
Specification", RFC 5905, June 2010.
10.2. Informative References
[RFC2119] S. Bradner, "Key words for use in RFCs to Indicate
Requirement Levels", RFC2119, March 1997.
[RFC4270] Hoffman, P. and B. Schneier, "Attacks on Cryptographic
Hashes in Internet Protocols", RFC 4270, November 2005.
[RFC5226] T. Narten and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", RFC 5226, May 2008.
[RFC6273] A. Kukec, S. Krishnan and S. Jiang "The Secure Neighbor
Discovery (SEND) Hash Threat Analysis", RFC 6274, June
2011.
[NewHash] S.Bellovin and E. Rescorla, "Deploying a New Hash
Algorithm", November 2005.
[I-D.draft-ietf-dhc-cga-config-dhcpv6]
S. Jiang and S. Xia, "Configuring Cryptographically
Generated Addresses (CGA) using DHCPv6", draft-ietf-dhc-
cga-config-dhcpv6, working in progress, April 2011.
[I-D.draft-ietf-csi-dhcpv6-cga-ps]
S. Jiang, S. Shen and T. Chown, "DHCPv6 and CGA
Interaction: Problem Statement", draft-ietf-csi-dhcpv6-
cga-ps, work in progress, May 2011.
[RSA] RSA Laboratories, "RSA Encryption Standard, Version 2.1",
PKCS 1, November 2002.
Jiang & Shen Expires December 22, 2011 [Page 15]
Internet-Draft draft-ietf-dhc-secure-dhcpv6-03.txt June 2011
[sha-1] National Institute of Standards and Technology, "Secure
Hash Standard", FIBS PUB 180-1, April 1995,
http://www.itl.nist.gov/fipspubs/fip180-1.htm.
Author's Addresses
Sheng Jiang
Huawei Technologies Co., Ltd
Huawei Building, No.3 Xinxi Rd.,
Shang-Di Information Industry Base, Hai-Dian District, Beijing
P.R. China
Email: jiangsheng@huawei.com
Sean Shen
CNNIC
4, South 4th Street, Zhongguancun
Beijing 100190
P.R. China
Email: shenshuo@cnnic.cn
Jiang & Shen Expires December 22, 2011 [Page 16]
