Cga & Send maIntenance
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The Secure Neighbor Discovery (SEND) protocol defined by RFC 3971
provides security mechanisms protecting different functions of the
Neighbor Discovery (ND) protocol defined by RFC 2461. This includes
address resolution (discovering link layer address of another node
attached to the link), router discovery (discovering routers attached
to the link), and neighbor unreachability detection (detecting that a
node attached to the link is no longer reachable). SEND protection of
address resolution and neighbor unreachability detection functions
relies on IPv6 address proof-of-ownership and message integrity
protection provided respectively via Cryptographically Generated
Addresses (CGAs) and RSA Digital Signatures.
CGAs are defined in RFC 3972, and are extended with a CGA extension
format defined in RFC 4581, and a support for multiple hash functions
defined in RFC 4982. While CGAs were originally defined for the SEND
protocol, they have proved to be a useful security tool in other
environments too, and its usage has been proposed to secure other
protocols such as the Shim6 multihoming protocol and the Mobile IPv6
protocol. While there is very little deployment of SEND to date, there
are a number of implementations, recommendations in the NIST and DOD
profiles call for use of SEND, and operating system vendors are
considering adding SEND to their next releases. As a result, it is
desirable to review the current state of the SEND and CGA
specifications, maintain and complement them where necessary. Up to
date cryptographic algorithms are needed, and the protocols need to be
able to deal with certain common situations currently not supported.
Specifically, the WG will look at the following issues:
- Develop an informational document analyzing the implications of
recent attacks on hash functions used by SeND protocol. Current SeND
specification uses the SHA-1 hash algorithm and does not provides
support for hash algorithm agility, hence the critical need for
understanding the impact of the attacks on the SeND protocol. In
addition, if as a result of the aforementioned analysis it is deemed
necessary, standard-track extensions to the SeND protocol to support
multiple hash algorithms will be defined.
- Specify a standards-track CGA and SeND extensions to support
multiple public key algorithms. As currently defined CGA and SeND can
only use RSA keys, and they lack support for other public key
algorithms (e.g. Elliptic Curve Cryptography -- ECC).
- Develop X.509 certificate management tools for SeND. SeND utilizes
X.509v3 certificates for performing router authorization. It uses the
X.509 extension for IP addresses to verify whether the router is
authorized to advertise the mentioned IP addresses. Since the IP
addresses extension does not explicitly mention what functions the
node can perform for the IP addresses it becomes impossible to know
the reason for which the certificate was allowed. In order to
facilitate issuance of certificates for specific functions, we need to
encode the functions permitted for the certificate into the
certificate itself. The WG will develop a certificate profile,
including a definition of X.509 Extended Key Usage for SeND . In
addition, the WG will recommend best practices for (1) enrollment, (2)
revocation checking, and (3) publishing of certificates. This WG will
ensure that the profile and recommended practices will cover usage by
hosts in addition to routers. The working group will coordinate this
activity with the PKIX and SIDR WGs. Prior to IESG submission of
the certificate profile, the working group will seek input from
and coordinate with other groups enabling cryptographic identification
of device-related properties (e.g., IEEE 802.1ar, IEEE 802.16, WiMAX
Forum, IETF CAPWAP WG).
- Develop a standard track document defining a mechanism to perform
SeND certificate provisioning for routers. SeND protocol as defined in
RFC3971 specifies how IPv6 nodes can trust the prefixes advertised by
a router. The solution is based on the use of the IP Address
Delegation extension (RFC3779) in X.509 v3 certificates (RFC3280).
This work will provide the tools require to provision with the
certificates to the routers in an automatic manner. The working will
coordinate this activity with the PKIX WG.
- Produce a problem statement document for Neighbor Discovery Proxies
and then specify standards-track SEND Extensions to support Neighbor
Discovery Proxies: SEND protocol as currently defined in RFC 3971
lacks of support for ND Proxies defined in RFC 3775 and RFC 4389.
Extensions to the SEND protocol will be defined in order to provide
equivalent SEND security capabilities to ND Proxies.
- Develop an informational document analysing different approaches to
allow SeND and CGAs to be used in conjunction with DHCP, and making
recommendations on which are the best suited. Recharter based on the
result of the analysis.
- Update base specifications (RFC 3971 and 3972).