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Versions: 00 01
Network Working Group P. Hoffman
Internet-Draft VPN Consortium
Updates: 2535, 3755, 4034 August 27, 2009
(if approved)
Intended status: Standards Track
Expires: February 28, 2010
Cryptographic Algorithm Identifier Allocation for DNSSEC
draft-hoffman-dnssec-alg-allocation-01
Status of this Memo
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Copyright Notice
Copyright (c) 2009 IETF Trust and the persons identified as the
document authors. All rights reserved.
Hoffman Expires February 28, 2010 [Page 1]
Internet-Draft DNSSEC Alg. Allocation August 2009
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Abstract
This document specifies how DNSSEC cryptographic algorithm
identifiers in the IANA registries are allocated. It changes the
rule from "standard required" to "RFC required".
1. Introduction
[RFC2535] specifies that that IANA registry for DNS Security
Algorithm Numbers be updated by IETF Standards Action only, with the
exception of two values 253 and 254. In essence, this means that for
an algorithm to get its own entry in the registry, the algorithm must
be defined in an RFC on Standards Track as defined in [RFC2026]. The
rule from RFC 2535 is repeated in [RFC3755] and [RFC4034].
RFC 2535 allows algorithms that are not on standards track to use
private values 253 and 254 in signatures. In each case, an
unregistered private name must be included with each use of the
algorithm in order to differentiate different algorithms that use the
value.
2. Requirements for Assignments in the DNS Security Algorithm Numbers
Registry
This document changes the rule for registration from requiring a
Standards Track RFC to requiring a published RFC of any type. There
are two reasons for relaxing the rule:
o There are some algorithms that are useful that may not be able to
be in a Standards Track RFC. For example, an algorithm might be
sponsored by a government and use cryptography that has not been
evaluated thoroughly enough to be able to be put on Standards
Track. Another example is that the algorithm might have an
unclear intellectual property rights situation, and that prevents
the algorithm from being put on Standards Track.
o Although the size of the registry is quite restricted (about 250
entries), new algorithms are proposed relatively rarely. It could
easily be many decades before there is any reason to consider
restricting the registry again.
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Some developers will care about the standards level of the RFCs that
are in the registry. The registry should reflect the current
standards level of each algorithm listed.
Because the size of the registry is smaller than many IETF
registries, and because some members of the DNS community have
expressed concern about the registry eventually filling up, the IETF
should re-evaluate the requirements for entry into this registry when
the registry is about half full. That evaluation may lead to tighter
restrictions or a new mechanism for essentially extending the size of
the registry.
The private-use values, 253 and 254, are still useful for developers
who want to test, in private, algorithms for which there is no RFC.
This document does not change the semantics of those two values.
3. Expectations For Implementations
It is important to note that, according to RFC 4034, DNSSEC
implementations are not expected to include all of the algorithms
listed in the IANA registry; in fact, RFC 4034 and the IANA registry
list an algorithm that implementations should not include. This
document does nothing to change the expectation that there will be
items listed in the IANA registry that need not be (and in some
cases, should not be) included in all implementations.
There are many reasons why a DNSSEC implementation might not include
one or more of the algorithms listed, even those on Standards Track.
In order to be compliant with the RFC 4034, an implementation only
needs to implement the algorithms listed as mandatory to implement in
the that standard, or updates to that standard. This document does
nothing to change the list of mandatory to implement algorithms in
RFC 4034.
4. IANA Considerations
This document updates allocation rules for unassigned values in the
"Domain Name System Security (DNSSEC) Algorithm Numbers" registry
located at http://www.iana.org/assignments/dns-sec-alg-numbers/
dns-sec-alg-numbers.xhtml, in the sub-registry titled "DNS Security
Algorithm Numbers". The registration procedure for values that were
not assigned before this document is published is "RFC Required".
IANA is requested to add a textual notation to the "References"
column in the registry that gives the current standards status for
each RFC that is listed in the registry.
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5. Security Considerations
An algorithm described in an RFC that is not on Standards Track may
have weaker security than one that is on standards track; in fact,
that may be the reason that the algorithm was not allowed on
Standards Track. Note, however, that not being on Standards Track
does not necessarily mean that an algorithm is weaker. There are
other reasons (such as intellectual property concerns) that can keep
algorithms that are widely considered to be strong off of Standards
Track.
6. References
6.1. Normative References
[RFC2535] Eastlake, D., "Domain Name System Security Extensions",
RFC 2535, March 1999.
[RFC3755] Weiler, S., "Legacy Resolver Compatibility for Delegation
Signer (DS)", RFC 3755, May 2004.
[RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S.
Rose, "Resource Records for the DNS Security Extensions",
RFC 4034, March 2005.
6.2. Informative References
[RFC2026] Bradner, S., "The Internet Standards Process -- Revision
3", BCP 9, RFC 2026, October 1996.
Appendix A. Experimental and Documentation Values
During the early discussion of this document, it was proposed that
maybe there should be a small number of values reserved for
"experimental" purposes. This proposal was not included in this
document because of the long history in the IETF of experimental
values that became permanent. That is, a developer would release
(maybe "experimentally") a version of software that had the
experimental value associated with a particular extension,
competitors would code their systems to test interoperability, and
then no one wanted to change the values in their software to the
"real" value that was later assigned.
There was also a proposal that IANA should reserve two values to be
used in documentation only, similar to the way that "example.com" has
been reserved as a domain name. That proposal was also not included
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in this document because all values need to be associated with some
algorithm, and there is no problem with having examples that point to
commonly-deployed algorithms.
Appendix B. Change History
This section is to be removed before publication as an RFC.
B.1. Differences between -00 and -01
A few editorial nits that really should have been caught in the -00.
Added the section on "Expectations For Implementations" to clarify
that this document is not changing any such expectations or updating
that part of RFC 4034.
Author's Address
Paul Hoffman
VPN Consortium
Email: paul.hoffman@vpnc.org
Hoffman Expires February 28, 2010 [Page 5]
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