draft-ietf-dnsext-dnssec-experiments-01.txt

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DNSEXT                                                         D. Blacka
Internet-Draft                                            Verisign, Inc.
Expires: January 19, 2006                                  July 18, 2005


                           DNSSEC Experiments
                draft-ietf-dnsext-dnssec-experiments-01

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Copyright Notice

   Copyright (C) The Internet Society (2005).

Abstract

   In the long history of the development of the DNS security extensions
   [1] (DNSSEC), a number of alternate methodologies and modifications
   have been proposed and rejected for practical, rather than strictly
   technical, reasons.  There is a desire to be able to experiment with
   these alternate methods in the public DNS.  This document describes a
   methodology for deploying alternate, non-backwards-compatible, DNSSEC
   methodologies in an experimental fashion without disrupting the
   deployment of standard DNSSEC.




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Table of Contents

   1.   Definitions and Terminology  . . . . . . . . . . . . . . . .   3
   2.   Overview . . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.   Experiments  . . . . . . . . . . . . . . . . . . . . . . . .   5
   4.   Method . . . . . . . . . . . . . . . . . . . . . . . . . . .   6
   5.   Defining an Experiment . . . . . . . . . . . . . . . . . . .   8
   6.   Considerations . . . . . . . . . . . . . . . . . . . . . . .   9
   7.   Transitions  . . . . . . . . . . . . . . . . . . . . . . . .  10
   8.   Security Considerations  . . . . . . . . . . . . . . . . . .  11
   9.   IANA Considerations  . . . . . . . . . . . . . . . . . . . .  12
   10.  References . . . . . . . . . . . . . . . . . . . . . . . . .  13
     10.1   Normative References . . . . . . . . . . . . . . . . . .  13
     10.2   Informative References . . . . . . . . . . . . . . . . .  13
        Author's Address . . . . . . . . . . . . . . . . . . . . . .  13
        Intellectual Property and Copyright Statements . . . . . . .  14



































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1.  Definitions and Terminology

   Throughout this document, familiarity with the DNS system (RFC 1035
   [4]) and the DNS security extensions ([1], [2], and [3].

   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 RFC 2119 [5].











































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2.  Overview

   Historically, experimentation with DNSSEC alternatives has been a
   problematic endeavor.  There has typically been a desire to both
   introduce non-backwards-compatible changes to DNSSEC, and to try
   these changes on real zones in the public DNS.  This creates a
   problem when the change to DNSSEC would make all or part of the zone
   using those changes appear bogus (bad) or otherwise broken to
   existing DNSSEC-aware resolvers.

   This document describes a standard methodology for setting up public
   DNSSEC experiments.  This methodology addresses the issue of co-
   existence with standard DNSSEC and DNS by using unknown algorithm
   identifiers to hide the experimental DNSSEC protocol modifications
   from standard DNSSEC-aware resolvers.




































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3.  Experiments

   When discussing DNSSEC experiments, it is necessary to classify these
   experiments into two broad categories:

   Backwards-Compatible: describes experimental changes that, while not
      strictly adhering to the DNSSEC standard, are nonetheless
      interoperable with clients and server that do implement the DNSSEC
      standard.

   Non-Backwards-Compatible: describes experiments that would cause a
      standard DNSSEC-aware resolver to (incorrectly) determine that all
      or part of a zone is bogus, or to otherwise not interoperable with
      standard DNSSEC clients and servers.

   Not included in these terms are experiments with the core DNS
   protocol itself.

   The methodology described in this document is not necessary for
   backwards-compatible experiments, although it certainly could be used
   if desired.

   Note that, in essence, this metholodolgy would also be used to
   introduce a new DNSSEC algorithm, independently from any DNSSEC
   experimental protocol change.


























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4.  Method

   The core of the methodology is the use of strictly "unknown"
   algorithms to sign the experimental zone, and more importantly,
   having only unknown algorithm DS records for the delegation to the
   zone at the parent.

   This technique works because of the way DNSSEC-compliant validators
   are expected to work in the presence of a DS set with only unknown
   algorithms.  From [3], Section 5.2:

      If the validator does not support any of the algorithms listed in
      an authenticated DS RRset, then the resolver has no supported
      authentication path leading from the parent to the child.  The
      resolver should treat this case as it would the case of an
      authenticated NSEC RRset proving that no DS RRset exists, as
      described above.

   And further:

      If the resolver does not support any of the algorithms listed in
      an authenticated DS RRset, then the resolver will not be able to
      verify the authentication path to the child zone.  In this case,
      the resolver SHOULD treat the child zone as if it were unsigned.

   While this behavior isn't strictly mandatory (as marked by MUST), it
   is unlikely that a validator would not implement the behavior, or,
   more to the point, it will not violate this behavior in an unsafe way
   (see below (Section 6).)

   Because we are talking about experiments, it is RECOMMENDED that
   private algorithm numbers be used (see [2], appendix A.1.1.  Note
   that secure handling of private algorithms requires special handing
   by the validator logic.  See [6] for futher details.)  Normally,
   instead of actually inventing new signing algorithms, the recommended
   path is to create alternate algorithm identifiers that are aliases
   for the existing, known algorithms.  While, strictly speaking, it is
   only necessary to create an alternate identifier for the mandatory
   algorithms, it is RECOMMENDED that all OPTIONAL defined algorithms be
   aliased as well.

   It is RECOMMENDED that for a particular DNSSEC experiment, a
   particular domain name base is chosen for all new algorithms, then
   the algorithm number (or name) is prepended to it.  For example, for
   experiment A, the base name of "dnssec-experiment-a.example.com" is
   chosen.  Then, aliases for algorithms 3 (DSA) and 5 (RSASHA1) are
   defined to be "3.dnssec-experiment-a.example.com" and "5.dnssec-
   experiment-a.example.com".  However, any unique identifier will



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   suffice.

   Using this method, resolvers (or, more specificially, DNSSEC
   validators) essentially indicate their ability to understand the
   DNSSEC experiment's semantics by understanding what the new algorithm
   identifiers signify.

   This method creates two classes of DNSSEC-aware servers and
   resolvers: servers and resolvers that are aware of the experiment
   (and thus recognize the experiments algorithm identifiers and
   experimental semantics), and servers and resolvers that are unware of
   the experiment.

   This method also precludes any zone from being both in an experiment
   and in a classic DNSSEC island of security.  That is, a zone is
   either in an experiment and only experimentally validatable, or it
   isn't.


































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