draft-ietf-dnsext-dnssec-experiments-00.txt   draft-ietf-dnsext-dnssec-experiments-01.txt 
Network Working Group D. Blacka DNSEXT D. Blacka
Internet-Draft Verisign, Inc. Internet-Draft Verisign, Inc.
Expires: August 3, 2005 February 2, 2005 Expires: January 19, 2006 July 18, 2005
DNSSEC Experiments DNSSEC Experiments
draft-ietf-dnsext-dnssec-experiments-00 draft-ietf-dnsext-dnssec-experiments-01
Status of this Memo Status of this Memo
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Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2005). Copyright (C) The Internet Society (2005).
Abstract Abstract
In the long history of the development of the DNS security [1] In the long history of the development of the DNS security extensions
extensions (DNSSEC), a number of alternate methodologies and [1] (DNSSEC), a number of alternate methodologies and modifications
modifications have been proposed and rejected for practical, rather have been proposed and rejected for practical, rather than strictly
than strictly technical, reasons. There is a desire to be able to technical, reasons. There is a desire to be able to experiment with
experiment with these alternate methods in the public DNS. This these alternate methods in the public DNS. This document describes a
document describes a methodology for deploying alternate, methodology for deploying alternate, non-backwards-compatible, DNSSEC
non-backwards-compatible, DNSSEC methodologies in an experimental methodologies in an experimental fashion without disrupting the
fashion without disrupting the deployment of standard DNSSEC. deployment of standard DNSSEC.
Table of Contents Table of Contents
1. Definitions and Terminology . . . . . . . . . . . . . . . . 3 1. Definitions and Terminology . . . . . . . . . . . . . . . . 3
2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Experiments . . . . . . . . . . . . . . . . . . . . . . . . 5 3. Experiments . . . . . . . . . . . . . . . . . . . . . . . . 5
4. Method . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 4. Method . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5. Defining an Experiment . . . . . . . . . . . . . . . . . . . 8 5. Defining an Experiment . . . . . . . . . . . . . . . . . . . 8
6. Considerations . . . . . . . . . . . . . . . . . . . . . . . 9 6. Considerations . . . . . . . . . . . . . . . . . . . . . . . 9
7. Transitions . . . . . . . . . . . . . . . . . . . . . . . . 10 7. Transitions . . . . . . . . . . . . . . . . . . . . . . . . 10
8. Security Considerations . . . . . . . . . . . . . . . . . . 11 8. Security Considerations . . . . . . . . . . . . . . . . . . 11
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . 12 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . 12
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 13 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
10.1 Normative References . . . . . . . . . . . . . . . . . . . 13 10.1 Normative References . . . . . . . . . . . . . . . . . . 13
10.2 Informative References . . . . . . . . . . . . . . . . . . 13 10.2 Informative References . . . . . . . . . . . . . . . . . 13
Editorial Comments . . . . . . . . . . . . . . . . . . . . . 14 Author's Address . . . . . . . . . . . . . . . . . . . . . . 13
Author's Address . . . . . . . . . . . . . . . . . . . . . . 14 Intellectual Property and Copyright Statements . . . . . . . 14
Intellectual Property and Copyright Statements . . . . . . . 15
1. Definitions and Terminology 1. Definitions and Terminology
Throughout this document, familiarity with the DNS system (RFC 1035 Throughout this document, familiarity with the DNS system (RFC 1035
[4]) and the DNS security extensions ([1], [2], and [3]. [4]) and the DNS security extensions ([1], [2], and [3].
The key words "MUST, "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST, "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY, and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY, and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [5]. document are to be interpreted as described in RFC 2119 [5].
2. Overview 2. Overview
Historically, experimentation with DNSSEC alternatives has been a Historically, experimentation with DNSSEC alternatives has been a
problematic endeavor. There has typically been a desire to both problematic endeavor. There has typically been a desire to both
introduce non-backwards-compatible changes to DNSSEC, and to try introduce non-backwards-compatible changes to DNSSEC, and to try
these changes on real zones in the public DNS. This creates a 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 problem when the change to DNSSEC would make all or part of the zone
using those changes appear bogus or otherwise broken to existing using those changes appear bogus (bad) or otherwise broken to
DNSSEC-aware resolvers. existing DNSSEC-aware resolvers.
This document describes a standard methodology for setting up public This document describes a standard methodology for setting up public
DNSSEC experiments. This methodology addresses the issue of DNSSEC experiments. This methodology addresses the issue of co-
co-existence with standard DNSSEC and DNS by using unknown algorithm existence with standard DNSSEC and DNS by using unknown algorithm
identifiers to hide the experimental DNSSEC protocol modifications identifiers to hide the experimental DNSSEC protocol modifications
from standard DNSSEC-aware resolvers. from standard DNSSEC-aware resolvers.
3. Experiments 3. Experiments
When discussing DNSSEC experiments, it is necessary to classify these When discussing DNSSEC experiments, it is necessary to classify these
experiments into two broad categories: experiments into two broad categories:
Backwards-Compatible: describes experimental changes that, while not Backwards-Compatible: describes experimental changes that, while not
strictly adhering to the DNSSEC standard, are nonetheless strictly adhering to the DNSSEC standard, are nonetheless
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The methodology described in this document is not necessary for The methodology described in this document is not necessary for
backwards-compatible experiments, although it certainly could be used backwards-compatible experiments, although it certainly could be used
if desired. if desired.
Note that, in essence, this metholodolgy would also be used to Note that, in essence, this metholodolgy would also be used to
introduce a new DNSSEC algorithm, independently from any DNSSEC introduce a new DNSSEC algorithm, independently from any DNSSEC
experimental protocol change. experimental protocol change.
4. Method 4. Method
The core of the methodology is the use of only "unknown" algorithms The core of the methodology is the use of strictly "unknown"
to sign the experimental zone, and more importantly, having only algorithms to sign the experimental zone, and more importantly,
unknown algorithm DS records for the delegation to the zone at the having only unknown algorithm DS records for the delegation to the
parent. zone at the parent.
This technique works because of the way DNSSEC-compliant validators This technique works because of the way DNSSEC-compliant validators
are expected to work in the presence of a DS set with only unknown are expected to work in the presence of a DS set with only unknown
algorithms. From [3], Section 5.2: algorithms. From [3], Section 5.2:
If the validator does not support any of the algorithms listed in If the validator does not support any of the algorithms listed in
an authenticated DS RRset, then the resolver has no supported an authenticated DS RRset, then the resolver has no supported
authentication path leading from the parent to the child. The authentication path leading from the parent to the child. The
resolver should treat this case as it would the case of an resolver should treat this case as it would the case of an
authenticated NSEC RRset proving that no DS RRset exists, as authenticated NSEC RRset proving that no DS RRset exists, as
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If the resolver does not support any of the algorithms listed in If the resolver does not support any of the algorithms listed in
an authenticated DS RRset, then the resolver will not be able to an authenticated DS RRset, then the resolver will not be able to
verify the authentication path to the child zone. In this case, verify the authentication path to the child zone. In this case,
the resolver SHOULD treat the child zone as if it were unsigned. the resolver SHOULD treat the child zone as if it were unsigned.
While this behavior isn't strictly mandatory (as marked by MUST), it While this behavior isn't strictly mandatory (as marked by MUST), it
is unlikely that a validator would not implement the behavior, or, 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 more to the point, it will not violate this behavior in an unsafe way
(see below (Section 6).) (see below (Section 6).)
Because we are talking about experiments, it is recommended that Because we are talking about experiments, it is RECOMMENDED that
private algorithm numbers be used (see [2], appendix A.1.1 private algorithm numbers be used (see [2], appendix A.1.1. Note
[Comment.1].) Normally, instead of actually inventing new signing that secure handling of private algorithms requires special handing
algorithms, the recommended path is to create alternate algorithm by the validator logic. See [6] for futher details.) Normally,
identifiers that are aliases for the existing, known algorithms. instead of actually inventing new signing algorithms, the recommended
While, strictly speaking, it is only necessary to create an alternate path is to create alternate algorithm identifiers that are aliases
identifier for the mandatory algorithms (currently, this is only for the existing, known algorithms. While, strictly speaking, it is
algorithm 5, RSASHA1), it is RECOMMENDED that all OPTIONAL defined only necessary to create an alternate identifier for the mandatory
algorithms be aliased as well. algorithms, it is RECOMMENDED that all OPTIONAL defined algorithms be
aliased as well.
It is RECOMMENDED that for a particular DNSSEC experiment, a It is RECOMMENDED that for a particular DNSSEC experiment, a
particular domain name base is chosen for all new algorithms, then particular domain name base is chosen for all new algorithms, then
the algorithm number (or name) is prepended to it. For example, for the algorithm number (or name) is prepended to it. For example, for
experiment A, the base name of "dnssec-experiment-a.example.com" is experiment A, the base name of "dnssec-experiment-a.example.com" is
chosen. Then, aliases for algorithms 3 (DSA) and 5 (RSASHA1) are chosen. Then, aliases for algorithms 3 (DSA) and 5 (RSASHA1) are
defined to be "3.dnssec-experiment-a.example.com" and defined to be "3.dnssec-experiment-a.example.com" and "5.dnssec-
"5.dnssec-experiment-a.example.com". However, any unique identifier experiment-a.example.com". However, any unique identifier will
will suffice. suffice.
Using this method, resolvers (or, more specificially, DNSSEC Using this method, resolvers (or, more specificially, DNSSEC
validators) essentially indicate their ability to understand the validators) essentially indicate their ability to understand the
DNSSEC experiment's semantics by understanding what the new algorithm DNSSEC experiment's semantics by understanding what the new algorithm
identifiers signify. identifiers signify.
This method creates two classes of DNSSEC-aware servers and This method creates two classes of DNSSEC-aware servers and
resolvers: servers and resolvers that are aware of the experiment resolvers: servers and resolvers that are aware of the experiment
(and thus recognize the experiments algorithm identifiers and (and thus recognize the experiments algorithm identifiers and
experimental semantics), and servers and resolvers that are unware of experimental semantics), and servers and resolvers that are unware of
the experiment. 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.
5. Defining an Experiment 5. Defining an Experiment
The DNSSEC experiment must define the particular set of (previously The DNSSEC experiment must define the particular set of (previously
unknown) algorithms that identify the experiment, and define what unknown) algorithms that identify the experiment, and define what
each unknown algorithm identifier means. Typically, unless the each unknown algorithm identifier means. Typically, unless the
experiment is actually experimenting with a new DNSSEC algorithm, experiment is actually experimenting with a new DNSSEC algorithm,
this will be a mapping of private algorithm identifiers to existing, this will be a mapping of private algorithm identifiers to existing,
known algorithms. known algorithms.
Typically, the experiment will choose a DNS name as the algorithm Normally the experiment will choose a DNS name as the algorithm
identifier base. This DNS name SHOULD be under the control of the identifier base. This DNS name SHOULD be under the control of the
authors of the experiment. Then the experiment will define a mapping authors of the experiment. Then the experiment will define a mapping
between known mandatory and optional algorithms into this private between known mandatory and optional algorithms into this private
algorithm identifier space. Alternately, the experiment MAY use the algorithm identifier space. Alternately, the experiment MAY use the
OID private algorithm space instead (using algorithm number 254), or OID private algorithm space instead (using algorithm number 254), or
may choose non-private algorithm numbers, although this would require may choose non-private algorithm numbers, although this would require
an IANA allocation (see below (Section 9).) an IANA allocation (see below (Section 9).)
For example, an experiment might specify in its description the DNS For example, an experiment might specify in its description the DNS
name "dnssec-experiment-a.example.com" as the base name, and provide name "dnssec-experiment-a.example.com" as the base name, and provide
the mapping of "3.dnssec-experiment-a.example.com" is an alias of the mapping of "3.dnssec-experiment-a.example.com" is an alias of
DNSSEC algorithm 3 (DSA), and "5.dnssec-experiment-a.example.com" is DNSSEC algorithm 3 (DSA), and "5.dnssec-experiment-a.example.com" is
an alias of DNSSEC algorithm 5 (RSASHA1). an alias of DNSSEC algorithm 5 (RSASHA1).
Resolvers MUST then only recognize the experiment's semantics when Resolvers MUST then only recognize the experiment's semantics when
present in a zone signed by one or more of these private algorithms. present in a zone signed by one or more of these private algorithms.
In general, however, resolvers involved in the experiment are In general, however, resolvers involved in the experiment are
expected to understand both standard DNSSEC and the defined expected to understand both standard DNSSEC and the defined
experimental DNSSEC protocol, although this isn't, strictly speaking, experimental DNSSEC protocol, although this isn't required.
required.
6. Considerations 6. Considerations
There are a number of considerations with using this methodology. There are a number of considerations with using this methodology.
1. Under some circumstances, it may be that the experiment will not 1. Under some circumstances, it may be that the experiment will not
be sufficiently masked by this technique and may cause resolution be sufficiently masked by this technique and may cause resolution
problem for resolvers not aware of the experiment. For instance, problem for resolvers not aware of the experiment. For instance,
the resolver may look at the not validatable response and the resolver may look at the not validatable response and
conclude that the response is bogus, either due to local policy conclude that the response is bogus, either due to local policy
or implementation details. This is not expected to be the common or implementation details. This is not expected to be the common
case, however. case, however.
2. It will, in general, not be possible for DNSSEC-aware resolvers
2. In general, it will not be possible for DNSSEC-aware resolvers
not aware of the experiment to build a chain of trust through an not aware of the experiment to build a chain of trust through an
experimental zone. experimental zone.
7. Transitions 7. Transitions
If an experiment is successful, there may be a desire to move the If an experiment is successful, there may be a desire to move the
experiment to a standards-track extension. One way to do so would be experiment to a standards-track extension. One way to do so would be
to move from private algorithm numbers to IANA allocated algorithm to move from private algorithm numbers to IANA allocated algorithm
numbers, with otherwise the same meaning. This would still leave a numbers, with otherwise the same meaning. This would still leave a
divide between resolvers that understood the extension versus divide between resolvers that understood the extension versus
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IANA may need to allocate new DNSSEC algorithm numbers if that IANA may need to allocate new DNSSEC algorithm numbers if that
transition approach is taken, or the experiment decides to use transition approach is taken, or the experiment decides to use
allocated numbers to begin with. No IANA action is required to allocated numbers to begin with. No IANA action is required to
deploy an experiment using private algorithm identifiers. deploy an experiment using private algorithm identifiers.
10. References 10. References
10.1 Normative References 10.1 Normative References
[1] Arends, R., Austein, R., Massey, D., Larson, M. and S. Rose, [1] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose,
"DNS Security Introduction and Requirements", "DNS Security Introduction and Requirements", RFC 4033,
draft-ietf-dnsext-dnssec-intro-13 (work in progress), October March 2005.
2004.
[2] Arends, R., "Resource Records for the DNS Security Extensions", [2] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose,
draft-ietf-dnsext-dnssec-records-11 (work in progress), October "Resource Records for the DNS Security Extensions", RFC 4034,
2004. March 2005.
[3] Arends, R., "Protocol Modifications for the DNS Security [3] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose,
Extensions", draft-ietf-dnsext-dnssec-protocol-09 (work in "Protocol Modifications for the DNS Security Extensions",
progress), October 2004. RFC 4035, March 2005.
10.2 Informative References 10.2 Informative References
[4] Mockapetris, P., "Domain names - implementation and [4] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, November 1987. specification", STD 13, RFC 1035, November 1987.
[5] Bradner, S., "Key words for use in RFCs to Indicate Requirement [5] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997. Levels", BCP 14, RFC 2119, March 1997.
Editorial Comments [6] Weiler, S., "Clarifications and Implementation Notes for
DNSSECbis", draft-weiler-dnsext-dnssec-bis-updates-00 (work in
[Comment.1] Note: how private algorithms work in DNSSEC is not well progress), March 2005.
explained in the DNSSECbis RFCs. In particular, how to
validate that the DS records contain only unknown
algorithms is not explained at all.
Author's Address Author's Address
David Blacka David Blacka
Verisign, Inc. Verisign, Inc.
21355 Ridgetop Circle 21355 Ridgetop Circle
Dulles, VA 20166 Dulles, VA 20166
US US
Phone: +1 703 948 3200 Phone: +1 703 948 3200
EMail: davidb@verisign.com Email: davidb@verisign.com
URI: http://www.verisignlabs.com URI: http://www.verisignlabs.com
Intellectual Property Statement Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information made any independent effort to identify any such rights. Information
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