draft-ietf-dnsext-dnssec-experiments-03.txt   draft-ietf-dnsext-dnssec-experiments-04.txt 
DNSEXT D. Blacka DNSEXT D. Blacka
Internet-Draft VeriSign, Inc. Internet-Draft VeriSign, Inc.
Intended status: Standards Track April 7, 2006 Intended status: Best Current March 20, 2007
Expires: October 9, 2006 Practice
Expires: September 21, 2007
DNSSEC Experiments DNSSEC Experiments
draft-ietf-dnsext-dnssec-experiments-03 draft-ietf-dnsext-dnssec-experiments-04
Status of this Memo Status of this Memo
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have been or will be disclosed, and any of which he or she becomes have been or will be disclosed, and any of which he or she becomes
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on October 9, 2006. This Internet-Draft will expire on September 21, 2007.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2006). Copyright (C) The IETF Trust (2007).
Abstract Abstract
This document describes a methodology for deploying alternate, non- This document describes a methodology for deploying alternate, non-
backwards-compatible, DNSSEC methodologies in an experimental fashion backwards-compatible, DNSSEC methodologies in an experimental fashion
without disrupting the deployment of standard DNSSEC. without disrupting the deployment of standard DNSSEC.
Table of Contents Table of Contents
1. Definitions and Terminology . . . . . . . . . . . . . . . . . 3 1. Definitions and Terminology . . . . . . . . . . . . . . . . . 3
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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
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 14 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 14
Intellectual Property and Copyright Statements . . . . . . . . . . 15 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
[5]) and the DNS security extensions ([2], [3], and [4] is assumed. [5]) and the DNS security extensions (RFC 4033 [2], RFC 4034 [3], and
RFC 4035 [4]) is assumed.
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 [1]. document are to be interpreted as described in RFC 2119 [1].
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 these introduce non-backwards-compatible changes to DNSSEC and to try these
changes on real zones in the public DNS. This creates a problem when 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 the change to DNSSEC would make all or part of the zone using those
changes appear bogus (bad) or otherwise broken to existing security- changes appear bogus (bad) or otherwise broken to existing security-
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4. Method 4. Method
The core of the methodology is the use of strictly unknown algorithm The core of the methodology is the use of strictly unknown algorithm
identifiers when signing the experimental zone, and more importantly, identifiers when signing the experimental zone, and more importantly,
having only unknown algorithm identifiers in the DS records for the having only unknown algorithm identifiers in the DS records for the
delegation to the zone at the parent. delegation to the 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
algorithm identifiers. From [4], Section 5.2: algorithm identifiers. From RFC 4035 [4], 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
described above. described above.
And further: And further:
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 Although this behavior isn't strictly mandatory (as marked by MUST),
is likely that a validator would implement this behavior, or, more to it is unlikely for a validator to implement a substantially different
the point, it would handle this situation in a safe way (see below behavior. Essentially, if the validator does not have a usable chain
(Section 6).) of trust to a child zone, then it can only do one of two things:
treat responses from the zone as insecure (the recommended behavior),
or treat the responses as bogus. If the validator chooses the
latter, this will both violate the expectation of the zone owner and
defeat the purpose of the above rule. However, with local policy, it
is within the right of a validator to refuse to trust certain zones
based on any criteria, including the use of unknown signing
algorithms.
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 [3], appendix A.1.1. Note private algorithm numbers be used (see RFC 4034 [3], appendix A.1.1.
that secure handling of private algorithms requires special handing Note that secure handling of private algorithms requires special
by the validator logic. See [6] for further details.) Normally, handing by the validator logic. See draft-ietf-dnssec-bis-updates
instead of actually inventing new signing algorithms, the recommended [6] for further details.) Normally, instead of actually inventing
path is to create alternate algorithm identifiers that are aliases new signing algorithms, the recommended path is to create alternate
for the existing, known algorithms. While, strictly speaking, it is algorithm identifiers that are aliases for the existing, known
only necessary to create an alternate identifier for the mandatory algorithms. While, strictly speaking, it is only necessary to create
algorithms, it is suggested that all optional defined algorithms be an alternate identifier for the mandatory algorithms, it is suggested
aliased as well. 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-experiment-a.example.com". However, any unique identifier "5.dnssec-experiment-a.example.com". However, any unique identifier
will suffice. will suffice.
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identifiers signify. identifiers signify.
This method creates two classes of security-aware servers and This method creates two classes of security-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 experiment's algorithm identifiers and (and thus recognize the experiment's algorithm identifiers and
experimental semantics), and servers and resolvers that are unaware experimental semantics), and servers and resolvers that are unaware
of the experiment. of the experiment.
This method also precludes any zone from being both in an 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 and in a classic DNSSEC island of security. That is, a zone is
either in an experiment and only experimentally validatable, or it is either in an experiment and only possible to validate experimentally,
not. or it is not.
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) algorithm identifiers that identify the experiment, and unknown) algorithm identifiers that identify the experiment, and
define what each unknown algorithm identifier means. Typically, define what each unknown algorithm identifier means. Typically,
unless the experiment is actually experimenting with a new DNSSEC unless the experiment is actually experimenting with a new DNSSEC
algorithm, this will be a mapping of private algorithm identifiers to algorithm, this will be a mapping of private algorithm identifiers to
existing, known algorithms. existing, known algorithms.
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others that the resolver might understand. others that the resolver might understand.
In general, resolvers involved in the experiment are expected to In general, resolvers involved in the experiment are expected to
understand both standard DNSSEC and the defined experimental DNSSEC understand both standard DNSSEC and the defined experimental DNSSEC
protocol, although this isn't required. protocol, although this isn't 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. If an unaware validator does not correctly follow the rules laid
be sufficiently masked by this technique and may cause resolution out in RFC 4035 (e.g., the validator interprets a DNSSEC record
problem for resolvers not aware of the experiment. For instance, prior to validating it), or if the experiment is broader in scope
the resolver may look at a non-validatable response and conclude that just modifying the DNSSEC semantics, the experiment may not
that the response is bogus, either due to local policy or be sufficiently masked by this technique. This may cause
implementation details. This is not expected to be a common unintended resolution failures.
case, however.
2. It will not be possible for security-aware resolvers unaware of 2. It will not be possible for security-aware resolvers unaware of
the experiment to build a chain of trust through an experimental the experiment to build a chain of trust through an experimental
zone. zone.
7. Use in Non-Experiments 7. Use in Non-Experiments
This general methodology MAY be used for non-backwards compatible This general methodology MAY be used for non-backwards compatible
DNSSEC protocol changes that start out as or become standards. In DNSSEC protocol changes that start out as or become standards. In
this case: this case:
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o Resolvers MAY recognize the protocol change in zones not signed o Resolvers MAY recognize the protocol change in zones not signed
(or not solely signed) using the new algorithm identifiers. (or not solely signed) using the new algorithm identifiers.
8. Security Considerations 8. Security Considerations
Zones using this methodology will be considered insecure by all Zones using this methodology will be considered insecure by all
resolvers except those aware of the experiment. It is not generally resolvers except those aware of the experiment. It is not generally
possible to create a secure delegation from an experimental zone that possible to create a secure delegation from an experimental zone that
will be followed by resolvers unaware of the experiment. will be followed by resolvers unaware of the experiment.
Implementers should take into account any security issues that may
result from environments being configured to trust both experimental
and non-experimental zones. If the experimental zone is more
vulnerable to attacks, it could, for example, be used promote trust
in zones not part of the experiment, possibly under the control of an
attacker.
9. IANA Considerations 9. IANA Considerations
This document has no IANA actions. This document has no IANA actions.
10. References 10. References
10.1. Normative References 10.1. Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement [1] 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.
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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
Full Copyright Statement Full Copyright Statement
Copyright (C) The Internet Society (2006). Copyright (C) The IETF Trust (2007).
This document is subject to the rights, licenses and restrictions This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors contained in BCP 78, and except as set forth therein, the authors
retain all their rights. retain all their rights.
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