draft-ietf-dnsext-dnssec-experiments-02.txt   draft-ietf-dnsext-dnssec-experiments-03.txt 
DNSEXT D. Blacka DNSEXT D. Blacka
Internet-Draft Verisign, Inc. Internet-Draft VeriSign, Inc.
Expires: August 27, 2006 February 23, 2006 Intended status: Standards Track April 7, 2006
Expires: October 9, 2006
DNSSEC Experiments DNSSEC Experiments
draft-ietf-dnsext-dnssec-experiments-02 draft-ietf-dnsext-dnssec-experiments-03
Status of this Memo Status of this Memo
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Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2006). Copyright (C) The Internet Society (2006).
Abstract Abstract
In the long history of the development of the DNS security extensions This document describes a methodology for deploying alternate, non-
[1] (DNSSEC), a number of alternate methodologies and modifications backwards-compatible, DNSSEC methodologies in an experimental fashion
have been proposed and rejected for practical, rather than strictly without disrupting the deployment of standard DNSSEC.
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.
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. Use in Non-Experiments . . . . . . . . . . . . . . . . . . . . 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
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
[4]) and the DNS security extensions ([1], [2], and [3]. [5]) and the DNS security extensions ([2], [3], and [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 [5]. 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 introduce non-backwards-compatible changes to DNSSEC and to try these
these changes on real zones in the public DNS. This creates a changes on real zones in the public DNS. This creates a problem when
problem when the change to DNSSEC would make all or part of the zone the change to DNSSEC would make all or part of the zone using those
using those changes appear bogus (bad) or otherwise broken to changes appear bogus (bad) or otherwise broken to existing security-
existing DNSSEC-aware resolvers. aware resolvers.
This document describes a standard methodology for setting up public This document describes a standard methodology for setting up DNSSEC
DNSSEC experiments. This methodology addresses the issue of co- experiments. This methodology addresses the issue of co-existence
existence with standard DNSSEC and DNS by using unknown algorithm with standard DNSSEC and DNS by using unknown algorithm identifiers
identifiers to hide the experimental DNSSEC protocol modifications to hide the experimental DNSSEC protocol modifications from standard
from standard DNSSEC-aware resolvers. security-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
interoperable with clients and server that do implement the DNSSEC interoperable with clients and servers that do implement the
standard. DNSSEC standard.
Non-Backwards-Compatible: describes experiments that would cause a Non-Backwards-Compatible: describes experiments that would cause a
standard DNSSEC-aware resolver to (incorrectly) determine that all standard security-aware resolver to (incorrectly) determine that
or part of a zone is bogus, or to otherwise not interoperate with all or part of a zone is bogus, or to otherwise not interoperate
standard DNSSEC clients and servers. with standard DNSSEC clients and servers.
Not included in these terms are experiments with the core DNS Not included in these terms are experiments with the core DNS
protocol itself. protocol itself.
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 may be used
if desired. if desired.
Note that, in essence, this metholodology would also be used to
introduce a new DNSSEC algorithm, independently from any DNSSEC
experimental protocol change.
4. Method 4. Method
The core of the methodology is the use of strictly "unknown" The core of the methodology is the use of strictly unknown algorithm
algorithms to sign the experimental zone, and more importantly, identifiers when signing the experimental zone, and more importantly,
having only unknown algorithm DS records for the delegation to the having only unknown algorithm identifiers in the DS records for 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
algorithms. From [3], Section 5.2: algorithm identifiers. From [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 While this behavior isn't strictly mandatory (as marked by MUST), it
is unlikely that a validator would not implement the behavior, or, is likely that a validator would implement this behavior, or, more to
more to the point, it will not violate this behavior in an unsafe way the point, it would handle this situation in a safe way (see below
(see below (Section 6).) (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. Note private algorithm numbers be used (see [3], appendix A.1.1. Note
that secure handling of private algorithms requires special handing that secure handling of private algorithms requires special handing
by the validator logic. See [6] for futher details.) Normally, by the validator logic. See [6] for further details.) Normally,
instead of actually inventing new signing algorithms, the recommended instead of actually inventing new signing algorithms, the recommended
path is to create alternate algorithm identifiers that are aliases path is to create alternate algorithm identifiers that are aliases
for the existing, known algorithms. While, strictly speaking, it is for the existing, known algorithms. While, strictly speaking, it is
only necessary to create an alternate identifier for the mandatory only necessary to create an alternate identifier for the mandatory
algorithms, it is RECOMMENDED that all OPTIONAL defined algorithms be algorithms, it is suggested that all optional defined algorithms be
aliased as well. 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.
Using this method, resolvers (or, more specificially, DNSSEC Using this method, resolvers (or, more specifically, 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 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 experiments algorithm identifiers and (and thus recognize the experiment's algorithm identifiers and
experimental semantics), and servers and resolvers that are unware of experimental semantics), and servers and resolvers that are unaware
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 either in an experiment and only experimentally validatable, or it is
isn't. 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) algorithms that identify the experiment, and define what unknown) algorithm identifiers that identify the experiment, and
each unknown algorithm identifier means. Typically, unless the define what each unknown algorithm identifier means. Typically,
experiment is actually experimenting with a new DNSSEC algorithm, unless the experiment is actually experimenting with a new DNSSEC
this will be a mapping of private algorithm identifiers to existing, algorithm, this will be a mapping of private algorithm identifiers to
known algorithms. existing, known algorithms.
Normally 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.
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 declare
the mapping of "3.dnssec-experiment-a.example.com" is an alias of that "3.dnssec-experiment-a.example.com" is an alias of DNSSEC
DNSSEC algorithm 3 (DSA), and "5.dnssec-experiment-a.example.com" is algorithm 3 (DSA), and that "5.dnssec-experiment-a.example.com" is an
an alias of DNSSEC algorithm 5 (RSASHA1). alias of DNSSEC algorithm 5 (RSASHA1).
Resolvers MUST then only recognize the experiment's semantics when Resolvers MUST only recognize the experiment's semantics when present
present in a zone signed by one or more of these private algorithms. in a zone signed by one or more of these algorithm identifiers. This
is necessary to isolate the semantics of one experiment from any
others that the resolver might understand.
In general, however, resolvers involved in the experiment are In general, resolvers involved in the experiment are expected to
expected to understand both standard DNSSEC and the defined understand both standard DNSSEC and the defined experimental DNSSEC
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. 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 a non-validatable response and conclude
conclude that the response is bogus, either due to local policy that the response is bogus, either due to local policy or
or implementation details. This is not expected to be the common implementation details. This is not expected to be a common
case, however. case, however.
2. It will not be possible for DNSSEC-aware resolvers not aware 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. Transitions 7. Use in Non-Experiments
If an experiment is successful, there may be a desire to move the This general methodology MAY be used for non-backwards compatible
experiment to a standards-track extension. One way to do so would be DNSSEC protocol changes that start out as or become standards. In
to move from private algorithm numbers to IANA allocated algorithm this case:
numbers, with otherwise the same meaning. This would still leave a
divide between resolvers that understood the extension versus
resolvers that did not. It would, in essence, create an additional
version of DNSSEC.
An alternate technique might be to do a typecode rollover, thus o The protocol change SHOULD use public IANA allocated algorithm
actually creating a definitive new version of DNSSEC. There may be identifiers instead of private algorithm identifiers. This will
other transition techniques available, as well. help identify the protocol change as a standard, rather than an
experiment.
o Resolvers MAY recognize the protocol change in zones not signed
(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.
9. IANA Considerations 9. IANA Considerations
IANA may need to allocate new DNSSEC algorithm numbers if that This document has no IANA actions.
transition approach is taken, or the experiment decides to use
allocated numbers to begin with. No IANA action is required to
deploy an experiment using private algorithm identifiers.
10. References 10. References
10.1. Normative References 10.1. Normative References
[1] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose, [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[2] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose,
"DNS Security Introduction and Requirements", RFC 4033, "DNS Security Introduction and Requirements", RFC 4033,
March 2005. March 2005.
[2] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose, [3] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose,
"Resource Records for the DNS Security Extensions", RFC 4034, "Resource Records for the DNS Security Extensions", RFC 4034,
March 2005. March 2005.
[3] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose, [4] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose,
"Protocol Modifications for the DNS Security Extensions", "Protocol Modifications for the DNS Security Extensions",
RFC 4035, March 2005. RFC 4035, March 2005.
10.2. Informative References 10.2. Informative References
[4] Mockapetris, P., "Domain names - implementation and [5] 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
Levels", BCP 14, RFC 2119, March 1997.
[6] Austein, R. and S. Weiler, "Clarifications and Implementation [6] Austein, R. and S. Weiler, "Clarifications and Implementation
Notes for DNSSECbis", draft-ietf-dnsext-dnssec-bis-updates-02 Notes for DNSSECbis", draft-ietf-dnsext-dnssec-bis-updates-02
(work in progress), January 2006. (work in progress), January 2006.
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
Full Copyright Statement Full Copyright Statement
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http://www.ietf.org/ipr. http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at this standard. Please address the information to the IETF at
ietf-ipr@ietf.org. ietf-ipr@ietf.org.
Acknowledgment Acknowledgment
Funding for the RFC Editor function is currently provided by the Funding for the RFC Editor function is provided by the IETF
Internet Society. Administrative Support Activity (IASA).
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