One document matched: draft-ietf-dnsext-rfc2539bis-dhk-08.txt
Differences from draft-ietf-dnsext-rfc2539bis-dhk-07.txt
INTERNET-DRAFT Diffie-Hellman Information in the DNS
OBSOLETES: RFC 2539 Donald E. Eastlake 3rd
Motorola Laboratories
Expires: April 2007 October 2006
Storage of Diffie-Hellman Keying Information in the DNS
------- -- -------------- ------ ----------- -- --- ---
<draft-ietf-dnsext-rfc2539bis-dhk-08.txt>
Status of This Document
By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79.
Distribution of this document is unlimited. Comments should be sent
to the DNS extensions working group mailing list
<namedroppers@ops.ietf.org>.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/1id-abstracts.html
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html
Abstract
The standard method for encoding Diffie-Hellman keys in the Domain
Name System is specified.
D. Eastlake 3rd [Page 1]
INTERNET-DRAFT Diffie-Hellman Information in the DNS
Acknowledgements
Part of the format for Diffie-Hellman keys and the description
thereof was taken from a work in progress by Ashar Aziz, Tom Markson,
and Hemma Prafullchandra. In addition, the following persons
provided useful comments that were incorporated into the predecessor
of this document: Ran Atkinson, Thomas Narten.
Table of Contents
Status of This Document....................................1
Abstract...................................................1
Acknowledgements...........................................2
Table of Contents..........................................2
1. Introduction............................................3
1.1 About This Document....................................3
1.2 About Diffie-Hellman...................................3
2. Encoding Diffie-Hellman Keying Information..............4
3. Performance Considerations..............................5
4. IANA Considerations.....................................5
5. Security Considerations.................................5
Copyright, Disclaimer, and Additional IPR Provisions.......5
Normative References.......................................7
Informative References.....................................7
Appendix A: Well known prime/generator pairs...............9
A.1. Well-Known Group 1: A 768 bit prime..................9
A.2. Well-Known Group 2: A 1024 bit prime.................9
A.3. Well-Known Group 3: A 1536 bit prime................10
A.4 Well known Groups 4 through 8.........................10
Appendix B: Changes from RFC 2539.........................10
Author's Address..........................................12
Expiration and File Name..................................12
D. Eastlake 3rd [Page 2]
INTERNET-DRAFT Diffie-Hellman Information in the DNS
1. Introduction
The Domain Name System (DNS) is the global hierarchical replicated
distributed database system for Internet addressing, mail proxy, and
other information [RFC1034], [RFC1035]. The DNS has been extended to
include digital signatures and cryptographic keys as described in
[RFC4033], [RFC4034, [RFC4035] and there is additional work which
would use keying information in the DNS such as TKEY [RFC2930] and
GSS-TSIG [RFC3645]. This document does not change the wire format of
KEY RR's but extends the use of Diffie-Hellman DNS keys to cover the
DNSKEY RR.
1.1 About This Document
This document describes how to store Diffie-Hellman keys in the DNS.
Familiarity with the Diffie-Hellman key exchange algorithm is assumed
[Schneier], [RFC2631].
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 [RFC2119].
1.2 About Diffie-Hellman
Diffie-Hellman requires two parties to interact to derive keying
information which can then be used for authentication. Thus Diffie-
Hellman is inherently a key agreement algorithm. As a result, no
format is defined for Diffie-Hellman "signature information". For
example, assume that two parties have local secrets "i" and "j".
Assume they each respectively calculate X and Y as follows:
X = g**i ( mod p )
Y = g**j ( mod p )
They exchange these quantities and then each calculates a Z as
follows:
Zi = Y**i ( mod p )
Zj = X**j ( mod p )
Zi and Zj will both be equal to g**(i*j)(mod p) and will be a shared
secret between the two parties that an adversary who does not know i
or j will not be able to learn from the exchanged messages (unless
the adversary can derive i or j by performing a discrete logarithm
D. Eastlake 3rd [Page 3]
INTERNET-DRAFT Diffie-Hellman Information in the DNS
mod p which is hard for strong p and g).
The private key for each party is their secret i (or j). The public
key is the pair p and g, which is the same for both parties, and
their individual X (or Y).
For further information about Diffie-Hellman and precautions to take
in deciding on a p and g, see [RFC2631].
2. Encoding Diffie-Hellman Keying Information
When Diffie-Hellman keys appear within the RDATA portion of a RR,
they are encoded as shown below.
The period of key validity is not included in this data but is
indicated separately, for example by an RR such as RRSIG which signs
and authenticates the RR containing the keying information.
1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| prime length (or flag) | prime (p) (or special) /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ prime (p) (variable length) | generator length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| generator (g) (variable length) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| public value length | public value (variable length)/
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ public value (g^i mod p) (variable length) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Prime length is the length of the Diffie-Hellman prime (p) in bytes
if it is 16 or greater. Prime contains the binary representation of
the Diffie-Hellman prime with most significant byte first (i.e., in
network order). If "prime length" field is 1 or 2, then the "prime"
field is actually an unsigned index into a table of 65,536
prime/generator pairs and the generator length SHOULD be zero. See
Appendix A for defined table entries and Section 4 for information on
allocating additional table entries. The meaning of a zero or 3
through 15 value for "prime length" is reserved.
Generator length is the length of the generator (g) in bytes.
Generator is the binary representation of generator with most
significant byte first. PublicValueLen is the Length of the Public
Value (g**i (mod p)) in bytes. PublicValue is the binary
representation of the DH public value with most significant byte
first.
D. Eastlake 3rd [Page 4]
INTERNET-DRAFT Diffie-Hellman Information in the DNS
3. Performance Considerations
Current DNS implementations are optimized for small transfers,
typically less than 512 bytes including DNS overhead. Larger
transfers will perform correctly and extensions have been
standardized [RFC2671] to make larger transfers more efficient. But
it is still advisable at this time to make reasonable efforts to
minimize the size of RR sets containing keying information consistent
with adequate security.
4. IANA Considerations
Assignment of meaning to Prime Lengths of 0 and 3 through 15 requires
an IETF consensus as defined in [RFC2434].
Well known prime/generator pairs number 0x0000 through 0x07FF can
only be assigned by an IETF Standards Action. [RFC2539], the Proposed
Standard predecessor of this document, assigned 0x0001 through
0x0002. This document additionally assigns 0x0003 through 0x0008.
Pairs number 0s0800 through 0xBFFF can be assigned based on
Specification Required as specified in [RFC2434]. Pairs number 0xC000
through 0xFFFF are available for private use and are not centrally
coordinated. Use of such private pairs outside of a closed
environment may result in conflicts and/or security failures.
5. Security Considerations
Keying information retrieved from the DNS should not be trusted
unless (1) it has been securely obtained from a secure resolver or
independently verified by the user and (2) this secure resolver and
secure obtainment or independent verification conform to security
policies acceptable to the user. As with all cryptographic
algorithms, evaluating the necessary strength of the key is important
and dependent on security policy.
In addition, the usual Diffie-Hellman key strength considerations
apply. (p-1)/2 SHOULD also be prime, g SHOULD be primitive mod p, p
SHOULD be "large", etc. See [RFC2631], [Schneier].
Copyright, Disclaimer, and Additional IPR Provisions
Copyright (C) The Internet Society 2006. This document is subject to
the rights, licenses and restrictions contained in BCP 78, and except
as set forth therein, the authors retain all their rights.
D. Eastlake 3rd [Page 5]
INTERNET-DRAFT Diffie-Hellman Information in the DNS
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in
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
made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at ietf-
ipr@ietf.org.
D. Eastlake 3rd [Page 6]
INTERNET-DRAFT Diffie-Hellman Information in the DNS
Normative References
[RFC2119] - Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2434] - "Guidelines for Writing an IANA Considerations Section in
RFCs", T. Narten, H. Alvestrand, October 1998.
[RFC2631] - "Diffie-Hellman Key Agreement Method", E. Rescorla, June
1999.
[RFC3526] - Kivinen, T., and M. Kojo, "More Modular Exponential
(MODP) Diffie-Hellman groups for Internet Key Exchange (IKE)", May
2003.
[RFC4034] - Arends, R., Austein, R., Larson, M., Massey, D., and S.
Rose, "Resource Records for the DNS Security Extensions", RFC 4034,
March 2005.
Informative References
[RFC1034] - "Domain names - concepts and facilities", P. Mockapetris,
November 1987.
[RFC1035] - "Domain names - implementation and specification", P.
Mockapetris, November 1987.
[RFC2930] - Eastlake, D., "Secret Key Establishment for DNS (TKEY
RR)", September 2000.
[RFC2539] - "Storage of Diffie-Hellman Keys in the Domain Name System
(DNS)", D. Eastlake, March 1999, obsoleted by this RFC.
[RFC2671] - "Extension Mechanisms for DNS (EDNS0)", P. Vixie, August
1999.
[RFC3645] - Kwan, S., et al "Generic Security Service Algorithm for
Secret Key Transaction Authentication for DNS (GSS-TSIG)", October
2000.
[RFC3755] - Weiler, S., "Legacy Resolver Compatibility for Delegation
Signer (DS)", May 2004.
[RFC4033] - Arends, R., Austein, R., Larson, M., Massey, D., and S.
Rose, "DNS Security Introduction and Requirements", RFC 4033, March
2005.
[RFC4035] - Arends, R., Austein, R., Larson, M., Massey, D., and S.
D. Eastlake 3rd [Page 7]
INTERNET-DRAFT Diffie-Hellman Information in the DNS
Rose, "Protocol Modifications for the DNS Security Extensions", RFC
4035, March 2005.
[Schneier] - Bruce Schneier, "Applied Cryptography: Protocols,
Algorithms, and Source Code in C" (Second Edition), 1996, John Wiley
and Sons.
D. Eastlake 3rd [Page 8]
INTERNET-DRAFT Diffie-Hellman Information in the DNS
Appendix A: Well known prime/generator pairs
These numbers are copied from the IPSEC effort where the derivation
of these values is more fully explained and additional information is
available. Richard Schroeppel performed all the mathematical and
computational work for this appendix.
A.1. Well-Known Group 1: A 768 bit prime
The prime is 2^768 - 2^704 - 1 + 2^64 * { [2^638 pi] + 149686 }. Its
decimal value is
155251809230070893513091813125848175563133404943451431320235
119490296623994910210725866945387659164244291000768028886422
915080371891804634263272761303128298374438082089019628850917
0691316593175367469551763119843371637221007210577919
Prime modulus: Length (32 bit words): 24, Data (hex):
FFFFFFFF FFFFFFFF C90FDAA2 2168C234 C4C6628B 80DC1CD1
29024E08 8A67CC74 020BBEA6 3B139B22 514A0879 8E3404DD
EF9519B3 CD3A431B 302B0A6D F25F1437 4FE1356D 6D51C245
E485B576 625E7EC6 F44C42E9 A63A3620 FFFFFFFF FFFFFFFF
Generator: Length (32 bit words): 1, Data (hex): 2
A.2. Well-Known Group 2: A 1024 bit prime
The prime is 2^1024 - 2^960 - 1 + 2^64 * { [2^894 pi] + 129093 }.
Its decimal value is
179769313486231590770839156793787453197860296048756011706444
423684197180216158519368947833795864925541502180565485980503
646440548199239100050792877003355816639229553136239076508735
759914822574862575007425302077447712589550957937778424442426
617334727629299387668709205606050270810842907692932019128194
467627007
Prime modulus: Length (32 bit words): 32, Data (hex):
FFFFFFFF FFFFFFFF C90FDAA2 2168C234 C4C6628B 80DC1CD1
29024E08 8A67CC74 020BBEA6 3B139B22 514A0879 8E3404DD
EF9519B3 CD3A431B 302B0A6D F25F1437 4FE1356D 6D51C245
E485B576 625E7EC6 F44C42E9 A637ED6B 0BFF5CB6 F406B7ED
EE386BFB 5A899FA5 AE9F2411 7C4B1FE6 49286651 ECE65381
FFFFFFFF FFFFFFFF
Generator: Length (32 bit words): 1, Data (hex): 2
D. Eastlake 3rd [Page 9]
INTERNET-DRAFT Diffie-Hellman Information in the DNS
A.3. Well-Known Group 3: A 1536 bit prime
The prime is 2^1536 - 2^1472 - 1 + 2^64 * { [2^1406 pi] + 741804 }.
Its decimal value is
241031242692103258855207602219756607485695054850245994265411
694195810883168261222889009385826134161467322714147790401219
650364895705058263194273070680500922306273474534107340669624
601458936165977404102716924945320037872943417032584377865919
814376319377685986952408894019557734611984354530154704374720
774996976375008430892633929555996888245787241299381012913029
459299994792636526405928464720973038494721168143446471443848
8520940127459844288859336526896320919633919
Prime modulus Length (32 bit words): 48, Data (hex):
FFFFFFFF FFFFFFFF C90FDAA2 2168C234 C4C6628B 80DC1CD1
29024E08 8A67CC74 020BBEA6 3B139B22 514A0879 8E3404DD
EF9519B3 CD3A431B 302B0A6D F25F1437 4FE1356D 6D51C245
E485B576 625E7EC6 F44C42E9 A637ED6B 0BFF5CB6 F406B7ED
EE386BFB 5A899FA5 AE9F2411 7C4B1FE6 49286651 ECE45B3D
C2007CB8 A163BF05 98DA4836 1C55D39A 69163FA8 FD24CF5F
83655D23 DCA3AD96 1C62F356 208552BB 9ED52907 7096966D
670C354E 4ABC9804 F1746C08 CA237327 FFFFFFFF FFFFFFFF
Generator: Length (32 bit words): 1, Data (hex): 2
A.4 Well known Groups 4 through 8
The additional Diffie-Hellman Groups specified in [RFC3526] are also
adopted and assigned well known group numbers as follows:
Group Number Size
4 2048-bit
5 3072-bit
6 4096-bit
7 6144-bit
8 8192-bit
Appendix B: Changes from RFC 2539
When [RFC2539] was published, keys in the DNS appeared only in KEY
resource records. As described in [RFC3755], due to a revision in DNS
data origin authentication security, the recommended RR was changed
to DNSKEY which is described in [RFC4034]; however KEY continues to
be used in connection with TKEY [RFC2930].
Thus the primary change from [RFC2539] in this document is to
D. Eastlake 3rd [Page 10]
INTERNET-DRAFT Diffie-Hellman Information in the DNS
eliminate the tie to the KEY RRs. In addition, more well known
Diffie-Hellman Groups are listed and assigned identification numbers
and many references have been updated.
D. Eastlake 3rd [Page 11]
INTERNET-DRAFT Diffie-Hellman Information in the DNS
Author's Address
Donald E. Eastlake 3rd
Motorola Laboratories
111 Locke Drive
Marlborough, MA 01752 USA
Telephone: +1-508-786-7554
EMail: Donald.Eastlake@motorola.com
Expiration and File Name
This draft expires in April 2007.
Its file name is draft-ietf-dnsext-rfc2539bis-dhk-08.txt.
D. Eastlake 3rd [Page 12]
| PAFTECH AB 2003-2026 | 2026-04-23 11:45:12 |