draft-ietf-dnsext-rfc2539bis-dhk-07.txt   draft-ietf-dnsext-rfc2539bis-dhk-08.txt 
INTERNET-DRAFT Diffie-Hellman Information in the DNS INTERNET-DRAFT Diffie-Hellman Information in the DNS
OBSOLETES: RFC 2539 Donald E. Eastlake 3rd OBSOLETES: RFC 2539 Donald E. Eastlake 3rd
Motorola Laboratories Motorola Laboratories
Expires: April 2007 October 2006
Storage of Diffie-Hellman Keying Information in the DNS Storage of Diffie-Hellman Keying Information in the DNS
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<draft-ietf-dnsext-rfc2539bis-dhk-07.txt> <draft-ietf-dnsext-rfc2539bis-dhk-08.txt>
Status of This Document Status of This Document
By submitting this Internet-Draft, each author represents that any By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware 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 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. aware will be disclosed, in accordance with Section 6 of BCP 79.
Distribution of this document is unlimited. Comments should be sent Distribution of this document is unlimited. Comments should be sent
to the DNS extensions working group mailing list to the DNS extensions working group mailing list
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1. Introduction............................................3 1. Introduction............................................3
1.1 About This Document....................................3 1.1 About This Document....................................3
1.2 About Diffie-Hellman...................................3 1.2 About Diffie-Hellman...................................3
2. Encoding Diffie-Hellman Keying Information..............4 2. Encoding Diffie-Hellman Keying Information..............4
3. Performance Considerations..............................5 3. Performance Considerations..............................5
4. IANA Considerations.....................................5 4. IANA Considerations.....................................5
5. Security Considerations.................................5 5. Security Considerations.................................5
Copyright, Disclaimer, and Additional IPR Provisions.......5 Copyright, Disclaimer, and Additional IPR Provisions.......5
Normative References.......................................7 Normative References.......................................7
Informative Refences.......................................7 Informative References.....................................7
Author's Address...........................................8
Expiration and File Name...................................8
Appendix A: Well known prime/generator pairs...............9 Appendix A: Well known prime/generator pairs...............9
A.1. Well-Known Group 1: A 768 bit prime..................9 A.1. Well-Known Group 1: A 768 bit prime..................9
A.2. Well-Known Group 2: A 1024 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.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
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1. Introduction 1. Introduction
The Domain Name System (DNS) is the global hierarchical replicated The Domain Name System (DNS) is the global hierarchical replicated
distributed database system for Internet addressing, mail proxy, and distributed database system for Internet addressing, mail proxy, and
similar information [RFC 1034, 1035]. The DNS has been extended to other information [RFC1034], [RFC1035]. The DNS has been extended to
include digital signatures and cryptographic keys as described in include digital signatures and cryptographic keys as described in
[RFC 4033, 4034, 4035] and additonal work is underway which would use [RFC4033], [RFC4034, [RFC4035] and there is additional work which
the storage of keying information in the DNS. 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 1.1 About This Document
This document describes how to store Diffie-Hellman keys in the DNS. This document describes how to store Diffie-Hellman keys in the DNS.
Familiarity with the Diffie-Hellman key exchange algorithm is assumed Familiarity with the Diffie-Hellman key exchange algorithm is assumed
[Schneier, RFC 2631]. [Schneier], [RFC2631].
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. document are to be interpreted as described in [RFC2119].
1.2 About Diffie-Hellman 1.2 About Diffie-Hellman
Diffie-Hellman requires two parties to interact to derive keying Diffie-Hellman requires two parties to interact to derive keying
information which can then be used for authentication. Thus Diffie- information which can then be used for authentication. Thus Diffie-
Hellman is inherently a key agreement algorithm. As a result, no Hellman is inherently a key agreement algorithm. As a result, no
format is defined for Diffie-Hellman "signature information". For format is defined for Diffie-Hellman "signature information". For
example, assume that two parties have local secrets "i" and "j". example, assume that two parties have local secrets "i" and "j".
Assume they each respectively calculate X and Y as follows: Assume they each respectively calculate X and Y as follows:
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follows: follows:
Zi = Y**i ( mod p ) Zi = Y**i ( mod p )
Zj = X**j ( 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 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 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 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 the adversary can derive i or j by performing a discrete logarithm
mod p which is hard for strong p and g).
The private key for each party is their secret i (or j). The public
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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 key is the pair p and g, which is the same for both parties, and
their individual X (or Y). their individual X (or Y).
For further information about Diffie-Hellman and precautions to take For further information about Diffie-Hellman and precautions to take
in deciding on a p and g, see [RFC 2631]. in deciding on a p and g, see [RFC 2631].
2. Encoding Diffie-Hellman Keying Information 2. Encoding Diffie-Hellman Keying Information
When Diffie-Hellman keys appear within the RDATA portion of a RR, When Diffie-Hellman keys appear within the RDATA portion of a RR,
they are encoded as shown below. they are encoded as shown below.
The period of key validity is not included in this data but is 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 indicated separately, for example by an RR such as RRSIG which signs
and authenticates the RR containing the keying information. 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 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| KEY flags | protocol | algorithm=2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| prime length (or flag) | prime (p) (or special) / | prime length (or flag) | prime (p) (or special) /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ prime (p) (variable length) | generator length | / prime (p) (variable length) | generator length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| generator (g) (variable length) | | generator (g) (variable length) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| public value length | public value (variable length)/ | public value length | public value (variable length)/
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ public value (g^i mod p) (variable length) | / public value (g^i mod p) (variable length) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Prime length is the length of the Diffie-Hellman prime (p) in bytes 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 if it is 16 or greater. Prime contains the binary representation of
the Diffie-Hellman prime with most significant byte first (i.e., in 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" 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 field is actually an unsigned index into a table of 65,536
prime/generator pairs and the generator length SHOULD be zero. See prime/generator pairs and the generator length SHOULD be zero. See
Appedix A for defined table entries and Section 4 for information on Appendix A for defined table entries and Section 4 for information on
allocating additional table entries. The meaning of a zero or 3 allocating additional table entries. The meaning of a zero or 3
through 15 value for "prime length" is reserved. through 15 value for "prime length" is reserved.
Generator length is the length of the generator (g) in bytes. Generator length is the length of the generator (g) in bytes.
Generator is the binary representation of generator with most Generator is the binary representation of generator with most
significant byte first. PublicValueLen is the Length of the Public significant byte first. PublicValueLen is the Length of the Public
Value (g**i (mod p)) in bytes. PublicValue is the binary Value (g**i (mod p)) in bytes. PublicValue is the binary
representation of the DH public value with most significant byte representation of the DH public value with most significant byte
first. first.
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it is still advisable at this time to make reasonable efforts to it is still advisable at this time to make reasonable efforts to
minimize the size of RR sets containing keying information consistent minimize the size of RR sets containing keying information consistent
with adequate security. with adequate security.
4. IANA Considerations 4. IANA Considerations
Assignment of meaning to Prime Lengths of 0 and 3 through 15 requires Assignment of meaning to Prime Lengths of 0 and 3 through 15 requires
an IETF consensus as defined in [RFC 2434]. an IETF consensus as defined in [RFC 2434].
Well known prime/generator pairs number 0x0000 through 0x07FF can Well known prime/generator pairs number 0x0000 through 0x07FF can
only be assigned by an IETF standards action. [RFC 2539], the only be assigned by an IETF Standards Action. [RFC2539], the Proposed
Proposed Standard predecessor of this document, assigned 0x0001 Standard predecessor of this document, assigned 0x0001 through
through 0x0002. This document additionally assigns 0x0003. Pairs 0x0002. This document additionally assigns 0x0003 through 0x0008.
number 0s0800 through 0xBFFF can be assigned based on RFC Pairs number 0s0800 through 0xBFFF can be assigned based on
documentation. Pairs number 0xC000 through 0xFFFF are available for Specification Required as specified in [RFC2434]. Pairs number 0xC000
private use and are not centrally coordinated. Use of such private through 0xFFFF are available for private use and are not centrally
pairs outside of a closed environment may result in conflicts and/or coordinated. Use of such private pairs outside of a closed
security failures. environment may result in conflicts and/or security failures.
5. Security Considerations 5. Security Considerations
Keying information retrieved from the DNS should not be trusted Keying information retrieved from the DNS should not be trusted
unless (1) it has been securely obtained from a secure resolver or unless (1) it has been securely obtained from a secure resolver or
independently verified by the user and (2) this secure resolver and independently verified by the user and (2) this secure resolver and
secure obtainment or independent verification conform to security secure obtainment or independent verification conform to security
policies acceptable to the user. As with all cryptographic policies acceptable to the user. As with all cryptographic
algorithms, evaluating the necessary strength of the key is important algorithms, evaluating the necessary strength of the key is important
and dependent on security policy. and dependent on security policy.
In addition, the usual Diffie-Hellman key strength considerations In addition, the usual Diffie-Hellman key strength considerations
apply. (p-1)/2 SHOULD also be prime, g SHOULD be primitive mod p, p apply. (p-1)/2 SHOULD also be prime, g SHOULD be primitive mod p, p
SHOULD be "large", etc. See [RFC 2631, Schneier]. SHOULD be "large", etc. See [RFC2631], [Schneier].
Copyright, Disclaimer, and Additional IPR Provisions Copyright, Disclaimer, and Additional IPR Provisions
Copyright (C) The Internet Society (2006). This document is subject to Copyright (C) The Internet Society 2006. This document is subject to
the rights, licenses and restrictions contained in BCP 78, and except the rights, licenses and restrictions contained in BCP 78, and except
as set forth therein, the authors retain all their rights. as set forth therein, the authors retain all their rights.
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This document and the information contained herein are provided on an This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
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this standard. Please address the information to the IETF at ietf- this standard. Please address the information to the IETF at ietf-
ipr@ietf.org. ipr@ietf.org.
INTERNET-DRAFT Diffie-Hellman Information in the DNS INTERNET-DRAFT Diffie-Hellman Information in the DNS
Normative References Normative References
[RFC 2119] - Bradner, S., "Key words for use in RFCs to Indicate [RFC 2119] - Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC 2434] - "Guidelines for Writing an IANA Considerations Section [RFC2434] - "Guidelines for Writing an IANA Considerations Section in
in RFCs", T. Narten, H. Alvestrand, October 1998. RFCs", T. Narten, H. Alvestrand, October 1998.
[RFC 2631] - "Diffie-Hellman Key Agreement Method", E. Rescorla, June [RFC 2631] - "Diffie-Hellman Key Agreement Method", E. Rescorla, June
1999. 1999.
[RFC3526] - Kivinen, T., and M. Kojo, "More Modular Exponential
(MODP) Diffie-Hellman groups for Internet Key Exchange (IKE)", May
2003.
[RFC 4034] - Arends, R., Austein, R., Larson, M., Massey, D., and S. [RFC 4034] - Arends, R., Austein, R., Larson, M., Massey, D., and S.
Rose, "Resource Records for the DNS Security Extensions", RFC 4034, Rose, "Resource Records for the DNS Security Extensions", RFC 4034,
March 2005. March 2005.
Informative Refences Informative References
[RFC 1034] - "Domain names - concepts and facilities", P. [RFC1034] - "Domain names - concepts and facilities", P. Mockapetris,
Mockapetris, November 1987. November 1987.
[RFC 1035] - "Domain names - implementation and specification", P. [RFC 1035] - "Domain names - implementation and specification", P.
Mockapetris, November 1987. Mockapetris, November 1987.
[RFC 2539] - "Storage of Diffie-Hellman Keys in the Domain Name [RFC2930] - Eastlake, D., "Secret Key Establishment for DNS (TKEY
System (DNS)", D. Eastlake, March 1999, obsoleted by this RFC. RR)", September 2000.
[RFC2539] - "Storage of Diffie-Hellman Keys in the Domain Name System
(DNS)", D. Eastlake, March 1999, obsoleted by this RFC.
[RFC 2671] - "Extension Mechanisms for DNS (EDNS0)", P. Vixie, August [RFC 2671] - "Extension Mechanisms for DNS (EDNS0)", P. Vixie, August
1999. 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.
[RFC 4033] - Arends, R., Austein, R., Larson, M., Massey, D., and S. [RFC 4033] - Arends, R., Austein, R., Larson, M., Massey, D., and S.
Rose, "DNS Security Introduction and Requirements", RFC 4033, March Rose, "DNS Security Introduction and Requirements", RFC 4033, March
2005. 2005.
[RFC 4035] - Arends, R., Austein, R., Larson, M., Massey, D., and S. [RFC 4035] - Arends, R., Austein, R., Larson, M., Massey, D., and S.
INTERNET-DRAFT Diffie-Hellman Information in the DNS
Rose, "Protocol Modifications for the DNS Security Extensions", RFC Rose, "Protocol Modifications for the DNS Security Extensions", RFC
4035, March 2005. 4035, March 2005.
[Schneier] - Bruce Schneier, "Applied Cryptography: Protocols, [Schneier] - Bruce Schneier, "Applied Cryptography: Protocols,
Algorithms, and Source Code in C" (Second Edition), 1996, John Wiley Algorithms, and Source Code in C" (Second Edition), 1996, John Wiley
and Sons. and Sons.
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Author's Address
Donald E. Eastlake 3rd
Motorola Laboratories
155 Beaver Street
Milford, MA 01757 USA
Telephone: +1-508-786-7554
EMail: Donald.Eastlake@motorola.com
Expiration and File Name
This draft expires in September 2006.
Its file name is draft-ietf-dnsext-rfc2539bis-dhk-07.txt.
INTERNET-DRAFT Diffie-Hellman Information in the DNS
Appendix A: Well known prime/generator pairs Appendix A: Well known prime/generator pairs
These numbers are copied from the IPSEC effort where the derivation These numbers are copied from the IPSEC effort where the derivation
of these values is more fully explained and additional information is of these values is more fully explained and additional information is
available. Richard Schroeppel performed all the mathematical and available. Richard Schroeppel performed all the mathematical and
computational work for this appendix. computational work for this appendix.
A.1. Well-Known Group 1: A 768 bit prime 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 The prime is 2^768 - 2^704 - 1 + 2^64 * { [2^638 pi] + 149686 }. Its
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FFFFFFFF FFFFFFFF C90FDAA2 2168C234 C4C6628B 80DC1CD1 FFFFFFFF FFFFFFFF C90FDAA2 2168C234 C4C6628B 80DC1CD1
29024E08 8A67CC74 020BBEA6 3B139B22 514A0879 8E3404DD 29024E08 8A67CC74 020BBEA6 3B139B22 514A0879 8E3404DD
EF9519B3 CD3A431B 302B0A6D F25F1437 4FE1356D 6D51C245 EF9519B3 CD3A431B 302B0A6D F25F1437 4FE1356D 6D51C245
E485B576 625E7EC6 F44C42E9 A637ED6B 0BFF5CB6 F406B7ED E485B576 625E7EC6 F44C42E9 A637ED6B 0BFF5CB6 F406B7ED
EE386BFB 5A899FA5 AE9F2411 7C4B1FE6 49286651 ECE45B3D EE386BFB 5A899FA5 AE9F2411 7C4B1FE6 49286651 ECE45B3D
C2007CB8 A163BF05 98DA4836 1C55D39A 69163FA8 FD24CF5F C2007CB8 A163BF05 98DA4836 1C55D39A 69163FA8 FD24CF5F
83655D23 DCA3AD96 1C62F356 208552BB 9ED52907 7096966D 83655D23 DCA3AD96 1C62F356 208552BB 9ED52907 7096966D
670C354E 4ABC9804 F1746C08 CA237327 FFFFFFFF FFFFFFFF 670C354E 4ABC9804 F1746C08 CA237327 FFFFFFFF FFFFFFFF
Generator: Length (32 bit words): 1, Data (hex): 2 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
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.
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.
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