TOC 
IPSECKEY WGM. Richardson
Internet-DraftSSW
Expires: October 27, 2003April 28, 2003

A method for storing IPsec keying material in DNS.
draft-ietf-ipseckey-rr-01.txt

Status of this Memo

This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026.

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/ietf/1id-abstracts.txt.

The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html.

This Internet-Draft will expire on October 27, 2003.

Copyright Notice

Copyright (C) The Internet Society (2003). All Rights Reserved.

Abstract

This document describes a new resource record for DNS. This record may be used to store public keys for use in IPsec systems.

This record replaces the functionality of the sub-type #1 of the KEY Resource Record, which has been proposed to be obsoleted by RFC3445 [11].



 TOC 

Table of Contents




 TOC 

1. Introduction

1.1 Overview

The IPSECKEY resource record (RR) is used to publish a public key that is to be associated with a Domain Name System (DNS) name. This can be the public key of a host, network, or application (in the case of per-port keying).

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 [6].

An IPSECKEY resource record SHOULD be authenticated DNSSEC resource record.

It is expected that there will often be multiple IPSECKEY resource records at the same terminal node. This will be due to the presence of multiple gateways and the need to rollover keys.

This resource record is class independent.



 TOC 

2. Storage formats

The type number for the IPSECKEY RR is TBD.

2.1 IPSECKEY RDATA format

The RDATA for an IPSECKEY RR consists of a precedence value, a public key (and algorithm type), and an optional gateway address.

    0                   1                   2                   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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  precedence   | gateway type  |  algorithm  |     gateway     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-------------+                 +
   ~                            gateway                            ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               /
   /                          public key                           /
   /                                                               /
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|

2.2 RDATA format - precedence

This is an 8-bit precedence for this record. This is interpreted in the same way as the PREFERENCE field described in section 3.3.9 of RFC1035 [2].

2.3 RDATA format - algorithm type

The algorithm field indicates the type of key that is present in the public key field. A positive number, larger than 0 identifies an algorithm type. The following values, which have been previously defined by IANA are useful (see RFC2535 [8]).

A value of 0 indicates that no key is present.

The following values defined by IANA are useful:

3
A DSA key is present, in the format defined in RFC2536 [9]
5
A RSA key is present, in the format defined in RFC3110 [10]

2.4 RDATA format - gateway type

The gateway type field indicates the format of the gateway that is stored in the gateway field.

The following values are defined:

0
No gateway is present
1
A 4-byte IPv4 address is present
2
A 16-byte IPv6 address is present
3
A wire-encoded domain-name is present. The wire-encoded format is self-describing, so the length is implicit.

2.5 RDATA format - gateway

The gateway field indicates a gateway to which an IPsec tunnel may be created in order to reach the entity holding this resource record.

There are three formats:

A 32-bit IPv4 address is present in the gateway field, as defined in section 3.4.1 of RFC1035[2]. This is a 32-bit number in network byte order.

A 128-bit IPv6 address is present in the gateway field. The data portion is an IPv6 address as described in section 3.2 of RFC1886[5]. This is a 128-bit number in network byte order.

The gateway field is a normal wire-encoded domain name (section 3.3 of RFC1035 [2]).

2.6 RDATA format - RSA public key

If the algorithm type has the value 5 then public key portion contains an RSA public key, encoded as described in secion 2 of RFC3110 [10].

RFC2065 limited the exponent and modulus to 2552 bits in length, and RFC3110 to 4096 bits. No such limit is specified here for the purposes of encoding and decoding.

The length in octets of the public exponent length is represented as one octet if it is in the range of 1 to 255 and by a zero octet followed by a two octet unsigned length if it is longer than 255 bytes. The public key modulus field is a multiprecision unsigned integer. The length of the modulus can be determined from the RDLENGTH and the preceding RDATA fields including the exponent.

Leading zero bytes are prohibited in the exponent and modulus.

2.7 RDATA format - DSA public key

If the algorithm type has the value 3, then public key portion contains an DSA public key, encoded as described in RFC2536 [9].



 TOC 

3. Presentation formats

3.1 Representation of IPSECKEY RRs

IPSECKEY RRs may appear as lines in a zone data master file. The precedence, gateway type and algorithm and gateway fields are REQUIRED. There base64 encoded public key block is OPTIONAL.

If no gateway is to be indicated, then the root (".") SHOULD be used.

IN     IPSECKEY ( precedence gateway-type algorithm
                  gateway base64-encoded-public-key )

3.2 Examples

An example of a node 192.2.0.38 that will accept IPsec tunnels on its own behalf.

38.0.2.192.in-addr.arpa. 7200 IN     IPSECKEY ( 10 5 1
                 192.2.0.38
                 AQOrXJxB56Q28iOO43Va36elIFFKc/QB2orIeL94BdC5X4idFQZjSpsZ
                 Th48wKVXUE9xjwUkwR4R4/+1vjNN7KFp9fcqa2OxgjsoGqCn+3OPR8La 
                 9uyvZg0OBuSTj3qkbh/2HacAUJ7vqvjQ3W8Wj6sMXtTueR8NNcdSzJh1 
                 49ch3zqfiXrxxna8+8UEDQaRR9KOPiSvXb2KjnuDan6hDKOT4qTZRRRC 
                 MWwnNQ9zPIMNbLBp0rNcZ+ZGFg2ckWtWh5yhv1iXYLV2vmd9DB6d4Dv8 
                 cW7scc3rPmDXpYR6APqPBRHlcbenfHCt+oCkEWse8OQhMM56KODIVQq3 
                 fejrfi1H )

An example of a node, 192.2.0.38 that has published its key only.

38.0.2.192.in-addr.arpa. 7200 IN     IPSECKEY ( 10 0 5
                 .
                 AQOrXJxB56Q28iOO43Va36elIFFKc/QB2orIeL94BdC5X4idFQZjSpsZ
                 Th48wKVXUE9xjwUkwR4R4/+1vjNN7KFp9fcqa2OxgjsoGqCn+3OPR8La 
                 9uyvZg0OBuSTj3qkbh/2HacAUJ7vqvjQ3W8Wj6sMXtTueR8NNcdSzJh1 
                 49ch3zqfiXrxxna8+8UEDQaRR9KOPiSvXb2KjnuDan6hDKOT4qTZRRRC 
                 MWwnNQ9zPIMNbLBp0rNcZ+ZGFg2ckWtWh5yhv1iXYLV2vmd9DB6d4Dv8 
                 cW7scc3rPmDXpYR6APqPBRHlcbenfHCt+oCkEWse8OQhMM56KODIVQq3 
                 fejrfi1H )

An example of a node, 192.2.0.38 that has delegated authority to the node 192.2.3.5.

38.0.2.192.in-addr.arpa. 7200 IN     IPSECKEY ( 10 5 1
                 192.2.3.5
                 AQOrXJxB56Q28iOO43Va36elIFFKc/QB2orIeL94BdC5X4idFQZjSpsZ
                 Th48wKVXUE9xjwUkwR4R4/+1vjNN7KFp9fcqa2OxgjsoGqCn+3OPR8La 
                 9uyvZg0OBuSTj3qkbh/2HacAUJ7vqvjQ3W8Wj6sMXtTueR8NNcdSzJh1 
                 49ch3zqfiXrxxna8+8UEDQaRR9KOPiSvXb2KjnuDan6hDKOT4qTZRRRC 
                 MWwnNQ9zPIMNbLBp0rNcZ+ZGFg2ckWtWh5yhv1iXYLV2vmd9DB6d4Dv8 
                 cW7scc3rPmDXpYR6APqPBRHlcbenfHCt+oCkEWse8OQhMM56KODIVQq3 
                 fejrfi1H )

An example of a node, 192.1.0.38 that has delegated authority to the node with the identity "mygateway.example.com".

38.0.2.192.in-addr.arpa. 7200 IN     IPSECKEY ( 10 3 5
                 mygateway.example.com.
                 AQOrXJxB56Q28iOO43Va36elIFFKc/QB2orIeL94BdC5X4idFQZjSpsZ
                 Th48wKVXUE9xjwUkwR4R4/+1vjNN7KFp9fcqa2OxgjsoGqCn+3OPR8La 
                 9uyvZg0OBuSTj3qkbh/2HacAUJ7vqvjQ3W8Wj6sMXtTueR8NNcdSzJh1 
                 49ch3zqfiXrxxna8+8UEDQaRR9KOPiSvXb2KjnuDan6hDKOT4qTZRRRC 
                 MWwnNQ9zPIMNbLBp0rNcZ+ZGFg2ckWtWh5yhv1iXYLV2vmd9DB6d4Dv8 
                 cW7scc3rPmDXpYR6APqPBRHlcbenfHCt+oCkEWse8OQhMM56KODIVQq3 
                 fejrfi1H )

An example of a node, 3ffe:501:4819:2000:210:f3ff:fe03:4d0 that has delegated authority to the node

$ORIGIN 0.0.0.2.9.1.8.4.1.0.5.0.e.f.f.3.ip6.int.
0.d.4.0.3.0.e.f.f.f.3.f.0.1.2.0 7200 IN     IPSECKEY ( 10 2 5
                 2001:200:0:8002::2000:1
                 AQOrXJxB56Q28iOO43Va36elIFFKc/QB2orIeL94BdC5X4idFQZjSpsZ
                 Th48wKVXUE9xjwUkwR4R4/+1vjNN7KFp9fcqa2OxgjsoGqCn+3OPR8La 
                 9uyvZg0OBuSTj3qkbh/2HacAUJ7vqvjQ3W8Wj6sMXtTueR8NNcdSzJh1 
                 49ch3zqfiXrxxna8+8UEDQaRR9KOPiSvXb2KjnuDan6hDKOT4qTZRRRC 
                 MWwnNQ9zPIMNbLBp0rNcZ+ZGFg2ckWtWh5yhv1iXYLV2vmd9DB6d4Dv8 
                 cW7scc3rPmDXpYR6APqPBRHlcbenfHCt+oCkEWse8OQhMM56KODIVQq3 
                 fejrfi1H )



 TOC 

4. Security Considerations

This entire memo pertains to the provision of public keying material for use by key management protocols such as ISAKMP/IKE (RFC2407) [7].

Implementations of DNS servers and resolvers SHOULD take care to make sure that the keying material is delivered intact to the end application. The use of DNSSEC to provide end-to-end integrity protection is strongly encouraged.

The semantics of this record is outside of the scope of this document, so no advice for users of this information is provided. Any user of this resource record MUST carefully document their trust model, and why the trust model of DNSSEC is appropriate.



 TOC 

5. IANA Considerations

IANA is asked to assign a resource record type number from the normal resource record number space.

The algorithm field does not require any IANA action, as it is inherited from DNS KEY algorithm values.



 TOC 

6. Acknowledgments

My thanks to Paul Hoffman, Sam Weiler, Jean-Jacques Puig, and Ólafur Guðmundsson who reviewed this document carefully. Additional thanks to Ólafur Guðmundsson for a reference implementation.



 TOC 

Normative references

[1] Mockapetris, P., "Domain names - concepts and facilities", STD 13, RFC 1034, November 1987.
[2] Mockapetris, P., "Domain names - implementation and specification", STD 13, RFC 1035, November 1987.
[3] Bradner, S., "The Internet Standards Process -- Revision 3", BCP 9, RFC 2026, October 1996.
[4] Eastlake, D. and C. Kaufman, "Domain Name System Security Extensions", RFC 2065, January 1997.


 TOC 

Non-normative references

[5] Thomson, S. and C. Huitema, "DNS Extensions to support IP version 6", RFC 1886, December 1995.
[6] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
[7] Piper, D., "The Internet IP Security Domain of Interpretation for ISAKMP", RFC 2407, November 1998.
[8] Eastlake, D., "Domain Name System Security Extensions", RFC 2535, March 1999.
[9] Eastlake, D., "DSA KEYs and SIGs in the Domain Name System (DNS)", RFC 2536, March 1999.
[10] Eastlake, D., "RSA/SHA-1 SIGs and RSA KEYs in the Domain Name System (DNS)", RFC 3110, May 2001.
[11] Massey, D. and S. Rose, "Limiting the Scope of the KEY Resource Record (RR)", RFC 3445, December 2002.


 TOC 

Author's Address

  Michael C. Richardson
  Sandelman Software Works
  470 Dawson Avenue
  Ottawa, ON K1Z 5V7
  CA
EMail:  mcr@sandelman.ottawa.on.ca
URI:  http://www.sandelman.ottawa.on.ca/


 TOC 

Full Copyright Statement

Acknowledgement