Independent submission M. Richardson
Internet-Draft SSW
Expires: August 24, 2003 February 23, 2003
A method for storing IPsec keying material in DNS.
draft-richardson-ipsec-rr-02.txt
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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 [1].
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Storage formats . . . . . . . . . . . . . . . . . . . . . . . 4
3. IPSECKEY RDATA format . . . . . . . . . . . . . . . . . . . . 5
3.1 RDATA format - algo type . . . . . . . . . . . . . . . . . . . 5
3.2 RDATA format - precedence . . . . . . . . . . . . . . . . . . 5
3.3 RDATA format - RSA public key . . . . . . . . . . . . . . . . 5
3.4 RDATA format - DSA public key . . . . . . . . . . . . . . . . 6
3.5 RDATA format - gateway . . . . . . . . . . . . . . . . . . . . 6
4. Presentation formats . . . . . . . . . . . . . . . . . . . . . 7
4.1 Representation of IPSECKEY RRs . . . . . . . . . . . . . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 9
Normative references . . . . . . . . . . . . . . . . . . . . . 10
Author's Address . . . . . . . . . . . . . . . . . . . . . . . 10
Full Copyright Statement . . . . . . . . . . . . . . . . . . . 11
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1. Introduction
1.1 Overview
Overview.
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2. Storage formats
The IPSECKEY resource record (RR) is used to publish a public key
that is to be associated with a Domain Name System (DNS) name. It
will be a public key as only public keys are stored in the DNS. This
can be the public key of a host, network, or application (in the case
of per-port keying).
An IPSECKEY RR is, like any other RR, authenticated by a SIG RR.
It is expected that there will often be multiple resource records of
the IPSECKEY type. This will be due to the need to rollover keys,
and due to the presence of multiple gateways.
The type number for the IPSECKEY RR is 45 (IANA TBD).
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3. 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.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RESV | algo | precedence | public key length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| /
/ public key
/ /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
~ gateway ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.1 RDATA format - algo type
The algorithm type ("algo") field indicates the type of key that is
present in the public key field. Valid values are:
0 No key is present.
1 A RSA key is present, in the format defined in
2 A DSA key is present, in the format defined in
3.2 RDATA format - precedence
This is an 8-bit precedence for this record. This is interpreted in
a similar way to the PREFERENCE field described in section 3.3.9 of
[3].
3.3 RDATA format - RSA public key
If the algorithm type has the value 1, then public key portion
contains an RSA public key, encoded as described in secion 2 of [8],
and repeated here:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| pub exp length| public key exponent /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| /
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+- modulus /
| /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-/
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.
3.4 RDATA format - DSA public key
If the algorithm type has the value 2, then public key portion
contains an DSA public key, encoded as described in [7].
3.5 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.
The length of this field is the size of the data portion minus the
public key length, and the 4 bytes of header. The gateway field may
be absent.
The gateway field is a string. It is most commonly a simple fully
qualified domain name (FQDN). IP version 4 and IP version 6
addresses may be represented using names from in-addr.arpa. and
ip6.arpa.
The gateway field may also include a @-character in it. Either in
the form @FQDN, or user@FQDN. In this context, it does not reference
a single destination, but just an identifier that will be used when
doing key negotiations. This may be used in the context where the
gateway does not have a permanent IP address, but has permanent
address space behind it, and will be initiating connections only.
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4. Presentation formats
4.1 Representation of IPSECKEY RRs
IPSECKEY RRs may appear as lines in a zone data master file. The
precedence field is mandatory. While both the gateway and public key
fields are optional, it is illegal for neither to be present.
As the IPv4, IPv6 and FQDN references to the gateway are mutually
exclusive, they can share a position. If no gateway is to be
indicated, then the special tokens of either "-" or "none" may be
used.
IPv4 addresses are to be represented as a dotted decimal quad, with
no leading zeroes. IPv6 addresses are to be presented as specified
in section 2.2 of [4].
38.46.139.192.in-addr.arpa. 7200 IN IPSECKEY ( 10 192.139.46.38
RSA: AQOrXJxB56Q28iOO43Va36elIFFKc/QB2orIeL94BdC5X4idFQZjSpsZ
Th48wKVXUE9xjwUkwR4R4/+1vjNN7KFp9fcqa2OxgjsoGqCn+3OPR8La
9uyvZg0OBuSTj3qkbh/2HacAUJ7vqvjQ3W8Wj6sMXtTueR8NNcdSzJh1
49ch3zqfiXrxxna8+8UEDQaRR9KOPiSvXb2KjnuDan6hDKOT4qTZRRRC
MWwnNQ9zPIMNbLBp0rNcZ+ZGFg2ckWtWh5yhv1iXYLV2vmd9DB6d4Dv8
cW7scc3rPmDXpYR6APqPBRHlcbenfHCt+oCkEWse8OQhMM56KODIVQq3
fejrfi1H )
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5. IANA Considerations
IANA is asked to assign resource record 45 to this resource record.
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6. Acknowledgments
People who pushed me to write this.
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Normative references
[1] Massey, D. and S. Rose, "Limiting the Scope of the KEY Resource
Record (RR)", RFC 3445, December 2002.
[2] Mockapetris, P., "Domain names - concepts and facilities", STD
13, RFC 1034, November 1987.
[3] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, November 1987.
[4] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 1884, December 1995.
[5] Thomson, S. and C. Huitema, "DNS Extensions to support IP
version 6", RFC 1886, December 1995.
[6] Eastlake, D., "Domain Name System Security Extensions", RFC
2535, March 1999.
[7] Eastlake, D., "DSA KEYs and SIGs in the Domain Name System
(DNS)", RFC 2536, March 1999.
[8] Eastlake, D., "RSA/SHA-1 SIGs and RSA KEYs in the Domain Name
System (DNS)", RFC 3110, May 2001.
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/
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