IPSEC Working Group Ashar Aziz
INTERNET-DRAFT Tom Markson
Hemma Prafullchandra
Sun Microsystems, Inc.
Expires in six months December 21, 1995
X.509 Encoding of Diffie-Hellman Public Values
<draft-ietf-ipsec-skip-x509-00.txt>
Status of this Memo
This document is a submission to the IETF Internet Protocol Security
(IPSEC) Working Group. Comments are solicited and should be addressed to
to the working group mailing list (ipsec@ans.net) or to the authors.
This document is an Internet-Draft. Internet Drafts are working
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Distribution of this memo is unlimited.
draft-ietf-ipsec-skip-X509-00.txt [Page 1]
INTERNET-DRAFT SKIP-X509 December 21, 1995
Abstract
This document describes the ASN.1 [1] encoding of the CCITT 1988 X.509
[2] certificate with Diffie-Hellman public values for use with SKIP [5].
draft-ietf-ipsec-skip-X509-00.txt [Page 2]
CONTENTS
Status of this Memo.................................. 1
Abstract............................................. 2
1. Encoding of DH public values......................... 3
2. Encoding of the Distinguished Name (DN).............. 4
3. Security Considerations.............................. 5
Acknowledgements..................................... 5
References........................................... 5
Author's Address(es)................................. 6
- i -
INTERNET-DRAFT SKIP-X509 December 21, 1995
1. Encoding of DH public values
The X.509 certificate format is defined by the following ASN.1 syntax:
Certificate ::= SIGNED SEQUENCE {
version [0] Version DEFAULT v1988,
serialNumber CertificateSerialNumber,
signature AlgorithmIdentifier,
issuer Name,
validity Validity,
subject Name,
subjectPublicKeyInfo SubjectPublicKeyInfo
}
Version ::= INTEGER { v1988(0) }
CertificateSerialNumber ::= INTEGER
Validity ::= SEQUENCE {
notBefore UTCTime,
notAfter UTCTime
}
SubjectPublicKeyInfo ::= SEQUENCE {
algorithm AlgorithmIdentifier,
subjectPublicKey BIT STRING
}
AlgorithmIdentifier ::= SEQUENCE {
algorithm OBJECT IDENTIFIER,
parameters ANY DEFINED BY algorithm OPTIONAL
}
The encoding of a Diffie-Hellman public value in an X.509 certificate
will be in the form of an INTEGER. The algorithm identifier will be as
defined in PKCS #3 [3].
draft-ietf-ipsec-skip-X509-00.txt [Page 3]
INTERNET-DRAFT SKIP-X509 December 21, 1995
Thus,
DHPublicKey ::= INTEGER
AlgorithmIdentifier ::= SEQUENCE {
algorithm OBJECT IDENTIFIER
SEQUENCE {
prime INTEGER, -- p
base INTEGER, -- g
privateValueLength INTEGER OPTIONAL
}
}
with the OBJECT IDENTIFIER value being,
dhKeyAgreement OBJECT IDENTIFIER ::= { iso(1) member-body(2) US(840)
rsadsi(113549) pkcs(1) 3 1 }
The DHPublicKey gets encapsulated as the BIT STRING in
SubjectPublicKeyInfo of an X.509 certificate in the following manner.
First the DHPublicKey is encoded as an INTEGER, and then this INTEGER is
encoded as the payload of the BIT STRING.
The certificate and Certificate Revocation List (CRL) encoding is the
same as in RFC 1422. CRLs can be used with SKIP in accordance with each
site's certificate/CRL management policies.
2. Encoding of the Distinguished Name (DN)
When the name space is the IP address space, a certificate is allowed to
bind multiple IP addresses to a single public value to accommodate cases
where a single IP node has multiple IP addresses. The SEQUENCE-OF
construct in a DN readily allows for this. What is needed is an ASN.1
OBJECT IDENTIFIER for an AttributeType specifying an IP address.
draft-ietf-ipsec-skip-X509-00.txt [Page 4]
INTERNET-DRAFT SKIP-X509 December 21, 1995
This is defined here as,
ipAddress ATTRIBUTE
WITH ATTRIBUTE-SYNTAX
PrintableString (SIZE(1 .. ub-ipAddress))
::= { 1, 3, 6, 1, 4, 1, 42, 2, 11, 2, 1 }
ub-ipAddress ::= 256
The DN in the certificate can contain multiple of these by iterating on
the SEQUENCE-OF construct of the Relative Distinguished Name Sequence.
The PrintableString contains either the hexadecimal representation or
standard dot notation representation of an IP address. Note that all
three conventional forms for representing IPv6 addresses [7] as text
strings are allowed by this definition.
When individual users are identified using DNs, then the certificate
naturally contains their DNs. The SKIP internet draft [5] describes how
DNs may be used with SKIP, by identifying the DN name space using the
Source and destination NSID bytes in the SKIP header.
3. Security Considerations
Security issues are not discussed in this document.
Acknowledgements
We would like to thank all of the people who helped make this draft
possible.
References
[1] CCITT Recommendation X.208 (1992), "Abstract Syntax Notation One"
[2] CCITT Recommendation X.509 (1988), "The Directory - Authentication
Framework"
[3] "Public Key Cryptography Standards", PKCS#s 1-11 from RSA Data
Security Inc., Redwood City, CA, ftp://ftp.rsa.com/pub/pkcs
draft-ietf-ipsec-skip-X509-00.txt [Page 5]
INTERNET-DRAFT SKIP-X509 December 21, 1995
[4] Kent, S., "Privacy Enhancement for Internet Electronic Mail: Part
II: Certificate-Based Key Management", RFC 1422
[5] Aziz, A., Markson, T., Prafullchandra, H., "Simple Key-management
for Internet Protocols", (I-D draft-ietf-ipsec-skip-06.txt), Work In
Progress
[6] "NIST OIW Stable Implementors Workshop", September 1994, Part 12 -
OS Security
[7] Hinden, R., Deering, S., "IP Version 6 Addressing Architecture",
(I-D draft-ietf-ipngwg-addr-arch-03.txt), Work In Progress
Author's Address(es)
Ashar Aziz
Sun Microsystems, Inc.
M/S PAL1-550
2550 Garcia Avenue
Mountain View, CA 94043
Email: ashar.aziz@eng.sun.com
Alternate email address: ashar@incog.com
Tom Markson
Sun Microsystems, Inc.
M/S PAL1-550
2550 Garcia Avenue
Mountain View, CA 94043
Email: markson@incog.com
Alternate email address: markson@eng.sun.com
Hemma Prafullchandra
Sun Microsystems, Inc.
M/S PAL1-550
2550 Garcia Avenue
Mountain View, CA 94043
Email: hemma@eng.sun.com
Alternate email address: hemma@incog.com
draft-ietf-ipsec-skip-X509-00.txt [Page 6]
