Internet-Draft Keromytis, Angelos D.
October 2008 Columbia University
Expires: April 2009
Creation Date: 2008-10-01
Intended Status: Proposed
Transport Layer Security (TLS) Authorization Using KeyNote
<draft-keromytis-tls-authz-keynote-01.txt>
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Abstract
This document specifies the use of the KeyNote trust-management
system as an authorization extension in the Transport Layer
Security (TLS) Handshake Protocol, according to [AUTHZ].
Extensions carried in the client and server hello messages
confirm that both parties support the desired authorization
data types. Then, if supported by both the client and the
server, KeyNote credentials are exchanged during the
supplemental data handshake message.
1. Introduction
This document describes the identifiers necessary to exchange
KeyNote [KEYNOTE] credential assertions inside a TLS [TLS1.0]
[TLS1.1] [TLS1.2] exchange. Such credential assertions can
authorize the client and/or the server to perform certain
actions. In most usage scenarios, the KeyNote credential
assertions will be signed by a cryptographic public key
[RFC2792]. By using the X.509 key and signature encoding
[X509KEY], it is possible to add KeyNote-based authorization and
policy compliance support to the existing, unmodified X.509
authentication exchange in TLS.
A list of KeyNote credentials (e.g., forming a delegation chain)
may be sent as part of the same payload.
In most scenarios, at least one of these credentials will be
issued to the public key of the transmitter of the credentials,
i.e., said public key will appear in the ``Licensees'' field of
at least one KeyNote credential assertion. The same public key
will generally be used by the transmitter of the same credentials
to authenticate as part of the TLS exchange. The
authentication material (e.g., cryptographic public key) that was
used by the transmitter to authenticate in the TLS exchange will
be provided to the KeyNote evaluation engine as an ``Action
Authorizer''.
2. KeyNote Credential Assertion Lists
The KeyNote Assertion List type definition in the TLS Authorization
Data Formats registry is:
keynote_assertion_list(TBA)
When the keynote_assertion_list value is present, the authorization
data is a list of KeyNote credential assertions that conforms to
the profile in RFC 2704 [KEYNOTE].
A KeyNote assertion list is transmitted inside an AuthorizationData
structure as an opaque sequence of 1 - 2^16-1 bytes:
opaque KeyNoteAssertionList<1..2^16-1>;
When KeyNoteAssertion List is used, the field contains an ASCII-
encoded list of signed KeyNote assertions, as described in RFC 2704
[KEYNOTE]. The assertions are separated by two '\n' (newline)
characters. A KeyNote assertion is a structure similar to a public
key certificate; the main difference is that instead of a binding
between a name and a public key, KeyNote assertions bind public keys
to authorization rules that are evaluated by the peer when the sender
later issues specific requests.
When making an authorization decision based on a list of KeyNote
assertions, proper linkage between the KeyNote assertions and the
public key certificate that is transferred in the TLS Certificate
message is needed. Receivers of a KeyNote assertion list should
initialize the ACTION_AUTHORIZER variable to be the sender's public
key, which was used to authenticate the TLS exchange. If a
different authentication mechanism is used, it is the responsibility
of the credential issuer to issue the appropriate credentials.
3. IANA Considerations
This document requires a new entry in the IANA-maintained TLS
Authorization Data Formats registry, keynote_assertion_list(TBD).
This registry is defined in [AUTHZ].
4. Security Considerations
There are no security considerations beyond those discussed in
[KEYNOTE], [RFC2792], and [AUTHZ].
5. Normative References
[IANA] Narten, T., and H. Alvestrand, "Guidelines for Writing
an IANA Considerations Section in RFCs", RFC 3434,
October 1998.
[TLS1.0] Dierks, T., and C. Allen, "The TLS Protocol, Version
1.0", RFC 2246, January 1999.
[TLS1.1] Dierks, T., and E. Rescorla, "The Transport Layer
Security (TLS) Protocol, Version 1.1", RFC 4346,
February 2006.
[TLS1.2] Dierks, T., and E. Rescorla, "The Transport Layer
Security (TLS) Protocol, Version 1.2", RFC 5246,
August 2008.
6. Informative References
[KEYNOTE] Blaze, M., Feigenbaum, J., Ioannidis, J., and
A. Keromytis, "The KeyNote Trust-Management System,
Version 2", RFC 2704, September 1999.
[RFC2792] Blaze, M., Ioannidis, J., and A. Keromytis, "DSA and RSA
Key and Signature Encoding for the KeyNote Trust
Management System", RFC 2792, March 2000.
[AUTHZ] Brown, M., and R. Housley, "Transport Layer Security
(TLS) Authorization Extensions", June 2006
<draft-housley-tls-authz-extns-07.txt>
[X509KEY] A. D. Keromytis, "X.509 Key and Signature Encoding for
the KeyNote Trust Management System", October 2008
<draft-keromytis-keynote-x509-01.txt>
Author's Address
Angelos D. Keromytis
Department of Computer Science
Columbia University
Mail Code 0401
1214 Amsterdam Avenue
New York, New York 1007
USA
angelos <at> cs <dot> columbia <dot> edu
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