Internet-Draft                                           A. D. Keromytis
March 2008                                           Columbia University
Expires: October 2008
Creation Date: 2008-03-28
Intended Status: Proposed


        Transport Layer Security (TLS) Authorization Using KeyNote
                 <draft-keromytis-tls-authz-keynote-00.txt>


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Copyright Notice

   Copyright (C) The IETF Trust (2008).

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] 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.


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", March 2008
                <draft-keromytis-keynote-x509-00.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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