HTTPbis Working Group                                         J. Reschke
Internet-Draft                                                greenbytes
Updates: 2617 (if approved)                            February 10, 2015
Intended status: Standards Track
Expires: August 14, 2015


 The Hypertext Transfer Protocol (HTTP) Authentication-Info and Proxy-
               Authentication-Info Response Header Fields
                    draft-ietf-httpbis-auth-info-02

Abstract

   This specification defines the "Authentication-Info" and "Proxy-
   Authentication-Info" response header fields for use in HTTP
   authentication schemes which need to return additional information
   during or after authentication.

Editorial Note (To be removed by RFC Editor)

   Discussion of this draft takes place on the HTTPBIS working group
   mailing list (ietf-http-wg@w3.org), which is archived at
   <https://lists.w3.org/Archives/Public/ietf-http-wg/>.

   Working Group information can be found at
   <https://tools.ietf.org/wg/httpbis/> and <http://httpwg.github.io/>;
   source code and issues list for this draft can be found at
   <https://github.com/httpwg/http-extensions>.

   The changes in this draft are summarized in Appendix A.3.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   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."

   This Internet-Draft will expire on August 14, 2015.




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Copyright Notice

   Copyright (c) 2015 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  Notational Conventions  . . . . . . . . . . . . . . . . . . . . 3
   3.  The Authentication-Info Response Header Field . . . . . . . . . 3
     3.1.  Parameter Value Format  . . . . . . . . . . . . . . . . . . 3
   4.  The Proxy-Authentication-Info Response Header Field . . . . . . 4
   5.  Security Considerations . . . . . . . . . . . . . . . . . . . . 4
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 5
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 5
     8.1.  Normative References  . . . . . . . . . . . . . . . . . . . 5
     8.2.  Informative References  . . . . . . . . . . . . . . . . . . 5
   Appendix A.  Change Log (to be removed by RFC Editor before
                publication) . . . . . . . . . . . . . . . . . . . . . 5
     A.1.  draft-reschke-httpauth-auth-info-00 . . . . . . . . . . . . 5
     A.2.  draft-ietf-httpbis-auth-info-00 . . . . . . . . . . . . . . 6
     A.3.  draft-ietf-httpbis-auth-info-01 . . . . . . . . . . . . . . 6


















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1.  Introduction

   This specification defines the "Authentication-Info" and "Proxy-
   Authentication-Info" response header fields for use in HTTP
   authentication schemes ([RFC7235]) which need to return additional
   information during or after authentication.

   Both were previously defined in Section 3 of [RFC2617], defining the
   HTTP "Digest" authentication scheme.  This document generalizes the
   description for use not only in "Digest" ([DIGEST]), but also other
   future schemes that might have the same requirements for carrying
   additional information during authentication.

2.  Notational Conventions

   This specification uses the Augmented Backus-Naur Form (ABNF)
   notation of [RFC5234] with a list extension, defined in Section 7 of
   [RFC7230], that allows for compact definition of comma-separated
   lists using a '#' operator (similar to how the '*' operator indicates
   repetition).  The ABNF production for "auth-param" is defined in
   Section 2.1 of [RFC7235].

3.  The Authentication-Info Response Header Field

   HTTP authentication schemes can use the Authentication-Info response
   header field to communicate additional information regarding the
   successful authentication.

   The field value is a list of parameters (name/value pairs), using the
   "auth-param" syntax defined in Section 2.1 of [RFC7235].  This
   specification only describes the generic format; authentication
   schemes using "Authentication-Info" will define the individual
   parameters.  The "Digest" Authentication Scheme, for instance,
   defines multiple parameters in Section 3.5 of [DIGEST].

     Authentication-Info = #auth-param

   The Authentication-Info header field can be used in any HTTP
   response, independently of request method and status code.  Its
   semantics are defined by the applicable authentication scheme.
   Intermediaries are not allowed to modify the field value in any way.
   Authentication-Info can be used inside trailers ([RFC7230], Section
   4.1.2) when the authentication scheme explicitly allows this.

3.1.  Parameter Value Format

   Parameter values can be expressed either as "token" or as "quoted-
   string" (Section 3.2.6 of [RFC7230]).



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   Authentication scheme definitions need to allow both notations, both
   for senders and recipients.  This allows recipients to use generic
   parsing components, independent of the authentication scheme in use.

   For backwards compatibility, authentication scheme definitions can
   restrict the format for senders to one of the two variants.  This can
   be important when it is known that deployed implementations will fail
   when encountering one of the two formats.

4.  The Proxy-Authentication-Info Response Header Field

   The Proxy-Authentication-Info response header field is equivalent to
   Authentication-Info, except that it applies to proxy authentication
   ([RFC7235]):


     Proxy-Authentication-Info = #auth-param

5.  Security Considerations

   Adding information to HTTP responses that are sent over an
   unencrypted channel can affect security and privacy.  The presence of
   the header fields alone indicates that HTTP authentication is in use.
   Additional information could be exposed by the contents of the
   authentication-scheme specific parameters; this will have to be
   considered in the definitions of these schemes.

6.  IANA Considerations

   HTTP header fields are registered within the "Message Headers"
   registry located at
   <http://www.iana.org/assignments/message-headers>, as defined by
   [BCP90].

   This document updates the definitions of the "Authentication-Info"
   and "Proxy-Authentication-Info" header fields, so the "Permanent
   Message Header Field Names" registry shall be updated accordingly:

   +---------------------------+----------+----------+-----------------+
   | Header Field Name         | Protocol | Status   | Reference       |
   +---------------------------+----------+----------+-----------------+
   | Authentication-Info       | http     | standard | Section 3 of    |
   |                           |          |          | this document   |
   | Proxy-Authentication-Info | http     | standard | Section 4 of    |
   |                           |          |          | this document   |
   +---------------------------+----------+----------+-----------------+





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7.  Acknowledgements

   This document is based on the header field definitions in RFCs 2069
   and 2617, whose authors are: John Franks, Phillip M. Hallam-Baker,
   Jeffery L. Hostetler, Scott D. Lawrence, Paul J. Leach, Ari Luotonen,
   Eric W. Sink, and Lawrence C. Stewart.

   Additional thanks go to the members of the HTTPAuth and HTTPbis
   Working Groups, namely Amos Jeffries, Benjamin Kaduk, Alexey
   Melnikov, Mark Nottingham, Yutaka Oiwa, Rifaat Shekh-Yusef, and
   Martin Thomson.

8.  References

8.1.  Normative References

   [RFC5234]  Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", STD 68, RFC 5234, January 2008.

   [RFC7230]  Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
              Protocol (HTTP/1.1): Message Syntax and Routing",
              RFC 7230, June 2014.

   [RFC7235]  Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
              Protocol (HTTP/1.1): Authentication", RFC 7235, June 2014.

8.2.  Informative References

   [BCP90]    Klyne, G., Nottingham, M., and J. Mogul, "Registration
              Procedures for Message Header Fields", BCP 90, RFC 3864,
              September 2004.

   [DIGEST]   Shekh-Yusef, R., Ed., Ahrens, D., and S. Bremer, "HTTP
              Digest Access Authentication",
              draft-ietf-httpauth-digest-13 (work in progress),
              February 2015.

   [RFC2617]  Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S.,
              Leach, P., Luotonen, A., and L. Stewart, "HTTP
              Authentication: Basic and Digest Access Authentication",
              RFC 2617, June 1999.

Appendix A.  Change Log (to be removed by RFC Editor before publication)

A.1.  draft-reschke-httpauth-auth-info-00

   Changed boilerplate to make this an HTTPbis WG draft.  Added
   Acknowledgements.



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   In the Security Considerations, remind people that those apply to
   unencryped channels.

   Make it clearer that these are really just response header fields.

A.2.  draft-ietf-httpbis-auth-info-00

   Rephrase introduction of header field to be closer to what RFC 2617
   said ("successful authentication").

   Update DIGEST reference.

A.3.  draft-ietf-httpbis-auth-info-01

   State that scheme definitions need to define whether the header field
   can be used in trailers.

   Add "updates: 2617" to boilerplate.

Author's Address

   Julian F. Reschke
   greenbytes GmbH
   Hafenweg 16
   Muenster, NW  48155
   Germany

   EMail: julian.reschke@greenbytes.de
   URI:   http://greenbytes.de/tech/webdav/






















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