source: draft-ietf-httpbis/00/draft-ietf-httpbis-p7-auth-00.txt @ 588

Network Working Group                                   R. Fielding, Ed.
Internet-Draft                                              Day Software
Obsoletes: 2068, 2616                                          J. Gettys
(if approved)                                       One Laptop per Child
Updates: 2617 (if approved)                                     J. Mogul
Intended status: Standards Track                                      HP
Expires: June 22, 2008                                        H. Frystyk
                                                               Microsoft
                                                             L. Masinter
                                                           Adobe Systems
                                                                P. Leach
                                                               Microsoft
                                                          T. Berners-Lee
                                                                 W3C/MIT
                                                       December 20, 2007


                    HTTP/1.1, part 7: Authentication
                     draft-ietf-httpbis-p7-auth-00

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   Copyright (C) The IETF Trust (2007).



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Abstract

   The Hypertext Transfer Protocol (HTTP) is an application-level
   protocol for distributed, collaborative, hypermedia information
   systems.  HTTP has been in use by the World Wide Web global
   information initiative since 1990.  This document is Part 7 of the
   seven-part specification that defines the protocol referred to as
   "HTTP/1.1" and, taken together, obsoletes RFC 2616.  Part 7 defines
   HTTP Authentication.

Editorial Note (To be removed by RFC Editor)

   This version of the HTTP specification contains only minimal
   editorial changes from [RFC2616] (abstract, introductory paragraph,
   and authors' addresses).  All other changes are due to partitioning
   the original into seven mostly independent parts.  The intent is for
   readers of future drafts to able to use draft 00 as the basis for
   comparison when the WG makes later changes to the specification text.
   This draft will shortly be followed by draft 01 (containing the first
   round of changes that have already been agreed to on the mailing
   list).  There is no point in reviewing this draft other than to
   verify that the partitioning has been done correctly.  Roy T.
   Fielding, Yves Lafon, and Julian Reschke will be the editors after
   draft 00 is submitted.

   Discussion of this draft should take place on the HTTPBIS working
   group mailing list (ietf-http-wg@w3.org).  The current issues list is
   at <http://www3.tools.ietf.org/wg/httpbis/trac/report/11> and related
   documents (including fancy diffs) can be found at
   <http://www3.tools.ietf.org/wg/httpbis/>.





















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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Status Code Definitions  . . . . . . . . . . . . . . . . . . .  4
     2.1.  401 Unauthorized . . . . . . . . . . . . . . . . . . . . .  4
     2.2.  407 Proxy Authentication Required  . . . . . . . . . . . .  4
   3.  Header Field Definitions . . . . . . . . . . . . . . . . . . .  5
     3.1.  Authorization  . . . . . . . . . . . . . . . . . . . . . .  5
     3.2.  Proxy-Authenticate . . . . . . . . . . . . . . . . . . . .  6
     3.3.  Proxy-Authorization  . . . . . . . . . . . . . . . . . . .  6
     3.4.  WWW-Authenticate . . . . . . . . . . . . . . . . . . . . .  6
   4.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  7
   5.  Security Considerations  . . . . . . . . . . . . . . . . . . .  7
     5.1.  Authentication Credentials and Idle Clients  . . . . . . .  7
   6.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . .  8
   7.  References . . . . . . . . . . . . . . . . . . . . . . . . . .  8
   Index  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  8
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . .  9
   Intellectual Property and Copyright Statements . . . . . . . . . . 11
































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1.  Introduction

   This document will define aspects of HTTP related to access control
   and authentication.  Right now it only includes the extracted
   relevant sections of RFC 2616 [RFC2616] with only minor edits.

   HTTP provides several OPTIONAL challenge-response authentication
   mechanisms which can be used by a server to challenge a client
   request and by a client to provide authentication information.  The
   general framework for access authentication, and the specification of
   "basic" and "digest" authentication, are specified in "HTTP
   Authentication: Basic and Digest Access Authentication" [RFC2617].
   This specification adopts the definitions of "challenge" and
   "credentials" from that specification.


2.  Status Code Definitions

2.1.  401 Unauthorized

   The request requires user authentication.  The response MUST include
   a WWW-Authenticate header field (Section 3.4) containing a challenge
   applicable to the requested resource.  The client MAY repeat the
   request with a suitable Authorization header field (Section 3.1).  If
   the request already included Authorization credentials, then the 401
   response indicates that authorization has been refused for those
   credentials.  If the 401 response contains the same challenge as the
   prior response, and the user agent has already attempted
   authentication at least once, then the user SHOULD be presented the
   entity that was given in the response, since that entity might
   include relevant diagnostic information.  HTTP access authentication
   is explained in "HTTP Authentication: Basic and Digest Access
   Authentication" [RFC2617].

2.2.  407 Proxy Authentication Required

   This code is similar to 401 (Unauthorized), but indicates that the
   client must first authenticate itself with the proxy.  The proxy MUST
   return a Proxy-Authenticate header field (Section 3.2) containing a
   challenge applicable to the proxy for the requested resource.  The
   client MAY repeat the request with a suitable Proxy-Authorization
   header field (Section 3.3).  HTTP access authentication is explained
   in "HTTP Authentication: Basic and Digest Access Authentication"
   [RFC2617].







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3.  Header Field Definitions

   This section defines the syntax and semantics of all standard
   HTTP/1.1 header fields.  For entity-header fields, both sender and
   recipient refer to either the client or the server, depending on who
   sends and who receives the entity.

3.1.  Authorization

   A user agent that wishes to authenticate itself with a server--
   usually, but not necessarily, after receiving a 401 response--does so
   by including an Authorization request-header field with the request.
   The Authorization field value consists of credentials containing the
   authentication information of the user agent for the realm of the
   resource being requested.

          Authorization  = "Authorization" ":" credentials

   HTTP access authentication is described in "HTTP Authentication:
   Basic and Digest Access Authentication" [RFC2617].  If a request is
   authenticated and a realm specified, the same credentials SHOULD be
   valid for all other requests within this realm (assuming that the
   authentication scheme itself does not require otherwise, such as
   credentials that vary according to a challenge value or using
   synchronized clocks).

   When a shared cache (see Section 2.7 of [Part6]) receives a request
   containing an Authorization field, it MUST NOT return the
   corresponding response as a reply to any other request, unless one of
   the following specific exceptions holds:

   1.  If the response includes the "s-maxage" cache-control directive,
       the cache MAY use that response in replying to a subsequent
       request.  But (if the specified maximum age has passed) a proxy
       cache MUST first revalidate it with the origin server, using the
       request-headers from the new request to allow the origin server
       to authenticate the new request.  (This is the defined behavior
       for s-maxage.)  If the response includes "s-maxage=0", the proxy
       MUST always revalidate it before re-using it.

   2.  If the response includes the "must-revalidate" cache-control
       directive, the cache MAY use that response in replying to a
       subsequent request.  But if the response is stale, all caches
       MUST first revalidate it with the origin server, using the
       request-headers from the new request to allow the origin server
       to authenticate the new request.





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   3.  If the response includes the "public" cache-control directive, it
       MAY be returned in reply to any subsequent request.

3.2.  Proxy-Authenticate

   The Proxy-Authenticate response-header field MUST be included as part
   of a 407 (Proxy Authentication Required) response.  The field value
   consists of a challenge that indicates the authentication scheme and
   parameters applicable to the proxy for this Request-URI.

       Proxy-Authenticate  = "Proxy-Authenticate" ":" 1#challenge

   The HTTP access authentication process is described in "HTTP
   Authentication: Basic and Digest Access Authentication" [RFC2617].
   Unlike WWW-Authenticate, the Proxy-Authenticate header field applies
   only to the current connection and SHOULD NOT be passed on to
   downstream clients.  However, an intermediate proxy might need to
   obtain its own credentials by requesting them from the downstream
   client, which in some circumstances will appear as if the proxy is
   forwarding the Proxy-Authenticate header field.

3.3.  Proxy-Authorization

   The Proxy-Authorization request-header field allows the client to
   identify itself (or its user) to a proxy which requires
   authentication.  The Proxy-Authorization field value consists of
   credentials containing the authentication information of the user
   agent for the proxy and/or realm of the resource being requested.

       Proxy-Authorization     = "Proxy-Authorization" ":" credentials

   The HTTP access authentication process is described in "HTTP
   Authentication: Basic and Digest Access Authentication" [RFC2617].
   Unlike Authorization, the Proxy-Authorization header field applies
   only to the next outbound proxy that demanded authentication using
   the Proxy-Authenticate field.  When multiple proxies are used in a
   chain, the Proxy-Authorization header field is consumed by the first
   outbound proxy that was expecting to receive credentials.  A proxy
   MAY relay the credentials from the client request to the next proxy
   if that is the mechanism by which the proxies cooperatively
   authenticate a given request.

3.4.  WWW-Authenticate

   The WWW-Authenticate response-header field MUST be included in 401
   (Unauthorized) response messages.  The field value consists of at
   least one challenge that indicates the authentication scheme(s) and
   parameters applicable to the Request-URI.



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       WWW-Authenticate  = "WWW-Authenticate" ":" 1#challenge

   The HTTP access authentication process is described in "HTTP
   Authentication: Basic and Digest Access Authentication" [RFC2617].
   User agents are advised to take special care in parsing the WWW-
   Authenticate field value as it might contain more than one challenge,
   or if more than one WWW-Authenticate header field is provided, the
   contents of a challenge itself can contain a comma-separated list of
   authentication parameters.


4.  IANA Considerations

   TBD.


5.  Security Considerations

   This section is meant to inform application developers, information
   providers, and users of the security limitations in HTTP/1.1 as
   described by this document.  The discussion does not include
   definitive solutions to the problems revealed, though it does make
   some suggestions for reducing security risks.

5.1.  Authentication Credentials and Idle Clients

   Existing HTTP clients and user agents typically retain authentication
   information indefinitely.  HTTP/1.1. does not provide a method for a
   server to direct clients to discard these cached credentials.  This
   is a significant defect that requires further extensions to HTTP.
   Circumstances under which credential caching can interfere with the
   application's security model include but are not limited to:

   o  Clients which have been idle for an extended period following
      which the server might wish to cause the client to reprompt the
      user for credentials.

   o  Applications which include a session termination indication (such
      as a `logout' or `commit' button on a page) after which the server
      side of the application `knows' that there is no further reason
      for the client to retain the credentials.

   This is currently under separate study.  There are a number of work-
   arounds to parts of this problem, and we encourage the use of
   password protection in screen savers, idle time-outs, and other
   methods which mitigate the security problems inherent in this
   problem.  In particular, user agents which cache credentials are
   encouraged to provide a readily accessible mechanism for discarding



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   cached credentials under user control.


6.  Acknowledgments

   Based on an XML translation of RFC 2616 by Julian Reschke.


7.  References

   [Part6]    Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H.,
              Masinter, L., Leach, P., and T. Berners-Lee, "HTTP/1.1,
              part 6: Caching", draft-ietf-httpbis-p6-cache-00 (work in
              progress), December 2007.

   [RFC2616]  Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
              Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
              Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.

   [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.


Index

   4
      401 Unauthorized (status code)  4
      407 Proxy Authentication Required (status code)  4

   A
      Authorization header  5

   G
      Grammar
         Authorization  5
         Proxy-Authenticate  6
         Proxy-Authorization  6
         WWW-Authenticate  7

   H
      Headers
         Authorization  5
         Proxy-Authenticate  6
         Proxy-Authorization  6
         WWW-Authenticate  6




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   P
      Proxy-Authenticate header  6
      Proxy-Authorization header  6

   S
      Status Codes
         401 Unauthorized  4
         407 Proxy Authentication Required  4

   W
      WWW-Authenticate header  6


Authors' Addresses

   Roy T. Fielding (editor)
   Day Software
   23 Corporate Plaza DR, Suite 280
   Newport Beach, CA  92660
   USA

   Phone: +1-949-706-5300
   Fax:   +1-949-706-5305
   Email: fielding@gbiv.com
   URI:   http://roy.gbiv.com/


   Jim Gettys
   One Laptop per Child
   21 Oak Knoll Road
   Carlisle, MA  01741
   USA

   Email: jg@laptop.org
   URI:   http://www.laptop.org/


   Jeffrey C. Mogul
   Hewlett-Packard Company
   HP Labs, Large Scale Systems Group
   1501 Page Mill Road, MS 1177
   Palo Alto, CA  94304
   USA

   Email: JeffMogul@acm.org






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   Henrik Frystyk Nielsen
   Microsoft Corporation
   1 Microsoft Way
   Redmond, WA  98052
   USA

   Email: henrikn@microsoft.com


   Larry Masinter
   Adobe Systems, Incorporated
   345 Park Ave
   San Jose, CA  95110
   USA

   Email: LMM@acm.org
   URI:   http://larry.masinter.net/


   Paul J. Leach
   Microsoft Corporation
   1 Microsoft Way
   Redmond, WA  98052

   Email: paulle@microsoft.com


   Tim Berners-Lee
   World Wide Web Consortium
   MIT Computer Science and Artificial Intelligence Laboratory
   The Stata Center, Building 32
   32 Vassar Street
   Cambridge, MA  02139
   USA

   Email: timbl@w3.org
   URI:   http://www.w3.org/People/Berners-Lee/














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