source: draft-ietf-httpbis/02/draft-ietf-httpbis-p7-auth-02.xml @ 559

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<rfc obsoletes="2616" updates="2617" category="std" ipr="full3978" docName="draft-ietf-httpbis-p7-auth-02">
<front>

  <title abbrev="HTTP/1.1, Part 7">HTTP/1.1, part 7: Authentication</title>

  <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
    <organization abbrev="Day Software">Day Software</organization>
    <address>
      <postal>
        <street>23 Corporate Plaza DR, Suite 280</street>
        <city>Newport Beach</city>
        <region>CA</region>
        <code>92660</code>
        <country>USA</country>
      </postal>
      <phone>+1-949-706-5300</phone>
      <facsimile>+1-949-706-5305</facsimile>
      <email>fielding@gbiv.com</email>
      <uri>http://roy.gbiv.com/</uri>
    </address>
  </author>

  <author initials="J." surname="Gettys" fullname="Jim Gettys">
    <organization>One Laptop per Child</organization>
    <address>
      <postal>
        <street>21 Oak Knoll Road</street>
        <city>Carlisle</city>
        <region>MA</region>
        <code>01741</code>
        <country>USA</country>
      </postal>
      <email>jg@laptop.org</email>
      <uri>http://www.laptop.org/</uri>
    </address>
  </author>
  
  <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
    <organization abbrev="HP">Hewlett-Packard Company</organization>
    <address>
      <postal>
        <street>HP Labs, Large Scale Systems Group</street>
        <street>1501 Page Mill Road, MS 1177</street>
        <city>Palo Alto</city>
        <region>CA</region>
        <code>94304</code>
        <country>USA</country>
      </postal>
      <email>JeffMogul@acm.org</email>
    </address>
  </author>

  <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
    <organization abbrev="Microsoft">Microsoft Corporation</organization>
    <address>
      <postal>
        <street>1 Microsoft Way</street>
        <city>Redmond</city>
        <region>WA</region>
        <code>98052</code>
        <country>USA</country>
      </postal>
      <email>henrikn@microsoft.com</email>
    </address>
  </author>

  <author initials="L." surname="Masinter" fullname="Larry Masinter">
    <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
    <address>
      <postal>
        <street>345 Park Ave</street>
        <city>San Jose</city>
        <region>CA</region>
        <code>95110</code>
        <country>USA</country>
      </postal>
      <email>LMM@acm.org</email>
      <uri>http://larry.masinter.net/</uri>
    </address>
  </author>
  
  <author initials="P." surname="Leach" fullname="Paul J. Leach">
    <organization abbrev="Microsoft">Microsoft Corporation</organization>
    <address>
      <postal>
        <street>1 Microsoft Way</street>
        <city>Redmond</city>
        <region>WA</region>
        <code>98052</code>
      </postal>
      <email>paulle@microsoft.com</email>
    </address>
  </author>
   
  <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
    <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
    <address>
      <postal>
        <street>MIT Computer Science and Artificial Intelligence Laboratory</street>
        <street>The Stata Center, Building 32</street>
        <street>32 Vassar Street</street>
        <city>Cambridge</city>
        <region>MA</region>
        <code>02139</code>
        <country>USA</country>
      </postal>
      <email>timbl@w3.org</email>
      <uri>http://www.w3.org/People/Berners-Lee/</uri>
    </address>
  </author>

  <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
    <organization abbrev="W3C">World Wide Web Consortium</organization>
    <address>
      <postal>
        <street>W3C / ERCIM</street>
        <street>2004, rte des Lucioles</street>
        <city>Sophia-Antipolis</city>
        <region>AM</region>
        <code>06902</code>
        <country>France</country>
      </postal>
      <email>ylafon@w3.org</email>
      <uri>http://www.raubacapeu.net/people/yves/</uri>
    </address>
  </author>

  <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
    <organization abbrev="greenbytes">greenbytes GmbH</organization>
    <address>
      <postal>
        <street>Hafenweg 16</street>
        <city>Muenster</city><region>NW</region><code>48155</code>
        <country>Germany</country>
      </postal>
      <phone>+49 251 2807760</phone>    
      <facsimile>+49 251 2807761</facsimile>    
      <email>julian.reschke@greenbytes.de</email>       
      <uri>http://greenbytes.de/tech/webdav/</uri>      
    </address>
  </author>

  <date month="February" year="2008" day="24"/>

<abstract>
<t>
   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.
</t>
</abstract>

<note title="Editorial Note (To be removed by RFC Editor)">
  <t>
    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 <eref target="http://www.tools.ietf.org/wg/httpbis/trac/report/11"/>
    and related documents (including fancy diffs) can be found at
    <eref target="http://www.tools.ietf.org/wg/httpbis/"/>.
  </t>
  <t>
    This draft incorporates those issue resolutions that were either
    collected in the original RFC2616 errata list (<eref target="http://purl.org/NET/http-errata"/>),
    or which were agreed upon on the mailing list between October 2006 and 
    November 2007 (as published in "draft-lafon-rfc2616bis-03").
  </t>
</note>
</front>
<middle>
<section title="Introduction" anchor="introduction">
<t>
   This document defines HTTP/1.1 access control and authentication. Right now it
   includes the extracted relevant sections of
   RFC 2616 with only minor changes.
   The intention is to move the general framework for HTTP authentication here,
   as currently specified in <xref target="RFC2617"/>, and allow the individual
   authentication mechanisms to be defined elsewhere.  This introduction will
   be rewritten when that occurs. 
</t>
<t>
   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" <xref target="RFC2617"/>. This
   specification adopts the definitions of "challenge" and "credentials"
   from that specification.
</t>

<section title="Requirements" anchor="intro.requirements">
<t>
   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in <xref target="RFC2119"/>.
</t>
<t>
   An implementation is not compliant if it fails to satisfy one or more
   of the MUST or REQUIRED level requirements for the protocols it
   implements. An implementation that satisfies all the MUST or REQUIRED
   level and all the SHOULD level requirements for its protocols is said
   to be "unconditionally compliant"; one that satisfies all the MUST
   level requirements but not all the SHOULD level requirements for its
   protocols is said to be "conditionally compliant."
</t>
</section>
</section>

<section title="Notational Conventions and Generic Grammar" anchor="notation">
<t>
  This specification uses the ABNF syntax defined in Section 2.1 of <xref target="Part1"/>.
  <cref anchor="abnf.dep">ABNF syntax and basic rules will be adopted from RFC 5234, see
  &lt;http://tools.ietf.org/wg/httpbis/trac/ticket/36&gt;.</cref>
</t>
<t anchor="abnf.dependencies">
  The ABNF rules below are defined in other specifications: 
</t>
<figure><iref primary="true" item="Grammar" subitem="challenge"/><iref primary="true" item="Grammar" subitem="credentials"/><artwork type="abnf2616"><![CDATA[
  challenge   = <challenge, defined in [RFC2617], Section 1.2>
  credentials = <credentials, defined in [RFC2617], Section 1.2>
]]></artwork></figure>
</section>


<section title="Status Code Definitions">
<section title="401 Unauthorized" anchor="status.401">
  <iref primary="true" item="401 Unauthorized (status code)"/>
  <iref primary="true" item="Status Codes" subitem="401 Unauthorized"/>
<t>
   The request requires user authentication. The response MUST include a
   WWW-Authenticate header field (<xref target="header.www-authenticate"/>) containing a challenge
   applicable to the requested resource. The client MAY repeat the
   request with a suitable Authorization header field (<xref target="header.authorization"/>). 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" <xref target="RFC2617"/>.
</t>
</section>
<section title="407 Proxy Authentication Required" anchor="status.407">
  <iref primary="true" item="407 Proxy Authentication Required (status code)"/>
  <iref primary="true" item="Status Codes" subitem="407 Proxy Authentication Required"/>
<t>
   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 (<xref target="header.proxy-authenticate"/>) containing a
   challenge applicable to the proxy for the requested resource. The
   client MAY repeat the request with a suitable Proxy-Authorization
   header field (<xref target="header.proxy-authorization"/>). HTTP access authentication is explained
   in "HTTP Authentication: Basic and Digest Access Authentication"
   <xref target="RFC2617"/>.
</t>
</section>
</section>

<section title="Header Field Definitions" anchor="header.fields">
<t>
   This section defines the syntax and semantics of HTTP/1.1 header fields
   related to authentication.
</t>

<section title="Authorization" anchor="header.authorization">
  <iref primary="true" item="Authorization header"/>
  <iref primary="true" item="Headers" subitem="Authorization"/>
<t>
      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.
</t>
<figure><iref primary="true" item="Grammar" subitem="Authorization"/><artwork type="abnf2616"><![CDATA[
  Authorization  = "Authorization" ":" credentials
]]></artwork></figure>
<t>
      HTTP access authentication is described in "HTTP Authentication:
      Basic and Digest Access Authentication" <xref target="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).
</t>
<t>
      When a shared cache (see Section 9 of <xref target="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:
</t>
<t>
  <list style="numbers">
      <t>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.</t>

      <t>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.</t>

      <t>If the response includes the "public" cache-control directive,
         it MAY be returned in reply to any subsequent request.</t>
  </list>
</t>
</section>

<section title="Proxy-Authenticate" anchor="header.proxy-authenticate">
  <iref primary="true" item="Proxy-Authenticate header"/>
  <iref primary="true" item="Headers" subitem="Proxy-Authenticate"/>
<t>
   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.
</t>
<figure><iref primary="true" item="Grammar" subitem="Proxy-Authenticate"/><artwork type="abnf2616"><![CDATA[
  Proxy-Authenticate  = "Proxy-Authenticate" ":" 1#challenge
]]></artwork></figure>
<t>
   The HTTP access authentication process is described in "HTTP
   Authentication: Basic and Digest Access Authentication" <xref target="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.
</t>
</section>

<section title="Proxy-Authorization" anchor="header.proxy-authorization">
  <iref primary="true" item="Proxy-Authorization header"/>
  <iref primary="true" item="Headers" subitem="Proxy-Authorization"/>
<t>
   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.
</t>
<figure><iref primary="true" item="Grammar" subitem="Proxy-Authorization"/><artwork type="abnf2616"><![CDATA[
  Proxy-Authorization     = "Proxy-Authorization" ":" credentials
]]></artwork></figure>
<t>
   The HTTP access authentication process is described in "HTTP
   Authentication: Basic and Digest Access Authentication" <xref target="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.
</t>
</section>

<section title="WWW-Authenticate" anchor="header.www-authenticate">
  <iref primary="true" item="WWW-Authenticate header"/>
  <iref primary="true" item="Headers" subitem="WWW-Authenticate"/>
<t>
   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.
</t>
<figure><iref primary="true" item="Grammar" subitem="WWW-Authenticate"/><artwork type="abnf2616"><![CDATA[
  WWW-Authenticate  = "WWW-Authenticate" ":" 1#challenge
]]></artwork></figure>
<t>
   The HTTP access authentication process is described in "HTTP
   Authentication: Basic and Digest Access Authentication" <xref target="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.
</t>
</section>

</section>

<section title="IANA Considerations" anchor="IANA.considerations">
<t>
   <cref>TBD.</cref>
</t>
</section>

<section title="Security Considerations" anchor="security.considerations">
<t>
   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.
</t>

<section title="Authentication Credentials and Idle Clients" anchor="auth.credentials.and.idle.clients">
<t>
   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:
  <list style="symbols">
     <t>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.</t>

     <t>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.</t>
  </list>
</t>
<t>
   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
   cached credentials under user control.
</t>
</section>
</section>

<section title="Acknowledgments" anchor="ack">
<t>
  TBD.
</t>
</section>
</middle>

<back>

<references title="Normative References">

<reference anchor="Part1">
  <front>
    <title abbrev="HTTP/1.1">HTTP/1.1, part 1: URIs, Connections, and Message Parsing</title>
    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
      <organization abbrev="Day Software">Day Software</organization>
      <address><email>fielding@gbiv.com</email></address>
    </author>
    <author initials="J." surname="Gettys" fullname="Jim Gettys">
      <organization>One Laptop per Child</organization>
      <address><email>jg@laptop.org</email></address>
    </author>
    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
      <organization abbrev="HP">Hewlett-Packard Company</organization>
      <address><email>JeffMogul@acm.org</email></address>
    </author>
    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
      <organization abbrev="Microsoft">Microsoft Corporation</organization>
      <address><email>henrikn@microsoft.com</email></address>
    </author>
    <author initials="L." surname="Masinter" fullname="Larry Masinter">
      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
      <address><email>LMM@acm.org</email></address>
    </author>
    <author initials="P." surname="Leach" fullname="Paul J. Leach">
      <organization abbrev="Microsoft">Microsoft Corporation</organization>
      <address><email>paulle@microsoft.com</email></address>
    </author>
    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
      <address><email>timbl@w3.org</email></address>
    </author>
    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
      <organization abbrev="W3C">World Wide Web Consortium</organization>
      <address><email>ylafon@w3.org</email></address>
    </author>
    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
      <organization abbrev="greenbytes">greenbytes GmbH</organization>
      <address><email>julian.reschke@greenbytes.de</email></address>
    </author>
    <date month="February" year="2008"/>
  </front>
  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p1-messaging-02"/>
  
</reference>

<reference anchor="Part6">
  <front>
    <title abbrev="HTTP/1.1">HTTP/1.1, part 6: Caching</title>
    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
      <organization abbrev="Day Software">Day Software</organization>
      <address><email>fielding@gbiv.com</email></address>
    </author>
    <author initials="J." surname="Gettys" fullname="Jim Gettys">
      <organization>One Laptop per Child</organization>
      <address><email>jg@laptop.org</email></address>
    </author>
    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
      <organization abbrev="HP">Hewlett-Packard Company</organization>
      <address><email>JeffMogul@acm.org</email></address>
    </author>
    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
      <organization abbrev="Microsoft">Microsoft Corporation</organization>
      <address><email>henrikn@microsoft.com</email></address>
    </author>
    <author initials="L." surname="Masinter" fullname="Larry Masinter">
      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
      <address><email>LMM@acm.org</email></address>
    </author>
    <author initials="P." surname="Leach" fullname="Paul J. Leach">
      <organization abbrev="Microsoft">Microsoft Corporation</organization>
      <address><email>paulle@microsoft.com</email></address>
    </author>
    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
      <address><email>timbl@w3.org</email></address>
    </author>
    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
      <organization abbrev="W3C">World Wide Web Consortium</organization>
      <address><email>ylafon@w3.org</email></address>
    </author>
    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
      <organization abbrev="greenbytes">greenbytes GmbH</organization>
      <address><email>julian.reschke@greenbytes.de</email></address>
    </author>
    <date month="February" year="2008"/>
  </front>
  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p6-cache-02"/>
  
</reference>

<reference anchor="RFC2119">
  <front>
    <title>Key words for use in RFCs to Indicate Requirement Levels</title>
    <author initials="S." surname="Bradner" fullname="Scott Bradner">
      <organization>Harvard University</organization>
      <address><email>sob@harvard.edu</email></address>
    </author>
    <date month="March" year="1997"/>
  </front>
  <seriesInfo name="BCP" value="14"/>
  <seriesInfo name="RFC" value="2119"/>
</reference>

<reference anchor="RFC2617">
  <front>
    <title abbrev="HTTP Authentication">HTTP Authentication: Basic and Digest Access Authentication</title>
    <author initials="J." surname="Franks" fullname="John Franks">
      <organization>Northwestern University, Department of Mathematics</organization>
      <address><email>john@math.nwu.edu</email></address>
    </author>
    <author initials="P.M." surname="Hallam-Baker" fullname="Phillip M. Hallam-Baker">
      <organization>Verisign Inc.</organization>
      <address><email>pbaker@verisign.com</email></address>
    </author>
    <author initials="J.L." surname="Hostetler" fullname="Jeffery L. Hostetler">
      <organization>AbiSource, Inc.</organization>
      <address><email>jeff@AbiSource.com</email></address>
    </author>
    <author initials="S.D." surname="Lawrence" fullname="Scott D. Lawrence">
      <organization>Agranat Systems, Inc.</organization>
      <address><email>lawrence@agranat.com</email></address>
    </author>
    <author initials="P.J." surname="Leach" fullname="Paul J. Leach">
      <organization>Microsoft Corporation</organization>
      <address><email>paulle@microsoft.com</email></address>
    </author>
    <author initials="A." surname="Luotonen" fullname="Ari Luotonen">
      <organization>Netscape Communications Corporation</organization>
    </author>
    <author initials="L." surname="Stewart" fullname="Lawrence C. Stewart">
      <organization>Open Market, Inc.</organization>
      <address><email>stewart@OpenMarket.com</email></address>
    </author>
    <date month="June" year="1999"/>
  </front>
  <seriesInfo name="RFC" value="2617"/>
</reference>

</references>

<references title="Informative References">

<reference anchor="RFC2616">
  <front>
    <title>Hypertext Transfer Protocol -- HTTP/1.1</title>
    <author initials="R." surname="Fielding" fullname="R. Fielding">
      <organization>University of California, Irvine</organization>
      <address><email>fielding@ics.uci.edu</email></address>
    </author>
    <author initials="J." surname="Gettys" fullname="J. Gettys">
      <organization>W3C</organization>
      <address><email>jg@w3.org</email></address>
    </author>
    <author initials="J." surname="Mogul" fullname="J. Mogul">
      <organization>Compaq Computer Corporation</organization>
      <address><email>mogul@wrl.dec.com</email></address>
    </author>
    <author initials="H." surname="Frystyk" fullname="H. Frystyk">
      <organization>MIT Laboratory for Computer Science</organization>
      <address><email>frystyk@w3.org</email></address>
    </author>
    <author initials="L." surname="Masinter" fullname="L. Masinter">
      <organization>Xerox Corporation</organization>
      <address><email>masinter@parc.xerox.com</email></address>
    </author>
    <author initials="P." surname="Leach" fullname="P. Leach">
      <organization>Microsoft Corporation</organization>
      <address><email>paulle@microsoft.com</email></address>
    </author>
    <author initials="T." surname="Berners-Lee" fullname="T. Berners-Lee">
      <organization>W3C</organization>
      <address><email>timbl@w3.org</email></address>
    </author>
    <date month="June" year="1999"/>
  </front>
  <seriesInfo name="RFC" value="2616"/>
</reference>

</references>


<section title="Compatibility with Previous Versions" anchor="compatibility">

<section title="Changes from RFC 2616" anchor="changes.from.rfc.2616">
</section>

</section>

<section title="Change Log (to be removed by RFC Editor before publication)">

<section title="Since RFC2616">
<t>
  Extracted relevant partitions from <xref target="RFC2616"/>.
</t>
</section>

<section title="Since draft-ietf-httpbis-p7-auth-00">
<t>
  Closed issues:
  <list style="symbols"> 
    <t>
      <eref target="http://www3.tools.ietf.org/wg/httpbis/trac/ticket/35"/>:
      "Normative and Informative references"
    </t>
  </list>
</t>
</section>

<section title="Since draft-ietf-httpbis-p7-auth-01">
<t>
  Ongoing work on ABNF conversion (<eref target="http://www3.tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
  <list style="symbols"> 
    <t>
      Explicitly import BNF rules for "challenge" and "credentials" from RFC2617.
    </t>
    <t>
      Add explicit references to BNF syntax and rules imported from other parts of the specification.
    </t>
  </list>
</t>
</section>

</section>

</back>
</rfc>