source: draft-ietf-httpbis/latest/p7-auth.html

Last change on this file was 2748, checked in by julian.reschke@…, 4 years ago

Update XSLTs, fix Makefile wrt sorting of ABNF, regen HTML

  • Property svn:eol-style set to native
  • Property svn:mime-type set to text/html;charset=utf-8
File size: 88.5 KB
Line 
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496       content: "HTTP/1.1 Authentication";
497  }
498  @bottom-left {
499       content: "Fielding & Reschke";
500  }
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520</style><link rel="Contents" href="#rfc.toc">
521      <link rel="Author" href="#rfc.authors">
522      <link rel="Copyright" href="#rfc.copyrightnotice">
523      <link rel="Index" href="#rfc.index">
524      <link rel="Chapter" title="1 Introduction" href="#rfc.section.1">
525      <link rel="Chapter" title="2 Access Authentication Framework" href="#rfc.section.2">
526      <link rel="Chapter" title="3 Status Code Definitions" href="#rfc.section.3">
527      <link rel="Chapter" title="4 Header Field Definitions" href="#rfc.section.4">
528      <link rel="Chapter" title="5 IANA Considerations" href="#rfc.section.5">
529      <link rel="Chapter" title="6 Security Considerations" href="#rfc.section.6">
530      <link rel="Chapter" title="7 Acknowledgments" href="#rfc.section.7">
531      <link rel="Chapter" href="#rfc.section.8" title="8 References">
532      <link rel="Appendix" title="A Changes from RFCs 2616 and 2617" href="#rfc.section.A">
533      <link rel="Appendix" title="B Imported ABNF" href="#rfc.section.B">
534      <link rel="Appendix" title="C Collected ABNF" href="#rfc.section.C">
535      <link rel="Alternate" title="RFC7235" href="http://svn.tools.ietf.org/svn/wg/httpbis/specs/rfc7235.html">
536      <link href="p6-cache.html" rel="prev">
537      <meta name="generator" content="http://greenbytes.de/tech/webdav/rfc2629.xslt, Revision 1.756, 2015/12/31 17:59:21, XSLT vendor: Saxonica http://www.saxonica.com/">
538      <meta name="keywords" content="Hypertext Transfer Protocol, HTTP, HTTP authentication">
539      <link rel="schema.dct" href="http://purl.org/dc/terms/">
540      <meta name="dct.creator" content="Fielding, R.">
541      <meta name="dct.creator" content="Reschke, J. F.">
542      <meta name="dct.identifier" content="urn:ietf:id:draft-ietf-httpbis-p7-auth-latest">
543      <meta name="dct.issued" scheme="ISO8601" content="2014-06">
544      <meta name="dct.replaces" content="urn:ietf:rfc:2616">
545      <meta name="dct.abstract" content="The Hypertext Transfer Protocol (HTTP) is a stateless application-level protocol for distributed, collaborative, hypermedia information systems. This document defines the HTTP Authentication framework.">
546      <meta name="description" content="The Hypertext Transfer Protocol (HTTP) is a stateless application-level protocol for distributed, collaborative, hypermedia information systems. This document defines the HTTP Authentication framework.">
547   </head>
548   <body onload="initFeedback();">
549      <table class="header" id="rfc.headerblock">
550         <tbody>
551            <tr>
552               <td class="left">HTTPbis Working Group</td>
553               <td class="right">R. Fielding, Editor</td>
554            </tr>
555            <tr>
556               <td class="left">Internet-Draft</td>
557               <td class="right">Adobe</td>
558            </tr>
559            <tr>
560               <td class="left">Obsoletes: <a href="https://tools.ietf.org/html/rfc2616">2616</a> (if approved)
561               </td>
562               <td class="right">J. Reschke, Editor</td>
563            </tr>
564            <tr>
565               <td class="left">Updates: <a href="https://tools.ietf.org/html/rfc2617">2617</a> (if approved)
566               </td>
567               <td class="right">greenbytes</td>
568            </tr>
569            <tr>
570               <td class="left">Intended status: Standards Track</td>
571               <td class="right">June 2014</td>
572            </tr>
573            <tr>
574               <td class="left">Expires: December 2014</td>
575               <td class="right"></td>
576            </tr>
577         </tbody>
578      </table>
579      <div id="rfc.title">
580         <h1>Hypertext Transfer Protocol (HTTP/1.1): Authentication</h1>
581         <div class="filename">draft-ietf-httpbis-p7-auth-latest</div>
582      </div>
583      <p class="publishedasrfc"><b>Note:</b> a later version of this document has been published as <a href="http://svn.tools.ietf.org/svn/wg/httpbis/specs/rfc7235.html">RFC7235</a>.
584         
585      </p>
586      <h2 id="rfc.abstract"><a href="#rfc.abstract">Abstract</a></h2>
587      <p>The Hypertext Transfer Protocol (HTTP) is a stateless application-level protocol for
588         distributed, collaborative, hypermedia information systems. This document defines
589         the HTTP Authentication framework.
590      </p>
591      <h2 id="rfc.note.1"><a href="#rfc.note.1">Editorial Note (To be removed by RFC Editor)</a></h2>
592      <p>Discussion of this draft takes place on the HTTPBIS working group mailing list (ietf-http-wg@w3.org),
593         which is archived at &lt;<a href="http://lists.w3.org/Archives/Public/ietf-http-wg/">http://lists.w3.org/Archives/Public/ietf-http-wg/</a>&gt;.
594      </p>
595      <p>The current issues list is at &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/report/3">http://tools.ietf.org/wg/httpbis/trac/report/3</a>&gt; and related documents (including fancy diffs) can be found at &lt;<a href="http://tools.ietf.org/wg/httpbis/">http://tools.ietf.org/wg/httpbis/</a>&gt;.
596      </p>
597      <p><em>This is a temporary document for the purpose of tracking the editorial changes made
598            during the AUTH48 (RFC publication) phase.</em> 
599      </p>
600      <div id="rfc.status">
601         <h2><a href="#rfc.status">Status of This Memo</a></h2>
602         <p>This Internet-Draft is submitted in full conformance with the provisions of BCP 78
603            and BCP 79.
604         </p>
605         <p>Internet-Drafts are working documents of the Internet Engineering Task Force (IETF).
606            Note that other groups may also distribute working documents as Internet-Drafts. The
607            list of current Internet-Drafts is at <a href="http://datatracker.ietf.org/drafts/current/">http://datatracker.ietf.org/drafts/current/</a>.
608         </p>
609         <p>Internet-Drafts are draft documents valid for a maximum of six months and may be updated,
610            replaced, or obsoleted by other documents at any time. It is inappropriate to use
611            Internet-Drafts as reference material or to cite them other than as “work in progress”.
612         </p>
613         <p>This Internet-Draft will expire in December 2014.</p>
614      </div>
615      <div id="rfc.copyrightnotice">
616         <h2><a href="#rfc.copyrightnotice">Copyright Notice</a></h2>
617         <p>Copyright © 2014 IETF Trust and the persons identified as the document authors. All
618            rights reserved.
619         </p>
620         <p>This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating
621            to IETF Documents (<a href="http://trustee.ietf.org/license-info">http://trustee.ietf.org/license-info</a>) in effect on the date of publication of this document. Please review these documents
622            carefully, as they describe your rights and restrictions with respect to this document.
623            Code Components extracted from this document must include Simplified BSD License text
624            as described in Section 4.e of the Trust Legal Provisions and are provided without
625            warranty as described in the Simplified BSD License.
626         </p>
627         <p>This document may contain material from IETF Documents or IETF Contributions published
628            or made publicly available before November 10, 2008. The person(s) controlling the
629            copyright in some of this material may not have granted the IETF Trust the right to
630            allow modifications of such material outside the IETF Standards Process. Without obtaining
631            an adequate license from the person(s) controlling the copyright in such materials,
632            this document may not be modified outside the IETF Standards Process, and derivative
633            works of it may not be created outside the IETF Standards Process, except to format
634            it for publication as an RFC or to translate it into languages other than English.
635         </p>
636      </div>
637      <hr class="noprint">
638      <div id="rfc.toc">
639         <h2 class="np"><a href="#rfc.toc">Table of Contents</a></h2>
640         <ul class="toc">
641            <li><a href="#rfc.section.1">1.</a>&nbsp;&nbsp;&nbsp;<a href="#introduction">Introduction</a><ul>
642                  <li><a href="#rfc.section.1.1">1.1</a>&nbsp;&nbsp;&nbsp;<a href="#conformance">Conformance and Error Handling</a></li>
643                  <li><a href="#rfc.section.1.2">1.2</a>&nbsp;&nbsp;&nbsp;<a href="#notation">Syntax Notation</a></li>
644               </ul>
645            </li>
646            <li><a href="#rfc.section.2">2.</a>&nbsp;&nbsp;&nbsp;<a href="#access.authentication.framework">Access Authentication Framework</a><ul>
647                  <li><a href="#rfc.section.2.1">2.1</a>&nbsp;&nbsp;&nbsp;<a href="#challenge.and.response">Challenge and Response</a></li>
648                  <li><a href="#rfc.section.2.2">2.2</a>&nbsp;&nbsp;&nbsp;<a href="#protection.space">Protection Space (Realm)</a></li>
649               </ul>
650            </li>
651            <li><a href="#rfc.section.3">3.</a>&nbsp;&nbsp;&nbsp;<a href="#status.code.definitions">Status Code Definitions</a><ul>
652                  <li><a href="#rfc.section.3.1">3.1</a>&nbsp;&nbsp;&nbsp;<a href="#status.401">401 Unauthorized</a></li>
653                  <li><a href="#rfc.section.3.2">3.2</a>&nbsp;&nbsp;&nbsp;<a href="#status.407">407 Proxy Authentication Required</a></li>
654               </ul>
655            </li>
656            <li><a href="#rfc.section.4">4.</a>&nbsp;&nbsp;&nbsp;<a href="#header.field.definitions">Header Field Definitions</a><ul>
657                  <li><a href="#rfc.section.4.1">4.1</a>&nbsp;&nbsp;&nbsp;<a href="#header.www-authenticate">WWW-Authenticate</a></li>
658                  <li><a href="#rfc.section.4.2">4.2</a>&nbsp;&nbsp;&nbsp;<a href="#header.authorization">Authorization</a></li>
659                  <li><a href="#rfc.section.4.3">4.3</a>&nbsp;&nbsp;&nbsp;<a href="#header.proxy-authenticate">Proxy-Authenticate</a></li>
660                  <li><a href="#rfc.section.4.4">4.4</a>&nbsp;&nbsp;&nbsp;<a href="#header.proxy-authorization">Proxy-Authorization</a></li>
661               </ul>
662            </li>
663            <li><a href="#rfc.section.5">5.</a>&nbsp;&nbsp;&nbsp;<a href="#IANA.considerations">IANA Considerations</a><ul>
664                  <li><a href="#rfc.section.5.1">5.1</a>&nbsp;&nbsp;&nbsp;<a href="#authentication.scheme.registry">Authentication Scheme Registry</a><ul>
665                        <li><a href="#rfc.section.5.1.1">5.1.1</a>&nbsp;&nbsp;&nbsp;<a href="#authentication.scheme.registry.procedure">Procedure</a></li>
666                        <li><a href="#rfc.section.5.1.2">5.1.2</a>&nbsp;&nbsp;&nbsp;<a href="#considerations.for.new.authentication.schemes">Considerations for New Authentication Schemes</a></li>
667                     </ul>
668                  </li>
669                  <li><a href="#rfc.section.5.2">5.2</a>&nbsp;&nbsp;&nbsp;<a href="#status.code.registration">Status Code Registration</a></li>
670                  <li><a href="#rfc.section.5.3">5.3</a>&nbsp;&nbsp;&nbsp;<a href="#header.field.registration">Header Field Registration</a></li>
671               </ul>
672            </li>
673            <li><a href="#rfc.section.6">6.</a>&nbsp;&nbsp;&nbsp;<a href="#security.considerations">Security Considerations</a><ul>
674                  <li><a href="#rfc.section.6.1">6.1</a>&nbsp;&nbsp;&nbsp;<a href="#confidentiality.of.credentials">Confidentiality of Credentials</a></li>
675                  <li><a href="#rfc.section.6.2">6.2</a>&nbsp;&nbsp;&nbsp;<a href="#auth.credentials.and.idle.clients">Authentication Credentials and Idle Clients</a></li>
676                  <li><a href="#rfc.section.6.3">6.3</a>&nbsp;&nbsp;&nbsp;<a href="#protection.spaces">Protection Spaces</a></li>
677               </ul>
678            </li>
679            <li><a href="#rfc.section.7">7.</a>&nbsp;&nbsp;&nbsp;<a href="#acks">Acknowledgments</a></li>
680            <li><a href="#rfc.section.8">8.</a>&nbsp;&nbsp;&nbsp;<a href="#rfc.references">References</a><ul>
681                  <li><a href="#rfc.section.8.1">8.1</a>&nbsp;&nbsp;&nbsp;<a href="#rfc.references.1">Normative References</a></li>
682                  <li><a href="#rfc.section.8.2">8.2</a>&nbsp;&nbsp;&nbsp;<a href="#rfc.references.2">Informative References</a></li>
683               </ul>
684            </li>
685            <li><a href="#rfc.section.A">A.</a>&nbsp;&nbsp;&nbsp;<a href="#changes.from.rfc.2616">Changes from RFCs 2616 and 2617</a></li>
686            <li><a href="#rfc.section.B">B.</a>&nbsp;&nbsp;&nbsp;<a href="#imported.abnf">Imported ABNF</a></li>
687            <li><a href="#rfc.section.C">C.</a>&nbsp;&nbsp;&nbsp;<a href="#collected.abnf">Collected ABNF</a></li>
688            <li><a href="#rfc.index">Index</a></li>
689            <li><a href="#rfc.authors">Authors' Addresses</a></li>
690         </ul>
691      </div>
692      <div id="introduction">
693         <h2 id="rfc.section.1" class="np"><a href="#rfc.section.1">1.</a>&nbsp;<a href="#introduction">Introduction</a></h2>
694         <div id="rfc.section.1.p.1">
695            <p>HTTP provides a general framework for access control and authentication, via an extensible
696               set of challenge-response authentication schemes, which can be used by a server to
697               challenge a client request and by a client to provide authentication information.
698               This document defines HTTP/1.1 authentication in terms of the architecture defined
699               in "Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing" <a href="#RFC7230" id="rfc.xref.RFC7230.1"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing">[RFC7230]</cite></a>, including the general framework previously described in "HTTP Authentication: Basic
700               and Digest Access Authentication" <a href="#RFC2617" id="rfc.xref.RFC2617.1"><cite title="HTTP Authentication: Basic and Digest Access Authentication">[RFC2617]</cite></a> and the related fields and status codes previously defined in "Hypertext Transfer
701               Protocol -- HTTP/1.1" <a href="#RFC2616" id="rfc.xref.RFC2616.1"><cite title="Hypertext Transfer Protocol -- HTTP/1.1">[RFC2616]</cite></a>.
702            </p>
703         </div>
704         <div id="rfc.section.1.p.2">
705            <p>The IANA Authentication Scheme Registry (<a href="#authentication.scheme.registry" title="Authentication Scheme Registry">Section&nbsp;5.1</a>) lists registered authentication schemes and their corresponding specifications,
706               including the "basic" and "digest" authentication schemes previously defined by <cite title="HTTP Authentication: Basic and Digest Access Authentication" id="rfc.xref.RFC2617.2">RFC 2617</cite>.
707            </p>
708         </div>
709         <div id="conformance">
710            <h3 id="rfc.section.1.1"><a href="#rfc.section.1.1">1.1</a>&nbsp;<a href="#conformance">Conformance and Error Handling</a></h3>
711            <div id="rfc.section.1.1.p.1">
712               <p>The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD
713                  NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted
714                  as described in <a href="#RFC2119" id="rfc.xref.RFC2119.1"><cite title="Key words for use in RFCs to Indicate Requirement Levels">[RFC2119]</cite></a>.
715               </p>
716            </div>
717            <div id="rfc.section.1.1.p.2">
718               <p>Conformance criteria and considerations regarding error handling are defined in <a href="p1-messaging.html#conformance" title="Conformance and Error Handling">Section 2.5</a> of <a href="#RFC7230" id="rfc.xref.RFC7230.2"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing">[RFC7230]</cite></a>.
719               </p>
720            </div>
721         </div>
722         <div id="notation">
723            <h3 id="rfc.section.1.2"><a href="#rfc.section.1.2">1.2</a>&nbsp;<a href="#notation">Syntax Notation</a></h3>
724            <div id="rfc.section.1.2.p.1">
725               <p>This specification uses the Augmented Backus-Naur Form (ABNF) notation of <a href="#RFC5234" id="rfc.xref.RFC5234.1"><cite title="Augmented BNF for Syntax Specifications: ABNF">[RFC5234]</cite></a> with a list extension, defined in <a href="p1-messaging.html#abnf.extension" title="ABNF List Extension: #rule">Section 7</a> of <a href="#RFC7230" id="rfc.xref.RFC7230.3"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing">[RFC7230]</cite></a>, that allows for compact definition of comma-separated lists using a '#' operator
726                  (similar to how the '*' operator indicates repetition). <a href="#imported.abnf" title="Imported ABNF">Appendix&nbsp;B</a> describes rules imported from other documents. <a href="#collected.abnf" title="Collected ABNF">Appendix&nbsp;C</a> shows the collected grammar with all list operators expanded to standard ABNF notation.
727               </p>
728            </div>
729         </div>
730      </div>
731      <div id="access.authentication.framework">
732         <h2 id="rfc.section.2"><a href="#rfc.section.2">2.</a>&nbsp;<a href="#access.authentication.framework">Access Authentication Framework</a></h2>
733         <div id="challenge.and.response">
734            <h3 id="rfc.section.2.1"><a href="#rfc.section.2.1">2.1</a>&nbsp;<a href="#challenge.and.response">Challenge and Response</a></h3>
735            <div id="rfc.section.2.1.p.1">
736               <p>HTTP provides a simple challenge-response authentication framework that can be used
737                  by a server to challenge a client request and by a client to provide authentication
738                  information. It uses a case-insensitive token as a means to identify the authentication
739                  scheme, followed by additional information necessary for achieving authentication
740                  via that scheme. The latter can be either a comma-separated list of parameters or
741                  a single sequence of characters capable of holding base64-encoded information.
742               </p>
743            </div>
744            <div id="rfc.section.2.1.p.2">
745               <p>Authentication parameters are name=value pairs, where the name token is matched case-insensitively,
746                  and each parameter name <em class="bcp14">MUST</em> only occur once per challenge.
747               </p>
748            </div>
749            <div id="rfc.figure.u.1"><pre class="inline"><span id="rfc.iref.g.1"></span><span id="rfc.iref.g.2"></span><span id="rfc.iref.g.3"></span>  auth-scheme    = <a href="#imported.abnf" class="smpl">token</a>
750 
751  auth-param     = <a href="#imported.abnf" class="smpl">token</a> <a href="#imported.abnf" class="smpl">BWS</a> "=" <a href="#imported.abnf" class="smpl">BWS</a> ( <a href="#imported.abnf" class="smpl">token</a> / <a href="#imported.abnf" class="smpl">quoted-string</a> )
752
753  token68        = 1*( <a href="#imported.abnf" class="smpl">ALPHA</a> / <a href="#imported.abnf" class="smpl">DIGIT</a> /
754                       "-" / "." / "_" / "~" / "+" / "/" ) *"="
755</pre></div>
756            <div id="rfc.section.2.1.p.3">
757               <p>The token68 syntax allows the 66 unreserved URI characters (<a href="#RFC3986" id="rfc.xref.RFC3986.1"><cite title="Uniform Resource Identifier (URI): Generic Syntax">[RFC3986]</cite></a>), plus a few others, so that it can hold a base64, base64url (URL and filename safe
758                  alphabet), base32, or base16 (hex) encoding, with or without padding, but excluding
759                  whitespace (<a href="#RFC4648" id="rfc.xref.RFC4648.1"><cite title="The Base16, Base32, and Base64 Data Encodings">[RFC4648]</cite></a>).
760               </p>
761            </div>
762            <div id="rfc.section.2.1.p.4">
763               <p>A <a href="#status.401" class="smpl">401 (Unauthorized)</a> response message is used by an origin server to challenge the authorization of a user
764                  agent, including a <a href="#header.www-authenticate" class="smpl">WWW-Authenticate</a> header field containing at least one challenge applicable to the requested resource.
765               </p>
766            </div>
767            <div id="rfc.section.2.1.p.5">
768               <p>A <a href="#status.407" class="smpl">407 (Proxy Authentication Required)</a> response message is used by a proxy to challenge the authorization of a client, including
769                  a <a href="#header.proxy-authenticate" class="smpl">Proxy-Authenticate</a> header field containing at least one challenge applicable to the proxy for the requested
770                  resource.
771               </p>
772            </div>
773            <div id="rfc.figure.u.2"><pre class="inline"><span id="rfc.iref.g.4"></span>  <a href="#challenge.and.response" class="smpl">challenge</a>   = <a href="#challenge.and.response" class="smpl">auth-scheme</a> [ 1*<a href="#imported.abnf" class="smpl">SP</a> ( <a href="#challenge.and.response" class="smpl">token68</a> / #<a href="#challenge.and.response" class="smpl">auth-param</a> ) ]
774</pre></div>
775            <div class="note">
776               <div id="rfc.section.2.1.p.6">
777                  <p><b>Note:</b> Many clients fail to parse a challenge that contains an unknown scheme. A workaround
778                     for this problem is to list well-supported schemes (such as "basic") first.
779                  </p>
780               </div>
781            </div>
782            <div id="rfc.section.2.1.p.7">
783               <p>A user agent that wishes to authenticate itself with an origin server — usually, but
784                  not necessarily, after receiving a <a href="#status.401" class="smpl">401 (Unauthorized)</a> — can do so by including an <a href="#header.authorization" class="smpl">Authorization</a> header field with the request.
785               </p>
786            </div>
787            <div id="rfc.section.2.1.p.8">
788               <p>A client that wishes to authenticate itself with a proxy — usually, but not necessarily,
789                  after receiving a <a href="#status.407" class="smpl">407 (Proxy Authentication Required)</a> — can do so by including a <a href="#header.proxy-authorization" class="smpl">Proxy-Authorization</a> header field with the request.
790               </p>
791            </div>
792            <div id="rfc.section.2.1.p.9">
793               <p>Both the <a href="#header.authorization" class="smpl">Authorization</a> field value and the <a href="#header.proxy-authorization" class="smpl">Proxy-Authorization</a> field value contain the client's credentials for the realm of the resource being requested,
794                  based upon a challenge received in a response (possibly at some point in the past).
795                  When creating their values, the user agent ought to do so by selecting the challenge
796                  with what it considers to be the most secure auth-scheme that it understands, obtaining
797                  credentials from the user as appropriate. Transmission of credentials within header
798                  field values implies significant security considerations regarding the confidentiality
799                  of the underlying connection, as described in <a href="#confidentiality.of.credentials" title="Confidentiality of Credentials">Section&nbsp;6.1</a>.
800               </p>
801            </div>
802            <div id="rfc.figure.u.3"><pre class="inline"><span id="rfc.iref.g.5"></span>  <a href="#challenge.and.response" class="smpl">credentials</a> = <a href="#challenge.and.response" class="smpl">auth-scheme</a> [ 1*<a href="#imported.abnf" class="smpl">SP</a> ( <a href="#challenge.and.response" class="smpl">token68</a> / #<a href="#challenge.and.response" class="smpl">auth-param</a> ) ]
803</pre></div>
804            <div id="rfc.section.2.1.p.10">
805               <p>Upon receipt of a request for a protected resource that omits credentials, contains
806                  invalid credentials (e.g., a bad password) or partial credentials (e.g., when the
807                  authentication scheme requires more than one round trip), an origin server <em class="bcp14">SHOULD</em> send a <a href="#status.401" class="smpl">401 (Unauthorized)</a> response that contains a <a href="#header.www-authenticate" class="smpl">WWW-Authenticate</a> header field with at least one (possibly new) challenge applicable to the requested
808                  resource.
809               </p>
810            </div>
811            <div id="rfc.section.2.1.p.11">
812               <p>Likewise, upon receipt of a request that omits proxy credentials or contains invalid
813                  or partial proxy credentials, a proxy that requires authentication <em class="bcp14">SHOULD</em> generate a <a href="#status.407" class="smpl">407 (Proxy Authentication Required)</a> response that contains a <a href="#header.proxy-authenticate" class="smpl">Proxy-Authenticate</a> header field with at least one (possibly new) challenge applicable to the proxy.
814               </p>
815            </div>
816            <div id="rfc.section.2.1.p.12">
817               <p>A server that receives valid credentials that are not adequate to gain access ought
818                  to respond with the <a href="p2-semantics.html#status.403" class="smpl">403 (Forbidden)</a> status code (<a href="p2-semantics.html#status.403" title="403 Forbidden">Section 6.5.3</a> of <a href="#RFC7231" id="rfc.xref.RFC7231.1"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[RFC7231]</cite></a>).
819               </p>
820            </div>
821            <div id="rfc.section.2.1.p.13">
822               <p>HTTP does not restrict applications to this simple challenge-response framework for
823                  access authentication. Additional mechanisms can be used, such as authentication at
824                  the transport level or via message encapsulation, and with additional header fields
825                  specifying authentication information. However, such additional mechanisms are not
826                  defined by this specification.
827               </p>
828            </div>
829         </div>
830         <div id="protection.space">
831            <h3 id="rfc.section.2.2"><a href="#rfc.section.2.2">2.2</a>&nbsp;<a href="#protection.space">Protection Space (Realm)</a></h3>
832            <div id="rfc.section.2.2.p.1">
833               <p>The "<dfn>realm</dfn>" authentication parameter is reserved for use by authentication schemes that wish
834                  to indicate a scope of protection.
835               </p>
836            </div>
837            <div id="rfc.section.2.2.p.2">
838               <p>A <dfn>protection space</dfn> is defined by the canonical root URI (the scheme and authority components of the effective
839                  request URI; see <a href="p1-messaging.html#effective.request.uri" title="Effective Request URI">Section 5.5</a> of <a href="#RFC7230" id="rfc.xref.RFC7230.4"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing">[RFC7230]</cite></a>) of the server being accessed, in combination with the realm value if present. These
840                  realms allow the protected resources on a server to be partitioned into a set of protection
841                  spaces, each with its own authentication scheme and/or authorization database. The
842                  realm value is a string, generally assigned by the origin server, that can have additional
843                  semantics specific to the authentication scheme. Note that a response can have multiple
844                  challenges with the same auth-scheme but with different realms.
845               </p>
846            </div>
847            <div id="rfc.section.2.2.p.3">
848               <p>The protection space determines the domain over which credentials can be automatically
849                  applied. If a prior request has been authorized, the user agent <em class="bcp14">MAY</em> reuse the same credentials for all other requests within that protection space for
850                  a period of time determined by the authentication scheme, parameters, and/or user
851                  preferences (such as a configurable inactivity timeout). Unless specifically allowed
852                  by the authentication scheme, a single protection space cannot extend outside the
853                  scope of its server.
854               </p>
855            </div>
856            <div id="rfc.section.2.2.p.4">
857               <p>For historical reasons, a sender <em class="bcp14">MUST</em> only generate the quoted-string syntax. Recipients might have to support both token
858                  and quoted-string syntax for maximum interoperability with existing clients that have
859                  been accepting both notations for a long time.
860               </p>
861            </div>
862         </div>
863      </div>
864      <div id="status.code.definitions">
865         <h2 id="rfc.section.3"><a href="#rfc.section.3">3.</a>&nbsp;<a href="#status.code.definitions">Status Code Definitions</a></h2>
866         <div id="status.401">
867            <h3 id="rfc.section.3.1"><a href="#rfc.section.3.1">3.1</a>&nbsp;<a href="#status.401">401 Unauthorized</a></h3>
868            <div id="rfc.section.3.1.p.1">
869               <p>The <dfn>401 (Unauthorized)</dfn> status code indicates that the request has not been applied because it lacks valid
870                  authentication credentials for the target resource. The server generating a 401 response <em class="bcp14">MUST</em> send a <a href="#header.www-authenticate" class="smpl">WWW-Authenticate</a> header field (<a href="#header.www-authenticate" id="rfc.xref.header.www-authenticate.1" title="WWW-Authenticate">Section&nbsp;4.1</a>) containing at least one challenge applicable to the target resource.
871               </p>
872            </div>
873            <div id="rfc.section.3.1.p.2">
874               <p>If the request included authentication credentials, then the 401 response indicates
875                  that authorization has been refused for those credentials. The user agent <em class="bcp14">MAY</em> repeat the request with a new or replaced <a href="#header.authorization" class="smpl">Authorization</a> header field (<a href="#header.authorization" id="rfc.xref.header.authorization.1" title="Authorization">Section&nbsp;4.2</a>). If the 401 response contains the same challenge as the prior response, and the
876                  user agent has already attempted authentication at least once, then the user agent <em class="bcp14">SHOULD</em> present the enclosed representation to the user, since it usually contains relevant
877                  diagnostic information.
878               </p>
879            </div>
880         </div>
881         <div id="status.407">
882            <h3 id="rfc.section.3.2"><a href="#rfc.section.3.2">3.2</a>&nbsp;<a href="#status.407">407 Proxy Authentication Required</a></h3>
883            <div id="rfc.section.3.2.p.1">
884               <p>The <dfn>407 (Proxy Authentication Required)</dfn> status code is similar to <a href="#status.401" class="smpl">401 (Unauthorized)</a>, but it indicates that the client needs to authenticate itself in order to use a
885                  proxy. The proxy <em class="bcp14">MUST</em> send a <a href="#header.proxy-authenticate" class="smpl">Proxy-Authenticate</a> header field (<a href="#header.proxy-authenticate" id="rfc.xref.header.proxy-authenticate.1" title="Proxy-Authenticate">Section&nbsp;4.3</a>) containing a challenge applicable to that proxy for the target resource. The client <em class="bcp14">MAY</em> repeat the request with a new or replaced <a href="#header.proxy-authorization" class="smpl">Proxy-Authorization</a> header field (<a href="#header.proxy-authorization" id="rfc.xref.header.proxy-authorization.1" title="Proxy-Authorization">Section&nbsp;4.4</a>).
886               </p>
887            </div>
888         </div>
889      </div>
890      <div id="header.field.definitions">
891         <h2 id="rfc.section.4"><a href="#rfc.section.4">4.</a>&nbsp;<a href="#header.field.definitions">Header Field Definitions</a></h2>
892         <div id="rfc.section.4.p.1">
893            <p>This section defines the syntax and semantics of header fields related to the HTTP
894               authentication framework.
895            </p>
896         </div>
897         <div id="header.www-authenticate">
898            <h3 id="rfc.section.4.1"><a href="#rfc.section.4.1">4.1</a>&nbsp;<a href="#header.www-authenticate">WWW-Authenticate</a></h3>
899            <div id="rfc.section.4.1.p.1">
900               <p>The "WWW-Authenticate" header field indicates the authentication scheme(s) and parameters
901                  applicable to the target resource.
902               </p>
903            </div>
904            <div id="rfc.figure.u.4"><pre class="inline"><span id="rfc.iref.g.6"></span>  <a href="#header.www-authenticate" class="smpl">WWW-Authenticate</a> = 1#<a href="#challenge.and.response" class="smpl">challenge</a>
905</pre></div>
906            <div id="rfc.section.4.1.p.2">
907               <p>A server generating a <a href="#status.401" class="smpl">401 (Unauthorized)</a> response <em class="bcp14">MUST</em> send a WWW-Authenticate header field containing at least one challenge. A server <em class="bcp14">MAY</em> generate a WWW-Authenticate header field in other response messages to indicate that
908                  supplying credentials (or different credentials) might affect the response.
909               </p>
910            </div>
911            <div id="rfc.section.4.1.p.3">
912               <p>A proxy forwarding a response <em class="bcp14">MUST NOT</em> modify any <a href="#header.www-authenticate" class="smpl">WWW-Authenticate</a> fields in that response.
913               </p>
914            </div>
915            <div id="rfc.section.4.1.p.4">
916               <p>User agents are advised to take special care in parsing the field value, as it might
917                  contain more than one challenge, and each challenge can contain a comma-separated
918                  list of authentication parameters. Furthermore, the header field itself can occur
919                  multiple times.
920               </p>
921            </div>
922            <div id="rfc.figure.u.5">
923               <p>For instance:</p><pre class="text">  WWW-Authenticate: Newauth realm="apps", type=1,
924                    title="Login to \"apps\"", Basic realm="simple"
925</pre><p>This header field contains two challenges; one for the "Newauth" scheme with a realm
926                  value of "apps", and two additional parameters "type" and "title", and another one
927                  for the "Basic" scheme with a realm value of "simple".
928               </p>
929            </div>
930            <div class="note">
931               <div id="rfc.section.4.1.p.5">
932                  <p><b>Note:</b> The challenge grammar production uses the list syntax as well. Therefore, a sequence
933                     of comma, whitespace, and comma can be considered either as applying to the preceding
934                     challenge, or to be an empty entry in the list of challenges. In practice, this ambiguity
935                     does not affect the semantics of the header field value and thus is harmless.
936                  </p>
937               </div>
938            </div>
939         </div>
940         <div id="header.authorization">
941            <h3 id="rfc.section.4.2"><a href="#rfc.section.4.2">4.2</a>&nbsp;<a href="#header.authorization">Authorization</a></h3>
942            <div id="rfc.section.4.2.p.1">
943               <p>The "Authorization" header field allows a user agent to authenticate itself with an
944                  origin server — usually, but not necessarily, after receiving a <a href="#status.401" class="smpl">401 (Unauthorized)</a> response. Its value consists of credentials containing the authentication information
945                  of the user agent for the realm of the resource being requested.
946               </p>
947            </div>
948            <div id="rfc.figure.u.6"><pre class="inline"><span id="rfc.iref.g.7"></span>  <a href="#header.authorization" class="smpl">Authorization</a> = <a href="#challenge.and.response" class="smpl">credentials</a>
949</pre></div>
950            <div id="rfc.section.4.2.p.2">
951               <p>If a request is authenticated and a realm specified, the same credentials are presumed
952                  to be valid for all other requests within this realm (assuming that the authentication
953                  scheme itself does not require otherwise, such as credentials that vary according
954                  to a challenge value or using synchronized clocks).
955               </p>
956            </div>
957            <div id="rfc.section.4.2.p.3">
958               <p>A proxy forwarding a request <em class="bcp14">MUST NOT</em> modify any <a href="#header.authorization" class="smpl">Authorization</a> fields in that request. See <a href="p6-cache.html#caching.authenticated.responses" title="Storing Responses to Authenticated Requests">Section 3.2</a> of <a href="#RFC7234" id="rfc.xref.RFC7234.1"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Caching">[RFC7234]</cite></a> for details of and requirements pertaining to handling of the Authorization field
959                  by HTTP caches.
960               </p>
961            </div>
962         </div>
963         <div id="header.proxy-authenticate">
964            <h3 id="rfc.section.4.3"><a href="#rfc.section.4.3">4.3</a>&nbsp;<a href="#header.proxy-authenticate">Proxy-Authenticate</a></h3>
965            <div id="rfc.section.4.3.p.1">
966               <p>The "Proxy-Authenticate" header field consists of at least one challenge that indicates
967                  the authentication scheme(s) and parameters applicable to the proxy for this effective
968                  request URI (<a href="p1-messaging.html#effective.request.uri" title="Effective Request URI">Section 5.5</a> of <a href="#RFC7230" id="rfc.xref.RFC7230.5"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing">[RFC7230]</cite></a>). A proxy <em class="bcp14">MUST</em> send at least one Proxy-Authenticate header field in each <a href="#status.407" class="smpl">407 (Proxy Authentication Required)</a> response that it generates.
969               </p>
970            </div>
971            <div id="rfc.figure.u.7"><pre class="inline"><span id="rfc.iref.g.8"></span>  <a href="#header.proxy-authenticate" class="smpl">Proxy-Authenticate</a> = 1#<a href="#challenge.and.response" class="smpl">challenge</a>
972</pre></div>
973            <div id="rfc.section.4.3.p.2">
974               <p>Unlike <a href="#header.www-authenticate" class="smpl">WWW-Authenticate</a>, the Proxy-Authenticate header field applies only to the next outbound client on
975                  the response chain. This is because only the client that chose a given proxy is likely
976                  to have the credentials necessary for authentication. However, when multiple proxies
977                  are used within the same administrative domain, such as office and regional caching
978                  proxies within a large corporate network, it is common for credentials to be generated
979                  by the user agent and passed through the hierarchy until consumed. Hence, in such
980                  a configuration, it will appear as if Proxy-Authenticate is being forwarded because
981                  each proxy will send the same challenge set.
982               </p>
983            </div>
984            <div id="rfc.section.4.3.p.3">
985               <p>Note that the parsing considerations for <a href="#header.www-authenticate" class="smpl">WWW-Authenticate</a> apply to this header field as well; see <a href="#header.www-authenticate" id="rfc.xref.header.www-authenticate.2" title="WWW-Authenticate">Section&nbsp;4.1</a> for details.
986               </p>
987            </div>
988         </div>
989         <div id="header.proxy-authorization">
990            <h3 id="rfc.section.4.4"><a href="#rfc.section.4.4">4.4</a>&nbsp;<a href="#header.proxy-authorization">Proxy-Authorization</a></h3>
991            <div id="rfc.section.4.4.p.1">
992               <p>The "Proxy-Authorization" header field allows the client to identify itself (or its
993                  user) to a proxy that requires authentication. Its value consists of credentials containing
994                  the authentication information of the client for the proxy and/or realm of the resource
995                  being requested.
996               </p>
997            </div>
998            <div id="rfc.figure.u.8"><pre class="inline"><span id="rfc.iref.g.9"></span>  <a href="#header.proxy-authorization" class="smpl">Proxy-Authorization</a> = <a href="#challenge.and.response" class="smpl">credentials</a>
999</pre></div>
1000            <div id="rfc.section.4.4.p.2">
1001               <p>Unlike <a href="#header.authorization" class="smpl">Authorization</a>, the Proxy-Authorization header field applies only to the next inbound proxy that
1002                  demanded authentication using the <a href="#header.proxy-authenticate" class="smpl">Proxy-Authenticate</a> field. When multiple proxies are used in a chain, the Proxy-Authorization header field
1003                  is consumed by the first inbound proxy that was expecting to receive credentials.
1004                  A proxy <em class="bcp14">MAY</em> relay the credentials from the client request to the next proxy if that is the mechanism
1005                  by which the proxies cooperatively authenticate a given request.
1006               </p>
1007            </div>
1008         </div>
1009      </div>
1010      <div id="IANA.considerations">
1011         <h2 id="rfc.section.5"><a href="#rfc.section.5">5.</a>&nbsp;<a href="#IANA.considerations">IANA Considerations</a></h2>
1012         <div id="authentication.scheme.registry">
1013            <h3 id="rfc.section.5.1"><a href="#rfc.section.5.1">5.1</a>&nbsp;<a href="#authentication.scheme.registry">Authentication Scheme Registry</a></h3>
1014            <div id="rfc.section.5.1.p.1">
1015               <p>The "Hypertext Transfer Protocol (HTTP) Authentication Scheme Registry" defines the
1016                  namespace for the authentication schemes in challenges and credentials. It has been
1017                  created and is now maintained at &lt;<a href="http://www.iana.org/assignments/http-authschemes">http://www.iana.org/assignments/http-authschemes</a>&gt;.
1018               </p>
1019            </div>
1020            <div id="authentication.scheme.registry.procedure">
1021               <h4 id="rfc.section.5.1.1"><a href="#rfc.section.5.1.1">5.1.1</a>&nbsp;<a href="#authentication.scheme.registry.procedure">Procedure</a></h4>
1022               <div id="rfc.section.5.1.1.p.1">
1023                  <p>Registrations <em class="bcp14">MUST</em> include the following fields:
1024                  </p>
1025                  <ul>
1026                     <li>Authentication Scheme Name</li>
1027                     <li>Pointer to specification text</li>
1028                     <li>Notes (optional)</li>
1029                  </ul>
1030               </div>
1031               <div id="rfc.section.5.1.1.p.2">
1032                  <p>Values to be added to this namespace require IETF Review (see <a href="#RFC5226" id="rfc.xref.RFC5226.1"><cite title="Guidelines for Writing an IANA Considerations Section in RFCs">[RFC5226]</cite></a>, <a href="https://tools.ietf.org/html/rfc5226#section-4.1">Section 4.1</a>).
1033                  </p>
1034               </div>
1035            </div>
1036            <div id="considerations.for.new.authentication.schemes">
1037               <h4 id="rfc.section.5.1.2"><a href="#rfc.section.5.1.2">5.1.2</a>&nbsp;<a href="#considerations.for.new.authentication.schemes">Considerations for New Authentication Schemes</a></h4>
1038               <div id="rfc.section.5.1.2.p.1" class="avoidbreakafter">
1039                  <p>There are certain aspects of the HTTP Authentication Framework that put constraints
1040                     on how new authentication schemes can work:
1041                  </p>
1042               </div>
1043               <div id="rfc.section.5.1.2.p.2">
1044                  <ul>
1045                     <li>
1046                        <p>HTTP authentication is presumed to be stateless: all of the information necessary
1047                           to authenticate a request <em class="bcp14">MUST</em> be provided in the request, rather than be dependent on the server remembering prior
1048                           requests. Authentication based on, or bound to, the underlying connection is outside
1049                           the scope of this specification and inherently flawed unless steps are taken to ensure
1050                           that the connection cannot be used by any party other than the authenticated user
1051                           (see <a href="p1-messaging.html#intermediaries" title="Intermediaries">Section 2.3</a> of <a href="#RFC7230" id="rfc.xref.RFC7230.6"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing">[RFC7230]</cite></a>).
1052                        </p>
1053                     </li>
1054                     <li>
1055                        <p>The authentication parameter "realm" is reserved for defining protection spaces as
1056                           described in <a href="#protection.space" title="Protection Space (Realm)">Section&nbsp;2.2</a>. New schemes <em class="bcp14">MUST NOT</em> use it in a way incompatible with that definition.
1057                        </p>
1058                     </li>
1059                     <li>
1060                        <p>The "token68" notation was introduced for compatibility with existing authentication
1061                           schemes and can only be used once per challenge or credential. Thus, new schemes ought
1062                           to use the auth-param syntax instead, because otherwise future extensions will be
1063                           impossible.
1064                        </p>
1065                     </li>
1066                     <li>
1067                        <p>The parsing of challenges and credentials is defined by this specification and cannot
1068                           be modified by new authentication schemes. When the auth-param syntax is used, all
1069                           parameters ought to support both token and quoted-string syntax, and syntactical constraints
1070                           ought to be defined on the field value after parsing (i.e., quoted-string processing).
1071                           This is necessary so that recipients can use a generic parser that applies to all
1072                           authentication schemes.
1073                        </p>
1074                        <p><b>Note:</b> The fact that the value syntax for the "realm" parameter is restricted to quoted-string
1075                           was a bad design choice not to be repeated for new parameters.
1076                        </p>
1077                     </li>
1078                     <li>
1079                        <p>Definitions of new schemes ought to define the treatment of unknown extension parameters.
1080                           In general, a "must-ignore" rule is preferable to a "must-understand" rule, because
1081                           otherwise it will be hard to introduce new parameters in the presence of legacy recipients.
1082                           Furthermore, it's good to describe the policy for defining new parameters (such as
1083                           "update the specification" or "use this registry").
1084                        </p>
1085                     </li>
1086                     <li>
1087                        <p>Authentication schemes need to document whether they are usable in origin-server authentication
1088                           (i.e., using <a href="#header.www-authenticate" class="smpl">WWW-Authenticate</a>), and/or proxy authentication (i.e., using <a href="#header.proxy-authenticate" class="smpl">Proxy-Authenticate</a>).
1089                        </p>
1090                     </li>
1091                     <li>
1092                        <p>The credentials carried in an <a href="#header.authorization" class="smpl">Authorization</a> header field are specific to the user agent and, therefore, have the same effect on
1093                           HTTP caches as the "private" Cache-Control response directive (<a href="p6-cache.html#cache-response-directive.private" title="private">Section 5.2.2.6</a> of <a href="#RFC7234" id="rfc.xref.RFC7234.2"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Caching">[RFC7234]</cite></a>), within the scope of the request in which they appear.
1094                        </p>
1095                        <p>Therefore, new authentication schemes that choose not to carry credentials in the <a href="#header.authorization" class="smpl">Authorization</a> header field (e.g., using a newly defined header field) will need to explicitly disallow
1096                           caching, by mandating the use of either Cache-Control request directives (e.g., "no-store", <a href="p6-cache.html#cache-request-directive.no-store" title="no-store">Section 5.2.1.5</a> of <a href="#RFC7234" id="rfc.xref.RFC7234.3"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Caching">[RFC7234]</cite></a>) or response directives (e.g., "private").
1097                        </p>
1098                     </li>
1099                  </ul>
1100               </div>
1101            </div>
1102         </div>
1103         <div id="status.code.registration">
1104            <h3 id="rfc.section.5.2"><a href="#rfc.section.5.2">5.2</a>&nbsp;<a href="#status.code.registration">Status Code Registration</a></h3>
1105            <div id="rfc.section.5.2.p.1" class="avoidbreakafter">
1106               <p>The "Hypertext Transfer Protocol (HTTP) Status Code Registry" located at &lt;<a href="http://www.iana.org/assignments/http-status-codes">http://www.iana.org/assignments/http-status-codes</a>&gt; has been updated with the registrations below:
1107               </p>
1108            </div>
1109            <div id="rfc.table.1">
1110               <div id="iana.status.code.registration.table"></div>
1111               <table class="tt full tleft" cellpadding="3" cellspacing="0">
1112                  <thead>
1113                     <tr>
1114                        <th>Value</th>
1115                        <th>Description</th>
1116                        <th>Reference</th>
1117                     </tr>
1118                  </thead>
1119                  <tbody>
1120                     <tr>
1121                        <td class="left">401</td>
1122                        <td class="left">Unauthorized</td>
1123                        <td class="left"><a href="#status.401" id="rfc.xref.status.401.1" title="401 Unauthorized">Section&nbsp;3.1</a> 
1124                        </td>
1125                     </tr>
1126                     <tr>
1127                        <td class="left">407</td>
1128                        <td class="left">Proxy Authentication Required</td>
1129                        <td class="left"><a href="#status.407" id="rfc.xref.status.407.1" title="407 Proxy Authentication Required">Section&nbsp;3.2</a> 
1130                        </td>
1131                     </tr>
1132                  </tbody>
1133               </table>
1134            </div>
1135         </div>
1136         <div id="header.field.registration">
1137            <h3 id="rfc.section.5.3"><a href="#rfc.section.5.3">5.3</a>&nbsp;<a href="#header.field.registration">Header Field Registration</a></h3>
1138            <div id="rfc.section.5.3.p.1">
1139               <p>HTTP header fields are registered within the "Message Headers" registry maintained
1140                  at &lt;<a href="http://www.iana.org/assignments/message-headers/">http://www.iana.org/assignments/message-headers/</a>&gt;.
1141               </p>
1142            </div>
1143            <div id="rfc.section.5.3.p.2">
1144               <p>This document defines the following HTTP header fields, so the "Permanent Message
1145                  Header Field Names" registry has been updated accordingly (see <a href="#BCP90" id="rfc.xref.BCP90.1"><cite title="Registration Procedures for Message Header Fields">[BCP90]</cite></a>).
1146               </p>
1147            </div>
1148            <div id="rfc.table.2">
1149               <div id="iana.header.registration.table"></div>
1150               <table class="tt full tleft" cellpadding="3" cellspacing="0">
1151                  <thead>
1152                     <tr>
1153                        <th>Header Field Name</th>
1154                        <th>Protocol</th>
1155                        <th>Status</th>
1156                        <th>Reference</th>
1157                     </tr>
1158                  </thead>
1159                  <tbody>
1160                     <tr>
1161                        <td class="left">Authorization</td>
1162                        <td class="left">http</td>
1163                        <td class="left">standard</td>
1164                        <td class="left"><a href="#header.authorization" id="rfc.xref.header.authorization.2" title="Authorization">Section&nbsp;4.2</a> 
1165                        </td>
1166                     </tr>
1167                     <tr>
1168                        <td class="left">Proxy-Authenticate</td>
1169                        <td class="left">http</td>
1170                        <td class="left">standard</td>
1171                        <td class="left"><a href="#header.proxy-authenticate" id="rfc.xref.header.proxy-authenticate.2" title="Proxy-Authenticate">Section&nbsp;4.3</a> 
1172                        </td>
1173                     </tr>
1174                     <tr>
1175                        <td class="left">Proxy-Authorization</td>
1176                        <td class="left">http</td>
1177                        <td class="left">standard</td>
1178                        <td class="left"><a href="#header.proxy-authorization" id="rfc.xref.header.proxy-authorization.2" title="Proxy-Authorization">Section&nbsp;4.4</a> 
1179                        </td>
1180                     </tr>
1181                     <tr>
1182                        <td class="left">WWW-Authenticate</td>
1183                        <td class="left">http</td>
1184                        <td class="left">standard</td>
1185                        <td class="left"><a href="#header.www-authenticate" id="rfc.xref.header.www-authenticate.3" title="WWW-Authenticate">Section&nbsp;4.1</a> 
1186                        </td>
1187                     </tr>
1188                  </tbody>
1189               </table>
1190            </div>
1191            <div id="rfc.section.5.3.p.3">
1192               <p>The change controller is: "IETF (iesg@ietf.org) - Internet Engineering Task Force".</p>
1193            </div>
1194         </div>
1195      </div>
1196      <div id="security.considerations">
1197         <h2 id="rfc.section.6"><a href="#rfc.section.6">6.</a>&nbsp;<a href="#security.considerations">Security Considerations</a></h2>
1198         <div id="rfc.section.6.p.1">
1199            <p>This section is meant to inform developers, information providers, and users of known
1200               security concerns specific to HTTP authentication. More general security considerations
1201               are addressed in HTTP messaging <a href="#RFC7230" id="rfc.xref.RFC7230.7"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing">[RFC7230]</cite></a> and semantics <a href="#RFC7231" id="rfc.xref.RFC7231.2"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[RFC7231]</cite></a>.
1202            </p>
1203         </div>
1204         <div id="rfc.section.6.p.2">
1205            <p>Everything about the topic of HTTP authentication is a security consideration, so
1206               the list of considerations below is not exhaustive. Furthermore, it is limited to
1207               security considerations regarding the authentication framework, in general, rather
1208               than discussing all of the potential considerations for specific authentication schemes
1209               (which ought to be documented in the specifications that define those schemes). Various
1210               organizations maintain topical information and links to current research on Web application
1211               security (e.g., <a href="#OWASP" id="rfc.xref.OWASP.1"><cite title="A Guide to Building Secure Web Applications and Web Services">[OWASP]</cite></a>), including common pitfalls for implementing and using the authentication schemes
1212               found in practice.
1213            </p>
1214         </div>
1215         <div id="confidentiality.of.credentials">
1216            <h3 id="rfc.section.6.1"><a href="#rfc.section.6.1">6.1</a>&nbsp;<a href="#confidentiality.of.credentials">Confidentiality of Credentials</a></h3>
1217            <div id="rfc.section.6.1.p.1">
1218               <p>The HTTP authentication framework does not define a single mechanism for maintaining
1219                  the confidentiality of credentials; instead, each authentication scheme defines how
1220                  the credentials are encoded prior to transmission. While this provides flexibility
1221                  for the development of future authentication schemes, it is inadequate for the protection
1222                  of existing schemes that provide no confidentiality on their own, or that do not sufficiently
1223                  protect against replay attacks. Furthermore, if the server expects credentials that
1224                  are specific to each individual user, the exchange of those credentials will have
1225                  the effect of identifying that user even if the content within credentials remains
1226                  confidential.
1227               </p>
1228            </div>
1229            <div id="rfc.section.6.1.p.2">
1230               <p>HTTP depends on the security properties of the underlying transport- or session-level
1231                  connection to provide confidential transmission of header fields. In other words,
1232                  if a server limits access to authenticated users using this framework, the server
1233                  needs to ensure that the connection is properly secured in accordance with the nature
1234                  of the authentication scheme used. For example, services that depend on individual
1235                  user authentication often require a connection to be secured with TLS ("Transport
1236                  Layer Security", <a href="#RFC5246" id="rfc.xref.RFC5246.1"><cite title="The Transport Layer Security (TLS) Protocol Version 1.2">[RFC5246]</cite></a>) prior to exchanging any credentials.
1237               </p>
1238            </div>
1239         </div>
1240         <div id="auth.credentials.and.idle.clients">
1241            <h3 id="rfc.section.6.2"><a href="#rfc.section.6.2">6.2</a>&nbsp;<a href="#auth.credentials.and.idle.clients">Authentication Credentials and Idle Clients</a></h3>
1242            <div id="rfc.section.6.2.p.1">
1243               <p>Existing HTTP clients and user agents typically retain authentication information
1244                  indefinitely. HTTP does not provide a mechanism for the origin server to direct clients
1245                  to discard these cached credentials, since the protocol has no awareness of how credentials
1246                  are obtained or managed by the user agent. The mechanisms for expiring or revoking
1247                  credentials can be specified as part of an authentication scheme definition.
1248               </p>
1249            </div>
1250            <div id="rfc.section.6.2.p.2">
1251               <p>Circumstances under which credential caching can interfere with the application's
1252                  security model include but are not limited to:
1253               </p>
1254               <ul>
1255                  <li>Clients that have been idle for an extended period, following which the server might
1256                     wish to cause the client to re-prompt the user for credentials.
1257                  </li>
1258                  <li>Applications that include a session termination indication (such as a "logout" or
1259                     "commit" button on a page) after which the server side of the application "knows"
1260                     that there is no further reason for the client to retain the credentials.
1261                  </li>
1262               </ul>
1263            </div>
1264            <div id="rfc.section.6.2.p.3">
1265               <p>User agents that cache credentials are encouraged to provide a readily accessible
1266                  mechanism for discarding cached credentials under user control.
1267               </p>
1268            </div>
1269         </div>
1270         <div id="protection.spaces">
1271            <h3 id="rfc.section.6.3"><a href="#rfc.section.6.3">6.3</a>&nbsp;<a href="#protection.spaces">Protection Spaces</a></h3>
1272            <div id="rfc.section.6.3.p.1">
1273               <p>Authentication schemes that solely rely on the "realm" mechanism for establishing
1274                  a protection space will expose credentials to all resources on an origin server. Clients
1275                  that have successfully made authenticated requests with a resource can use the same
1276                  authentication credentials for other resources on the same origin server. This makes
1277                  it possible for a different resource to harvest authentication credentials for other
1278                  resources.
1279               </p>
1280            </div>
1281            <div id="rfc.section.6.3.p.2">
1282               <p>This is of particular concern when an origin server hosts resources for multiple parties
1283                  under the same canonical root URI (<a href="#protection.space" title="Protection Space (Realm)">Section&nbsp;2.2</a>). Possible mitigation strategies include restricting direct access to authentication
1284                  credentials (i.e., not making the content of the <a href="#header.authorization" class="smpl">Authorization</a> request header field available), and separating protection spaces by using a different
1285                  host name (or port number) for each party.
1286               </p>
1287            </div>
1288         </div>
1289      </div>
1290      <div id="acks">
1291         <h2 id="rfc.section.7"><a href="#rfc.section.7">7.</a>&nbsp;<a href="#acks">Acknowledgments</a></h2>
1292         <div id="rfc.section.7.p.1">
1293            <p>This specification takes over the definition of the HTTP Authentication Framework,
1294               previously defined in <cite title="HTTP Authentication: Basic and Digest Access Authentication" id="rfc.xref.RFC2617.3">RFC 2617</cite>. We thank John Franks, Phillip M. Hallam-Baker, Jeffery L. Hostetler, Scott D. Lawrence,
1295               Paul J. Leach, Ari Luotonen, and Lawrence C. Stewart for their work on that specification.
1296               See <a href="https://tools.ietf.org/html/rfc2617#section-6">Section 6</a> of <a href="#RFC2617" id="rfc.xref.RFC2617.4"><cite title="HTTP Authentication: Basic and Digest Access Authentication">[RFC2617]</cite></a> for further acknowledgements.
1297            </p>
1298         </div>
1299         <div id="rfc.section.7.p.2">
1300            <p>See <a href="p1-messaging.html#acks" title="Acknowledgments">Section 10</a> of <a href="#RFC7230" id="rfc.xref.RFC7230.8"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing">[RFC7230]</cite></a> for the Acknowledgments related to this document revision.
1301            </p>
1302         </div>
1303      </div>
1304      <h2 id="rfc.references"><a id="rfc.section.8" href="#rfc.section.8">8.</a> References
1305      </h2>
1306      <h3 id="rfc.references.1"><a href="#rfc.section.8.1" id="rfc.section.8.1">8.1</a> Normative References
1307      </h3>
1308      <dl class="reference">
1309         <dt id="RFC2119">[RFC2119]</dt>
1310         <dd>Bradner, S., “<a href="https://tools.ietf.org/html/rfc2119">Key words for use in RFCs to Indicate Requirement Levels</a>”, BCP&nbsp;14, RFC&nbsp;2119, March&nbsp;1997.
1311         </dd>
1312         <dt id="RFC5234">[RFC5234]</dt>
1313         <dd>Crocker, D., Ed. and P. Overell, “<a href="https://tools.ietf.org/html/rfc5234">Augmented BNF for Syntax Specifications: ABNF</a>”, STD&nbsp;68, RFC&nbsp;5234, January&nbsp;2008.
1314         </dd>
1315         <dt id="RFC7230">[RFC7230]</dt>
1316         <dd>Fielding, R., Ed. and J. Reschke, Ed., “<a href="https://tools.ietf.org/html/draft-ietf-httpbis-p1-messaging-latest">Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing</a>”, Internet-Draft&nbsp;draft-ietf-httpbis-p1-messaging-latest (work in progress), June&nbsp;2014.
1317         </dd>
1318         <dt id="RFC7231">[RFC7231]</dt>
1319         <dd>Fielding, R., Ed. and J. Reschke, Ed., “<a href="https://tools.ietf.org/html/draft-ietf-httpbis-p2-semantics-latest">Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content</a>”, Internet-Draft&nbsp;draft-ietf-httpbis-p2-semantics-latest (work in progress), June&nbsp;2014.
1320         </dd>
1321         <dt id="RFC7234">[RFC7234]</dt>
1322         <dd>Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke, Ed., “<a href="https://tools.ietf.org/html/draft-ietf-httpbis-p6-cache-latest">Hypertext Transfer Protocol (HTTP/1.1): Caching</a>”, Internet-Draft&nbsp;draft-ietf-httpbis-p6-cache-latest (work in progress), June&nbsp;2014.
1323         </dd>
1324      </dl>
1325      <h3 id="rfc.references.2"><a href="#rfc.section.8.2" id="rfc.section.8.2">8.2</a> Informative References
1326      </h3>
1327      <dl class="reference">
1328         <dt id="BCP90">[BCP90]</dt>
1329         <dd>Klyne, G., Nottingham, M., and J. Mogul, “<a href="https://tools.ietf.org/html/rfc3864">Registration Procedures for Message Header Fields</a>”, BCP&nbsp;90, RFC&nbsp;3864, September&nbsp;2004.
1330         </dd>
1331         <dt id="OWASP">[OWASP]</dt>
1332         <dd>van der Stock, A., Ed., “<a href="https://www.owasp.org/">A Guide to Building Secure Web Applications and Web Services</a>”, The Open Web Application Security Project (OWASP)&nbsp;2.0.1, July&nbsp;2005, &lt;<a href="https://www.owasp.org/">https://www.owasp.org/</a>&gt;.
1333         </dd>
1334         <dt id="RFC2616">[RFC2616]</dt>
1335         <dd>Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter, L., Leach, P., and T. Berners-Lee, “<a href="https://tools.ietf.org/html/rfc2616">Hypertext Transfer Protocol -- HTTP/1.1</a>”, RFC&nbsp;2616, June&nbsp;1999.
1336         </dd>
1337         <dt id="RFC2617">[RFC2617]</dt>
1338         <dd>Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S., Leach, P., Luotonen, A., and L. Stewart, “<a href="https://tools.ietf.org/html/rfc2617">HTTP Authentication: Basic and Digest Access Authentication</a>”, RFC&nbsp;2617, June&nbsp;1999.
1339         </dd>
1340         <dt id="RFC3986">[RFC3986]</dt>
1341         <dd>Berners-Lee, T., Fielding, R., and L. Masinter, “<a href="https://tools.ietf.org/html/rfc3986">Uniform Resource Identifier (URI): Generic Syntax</a>”, STD&nbsp;66, RFC&nbsp;3986, January&nbsp;2005.
1342         </dd>
1343         <dt id="RFC4648">[RFC4648]</dt>
1344         <dd>Josefsson, S., “<a href="https://tools.ietf.org/html/rfc4648">The Base16, Base32, and Base64 Data Encodings</a>”, RFC&nbsp;4648, October&nbsp;2006.
1345         </dd>
1346         <dt id="RFC5226">[RFC5226]</dt>
1347         <dd>Narten, T. and H. Alvestrand, “<a href="https://tools.ietf.org/html/rfc5226">Guidelines for Writing an IANA Considerations Section in RFCs</a>”, BCP&nbsp;26, RFC&nbsp;5226, May&nbsp;2008.
1348         </dd>
1349         <dt id="RFC5246">[RFC5246]</dt>
1350         <dd>Dierks, T. and E. Rescorla, “<a href="https://tools.ietf.org/html/rfc5246">The Transport Layer Security (TLS) Protocol Version 1.2</a>”, RFC&nbsp;5246, August&nbsp;2008.
1351         </dd>
1352      </dl>
1353      <div id="changes.from.rfc.2616">
1354         <h2 id="rfc.section.A" class="np"><a href="#rfc.section.A">A.</a>&nbsp;<a href="#changes.from.rfc.2616">Changes from RFCs 2616 and 2617</a></h2>
1355         <div id="rfc.section.A.p.1">
1356            <p>The framework for HTTP Authentication is now defined by this document, rather than
1357               RFC 2617.
1358            </p>
1359         </div>
1360         <div id="rfc.section.A.p.2">
1361            <p>The "realm" parameter is no longer always required on challenges; consequently, the
1362               ABNF allows challenges without any auth parameters. (<a href="#access.authentication.framework" title="Access Authentication Framework">Section&nbsp;2</a>)
1363            </p>
1364         </div>
1365         <div id="rfc.section.A.p.3">
1366            <p>The "token68" alternative to auth-param lists has been added for consistency with
1367               legacy authentication schemes such as "Basic". (<a href="#access.authentication.framework" title="Access Authentication Framework">Section&nbsp;2</a>)
1368            </p>
1369         </div>
1370         <div id="rfc.section.A.p.4">
1371            <p>This specification introduces the Authentication Scheme Registry, along with considerations
1372               for new authentication schemes. (<a href="#authentication.scheme.registry" title="Authentication Scheme Registry">Section&nbsp;5.1</a>)
1373            </p>
1374         </div>
1375      </div>
1376      <div id="imported.abnf">
1377         <h2 id="rfc.section.B"><a href="#rfc.section.B">B.</a>&nbsp;<a href="#imported.abnf">Imported ABNF</a></h2>
1378         <div id="rfc.section.B.p.1">
1379            <p>The following core rules are included by reference, as defined in <a href="https://tools.ietf.org/html/rfc5234#appendix-B.1">Appendix B.1</a> of <a href="#RFC5234" id="rfc.xref.RFC5234.2"><cite title="Augmented BNF for Syntax Specifications: ABNF">[RFC5234]</cite></a>: ALPHA (letters), CR (carriage return), CRLF (CR LF), CTL (controls), DIGIT (decimal
1380               0-9), DQUOTE (double quote), HEXDIG (hexadecimal 0-9/A-F/a-f), LF (line feed), OCTET
1381               (any 8-bit sequence of data), SP (space), and VCHAR (any visible US-ASCII character).
1382            </p>
1383         </div>
1384         <div id="rfc.section.B.p.2" class="avoidbreakafter">
1385            <p>The rules below are defined in <a href="#RFC7230" id="rfc.xref.RFC7230.9"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing">[RFC7230]</cite></a>:
1386            </p>
1387         </div>
1388         <div id="rfc.figure.u.9"><pre class="inline">  <a href="#imported.abnf" class="smpl">BWS</a>           = &lt;BWS, see <a href="#RFC7230" id="rfc.xref.RFC7230.10"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing">[RFC7230]</cite></a>, <a href="p1-messaging.html#whitespace" title="Whitespace">Section 3.2.3</a>&gt;
1389  <a href="#imported.abnf" class="smpl">OWS</a>           = &lt;OWS, see <a href="#RFC7230" id="rfc.xref.RFC7230.11"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing">[RFC7230]</cite></a>, <a href="p1-messaging.html#whitespace" title="Whitespace">Section 3.2.3</a>&gt;
1390  <a href="#imported.abnf" class="smpl">quoted-string</a> = &lt;quoted-string, see <a href="#RFC7230" id="rfc.xref.RFC7230.12"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing">[RFC7230]</cite></a>, <a href="p1-messaging.html#field.components" title="Field Value Components">Section 3.2.6</a>&gt;
1391  <a href="#imported.abnf" class="smpl">token</a>         = &lt;token, see <a href="#RFC7230" id="rfc.xref.RFC7230.13"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing">[RFC7230]</cite></a>, <a href="p1-messaging.html#field.components" title="Field Value Components">Section 3.2.6</a>&gt;
1392</pre></div>
1393      </div>
1394      <div id="collected.abnf">
1395         <h2 id="rfc.section.C"><a href="#rfc.section.C">C.</a>&nbsp;<a href="#collected.abnf">Collected ABNF</a></h2>
1396         <div id="rfc.section.C.p.1">
1397            <p>In the collected ABNF below, list rules are expanded as per <a href="p1-messaging.html#notation" title="Syntax Notation">Section 1.2</a> of <a href="#RFC7230" id="rfc.xref.RFC7230.14"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing">[RFC7230]</cite></a>.
1398            </p>
1399         </div>
1400         <div id="rfc.figure.u.10"><pre class="inline"><a href="#header.authorization" class="smpl">Authorization</a> = credentials
1401
1402<a href="#imported.abnf" class="smpl">BWS</a> = &lt;BWS, see [RFC7230], Section 3.2.3&gt;
1403
1404<a href="#imported.abnf" class="smpl">OWS</a> = &lt;OWS, see [RFC7230], Section 3.2.3&gt;
1405
1406<a href="#header.proxy-authenticate" class="smpl">Proxy-Authenticate</a> = *( "," OWS ) challenge *( OWS "," [ OWS
1407 challenge ] )
1408<a href="#header.proxy-authorization" class="smpl">Proxy-Authorization</a> = credentials
1409
1410<a href="#header.www-authenticate" class="smpl">WWW-Authenticate</a> = *( "," OWS ) challenge *( OWS "," [ OWS challenge
1411 ] )
1412
1413<a href="#challenge.and.response" class="smpl">auth-param</a> = token BWS "=" BWS ( token / quoted-string )
1414<a href="#challenge.and.response" class="smpl">auth-scheme</a> = token
1415
1416<a href="#challenge.and.response" class="smpl">challenge</a> = auth-scheme [ 1*SP ( token68 / [ ( "," / auth-param ) *(
1417 OWS "," [ OWS auth-param ] ) ] ) ]
1418<a href="#challenge.and.response" class="smpl">credentials</a> = auth-scheme [ 1*SP ( token68 / [ ( "," / auth-param )
1419 *( OWS "," [ OWS auth-param ] ) ] ) ]
1420
1421<a href="#imported.abnf" class="smpl">quoted-string</a> = &lt;quoted-string, see [RFC7230], Section 3.2.6&gt;
1422
1423<a href="#imported.abnf" class="smpl">token</a> = &lt;token, see [RFC7230], Section 3.2.6&gt;
1424<a href="#challenge.and.response" class="smpl">token68</a> = 1*( ALPHA / DIGIT / "-" / "." / "_" / "~" / "+" / "/" )
1425 *"="
1426</pre></div>
1427      </div>
1428      <h2 id="rfc.index"><a href="#rfc.index">Index</a></h2>
1429      <p class="noprint"><a href="#rfc.index.4">4</a> <a href="#rfc.index.A">A</a> <a href="#rfc.index.B">B</a> <a href="#rfc.index.C">C</a> <a href="#rfc.index.G">G</a> <a href="#rfc.index.O">O</a> <a href="#rfc.index.P">P</a> <a href="#rfc.index.R">R</a> <a href="#rfc.index.W">W</a> 
1430      </p>
1431      <div class="print2col">
1432         <ul class="ind">
1433            <li><a id="rfc.index.4" href="#rfc.index.4"><b>4</b></a><ul>
1434                  <li>401 Unauthorized (status code)&nbsp;&nbsp;<a href="#rfc.section.3.1"><b>3.1</b></a>, <a href="#rfc.xref.status.401.1">5.2</a></li>
1435                  <li>407 Proxy Authentication Required (status code)&nbsp;&nbsp;<a href="#rfc.section.3.2"><b>3.2</b></a>, <a href="#rfc.xref.status.407.1">5.2</a></li>
1436               </ul>
1437            </li>
1438            <li><a id="rfc.index.A" href="#rfc.index.A"><b>A</b></a><ul>
1439                  <li>Authorization header field&nbsp;&nbsp;<a href="#rfc.xref.header.authorization.1">3.1</a>, <a href="#rfc.section.4.2"><b>4.2</b></a>, <a href="#rfc.xref.header.authorization.2">5.3</a></li>
1440               </ul>
1441            </li>
1442            <li><a id="rfc.index.B" href="#rfc.index.B"><b>B</b></a><ul>
1443                  <li><em>BCP90</em>&nbsp;&nbsp;<a href="#rfc.xref.BCP90.1">5.3</a>, <a href="#BCP90"><b>8.2</b></a></li>
1444               </ul>
1445            </li>
1446            <li><a id="rfc.index.C" href="#rfc.index.C"><b>C</b></a><ul>
1447                  <li>Canonical Root URI&nbsp;&nbsp;<a href="#rfc.section.2.2">2.2</a></li>
1448               </ul>
1449            </li>
1450            <li><a id="rfc.index.G" href="#rfc.index.G"><b>G</b></a><ul>
1451                  <li><tt>Grammar</tt>&nbsp;&nbsp;
1452                     <ul>
1453                        <li><tt>auth-param</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.2"><b>2.1</b></a></li>
1454                        <li><tt>auth-scheme</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.1"><b>2.1</b></a></li>
1455                        <li><tt>Authorization</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.7"><b>4.2</b></a></li>
1456                        <li><tt>challenge</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.4"><b>2.1</b></a></li>
1457                        <li><tt>credentials</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.5"><b>2.1</b></a></li>
1458                        <li><tt>Proxy-Authenticate</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.8"><b>4.3</b></a></li>
1459                        <li><tt>Proxy-Authorization</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.9"><b>4.4</b></a></li>
1460                        <li><tt>token68</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.3"><b>2.1</b></a></li>
1461                        <li><tt>WWW-Authenticate</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.6"><b>4.1</b></a></li>
1462                     </ul>
1463                  </li>
1464               </ul>
1465            </li>
1466            <li><a id="rfc.index.O" href="#rfc.index.O"><b>O</b></a><ul>
1467                  <li><em>OWASP</em>&nbsp;&nbsp;<a href="#rfc.xref.OWASP.1">6</a>, <a href="#OWASP"><b>8.2</b></a></li>
1468               </ul>
1469            </li>
1470            <li><a id="rfc.index.P" href="#rfc.index.P"><b>P</b></a><ul>
1471                  <li>Protection Space&nbsp;&nbsp;<a href="#rfc.section.2.2">2.2</a></li>
1472                  <li>Proxy-Authenticate header field&nbsp;&nbsp;<a href="#rfc.xref.header.proxy-authenticate.1">3.2</a>, <a href="#rfc.section.4.3"><b>4.3</b></a>, <a href="#rfc.xref.header.proxy-authenticate.2">5.3</a></li>
1473                  <li>Proxy-Authorization header field&nbsp;&nbsp;<a href="#rfc.xref.header.proxy-authorization.1">3.2</a>, <a href="#rfc.section.4.4"><b>4.4</b></a>, <a href="#rfc.xref.header.proxy-authorization.2">5.3</a></li>
1474               </ul>
1475            </li>
1476            <li><a id="rfc.index.R" href="#rfc.index.R"><b>R</b></a><ul>
1477                  <li>Realm&nbsp;&nbsp;<a href="#rfc.section.2.2">2.2</a></li>
1478                  <li><em>RFC2119</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC2119.1">1.1</a>, <a href="#RFC2119"><b>8.1</b></a></li>
1479                  <li><em>RFC2616</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC2616.1">1</a>, <a href="#RFC2616"><b>8.2</b></a></li>
1480                  <li><em>RFC2617</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC2617.1">1</a>, <a href="#rfc.xref.RFC2617.2">1</a>, <a href="#rfc.xref.RFC2617.3">7</a>, <a href="#rfc.xref.RFC2617.4">7</a>, <a href="#RFC2617"><b>8.2</b></a><ul>
1481                        <li><em>Section 6</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC2617.4">7</a></li>
1482                     </ul>
1483                  </li>
1484                  <li><em>RFC3986</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC3986.1">2.1</a>, <a href="#RFC3986"><b>8.2</b></a></li>
1485                  <li><em>RFC4648</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC4648.1">2.1</a>, <a href="#RFC4648"><b>8.2</b></a></li>
1486                  <li><em>RFC5226</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC5226.1">5.1.1</a>, <a href="#RFC5226"><b>8.2</b></a><ul>
1487                        <li><em>Section 4.1</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC5226.1">5.1.1</a></li>
1488                     </ul>
1489                  </li>
1490                  <li><em>RFC5234</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC5234.1">1.2</a>, <a href="#RFC5234"><b>8.1</b></a>, <a href="#rfc.xref.RFC5234.2">B</a><ul>
1491                        <li><em>Appendix B.1</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC5234.2">B</a></li>
1492                     </ul>
1493                  </li>
1494                  <li><em>RFC5246</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC5246.1">6.1</a>, <a href="#RFC5246"><b>8.2</b></a></li>
1495                  <li><em>RFC7230</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC7230.1">1</a>, <a href="#rfc.xref.RFC7230.2">1.1</a>, <a href="#rfc.xref.RFC7230.3">1.2</a>, <a href="#rfc.xref.RFC7230.4">2.2</a>, <a href="#rfc.xref.RFC7230.5">4.3</a>, <a href="#rfc.xref.RFC7230.6">5.1.2</a>, <a href="#rfc.xref.RFC7230.7">6</a>, <a href="#rfc.xref.RFC7230.8">7</a>, <a href="#RFC7230"><b>8.1</b></a>, <a href="#rfc.xref.RFC7230.9">B</a>, <a href="#rfc.xref.RFC7230.10">B</a>, <a href="#rfc.xref.RFC7230.11">B</a>, <a href="#rfc.xref.RFC7230.12">B</a>, <a href="#rfc.xref.RFC7230.13">B</a>, <a href="#rfc.xref.RFC7230.14">C</a><ul>
1496                        <li><em>Section 1.2</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC7230.14">C</a></li>
1497                        <li><em>Section 2.3</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC7230.6">5.1.2</a></li>
1498                        <li><em>Section 2.5</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC7230.2">1.1</a></li>
1499                        <li><em>Section 3.2.3</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC7230.10">B</a>, <a href="#rfc.xref.RFC7230.11">B</a></li>
1500                        <li><em>Section 3.2.6</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC7230.12">B</a>, <a href="#rfc.xref.RFC7230.13">B</a></li>
1501                        <li><em>Section 5.5</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC7230.4">2.2</a>, <a href="#rfc.xref.RFC7230.5">4.3</a></li>
1502                        <li><em>Section 7</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC7230.3">1.2</a></li>
1503                        <li><em>Section 10</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC7230.8">7</a></li>
1504                     </ul>
1505                  </li>
1506                  <li><em>RFC7231</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC7231.1">2.1</a>, <a href="#rfc.xref.RFC7231.2">6</a>, <a href="#RFC7231"><b>8.1</b></a><ul>
1507                        <li><em>Section 6.5.3</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC7231.1">2.1</a></li>
1508                     </ul>
1509                  </li>
1510                  <li><em>RFC7234</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC7234.1">4.2</a>, <a href="#rfc.xref.RFC7234.2">5.1.2</a>, <a href="#rfc.xref.RFC7234.3">5.1.2</a>, <a href="#RFC7234"><b>8.1</b></a><ul>
1511                        <li><em>Section 3.2</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC7234.1">4.2</a></li>
1512                        <li><em>Section 5.2.1.5</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC7234.3">5.1.2</a></li>
1513                        <li><em>Section 5.2.2.6</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC7234.2">5.1.2</a></li>
1514                     </ul>
1515                  </li>
1516               </ul>
1517            </li>
1518            <li><a id="rfc.index.W" href="#rfc.index.W"><b>W</b></a><ul>
1519                  <li>WWW-Authenticate header field&nbsp;&nbsp;<a href="#rfc.xref.header.www-authenticate.1">3.1</a>, <a href="#rfc.section.4.1"><b>4.1</b></a>, <a href="#rfc.xref.header.www-authenticate.2">4.3</a>, <a href="#rfc.xref.header.www-authenticate.3">5.3</a></li>
1520               </ul>
1521            </li>
1522         </ul>
1523      </div>
1524      <div class="avoidbreakinside">
1525         <h2 id="rfc.authors"><a href="#rfc.authors">Authors' Addresses</a></h2>
1526         <p><b>Roy T. Fielding</b>
1527            (editor)
1528            <br>Adobe Systems Incorporated<br>345 Park Ave<br>San Jose, CA&nbsp;95110<br>USA<br>Email: fielding@gbiv.com<br>URI: <a href="http://roy.gbiv.com/">http://roy.gbiv.com/</a></p>
1529         <p><b>Julian F. Reschke</b>
1530            (editor)
1531            <br>greenbytes GmbH<br>Hafenweg 16<br>Muenster, NW&nbsp;48155<br>Germany<br>Email: julian.reschke@greenbytes.de<br>URI: <a href="http://greenbytes.de/tech/webdav/">http://greenbytes.de/tech/webdav/</a></p>
1532      </div>
1533   </body>
1534</html>
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