source: draft-ietf-httpbis/latest/p7-auth.html @ 2704

Last change on this file since 2704 was 2703, checked in by julian.reschke@…, 6 years ago

fix typo (#553)

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483</style><link rel="Contents" href="#rfc.toc">
484      <link rel="Author" href="#rfc.authors">
485      <link rel="Copyright" href="#rfc.copyrightnotice">
486      <link rel="Index" href="#rfc.index">
487      <link rel="Chapter" title="1 Introduction" href="#rfc.section.1">
488      <link rel="Chapter" title="2 Access Authentication Framework" href="#rfc.section.2">
489      <link rel="Chapter" title="3 Status Code Definitions" href="#rfc.section.3">
490      <link rel="Chapter" title="4 Header Field Definitions" href="#rfc.section.4">
491      <link rel="Chapter" title="5 IANA Considerations" href="#rfc.section.5">
492      <link rel="Chapter" title="6 Security Considerations" href="#rfc.section.6">
493      <link rel="Chapter" title="7 Acknowledgments" href="#rfc.section.7">
494      <link rel="Chapter" href="#rfc.section.8" title="8 References">
495      <link rel="Appendix" title="A Changes from RFCs 2616 and 2617" href="#rfc.section.A">
496      <link rel="Appendix" title="B Imported ABNF" href="#rfc.section.B">
497      <link rel="Appendix" title="C Collected ABNF" href="#rfc.section.C">
498      <link href="p6-cache.html" rel="prev">
499      <meta name="generator" content="http://greenbytes.de/tech/webdav/rfc2629.xslt, Revision 1.629, 2014/04/17 09:22:01, XSLT vendor: SAXON 8.9 from Saxonica http://www.saxonica.com/">
500      <meta name="keywords" content="Hypertext Transfer Protocol, HTTP, HTTP authentication">
501      <link rel="schema.dct" href="http://purl.org/dc/terms/">
502      <meta name="dct.creator" content="Fielding, R.">
503      <meta name="dct.creator" content="Reschke, J. F.">
504      <meta name="dct.identifier" content="urn:ietf:id:draft-ietf-httpbis-p7-auth-latest">
505      <meta name="dct.issued" scheme="ISO8601" content="2014-05-28">
506      <meta name="dct.replaces" content="urn:ietf:rfc:2616">
507      <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.">
508      <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.">
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511      <table class="header">
512         <tbody>
513            <tr>
514               <td class="left">HTTPbis Working Group</td>
515               <td class="right">R. Fielding, Editor</td>
516            </tr>
517            <tr>
518               <td class="left">Internet-Draft</td>
519               <td class="right">Adobe</td>
520            </tr>
521            <tr>
522               <td class="left">Obsoletes: <a href="http://tools.ietf.org/html/rfc2616">2616</a> (if approved)
523               </td>
524               <td class="right">J. Reschke, Editor</td>
525            </tr>
526            <tr>
527               <td class="left">Updates: <a href="http://tools.ietf.org/html/rfc2617">2617</a> (if approved)
528               </td>
529               <td class="right">greenbytes</td>
530            </tr>
531            <tr>
532               <td class="left">Intended status: Standards Track</td>
533               <td class="right">May 28, 2014</td>
534            </tr>
535            <tr>
536               <td class="left">Expires: November 29, 2014</td>
537               <td class="right"></td>
538            </tr>
539         </tbody>
540      </table>
541      <p class="title">Hypertext Transfer Protocol (HTTP/1.1): Authentication<br><span class="filename">draft-ietf-httpbis-p7-auth-latest</span></p>
542      <h1 id="rfc.abstract"><a href="#rfc.abstract">Abstract</a></h1>
543      <p>The Hypertext Transfer Protocol (HTTP) is a stateless application-level protocol for distributed, collaborative, hypermedia
544         information systems. This document defines the HTTP Authentication framework.
545      </p>
546      <h1 id="rfc.note.1"><a href="#rfc.note.1">Editorial Note (To be removed by RFC Editor)</a></h1>
547      <p>Discussion of this draft takes place on the HTTPBIS working group mailing list (ietf-http-wg@w3.org), 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;.
548      </p>
549      <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;.
550      </p>
551      <p><em>This is a temporary document for the purpose of tracking the editorial changes made during the AUTH48 (RFC publication) phase.</em>
552      </p>
553      <div id="rfc.status">
554         <h1><a href="#rfc.status">Status of This Memo</a></h1>
555         <p>This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.</p>
556         <p>Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute
557            working documents as Internet-Drafts. The list of current Internet-Drafts is at <a href="http://datatracker.ietf.org/drafts/current/">http://datatracker.ietf.org/drafts/current/</a>.
558         </p>
559         <p>Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other
560            documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as “work
561            in progress”.
562         </p>
563         <p>This Internet-Draft will expire on November 29, 2014.</p>
564      </div>
565      <div id="rfc.copyrightnotice">
566         <h1><a href="#rfc.copyrightnotice">Copyright Notice</a></h1>
567         <p>Copyright © 2014 IETF Trust and the persons identified as the document authors. All rights reserved.</p>
568         <p>This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating 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 carefully, as they describe your rights
569            and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License
570            text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified
571            BSD License.
572         </p>
573         <p>This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November
574            10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to
575            allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s)
576            controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative
577            works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate
578            it into languages other than English.
579         </p>
580      </div>
581      <hr class="noprint">
582      <h1 class="np" id="rfc.toc"><a href="#rfc.toc">Table of Contents</a></h1>
583      <ul class="toc">
584         <li><a href="#rfc.section.1">1.</a>&nbsp;&nbsp;&nbsp;<a href="#introduction">Introduction</a><ul>
585               <li><a href="#rfc.section.1.1">1.1</a>&nbsp;&nbsp;&nbsp;<a href="#conformance">Conformance and Error Handling</a></li>
586               <li><a href="#rfc.section.1.2">1.2</a>&nbsp;&nbsp;&nbsp;<a href="#notation">Syntax Notation</a></li>
587            </ul>
588         </li>
589         <li><a href="#rfc.section.2">2.</a>&nbsp;&nbsp;&nbsp;<a href="#access.authentication.framework">Access Authentication Framework</a><ul>
590               <li><a href="#rfc.section.2.1">2.1</a>&nbsp;&nbsp;&nbsp;<a href="#challenge.and.response">Challenge and Response</a></li>
591               <li><a href="#rfc.section.2.2">2.2</a>&nbsp;&nbsp;&nbsp;<a href="#protection.space">Protection Space (Realm)</a></li>
592            </ul>
593         </li>
594         <li><a href="#rfc.section.3">3.</a>&nbsp;&nbsp;&nbsp;<a href="#status.code.definitions">Status Code Definitions</a><ul>
595               <li><a href="#rfc.section.3.1">3.1</a>&nbsp;&nbsp;&nbsp;<a href="#status.401">401 Unauthorized</a></li>
596               <li><a href="#rfc.section.3.2">3.2</a>&nbsp;&nbsp;&nbsp;<a href="#status.407">407 Proxy Authentication Required</a></li>
597            </ul>
598         </li>
599         <li><a href="#rfc.section.4">4.</a>&nbsp;&nbsp;&nbsp;<a href="#header.field.definitions">Header Field Definitions</a><ul>
600               <li><a href="#rfc.section.4.1">4.1</a>&nbsp;&nbsp;&nbsp;<a href="#header.www-authenticate">WWW-Authenticate</a></li>
601               <li><a href="#rfc.section.4.2">4.2</a>&nbsp;&nbsp;&nbsp;<a href="#header.authorization">Authorization</a></li>
602               <li><a href="#rfc.section.4.3">4.3</a>&nbsp;&nbsp;&nbsp;<a href="#header.proxy-authenticate">Proxy-Authenticate</a></li>
603               <li><a href="#rfc.section.4.4">4.4</a>&nbsp;&nbsp;&nbsp;<a href="#header.proxy-authorization">Proxy-Authorization</a></li>
604            </ul>
605         </li>
606         <li><a href="#rfc.section.5">5.</a>&nbsp;&nbsp;&nbsp;<a href="#IANA.considerations">IANA Considerations</a><ul>
607               <li><a href="#rfc.section.5.1">5.1</a>&nbsp;&nbsp;&nbsp;<a href="#authentication.scheme.registry">Authentication Scheme Registry</a><ul>
608                     <li><a href="#rfc.section.5.1.1">5.1.1</a>&nbsp;&nbsp;&nbsp;<a href="#authentication.scheme.registry.procedure">Procedure</a></li>
609                     <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>
610                  </ul>
611               </li>
612               <li><a href="#rfc.section.5.2">5.2</a>&nbsp;&nbsp;&nbsp;<a href="#status.code.registration">Status Code Registration</a></li>
613               <li><a href="#rfc.section.5.3">5.3</a>&nbsp;&nbsp;&nbsp;<a href="#header.field.registration">Header Field Registration</a></li>
614            </ul>
615         </li>
616         <li><a href="#rfc.section.6">6.</a>&nbsp;&nbsp;&nbsp;<a href="#security.considerations">Security Considerations</a><ul>
617               <li><a href="#rfc.section.6.1">6.1</a>&nbsp;&nbsp;&nbsp;<a href="#confidentiality.of.credentials">Confidentiality of Credentials</a></li>
618               <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>
619               <li><a href="#rfc.section.6.3">6.3</a>&nbsp;&nbsp;&nbsp;<a href="#protection.spaces">Protection Spaces</a></li>
620            </ul>
621         </li>
622         <li><a href="#rfc.section.7">7.</a>&nbsp;&nbsp;&nbsp;<a href="#acks">Acknowledgments</a></li>
623         <li><a href="#rfc.section.8">8.</a>&nbsp;&nbsp;&nbsp;<a href="#rfc.references">References</a><ul>
624               <li><a href="#rfc.section.8.1">8.1</a>&nbsp;&nbsp;&nbsp;<a href="#rfc.references.1">Normative References</a></li>
625               <li><a href="#rfc.section.8.2">8.2</a>&nbsp;&nbsp;&nbsp;<a href="#rfc.references.2">Informative References</a></li>
626            </ul>
627         </li>
628         <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>
629         <li><a href="#rfc.section.B">B.</a>&nbsp;&nbsp;&nbsp;<a href="#imported.abnf">Imported ABNF</a></li>
630         <li><a href="#rfc.section.C">C.</a>&nbsp;&nbsp;&nbsp;<a href="#collected.abnf">Collected ABNF</a></li>
631         <li><a href="#rfc.index">Index</a></li>
632         <li><a href="#rfc.authors">Authors' Addresses</a></li>
633      </ul>
634      <div id="introduction">
635         <h1 id="rfc.section.1" class="np"><a href="#rfc.section.1">1.</a>&nbsp;<a href="#introduction">Introduction</a></h1>
636         <p id="rfc.section.1.p.1">HTTP provides a general framework for access control and authentication, via an extensible set of challenge-response authentication
637            schemes, which can be used by a server to challenge a client request and by a client to provide authentication information.
638            This document defines HTTP/1.1 authentication in terms of the architecture defined in "Hypertext Transfer Protocol (HTTP/1.1):
639            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 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 Protocol -- HTTP/1.1" <a href="#RFC2616" id="rfc.xref.RFC2616.1"><cite title="Hypertext Transfer Protocol -- HTTP/1.1">[RFC2616]</cite></a>.
640         </p>
641         <p id="rfc.section.1.p.2">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, including the "basic" and "digest" authentication
642            schemes previously defined by <cite title="HTTP Authentication: Basic and Digest Access Authentication" id="rfc.xref.RFC2617.2">RFC 2617</cite>.
643         </p>
644         <div id="conformance">
645            <h2 id="rfc.section.1.1"><a href="#rfc.section.1.1">1.1</a>&nbsp;<a href="#conformance">Conformance and Error Handling</a></h2>
646            <p id="rfc.section.1.1.p.1">The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL"
647               in this document are to be interpreted 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>.
648            </p>
649            <p id="rfc.section.1.1.p.2">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>.
650            </p>
651         </div>
652         <div id="notation">
653            <h2 id="rfc.section.1.2"><a href="#rfc.section.1.2">1.2</a>&nbsp;<a href="#notation">Syntax Notation</a></h2>
654            <p id="rfc.section.1.2.p.1">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 (similar to how the '*' operator indicates
655               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.
656            </p>
657         </div>
658      </div>
659      <div id="access.authentication.framework">
660         <h1 id="rfc.section.2"><a href="#rfc.section.2">2.</a>&nbsp;<a href="#access.authentication.framework">Access Authentication Framework</a></h1>
661         <div id="challenge.and.response">
662            <h2 id="rfc.section.2.1"><a href="#rfc.section.2.1">2.1</a>&nbsp;<a href="#challenge.and.response">Challenge and Response</a></h2>
663            <p id="rfc.section.2.1.p.1">HTTP provides a simple challenge-response authentication framework that can be used by a server to challenge a client request
664               and by a client to provide authentication information. It uses a case-insensitive token as a means to identify the authentication
665               scheme, followed by additional information necessary for achieving authentication via that scheme. The latter can be either
666               a comma-separated list of parameters or a single sequence of characters capable of holding base64-encoded information.
667            </p>
668            <p id="rfc.section.2.1.p.2">Authentication parameters are name=value pairs, where the name token is matched case-insensitively, and each parameter name <em class="bcp14">MUST</em> only occur once per challenge.
669            </p>
670            <div id="rfc.figure.u.1"></div><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>
671 
672  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> )
673
674  token68        = 1*( <a href="#imported.abnf" class="smpl">ALPHA</a> / <a href="#imported.abnf" class="smpl">DIGIT</a> /
675                       "-" / "." / "_" / "~" / "+" / "/" ) *"="
676</pre><p id="rfc.section.2.1.p.4">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 alphabet), base32, or base16 (hex) encoding,
677               with or without padding, but excluding whitespace (<a href="#RFC4648" id="rfc.xref.RFC4648.1"><cite title="The Base16, Base32, and Base64 Data Encodings">[RFC4648]</cite></a>).
678            </p>
679            <p id="rfc.section.2.1.p.5">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 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.
680            </p>
681            <p id="rfc.section.2.1.p.6">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 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 resource.
682            </p>
683            <div id="rfc.figure.u.2"></div><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> ) ]
684</pre><div class="note" id="rfc.section.2.1.p.8">
685               <p><b>Note:</b> Many clients fail to parse a challenge that contains an unknown scheme. A workaround for this problem is to list well-supported
686                  schemes (such as "basic") first.
687               </p>
688            </div>
689            <p id="rfc.section.2.1.p.9">A user agent that wishes to authenticate itself with an origin server — usually, but 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.
690            </p>
691            <p id="rfc.section.2.1.p.10">A client that wishes to authenticate itself with a proxy — usually, but not necessarily, 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.
692            </p>
693            <p id="rfc.section.2.1.p.11">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, based upon a challenge received
694               in a response (possibly at some point in the past). When creating their values, the user agent ought to do so by selecting
695               the challenge with what it considers to be the most secure auth-scheme that it understands, obtaining credentials from the
696               user as appropriate. Transmission of credentials within header field values implies significant security considerations regarding
697               the confidentiality of the underlying connection, as described in <a href="#confidentiality.of.credentials" title="Confidentiality of Credentials">Section&nbsp;6.1</a>.
698            </p>
699            <div id="rfc.figure.u.3"></div><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> ) ]
700</pre><p id="rfc.section.2.1.p.13">Upon receipt of a request for a protected resource that omits credentials, contains invalid credentials (e.g., a bad password)
701               or partial credentials (e.g., when the 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 resource.
702            </p>
703            <p id="rfc.section.2.1.p.14">Likewise, upon receipt of a request that omits proxy credentials or contains invalid or partial proxy credentials, a proxy
704               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.
705            </p>
706            <p id="rfc.section.2.1.p.15">A server that receives valid credentials that are not adequate to gain access ought 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>).
707            </p>
708            <p id="rfc.section.2.1.p.16">HTTP does not restrict applications to this simple challenge-response framework for access authentication. Additional mechanisms
709               can be used, such as authentication at the transport level or via message encapsulation, and with additional header fields
710               specifying authentication information. However, such additional mechanisms are not defined by this specification.
711            </p>
712         </div>
713         <div id="protection.space">
714            <div id="rfc.iref.p.1"></div>
715            <div id="rfc.iref.r.1"></div>
716            <div id="rfc.iref.c.1"></div>
717            <h2 id="rfc.section.2.2"><a href="#rfc.section.2.2">2.2</a>&nbsp;<a href="#protection.space">Protection Space (Realm)</a></h2>
718            <p id="rfc.section.2.2.p.1">The "<dfn>realm</dfn>" authentication parameter is reserved for use by authentication schemes that wish to indicate a scope of protection.
719            </p>
720            <p id="rfc.section.2.2.p.2">A <dfn>protection space</dfn> is defined by the canonical root URI (the scheme and authority components of the effective 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 realms allow the protected resources
721               on a server to be partitioned into a set of protection spaces, each with its own authentication scheme and/or authorization
722               database. The realm value is a string, generally assigned by the origin server, that can have additional semantics specific
723               to the authentication scheme. Note that a response can have multiple challenges with the same auth-scheme but with different
724               realms.
725            </p>
726            <p id="rfc.section.2.2.p.3">The protection space determines the domain over which credentials can be automatically applied. If a prior request has been
727               authorized, the user agent <em class="bcp14">MAY</em> reuse the same credentials for all other requests within that protection space for a period of time determined by the authentication
728               scheme, parameters, and/or user preferences (such as a configurable inactivity timeout). Unless specifically allowed by the
729               authentication scheme, a single protection space cannot extend outside the scope of its server.
730            </p>
731            <p id="rfc.section.2.2.p.4">For historical reasons, a sender <em class="bcp14">MUST</em> only generate the quoted-string syntax. Recipients might have to support both token and quoted-string syntax for maximum interoperability
732               with existing clients that have been accepting both notations for a long time.
733            </p>
734         </div>
735      </div>
736      <div id="status.code.definitions">
737         <h1 id="rfc.section.3"><a href="#rfc.section.3">3.</a>&nbsp;<a href="#status.code.definitions">Status Code Definitions</a></h1>
738         <div id="status.401">
739            <div id="rfc.iref.8"></div>
740            <h2 id="rfc.section.3.1"><a href="#rfc.section.3.1">3.1</a>&nbsp;<a href="#status.401">401 Unauthorized</a></h2>
741            <p id="rfc.section.3.1.p.1">The <dfn>401 (Unauthorized)</dfn> status code indicates that the request has not been applied because it lacks valid authentication credentials for the target
742               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.
743            </p>
744            <p id="rfc.section.3.1.p.2">If the request included authentication credentials, then the 401 response indicates that authorization has been refused for
745               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 user agent has already attempted authentication
746               at least once, then the user agent <em class="bcp14">SHOULD</em> present the enclosed representation to the user, since it usually contains relevant diagnostic information.
747            </p>
748         </div>
749         <div id="status.407">
750            <div id="rfc.iref.8"></div>
751            <h2 id="rfc.section.3.2"><a href="#rfc.section.3.2">3.2</a>&nbsp;<a href="#status.407">407 Proxy Authentication Required</a></h2>
752            <p id="rfc.section.3.2.p.1">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 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>).
753            </p>
754         </div>
755      </div>
756      <div id="header.field.definitions">
757         <h1 id="rfc.section.4"><a href="#rfc.section.4">4.</a>&nbsp;<a href="#header.field.definitions">Header Field Definitions</a></h1>
758         <p id="rfc.section.4.p.1">This section defines the syntax and semantics of header fields related to the HTTP authentication framework.</p>
759         <div id="header.www-authenticate">
760            <div id="rfc.iref.w.1"></div>
761            <h2 id="rfc.section.4.1"><a href="#rfc.section.4.1">4.1</a>&nbsp;<a href="#header.www-authenticate">WWW-Authenticate</a></h2>
762            <p id="rfc.section.4.1.p.1">The "WWW-Authenticate" header field indicates the authentication scheme(s) and parameters applicable to the target resource.</p>
763            <div id="rfc.figure.u.4"></div><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>
764</pre><p id="rfc.section.4.1.p.3">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 supplying credentials (or different credentials)
765               might affect the response.
766            </p>
767            <p id="rfc.section.4.1.p.4">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.
768            </p>
769            <p id="rfc.section.4.1.p.5">User agents are advised to take special care in parsing the field value, as it might contain more than one challenge, and
770               each challenge can contain a comma-separated list of authentication parameters. Furthermore, the header field itself can occur
771               multiple times.
772            </p>
773            <div id="rfc.figure.u.5"></div>
774            <p>For instance:</p><pre class="text">  WWW-Authenticate: Newauth realm="apps", type=1,
775                    title="Login to \"apps\"", Basic realm="simple"
776</pre><p>This header field contains two challenges; one for the "Newauth" scheme with a realm value of "apps", and two additional parameters
777               "type" and "title", and another one for the "Basic" scheme with a realm value of "simple".
778            </p>
779            <div class="note" id="rfc.section.4.1.p.7">
780               <p><b>Note:</b> The challenge grammar production uses the list syntax as well. Therefore, a sequence of comma, whitespace, and comma can be
781                  considered either as applying to the preceding challenge, or to be an empty entry in the list of challenges. In practice,
782                  this ambiguity does not affect the semantics of the header field value and thus is harmless.
783               </p>
784            </div>
785         </div>
786         <div id="header.authorization">
787            <div id="rfc.iref.a.1"></div>
788            <h2 id="rfc.section.4.2"><a href="#rfc.section.4.2">4.2</a>&nbsp;<a href="#header.authorization">Authorization</a></h2>
789            <p id="rfc.section.4.2.p.1">The "Authorization" header field allows a user agent to authenticate itself with an origin server — usually, but not necessarily,
790               after receiving a <a href="#status.401" class="smpl">401 (Unauthorized)</a> response. Its value consists of credentials containing the authentication information of the user agent for the realm of the
791               resource being requested.
792            </p>
793            <div id="rfc.figure.u.6"></div><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>
794</pre><p id="rfc.section.4.2.p.3">If a request is authenticated and a realm specified, the same credentials are presumed to be valid for all other requests
795               within this realm (assuming that the authentication scheme itself does not require otherwise, such as credentials that vary
796               according to a challenge value or using synchronized clocks).
797            </p>
798            <p id="rfc.section.4.2.p.4">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 by HTTP caches.
799            </p>
800         </div>
801         <div id="header.proxy-authenticate">
802            <div id="rfc.iref.p.2"></div>
803            <h2 id="rfc.section.4.3"><a href="#rfc.section.4.3">4.3</a>&nbsp;<a href="#header.proxy-authenticate">Proxy-Authenticate</a></h2>
804            <p id="rfc.section.4.3.p.1">The "Proxy-Authenticate" header field consists of at least one challenge that indicates the authentication scheme(s) and parameters
805               applicable to the proxy for this effective 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.
806            </p>
807            <div id="rfc.figure.u.7"></div><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>
808</pre><p id="rfc.section.4.3.p.3">Unlike <a href="#header.www-authenticate" class="smpl">WWW-Authenticate</a>, the Proxy-Authenticate header field applies only to the next outbound client on the response chain. This is because only
809               the client that chose a given proxy is likely to have the credentials necessary for authentication. However, when multiple
810               proxies are used within the same administrative domain, such as office and regional caching proxies within a large corporate
811               network, it is common for credentials to be generated by the user agent and passed through the hierarchy until consumed. Hence,
812               in such a configuration, it will appear as if Proxy-Authenticate is being forwarded because each proxy will send the same
813               challenge set.
814            </p>
815            <p id="rfc.section.4.3.p.4">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.
816            </p>
817         </div>
818         <div id="header.proxy-authorization">
819            <div id="rfc.iref.p.3"></div>
820            <h2 id="rfc.section.4.4"><a href="#rfc.section.4.4">4.4</a>&nbsp;<a href="#header.proxy-authorization">Proxy-Authorization</a></h2>
821            <p id="rfc.section.4.4.p.1">The "Proxy-Authorization" header field allows the client to identify itself (or its user) to a proxy that requires authentication.
822               Its value consists of credentials containing the authentication information of the client for the proxy and/or realm of the
823               resource being requested.
824            </p>
825            <div id="rfc.figure.u.8"></div><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>
826</pre><p id="rfc.section.4.4.p.3">Unlike <a href="#header.authorization" class="smpl">Authorization</a>, the Proxy-Authorization header field applies only to the next inbound proxy that 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 is consumed by the first inbound proxy
827               that was expecting to receive credentials. A proxy <em class="bcp14">MAY</em> relay the credentials from the client request to the next proxy if that is the mechanism by which the proxies cooperatively
828               authenticate a given request.
829            </p>
830         </div>
831      </div>
832      <div id="IANA.considerations">
833         <h1 id="rfc.section.5"><a href="#rfc.section.5">5.</a>&nbsp;<a href="#IANA.considerations">IANA Considerations</a></h1>
834         <div id="authentication.scheme.registry">
835            <h2 id="rfc.section.5.1"><a href="#rfc.section.5.1">5.1</a>&nbsp;<a href="#authentication.scheme.registry">Authentication Scheme Registry</a></h2>
836            <p id="rfc.section.5.1.p.1">The "Hypertext Transfer Protocol (HTTP) Authentication Scheme Registry" defines the namespace for the authentication schemes
837               in challenges and credentials. It has been 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;.
838            </p>
839            <div id="authentication.scheme.registry.procedure">
840               <h3 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></h3>
841               <p id="rfc.section.5.1.1.p.1">Registrations <em class="bcp14">MUST</em> include the following fields:
842               </p>
843               <ul>
844                  <li>Authentication Scheme Name</li>
845                  <li>Pointer to specification text</li>
846                  <li>Notes (optional)</li>
847               </ul>
848               <p id="rfc.section.5.1.1.p.2">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="http://tools.ietf.org/html/rfc5226#section-4.1">Section 4.1</a>).
849               </p>
850            </div>
851            <div id="considerations.for.new.authentication.schemes">
852               <h3 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></h3>
853               <p id="rfc.section.5.1.2.p.1">There are certain aspects of the HTTP Authentication Framework that put constraints on how new authentication schemes can
854                  work:
855               </p>
856               <p id="rfc.section.5.1.2.p.2"></p>
857               <ul>
858                  <li>
859                     <p>HTTP authentication is presumed to be stateless: all of the information necessary to authenticate a request <em class="bcp14">MUST</em> be provided in the request, rather than be dependent on the server remembering prior requests. Authentication based on, or
860                        bound to, the underlying connection is outside the scope of this specification and inherently flawed unless steps are taken
861                        to ensure that the connection cannot be used by any party other than the authenticated user (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>).
862                     </p>
863                  </li>
864                  <li>
865                     <p>The authentication parameter "realm" is reserved for defining protection spaces as 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.
866                     </p>
867                  </li>
868                  <li>
869                     <p>The "token68" notation was introduced for compatibility with existing authentication schemes and can only be used once per
870                        challenge or credential. Thus, new schemes ought to use the auth-param syntax instead, because otherwise future extensions
871                        will be impossible.
872                     </p>
873                  </li>
874                  <li>
875                     <p>The parsing of challenges and credentials is defined by this specification and cannot be modified by new authentication schemes.
876                        When the auth-param syntax is used, all parameters ought to support both token and quoted-string syntax, and syntactical constraints
877                        ought to be defined on the field value after parsing (i.e., quoted-string processing). This is necessary so that recipients
878                        can use a generic parser that applies to all authentication schemes.
879                     </p>
880                     <p><b>Note:</b> The fact that the value syntax for the "realm" parameter is restricted to quoted-string was a bad design choice not to be
881                        repeated for new parameters.
882                     </p>
883                  </li>
884                  <li>
885                     <p>Definitions of new schemes ought to define the treatment of unknown extension parameters. In general, a "must-ignore" rule
886                        is preferable to a "must-understand" rule, because otherwise it will be hard to introduce new parameters in the presence of
887                        legacy recipients. Furthermore, it's good to describe the policy for defining new parameters (such as "update the specification"
888                        or "use this registry").
889                     </p>
890                  </li>
891                  <li>
892                     <p>Authentication schemes need to document whether they are usable in origin-server authentication (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>).
893                     </p>
894                  </li>
895                  <li>
896                     <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 HTTP caches as the "private" Cache-Control
897                        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.
898                     </p>
899                     <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 caching, by mandating the use of
900                        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").
901                     </p>
902                  </li>
903               </ul>
904            </div>
905         </div>
906         <div id="status.code.registration">
907            <h2 id="rfc.section.5.2"><a href="#rfc.section.5.2">5.2</a>&nbsp;<a href="#status.code.registration">Status Code Registration</a></h2>
908            <p id="rfc.section.5.2.p.1">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:
909            </p>
910            <div id="rfc.table.1">
911               <div id="iana.status.code.registration.table"></div>
912               <table class="tt full left" cellpadding="3" cellspacing="0">
913                  <thead>
914                     <tr>
915                        <th>Value</th>
916                        <th>Description</th>
917                        <th>Reference</th>
918                     </tr>
919                  </thead>
920                  <tbody>
921                     <tr>
922                        <td class="left">401</td>
923                        <td class="left">Unauthorized</td>
924                        <td class="left"><a href="#status.401" id="rfc.xref.status.401.1" title="401 Unauthorized">Section&nbsp;3.1</a>
925                        </td>
926                     </tr>
927                     <tr>
928                        <td class="left">407</td>
929                        <td class="left">Proxy Authentication Required</td>
930                        <td class="left"><a href="#status.407" id="rfc.xref.status.407.1" title="407 Proxy Authentication Required">Section&nbsp;3.2</a>
931                        </td>
932                     </tr>
933                  </tbody>
934               </table>
935            </div>
936         </div>
937         <div id="header.field.registration">
938            <h2 id="rfc.section.5.3"><a href="#rfc.section.5.3">5.3</a>&nbsp;<a href="#header.field.registration">Header Field Registration</a></h2>
939            <p id="rfc.section.5.3.p.1">HTTP header fields are registered within the "Message Headers" registry maintained at &lt;<a href="http://www.iana.org/assignments/message-headers/">http://www.iana.org/assignments/message-headers/</a>&gt;.
940            </p>
941            <p id="rfc.section.5.3.p.2">This document defines the following HTTP header fields, so the "Permanent Message Header Field Names" registry has been updated
942               accordingly (see <a href="#BCP90" id="rfc.xref.BCP90.1"><cite title="Registration Procedures for Message Header Fields">[BCP90]</cite></a>).
943            </p>
944            <div id="rfc.table.2">
945               <div id="iana.header.registration.table"></div>
946               <table class="tt full left" cellpadding="3" cellspacing="0">
947                  <thead>
948                     <tr>
949                        <th>Header Field Name</th>
950                        <th>Protocol</th>
951                        <th>Status</th>
952                        <th>Reference</th>
953                     </tr>
954                  </thead>
955                  <tbody>
956                     <tr>
957                        <td class="left">Authorization</td>
958                        <td class="left">http</td>
959                        <td class="left">standard</td>
960                        <td class="left"><a href="#header.authorization" id="rfc.xref.header.authorization.2" title="Authorization">Section&nbsp;4.2</a>
961                        </td>
962                     </tr>
963                     <tr>
964                        <td class="left">Proxy-Authenticate</td>
965                        <td class="left">http</td>
966                        <td class="left">standard</td>
967                        <td class="left"><a href="#header.proxy-authenticate" id="rfc.xref.header.proxy-authenticate.2" title="Proxy-Authenticate">Section&nbsp;4.3</a>
968                        </td>
969                     </tr>
970                     <tr>
971                        <td class="left">Proxy-Authorization</td>
972                        <td class="left">http</td>
973                        <td class="left">standard</td>
974                        <td class="left"><a href="#header.proxy-authorization" id="rfc.xref.header.proxy-authorization.2" title="Proxy-Authorization">Section&nbsp;4.4</a>
975                        </td>
976                     </tr>
977                     <tr>
978                        <td class="left">WWW-Authenticate</td>
979                        <td class="left">http</td>
980                        <td class="left">standard</td>
981                        <td class="left"><a href="#header.www-authenticate" id="rfc.xref.header.www-authenticate.3" title="WWW-Authenticate">Section&nbsp;4.1</a>
982                        </td>
983                     </tr>
984                  </tbody>
985               </table>
986            </div>
987            <p id="rfc.section.5.3.p.3">The change controller is: "IETF (iesg@ietf.org) - Internet Engineering Task Force".</p>
988         </div>
989      </div>
990      <div id="security.considerations">
991         <h1 id="rfc.section.6"><a href="#rfc.section.6">6.</a>&nbsp;<a href="#security.considerations">Security Considerations</a></h1>
992         <p id="rfc.section.6.p.1">This section is meant to inform developers, information providers, and users of known security concerns specific to HTTP authentication.
993            More general security considerations 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>.
994         </p>
995         <p id="rfc.section.6.p.2">Everything about the topic of HTTP authentication is a security consideration, so the list of considerations below is not
996            exhaustive. Furthermore, it is limited to security considerations regarding the authentication framework, in general, rather
997            than discussing all of the potential considerations for specific authentication schemes (which ought to be documented in the
998            specifications that define those schemes). Various organizations maintain topical information and links to current research
999            on Web application 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 found in practice.
1000         </p>
1001         <div id="confidentiality.of.credentials">
1002            <h2 id="rfc.section.6.1"><a href="#rfc.section.6.1">6.1</a>&nbsp;<a href="#confidentiality.of.credentials">Confidentiality of Credentials</a></h2>
1003            <p id="rfc.section.6.1.p.1">The HTTP authentication framework does not define a single mechanism for maintaining the confidentiality of credentials; instead,
1004               each authentication scheme defines how the credentials are encoded prior to transmission. While this provides flexibility
1005               for the development of future authentication schemes, it is inadequate for the protection of existing schemes that provide
1006               no confidentiality on their own, or that do not sufficiently protect against replay attacks. Furthermore, if the server expects
1007               credentials that are specific to each individual user, the exchange of those credentials will have the effect of identifying
1008               that user even if the content within credentials remains confidential.
1009            </p>
1010            <p id="rfc.section.6.1.p.2">HTTP depends on the security properties of the underlying transport- or session-level connection to provide confidential transmission
1011               of header fields. In other words, if a server limits access to authenticated users using this framework, the server needs
1012               to ensure that the connection is properly secured in accordance with the nature of the authentication scheme used. For example,
1013               services that depend on individual user authentication often require a connection to be secured with TLS ("Transport Layer
1014               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.
1015            </p>
1016         </div>
1017         <div id="auth.credentials.and.idle.clients">
1018            <h2 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></h2>
1019            <p id="rfc.section.6.2.p.1">Existing HTTP clients and user agents typically retain authentication information indefinitely. HTTP does not provide a mechanism
1020               for the origin server to direct clients to discard these cached credentials, since the protocol has no awareness of how credentials
1021               are obtained or managed by the user agent. The mechanisms for expiring or revoking credentials can be specified as part of
1022               an authentication scheme definition.
1023            </p>
1024            <p id="rfc.section.6.2.p.2">Circumstances under which credential caching can interfere with the application's security model include but are not limited
1025               to:
1026            </p>
1027            <ul>
1028               <li>Clients that have been idle for an extended period, following which the server might wish to cause the client to re-prompt
1029                  the user for credentials.
1030               </li>
1031               <li>Applications that include a session termination indication (such as a "logout" or "commit" button on a page) after which the
1032                  server side of the application "knows" that there is no further reason for the client to retain the credentials.
1033               </li>
1034            </ul>
1035            <p id="rfc.section.6.2.p.3">User agents that cache credentials are encouraged to provide a readily accessible mechanism for discarding cached credentials
1036               under user control.
1037            </p>
1038         </div>
1039         <div id="protection.spaces">
1040            <h2 id="rfc.section.6.3"><a href="#rfc.section.6.3">6.3</a>&nbsp;<a href="#protection.spaces">Protection Spaces</a></h2>
1041            <p id="rfc.section.6.3.p.1">Authentication schemes that solely rely on the "realm" mechanism for establishing a protection space will expose credentials
1042               to all resources on an origin server. Clients that have successfully made authenticated requests with a resource can use the
1043               same authentication credentials for other resources on the same origin server. This makes it possible for a different resource
1044               to harvest authentication credentials for other resources.
1045            </p>
1046            <p id="rfc.section.6.3.p.2">This is of particular concern when an origin server hosts resources for multiple parties under the same canonical root URI
1047               (<a href="#protection.space" title="Protection Space (Realm)">Section&nbsp;2.2</a>). Possible mitigation strategies include restricting direct access to authentication credentials (i.e., not making the content
1048               of the <a href="#header.authorization" class="smpl">Authorization</a> request header field available), and separating protection spaces by using a different host name (or port number) for each
1049               party.
1050            </p>
1051         </div>
1052      </div>
1053      <div id="acks">
1054         <h1 id="rfc.section.7"><a href="#rfc.section.7">7.</a>&nbsp;<a href="#acks">Acknowledgments</a></h1>
1055         <p id="rfc.section.7.p.1">This specification takes over the definition of the HTTP Authentication Framework, 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, Paul J. Leach, Ari Luotonen, and
1056            Lawrence C. Stewart for their work on that specification. See <a href="http://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.
1057         </p>
1058         <p id="rfc.section.7.p.2">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.
1059         </p>
1060      </div>
1061      <h1 id="rfc.references"><a id="rfc.section.8" href="#rfc.section.8">8.</a> References
1062      </h1>
1063      <h2 id="rfc.references.1"><a href="#rfc.section.8.1" id="rfc.section.8.1">8.1</a> Normative References
1064      </h2>
1065      <table>
1066         <tr>
1067            <td class="reference"><b id="RFC2119">[RFC2119]</b></td>
1068            <td class="top"><a href="mailto:sob@harvard.edu" title="Harvard University">Bradner, S.</a>, “<a href="http://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.
1069            </td>
1070         </tr>
1071         <tr>
1072            <td class="reference"><b id="RFC5234">[RFC5234]</b></td>
1073            <td class="top"><a href="mailto:dcrocker@bbiw.net" title="Brandenburg InternetWorking">Crocker, D., Ed.</a> and <a href="mailto:paul.overell@thus.net" title="THUS plc.">P. Overell</a>, “<a href="http://tools.ietf.org/html/rfc5234">Augmented BNF for Syntax Specifications: ABNF</a>”, STD&nbsp;68, RFC&nbsp;5234, January&nbsp;2008.
1074            </td>
1075         </tr>
1076         <tr>
1077            <td class="reference"><b id="RFC7230">[RFC7230]</b></td>
1078            <td class="top"><a href="mailto:fielding@gbiv.com" title="Adobe Systems Incorporated">Fielding, R., Ed.</a> and <a href="mailto:julian.reschke@greenbytes.de" title="greenbytes GmbH">J. Reschke, Ed.</a>, “<a href="http://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), May&nbsp;2014.
1079            </td>
1080         </tr>
1081         <tr>
1082            <td class="reference"><b id="RFC7231">[RFC7231]</b></td>
1083            <td class="top"><a href="mailto:fielding@gbiv.com" title="Adobe Systems Incorporated">Fielding, R., Ed.</a> and <a href="mailto:julian.reschke@greenbytes.de" title="greenbytes GmbH">J. Reschke, Ed.</a>, “<a href="http://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), May&nbsp;2014.
1084            </td>
1085         </tr>
1086         <tr>
1087            <td class="reference"><b id="RFC7234">[RFC7234]</b></td>
1088            <td class="top"><a href="mailto:fielding@gbiv.com" title="Adobe Systems Incorporated">Fielding, R., Ed.</a>, <a href="mailto:mnot@mnot.net" title="Akamai">Nottingham, M., Ed.</a>, and <a href="mailto:julian.reschke@greenbytes.de" title="greenbytes GmbH">J. Reschke, Ed.</a>, “<a href="http://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), May&nbsp;2014.
1089            </td>
1090         </tr>
1091      </table>
1092      <h2 id="rfc.references.2"><a href="#rfc.section.8.2" id="rfc.section.8.2">8.2</a> Informative References
1093      </h2>
1094      <table>
1095         <tr>
1096            <td class="reference"><b id="BCP90">[BCP90]</b></td>
1097            <td class="top"><a href="mailto:GK-IETF@ninebynine.org" title="Nine by Nine">Klyne, G.</a>, <a href="mailto:mnot@pobox.com" title="BEA Systems">Nottingham, M.</a>, and <a href="mailto:JeffMogul@acm.org" title="HP Labs">J. Mogul</a>, “<a href="http://tools.ietf.org/html/rfc3864">Registration Procedures for Message Header Fields</a>”, BCP&nbsp;90, RFC&nbsp;3864, September&nbsp;2004.
1098            </td>
1099         </tr>
1100         <tr>
1101            <td class="reference"><b id="OWASP">[OWASP]</b></td>
1102            <td class="top">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;.
1103            </td>
1104         </tr>
1105         <tr>
1106            <td class="reference"><b id="RFC2616">[RFC2616]</b></td>
1107            <td class="top"><a href="mailto:fielding@ics.uci.edu" title="University of California, Irvine">Fielding, R.</a>, <a href="mailto:jg@w3.org" title="W3C">Gettys, J.</a>, <a href="mailto:mogul@wrl.dec.com" title="Compaq Computer Corporation">Mogul, J.</a>, <a href="mailto:frystyk@w3.org" title="MIT Laboratory for Computer Science">Frystyk, H.</a>, <a href="mailto:masinter@parc.xerox.com" title="Xerox Corporation">Masinter, L.</a>, <a href="mailto:paulle@microsoft.com" title="Microsoft Corporation">Leach, P.</a>, and <a href="mailto:timbl@w3.org" title="W3C">T. Berners-Lee</a>, “<a href="http://tools.ietf.org/html/rfc2616">Hypertext Transfer Protocol -- HTTP/1.1</a>”, RFC&nbsp;2616, June&nbsp;1999.
1108            </td>
1109         </tr>
1110         <tr>
1111            <td class="reference"><b id="RFC2617">[RFC2617]</b></td>
1112            <td class="top"><a href="mailto:john@math.nwu.edu" title="Northwestern University, Department of Mathematics">Franks, J.</a>, <a href="mailto:pbaker@verisign.com" title="Verisign Inc.">Hallam-Baker, P.</a>, <a href="mailto:jeff@AbiSource.com" title="AbiSource, Inc.">Hostetler, J.</a>, <a href="mailto:lawrence@agranat.com" title="Agranat Systems, Inc.">Lawrence, S.</a>, <a href="mailto:paulle@microsoft.com" title="Microsoft Corporation">Leach, P.</a>, Luotonen, A., and <a href="mailto:stewart@OpenMarket.com" title="Open Market, Inc.">L. Stewart</a>, “<a href="http://tools.ietf.org/html/rfc2617">HTTP Authentication: Basic and Digest Access Authentication</a>”, RFC&nbsp;2617, June&nbsp;1999.
1113            </td>
1114         </tr>
1115         <tr>
1116            <td class="reference"><b id="RFC3986">[RFC3986]</b></td>
1117            <td class="top"><a href="mailto:timbl@w3.org" title="World Wide Web Consortium">Berners-Lee, T.</a>, <a href="mailto:fielding@gbiv.com" title="Day Software">Fielding, R.</a>, and <a href="mailto:LMM@acm.org" title="Adobe Systems Incorporated">L. Masinter</a>, “<a href="http://tools.ietf.org/html/rfc3986">Uniform Resource Identifier (URI): Generic Syntax</a>”, STD&nbsp;66, RFC&nbsp;3986, January&nbsp;2005.
1118            </td>
1119         </tr>
1120         <tr>
1121            <td class="reference"><b id="RFC4648">[RFC4648]</b></td>
1122            <td class="top">Josefsson, S., “<a href="http://tools.ietf.org/html/rfc4648">The Base16, Base32, and Base64 Data Encodings</a>”, RFC&nbsp;4648, October&nbsp;2006.
1123            </td>
1124         </tr>
1125         <tr>
1126            <td class="reference"><b id="RFC5226">[RFC5226]</b></td>
1127            <td class="top"><a href="mailto:narten@us.ibm.com" title="IBM">Narten, T.</a> and <a href="mailto:Harald@Alvestrand.no" title="Google">H. Alvestrand</a>, “<a href="http://tools.ietf.org/html/rfc5226">Guidelines for Writing an IANA Considerations Section in RFCs</a>”, BCP&nbsp;26, RFC&nbsp;5226, May&nbsp;2008.
1128            </td>
1129         </tr>
1130         <tr>
1131            <td class="reference"><b id="RFC5246">[RFC5246]</b></td>
1132            <td class="top">Dierks, T. and E. Rescorla, “<a href="http://tools.ietf.org/html/rfc5246">The Transport Layer Security (TLS) Protocol Version 1.2</a>”, RFC&nbsp;5246, August&nbsp;2008.
1133            </td>
1134         </tr>
1135      </table>
1136      <div id="changes.from.rfc.2616">
1137         <h1 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></h1>
1138         <p id="rfc.section.A.p.1">The framework for HTTP Authentication is now defined by this document, rather than RFC 2617.</p>
1139         <p id="rfc.section.A.p.2">The "realm" parameter is no longer always required on challenges; consequently, the ABNF allows challenges without any auth
1140            parameters. (<a href="#access.authentication.framework" title="Access Authentication Framework">Section&nbsp;2</a>)
1141         </p>
1142         <p id="rfc.section.A.p.3">The "token68" alternative to auth-param lists has been added for consistency with legacy authentication schemes such as "Basic".
1143            (<a href="#access.authentication.framework" title="Access Authentication Framework">Section&nbsp;2</a>)
1144         </p>
1145         <p id="rfc.section.A.p.4">This specification introduces the Authentication Scheme Registry, along with considerations for new authentication schemes.
1146            (<a href="#authentication.scheme.registry" title="Authentication Scheme Registry">Section&nbsp;5.1</a>)
1147         </p>
1148      </div>
1149      <div id="imported.abnf">
1150         <h1 id="rfc.section.B"><a href="#rfc.section.B">B.</a>&nbsp;<a href="#imported.abnf">Imported ABNF</a></h1>
1151         <p id="rfc.section.B.p.1">The following core rules are included by reference, as defined in <a href="http://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 0-9), DQUOTE (double quote), HEXDIG
1152            (hexadecimal 0-9/A-F/a-f), LF (line feed), OCTET (any 8-bit sequence of data), SP (space), and VCHAR (any visible US-ASCII
1153            character).
1154         </p>
1155         <p id="rfc.section.B.p.2">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>:
1156         </p>
1157         <div id="rfc.figure.u.9"></div><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;
1158  <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;
1159  <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;
1160  <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;
1161</pre></div>
1162      <div id="collected.abnf">
1163         <h1 id="rfc.section.C"><a href="#rfc.section.C">C.</a>&nbsp;<a href="#collected.abnf">Collected ABNF</a></h1>
1164         <p id="rfc.section.C.p.1">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>.
1165         </p>
1166         <div id="rfc.figure.u.10"></div><pre class="inline"><a href="#header.authorization" class="smpl">Authorization</a> = credentials
1167
1168<a href="#imported.abnf" class="smpl">BWS</a> = &lt;BWS, see [RFC7230], Section 3.2.3&gt;
1169
1170<a href="#imported.abnf" class="smpl">OWS</a> = &lt;OWS, see [RFC7230], Section 3.2.3&gt;
1171
1172<a href="#header.proxy-authenticate" class="smpl">Proxy-Authenticate</a> = *( "," OWS ) challenge *( OWS "," [ OWS
1173 challenge ] )
1174<a href="#header.proxy-authorization" class="smpl">Proxy-Authorization</a> = credentials
1175
1176<a href="#header.www-authenticate" class="smpl">WWW-Authenticate</a> = *( "," OWS ) challenge *( OWS "," [ OWS challenge
1177 ] )
1178
1179<a href="#challenge.and.response" class="smpl">auth-param</a> = token BWS "=" BWS ( token / quoted-string )
1180<a href="#challenge.and.response" class="smpl">auth-scheme</a> = token
1181
1182<a href="#challenge.and.response" class="smpl">challenge</a> = auth-scheme [ 1*SP ( token68 / [ ( "," / auth-param ) *(
1183 OWS "," [ OWS auth-param ] ) ] ) ]
1184<a href="#challenge.and.response" class="smpl">credentials</a> = auth-scheme [ 1*SP ( token68 / [ ( "," / auth-param )
1185 *( OWS "," [ OWS auth-param ] ) ] ) ]
1186
1187<a href="#imported.abnf" class="smpl">quoted-string</a> = &lt;quoted-string, see [RFC7230], Section 3.2.6&gt;
1188
1189<a href="#imported.abnf" class="smpl">token</a> = &lt;token, see [RFC7230], Section 3.2.6&gt;
1190<a href="#challenge.and.response" class="smpl">token68</a> = 1*( ALPHA / DIGIT / "-" / "." / "_" / "~" / "+" / "/" )
1191 *"="
1192</pre></div>
1193      <h1 id="rfc.index"><a href="#rfc.index">Index</a></h1>
1194      <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>
1195      </p>
1196      <div class="print2col">
1197         <ul class="ind">
1198            <li><a id="rfc.index.4" href="#rfc.index.4"><b>4</b></a><ul>
1199                  <li>401 Unauthorized (status code)&nbsp;&nbsp;<a href="#rfc.iref.8"><b>3.1</b></a>, <a href="#rfc.xref.status.401.1">5.2</a></li>
1200                  <li>407 Proxy Authentication Required (status code)&nbsp;&nbsp;<a href="#rfc.iref.8"><b>3.2</b></a>, <a href="#rfc.xref.status.407.1">5.2</a></li>
1201               </ul>
1202            </li>
1203            <li><a id="rfc.index.A" href="#rfc.index.A"><b>A</b></a><ul>
1204                  <li>Authorization header field&nbsp;&nbsp;<a href="#rfc.xref.header.authorization.1">3.1</a>, <a href="#rfc.iref.a.1"><b>4.2</b></a>, <a href="#rfc.xref.header.authorization.2">5.3</a></li>
1205               </ul>
1206            </li>
1207            <li><a id="rfc.index.B" href="#rfc.index.B"><b>B</b></a><ul>
1208                  <li><em>BCP90</em>&nbsp;&nbsp;<a href="#rfc.xref.BCP90.1">5.3</a>, <a href="#BCP90"><b>8.2</b></a></li>
1209               </ul>
1210            </li>
1211            <li><a id="rfc.index.C" href="#rfc.index.C"><b>C</b></a><ul>
1212                  <li>Canonical Root URI&nbsp;&nbsp;<a href="#rfc.iref.c.1">2.2</a></li>
1213               </ul>
1214            </li>
1215            <li><a id="rfc.index.G" href="#rfc.index.G"><b>G</b></a><ul>
1216                  <li><tt>Grammar</tt>&nbsp;&nbsp;
1217                     <ul>
1218                        <li><tt>auth-param</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.2"><b>2.1</b></a></li>
1219                        <li><tt>auth-scheme</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.1"><b>2.1</b></a></li>
1220                        <li><tt>Authorization</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.7"><b>4.2</b></a></li>
1221                        <li><tt>challenge</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.4"><b>2.1</b></a></li>
1222                        <li><tt>credentials</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.5"><b>2.1</b></a></li>
1223                        <li><tt>Proxy-Authenticate</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.8"><b>4.3</b></a></li>
1224                        <li><tt>Proxy-Authorization</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.9"><b>4.4</b></a></li>
1225                        <li><tt>token68</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.3"><b>2.1</b></a></li>
1226                        <li><tt>WWW-Authenticate</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.6"><b>4.1</b></a></li>
1227                     </ul>
1228                  </li>
1229               </ul>
1230            </li>
1231            <li><a id="rfc.index.O" href="#rfc.index.O"><b>O</b></a><ul>
1232                  <li><em>OWASP</em>&nbsp;&nbsp;<a href="#rfc.xref.OWASP.1">6</a>, <a href="#OWASP"><b>8.2</b></a></li>
1233               </ul>
1234            </li>
1235            <li><a id="rfc.index.P" href="#rfc.index.P"><b>P</b></a><ul>
1236                  <li>Protection Space&nbsp;&nbsp;<a href="#rfc.iref.p.1">2.2</a></li>
1237                  <li>Proxy-Authenticate header field&nbsp;&nbsp;<a href="#rfc.xref.header.proxy-authenticate.1">3.2</a>, <a href="#rfc.iref.p.2"><b>4.3</b></a>, <a href="#rfc.xref.header.proxy-authenticate.2">5.3</a></li>
1238                  <li>Proxy-Authorization header field&nbsp;&nbsp;<a href="#rfc.xref.header.proxy-authorization.1">3.2</a>, <a href="#rfc.iref.p.3"><b>4.4</b></a>, <a href="#rfc.xref.header.proxy-authorization.2">5.3</a></li>
1239               </ul>
1240            </li>
1241            <li><a id="rfc.index.R" href="#rfc.index.R"><b>R</b></a><ul>
1242                  <li>Realm&nbsp;&nbsp;<a href="#rfc.iref.r.1">2.2</a></li>
1243                  <li><em>RFC2119</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC2119.1">1.1</a>, <a href="#RFC2119"><b>8.1</b></a></li>
1244                  <li><em>RFC2616</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC2616.1">1</a>, <a href="#RFC2616"><b>8.2</b></a></li>
1245                  <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>
1246                        <li><em>Section 6</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC2617.4">7</a></li>
1247                     </ul>
1248                  </li>
1249                  <li><em>RFC3986</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC3986.1">2.1</a>, <a href="#RFC3986"><b>8.2</b></a></li>
1250                  <li><em>RFC4648</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC4648.1">2.1</a>, <a href="#RFC4648"><b>8.2</b></a></li>
1251                  <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>
1252                        <li><em>Section 4.1</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC5226.1">5.1.1</a></li>
1253                     </ul>
1254                  </li>
1255                  <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>
1256                        <li><em>Appendix B.1</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC5234.2">B</a></li>
1257                     </ul>
1258                  </li>
1259                  <li><em>RFC5246</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC5246.1">6.1</a>, <a href="#RFC5246"><b>8.2</b></a></li>
1260                  <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>
1261                        <li><em>Section 1.2</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC7230.14">C</a></li>
1262                        <li><em>Section 2.3</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC7230.6">5.1.2</a></li>
1263                        <li><em>Section 2.5</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC7230.2">1.1</a></li>
1264                        <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>
1265                        <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>
1266                        <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>
1267                        <li><em>Section 7</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC7230.3">1.2</a></li>
1268                        <li><em>Section 10</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC7230.8">7</a></li>
1269                     </ul>
1270                  </li>
1271                  <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>
1272                        <li><em>Section 6.5.3</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC7231.1">2.1</a></li>
1273                     </ul>
1274                  </li>
1275                  <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>
1276                        <li><em>Section 3.2</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC7234.1">4.2</a></li>
1277                        <li><em>Section 5.2.1.5</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC7234.3">5.1.2</a></li>
1278                        <li><em>Section 5.2.2.6</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC7234.2">5.1.2</a></li>
1279                     </ul>
1280                  </li>
1281               </ul>
1282            </li>
1283            <li><a id="rfc.index.W" href="#rfc.index.W"><b>W</b></a><ul>
1284                  <li>WWW-Authenticate header field&nbsp;&nbsp;<a href="#rfc.xref.header.www-authenticate.1">3.1</a>, <a href="#rfc.iref.w.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>
1285               </ul>
1286            </li>
1287         </ul>
1288      </div>
1289      <div class="avoidbreak">
1290         <h1 id="rfc.authors"><a href="#rfc.authors">Authors' Addresses</a></h1>
1291         <p><b>Roy T. Fielding</b>
1292            (editor)
1293            <br>Adobe Systems Incorporated<br>345 Park Ave<br>San Jose, CA&nbsp;95110<br>USA<br>Email: <a href="mailto:fielding@gbiv.com">fielding@gbiv.com</a><br>URI: <a href="http://roy.gbiv.com/">http://roy.gbiv.com/</a></p>
1294         <p><b>Julian F. Reschke</b>
1295            (editor)
1296            <br>greenbytes GmbH<br>Hafenweg 16<br>Muenster, NW&nbsp;48155<br>Germany<br>Email: <a href="mailto:julian.reschke@greenbytes.de">julian.reschke@greenbytes.de</a><br>URI: <a href="http://greenbytes.de/tech/webdav/">http://greenbytes.de/tech/webdav/</a></p>
1297      </div>
1298   </body>
1299</html>
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