source: draft-ietf-httpbis/latest/p7-auth.xml @ 2573

Last change on this file since 2573 was 2573, checked in by fielding@…, 8 years ago

(editorial) move and expand on discussion of confidentiality of credentials in its own security considerations section; see #539

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  • Property svn:mime-type set to text/xml
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1<?xml version="1.0" encoding="utf-8"?>
2<?xml-stylesheet type='text/xsl' href='../myxml2rfc.xslt'?>
3<!DOCTYPE rfc [
4  <!ENTITY MAY "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>MAY</bcp14>">
5  <!ENTITY MUST "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>MUST</bcp14>">
6  <!ENTITY MUST-NOT "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>MUST NOT</bcp14>">
7  <!ENTITY OPTIONAL "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>OPTIONAL</bcp14>">
8  <!ENTITY RECOMMENDED "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>RECOMMENDED</bcp14>">
9  <!ENTITY REQUIRED "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>REQUIRED</bcp14>">
10  <!ENTITY SHALL "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>SHALL</bcp14>">
11  <!ENTITY SHALL-NOT "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>SHALL NOT</bcp14>">
12  <!ENTITY SHOULD "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>SHOULD</bcp14>">
13  <!ENTITY SHOULD-NOT "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>SHOULD NOT</bcp14>">
14  <!ENTITY ID-VERSION "latest">
15  <!ENTITY ID-MONTH "January">
16  <!ENTITY ID-YEAR "2014">
17  <!ENTITY mdash "&#8212;">
18  <!ENTITY Note "<x:h xmlns:x='http://purl.org/net/xml2rfc/ext'>Note:</x:h>">
19  <!ENTITY messaging                    "<xref target='Part1' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
20  <!ENTITY semantics                    "<xref target='Part2' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
21  <!ENTITY architecture                 "<xref target='Part1' x:rel='#architecture' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
22  <!ENTITY conformance                  "<xref target='Part1' x:rel='#conformance' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
23  <!ENTITY notation                     "<xref target='Part1' x:rel='#notation' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
24  <!ENTITY abnf-extension               "<xref target='Part1' x:rel='#abnf.extension' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
25  <!ENTITY acks                         "<xref target='Part1' x:rel='#acks' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
26  <!ENTITY whitespace                   "<xref target='Part1' x:rel='#whitespace' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
27  <!ENTITY field-components             "<xref target='Part1' x:rel='#field.components' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
28  <!ENTITY effective-request-uri        "<xref target='Part1' x:rel='#effective.request.uri' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
29  <!ENTITY msg-orient-and-buffering     "<xref target='Part1' x:rel='#intermediaries' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
30  <!ENTITY end-to-end.and-hop-by-hop    "<xref target='Part1' x:rel='#end-to-end.and.hop-by-hop.header-fields' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
31  <!ENTITY status.403                   "<xref target='Part2' x:rel='#status.403' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
32  <!ENTITY caching-authenticated-responses "<xref target='Part6' x:rel='#caching.authenticated.responses' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
33  <!ENTITY caching-rqd-no-store         "<xref target='Part6' x:rel='#cache-request-directive.no-store' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
34  <!ENTITY caching-rsd-private          "<xref target='Part6' x:rel='#cache-response-directive.private' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
35]>
36<?rfc toc="yes" ?>
37<?rfc symrefs="yes" ?>
38<?rfc sortrefs="yes" ?>
39<?rfc compact="yes"?>
40<?rfc subcompact="no" ?>
41<?rfc linkmailto="no" ?>
42<?rfc editing="no" ?>
43<?rfc comments="yes"?>
44<?rfc inline="yes"?>
45<?rfc rfcedstyle="yes"?>
46<?rfc-ext allow-markup-in-artwork="yes" ?>
47<?rfc-ext include-references-in-index="yes" ?>
48<rfc obsoletes="2616" updates="2617" category="std" x:maturity-level="proposed"
49     ipr="pre5378Trust200902" docName="draft-ietf-httpbis-p7-auth-&ID-VERSION;"
50     xmlns:x='http://purl.org/net/xml2rfc/ext'>
51<x:link rel="prev" basename="p6-cache"/>
52<x:feedback template="mailto:ietf-http-wg@w3.org?subject={docname},%20%22{section}%22&amp;body=&lt;{ref}&gt;:"/>
53<front>
54
55  <title abbrev="HTTP/1.1 Authentication">Hypertext Transfer Protocol (HTTP/1.1): Authentication</title>
56
57  <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
58    <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
59    <address>
60      <postal>
61        <street>345 Park Ave</street>
62        <city>San Jose</city>
63        <region>CA</region>
64        <code>95110</code>
65        <country>USA</country>
66      </postal>
67      <email>fielding@gbiv.com</email>
68      <uri>http://roy.gbiv.com/</uri>
69    </address>
70  </author>
71
72  <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
73    <organization abbrev="greenbytes">greenbytes GmbH</organization>
74    <address>
75      <postal>
76        <street>Hafenweg 16</street>
77        <city>Muenster</city><region>NW</region><code>48155</code>
78        <country>Germany</country>
79      </postal>
80      <email>julian.reschke@greenbytes.de</email>
81      <uri>http://greenbytes.de/tech/webdav/</uri>
82    </address>
83  </author>
84
85  <date month="&ID-MONTH;" year="&ID-YEAR;"/>
86  <workgroup>HTTPbis Working Group</workgroup>
87
88<abstract>
89<t>
90   The Hypertext Transfer Protocol (HTTP) is a stateless application-level protocol for
91   distributed, collaborative, hypermedia information systems. This document
92   defines the HTTP Authentication framework.
93</t>
94</abstract>
95
96<note title="Editorial Note (To be removed by RFC Editor)">
97  <t>
98    Discussion of this draft takes place on the HTTPBIS working group
99    mailing list (ietf-http-wg@w3.org), which is archived at
100    <eref target="http://lists.w3.org/Archives/Public/ietf-http-wg/"/>.
101  </t>
102  <t>
103    The current issues list is at
104    <eref target="http://tools.ietf.org/wg/httpbis/trac/report/3"/> and related
105    documents (including fancy diffs) can be found at
106    <eref target="http://tools.ietf.org/wg/httpbis/"/>.
107  </t>
108  <t>
109    The changes in this draft are summarized in <xref target="changes.since.25"/>.
110  </t>
111</note>
112</front>
113<middle>
114<section title="Introduction" anchor="introduction">
115<t>
116   This document defines HTTP/1.1 access control and authentication. It
117   includes the relevant parts of <xref target="RFC2616" x:fmt="none">RFC 2616</xref>
118   with only minor changes (<xref target="RFC2616"/>), plus the general framework for HTTP authentication,
119   as previously defined in "HTTP Authentication: Basic and Digest Access
120   Authentication" (<xref target="RFC2617"/>).
121</t>
122<t>
123   HTTP provides several &OPTIONAL; challenge-response authentication
124   schemes that can be used by a server to challenge a client request and
125   by a client to provide authentication information. See the IANA
126   Authentication Scheme Registry (<xref target="authentication.scheme.registry"/>)
127   for the definitions of the "basic" and "digest" authentication schemes
128   which were defined by <xref target="RFC2617" x:fmt="none">RFC 2617</xref>.
129</t>
130
131<section title="Conformance and Error Handling" anchor="conformance">
132<t>
133   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
134   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
135   document are to be interpreted as described in <xref target="RFC2119"/>.
136</t>
137<t>
138   Conformance criteria and considerations regarding error handling
139   are defined in &conformance;.
140</t>
141</section>
142
143<section title="Syntax Notation" anchor="notation">
144<t>
145   This specification uses the Augmented Backus-Naur Form (ABNF) notation of
146   <xref target="RFC5234"/> with a list extension, defined in
147   &abnf-extension;, that allows for compact definition of
148   comma-separated lists using a '#' operator (similar to how the '*' operator
149   indicates repetition).
150   <xref target="imported.abnf"/> describes rules imported from
151   other documents.
152   <xref target="collected.abnf"/> shows the collected grammar with all list
153   operators expanded to standard ABNF notation.
154</t>
155</section>
156</section>
157
158<section title="Access Authentication Framework" anchor="access.authentication.framework">
159
160<section title="Challenge and Response" anchor="challenge.and.response">
161  <x:anchor-alias value="auth-scheme"/>
162  <x:anchor-alias value="auth-param"/>
163  <x:anchor-alias value="token68"/>
164  <x:anchor-alias value="challenge"/>
165  <x:anchor-alias value="credentials"/>
166<t>
167   HTTP provides a simple challenge-response authentication framework
168   that can be used by a server to challenge a client request and by a
169   client to provide authentication information. It uses a case-insensitive
170   token as a means to identify the authentication scheme, followed
171   by additional information necessary for achieving authentication via that
172   scheme. The latter can either be a comma-separated list of parameters or a
173   single sequence of characters capable of holding base64-encoded
174   information.
175</t>
176<t>
177   Authentication parameters are name=value pairs, where the name token is
178   matched case-insensitively,
179   and each parameter name &MUST; only occur once per challenge.
180</t>
181<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="auth-scheme"/><iref primary="true" item="Grammar" subitem="auth-param"/><iref primary="true" item="Grammar" subitem="token68"/>
182  auth-scheme    = <x:ref>token</x:ref>
183 
184  auth-param     = <x:ref>token</x:ref> <x:ref>BWS</x:ref> "=" <x:ref>BWS</x:ref> ( <x:ref>token</x:ref> / <x:ref>quoted-string</x:ref> )
185
186  token68        = 1*( <x:ref>ALPHA</x:ref> / <x:ref>DIGIT</x:ref> /
187                       "-" / "." / "_" / "~" / "+" / "/" ) *"="
188</artwork></figure>
189<t>
190   The "token68" syntax allows the 66 unreserved URI characters (<xref target="RFC3986"/>),
191   plus a few others, so that it can hold a base64, base64url (URL and filename
192   safe alphabet), base32, or base16 (hex) encoding, with or without padding, but
193   excluding whitespace (<xref target="RFC4648"/>).
194</t>
195<t>
196   The <x:ref>401 (Unauthorized)</x:ref> response message is used by an origin server
197   to challenge the authorization of a user agent. This response &MUST;
198   include a <x:ref>WWW-Authenticate</x:ref> header field containing at least one
199   challenge applicable to the requested resource.
200</t>
201<t>  
202   The <x:ref>407 (Proxy Authentication Required)</x:ref> response message is
203   used by a proxy to challenge the authorization of a client and &MUST;
204   include a <x:ref>Proxy-Authenticate</x:ref> header field containing at least
205   one challenge applicable to the proxy for the requested resource.
206</t>
207<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="challenge"/>
208  <x:ref>challenge</x:ref>   = <x:ref>auth-scheme</x:ref> [ 1*<x:ref>SP</x:ref> ( <x:ref>token68</x:ref> / #<x:ref>auth-param</x:ref> ) ]
209</artwork></figure>
210<x:note>
211  <t>
212     &Note; Many clients fail to parse a challenge that contains an unknown
213     scheme. A workaround for this problem is to list well-supported schemes
214     (such as "basic") first.<!-- see http://greenbytes.de/tech/tc/httpauth/#multibasicunknown2 -->
215  </t>
216</x:note>
217<t>
218   A user agent that wishes to authenticate itself with an origin server
219   &mdash; usually, but not necessarily, after receiving a <x:ref>401 (Unauthorized)</x:ref>
220   &mdash; can do so by including an <x:ref>Authorization</x:ref> header field with the
221   request.
222</t>
223<t>  
224   A client that wishes to authenticate itself with a proxy &mdash; usually,
225   but not necessarily, after receiving a <x:ref>407 (Proxy Authentication Required)</x:ref>
226   &mdash; can do so by including a <x:ref>Proxy-Authorization</x:ref> header field with the
227   request.
228</t>
229<t>
230   Both the <x:ref>Authorization</x:ref> field value and the
231   <x:ref>Proxy-Authorization</x:ref> field value contain the client's
232   credentials for the realm of the resource being requested, based upon a
233   challenge received in a response (possibly at some point in the past).
234   When creating their values, the user agent ought to do so by selecting the
235   challenge with what it considers to be the most secure auth-scheme that it
236   understands, obtaining credentials from the user as appropriate.
237   Transmission of credentials within header field values implies significant
238   security considerations regarding the confidentiality of the underlying
239   connection, as described in
240   <xref target="confidentiality.of.credentials"/>.
241</t>
242<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="credentials"/>
243  <x:ref>credentials</x:ref> = <x:ref>auth-scheme</x:ref> [ 1*<x:ref>SP</x:ref> ( <x:ref>token68</x:ref> / #<x:ref>auth-param</x:ref> ) ]
244</artwork></figure>
245<t>
246   Upon receipt of a request for a protected resource that omits credentials,
247   contains invalid credentials (e.g., a bad password) or partial credentials
248   (e.g., when the authentication scheme requires more than one round trip), an
249   origin server &SHOULD; send a <x:ref>401 (Unauthorized)</x:ref> response that
250   contains a <x:ref>WWW-Authenticate</x:ref> header field with at least one
251   (possibly new) challenge applicable to the requested resource.
252</t>
253<t>
254   Likewise, upon receipt of a request that requires authentication by proxies
255   that omit credentials or contain invalid or partial credentials, a proxy
256   &SHOULD; send a <x:ref>407 (Proxy Authentication Required)</x:ref> response
257   that contains a <x:ref>Proxy-Authenticate</x:ref> header field with a
258   (possibly new) challenge applicable to the proxy.
259</t>
260<t>
261   A server receiving credentials that are valid, but not adequate to gain
262   access, ought to respond with the <x:ref>403 (Forbidden)</x:ref> status code (&status.403;).
263</t>
264<t>
265   HTTP does not restrict applications to this simple challenge-response
266   framework for access authentication. Additional mechanisms can be used,
267   such as authentication at the transport level or via message encapsulation,
268   and with additional header fields specifying authentication information.
269   However, such additional mechanisms are not defined by this specification.
270</t>
271<t>
272   A proxy &MUST; forward the <x:ref>WWW-Authenticate</x:ref> and
273   <x:ref>Authorization</x:ref> header fields unmodified and follow the rules
274   found in <xref target="header.authorization"/>.
275</t>
276</section>
277
278<section title="Protection Space (Realm)" anchor="protection.space">
279  <iref item="Protection Space"/>
280  <iref item="Realm"/>
281  <iref item="Canonical Root URI"/>
282<t>
283   The authentication parameter realm is reserved for use by authentication
284   schemes that wish to indicate the scope of protection.
285</t>
286<t>
287   A <x:dfn>protection space</x:dfn> is defined by the canonical root URI (the
288   scheme and authority components of the effective request URI; see
289   <xref target="Part1" x:fmt="of" x:rel="#effective.request.uri"/>) of the
290   server being accessed, in combination with the realm value if present.
291   These realms allow the protected resources on a server to be
292   partitioned into a set of protection spaces, each with its own
293   authentication scheme and/or authorization database. The realm value
294   is a string, generally assigned by the origin server, which can have
295   additional semantics specific to the authentication scheme. Note that a
296   response can have multiple challenges with the same auth-scheme but
297   different realms.
298</t>
299<t>
300   The protection space determines the domain over which credentials can
301   be automatically applied. If a prior request has been authorized, the
302   user agent &MAY; reuse the same credentials for all other requests within
303   that protection space for a period of time determined by the authentication
304   scheme, parameters, and/or user preferences (such as a configurable
305   inactivity timeout). Unless specifically allowed by the authentication
306   scheme, a single protection space cannot extend outside the scope of its
307   server.
308</t>
309<t>
310   For historical reasons, a sender &MUST; only generate the quoted-string syntax.
311   Recipients might have to support both token and quoted-string syntax for
312   maximum interoperability with existing clients that have been accepting both
313   notations for a long time.
314</t>
315</section>
316
317</section>
318
319<section title="Status Code Definitions" anchor="status.code.definitions">
320<section title="401 Unauthorized" anchor="status.401">
321  <iref primary="true" item="401 Unauthorized (status code)" x:for-anchor=""/>
322  <x:anchor-alias value="401 (Unauthorized)"/>
323<t>
324   The <x:dfn>401 (Unauthorized)</x:dfn> status code indicates that the
325   request has not been applied because it lacks valid authentication
326   credentials for the target resource. The origin server &MUST; send a
327   <x:ref>WWW-Authenticate</x:ref> header field (<xref target="header.www-authenticate"/>)
328   containing at least one challenge applicable to the target resource.
329   If the request included authentication credentials, then the 401 response
330   indicates that authorization has been refused for those credentials.
331   The user agent &MAY; repeat the request with a new or replaced
332   <x:ref>Authorization</x:ref> header field (<xref target="header.authorization"/>).
333   If the 401 response contains the same challenge as the prior response, and
334   the user agent has already attempted authentication at least once, then the
335   user agent &SHOULD; present the enclosed representation to the user, since
336   it usually contains relevant diagnostic information.
337</t>
338</section>
339<section title="407 Proxy Authentication Required" anchor="status.407">
340  <iref primary="true" item="407 Proxy Authentication Required (status code)" x:for-anchor=""/>
341  <x:anchor-alias value="407 (Proxy Authentication Required)"/>
342<t>
343   The <x:dfn>407 (Proxy Authentication Required)</x:dfn> status code is
344   similar to <x:ref>401 (Unauthorized)</x:ref>, but indicates that the client
345   needs to authenticate itself in order to use a proxy.
346   The proxy &MUST; send a <x:ref>Proxy-Authenticate</x:ref> header field
347   (<xref target="header.proxy-authenticate"/>) containing a challenge
348   applicable to that proxy for the target resource. The client &MAY; repeat
349   the request with a new or replaced <x:ref>Proxy-Authorization</x:ref>
350   header field (<xref target="header.proxy-authorization"/>).
351</t>
352</section>
353</section>
354
355<section title="Header Field Definitions" anchor="header.field.definitions">
356<t>
357   This section defines the syntax and semantics of HTTP/1.1 header fields
358   related to authentication.
359</t>
360
361<section title="Authorization" anchor="header.authorization">
362  <iref primary="true" item="Authorization header field" x:for-anchor=""/>
363  <x:anchor-alias value="Authorization"/>
364<t>
365   The "Authorization" header field allows a user agent to authenticate itself
366   with an origin server &mdash; usually, but not necessarily, after receiving
367   a <x:ref>401 (Unauthorized)</x:ref> response. Its value consists of
368   credentials containing the authentication information of the user agent for
369   the realm of the resource being requested.
370</t>
371<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Authorization"/>
372  <x:ref>Authorization</x:ref> = <x:ref>credentials</x:ref>
373</artwork></figure>
374<t>
375   If a request is authenticated and a realm specified, the same credentials
376   are presumed to be valid for all other requests within this realm (assuming
377   that the authentication scheme itself does not require otherwise, such as
378   credentials that vary according to a challenge value or using synchronized
379   clocks).
380</t>
381<t>
382   See &caching-authenticated-responses; for details of and requirements
383   pertaining to handling of the Authorization field by HTTP caches.
384</t>
385</section>
386
387<section title="Proxy-Authenticate" anchor="header.proxy-authenticate">
388  <iref primary="true" item="Proxy-Authenticate header field" x:for-anchor=""/>
389  <x:anchor-alias value="Proxy-Authenticate"/>
390<t>
391   The "Proxy-Authenticate" header field consists of at least one
392   challenge that indicates the authentication scheme(s) and parameters
393   applicable to the proxy for this effective request URI
394   (&effective-request-uri;).
395   A proxy &MUST; send at least one Proxy-Authenticate header field in
396   each <x:ref>407 (Proxy Authentication Required)</x:ref> response that it
397   generates.
398</t>
399<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Proxy-Authenticate"/>
400  <x:ref>Proxy-Authenticate</x:ref> = 1#<x:ref>challenge</x:ref>
401</artwork></figure>
402<t>
403   Unlike <x:ref>WWW-Authenticate</x:ref>, the Proxy-Authenticate header field
404   applies only to the next outbound client on the response chain.
405   This is because only the client that chose a given proxy is likely to have
406   the credentials necessary for authentication.  However, when multiple
407   proxies are used within the same administrative domain, such as office and
408   regional caching proxies within a large corporate network, it is common
409   for credentials to be generated by the user agent and passed through the
410   hierarchy until consumed.  Hence, in such a configuration, it will appear
411   as if Proxy-Authenticate is being forwarded because each proxy will send
412   the same challenge set.
413</t>
414<t>
415   Note that the parsing considerations for <x:ref>WWW-Authenticate</x:ref>
416   apply to this header field as well; see <xref target="header.www-authenticate"/>
417   for details.
418</t>
419</section>
420
421<section title="Proxy-Authorization" anchor="header.proxy-authorization">
422  <iref primary="true" item="Proxy-Authorization header field" x:for-anchor=""/>
423  <x:anchor-alias value="Proxy-Authorization"/>
424<t>
425   The "Proxy-Authorization" header field allows the client to
426   identify itself (or its user) to a proxy that requires
427   authentication. Its value consists of credentials containing the
428   authentication information of the client for the proxy and/or realm of the
429   resource being requested.
430</t>
431<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Proxy-Authorization"/>
432  <x:ref>Proxy-Authorization</x:ref> = <x:ref>credentials</x:ref>
433</artwork></figure>
434<t>
435   Unlike <x:ref>Authorization</x:ref>, the Proxy-Authorization header field
436   applies only to the next inbound proxy that demanded authentication using
437   the <x:ref>Proxy-Authenticate</x:ref> field. When multiple proxies are used
438   in a chain, the Proxy-Authorization header field is consumed by the first
439   inbound proxy that was expecting to receive credentials. A proxy &MAY;
440   relay the credentials from the client request to the next proxy if that is
441   the mechanism by which the proxies cooperatively authenticate a given
442   request.
443</t>
444</section>
445
446<section title="WWW-Authenticate" anchor="header.www-authenticate">
447  <iref primary="true" item="WWW-Authenticate header field" x:for-anchor=""/>
448  <x:anchor-alias value="WWW-Authenticate"/>
449<t>
450   The "WWW-Authenticate" header field consists of at least one
451   challenge that indicates the authentication scheme(s) and parameters
452   applicable to the effective request URI (&effective-request-uri;).
453</t>
454<t>  
455   It &MUST; be included in <x:ref>401 (Unauthorized)</x:ref> response messages and &MAY; be
456   included in other response messages to indicate that supplying credentials
457   (or different credentials) might affect the response.
458</t>
459<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="WWW-Authenticate"/>
460  <x:ref>WWW-Authenticate</x:ref> = 1#<x:ref>challenge</x:ref>
461</artwork></figure>
462<t>
463   User agents are advised to take special care in parsing the field value, as
464   it might contain more than one challenge, and each challenge can contain a
465   comma-separated list of authentication parameters. Furthermore, the header
466   field itself can occur multiple times.
467</t>
468<figure>
469  <preamble>For instance:</preamble>
470  <artwork type="example">
471  WWW-Authenticate: Newauth realm="apps", type=1,
472                    title="Login to \"apps\"", Basic realm="simple"
473</artwork>
474  <postamble>
475  This header field contains two challenges; one for the "Newauth" scheme
476  with a realm value of "apps", and two additional parameters "type" and
477  "title", and another one for the "Basic" scheme with a realm value of
478  "simple".
479</postamble></figure>
480<x:note>
481  <t>
482    &Note; The challenge grammar production uses the list syntax as
483    well. Therefore, a sequence of comma, whitespace, and comma can be
484    considered either as applying to the preceding challenge, or to be an
485    empty entry in the list of challenges. In practice, this ambiguity
486    does not affect the semantics of the header field value and thus is
487    harmless.
488  </t>
489</x:note>
490</section>
491
492</section>
493
494<section title="IANA Considerations" anchor="IANA.considerations">
495
496<section title="Authentication Scheme Registry" anchor="authentication.scheme.registry">
497<t>
498   The HTTP Authentication Scheme Registry defines the name space for the
499   authentication schemes in challenges and credentials. It will be created and
500   maintained at (the suggested URI) <eref target="http://www.iana.org/assignments/http-authschemes"/>.
501</t>
502
503<section title="Procedure" anchor="authentication.scheme.registry.procedure">
504<t>
505  Registrations &MUST; include the following fields:
506  <list style="symbols">
507    <t>Authentication Scheme Name</t>
508    <t>Pointer to specification text</t>
509    <t>Notes (optional)</t>
510  </list>
511</t>
512<t>
513  Values to be added to this name space require IETF Review
514  (see <xref target="RFC5226" x:fmt="," x:sec="4.1"/>).
515</t>
516</section>
517
518<section title="Considerations for New Authentication Schemes" anchor="considerations.for.new.authentication.schemes">
519<t>
520  There are certain aspects of the HTTP Authentication Framework that put
521  constraints on how new authentication schemes can work:
522</t>
523<t>
524  <list style="symbols">
525    <x:lt>
526    <t>
527      HTTP authentication is presumed to be stateless: all of the information
528      necessary to authenticate a request &MUST; be provided in the request,
529      rather than be dependent on the server remembering prior requests.
530      Authentication based on, or bound to, the underlying connection is
531      outside the scope of this specification and inherently flawed unless
532      steps are taken to ensure that the connection cannot be used by any
533      party other than the authenticated user
534      (see &msg-orient-and-buffering;).
535    </t>
536    </x:lt>
537    <x:lt>
538    <t>
539      The authentication parameter "realm" is reserved for defining Protection
540      Spaces as defined in <xref target="protection.space"/>. New schemes
541      &MUST-NOT; use it in a way incompatible with that definition.
542    </t>
543    </x:lt>
544    <x:lt>
545    <t>
546      The "token68" notation was introduced for compatibility with existing
547      authentication schemes and can only be used once per challenge or credential.
548      New schemes thus ought to use the "auth-param" syntax instead, because
549      otherwise future extensions will be impossible.
550    </t>
551    </x:lt>
552    <x:lt>
553    <t>
554      The parsing of challenges and credentials is defined by this specification,
555      and cannot be modified by new authentication schemes. When the auth-param
556      syntax is used, all parameters ought to support both token and
557      quoted-string syntax, and syntactical constraints ought to be defined on
558      the field value after parsing (i.e., quoted-string processing). This is
559      necessary so that recipients can use a generic parser that applies to
560      all authentication schemes.
561    </t>
562    <t>
563      &Note; The fact that the value syntax for the "realm" parameter
564      is restricted to quoted-string was a bad design choice not to be repeated
565      for new parameters.
566    </t>
567    </x:lt>
568    <x:lt>
569    <t>
570      Definitions of new schemes ought to define the treatment of unknown
571      extension parameters. In general, a "must-ignore" rule is preferable
572      over "must-understand", because otherwise it will be hard to introduce
573      new parameters in the presence of legacy recipients. Furthermore,
574      it's good to describe the policy for defining new parameters (such
575      as "update the specification", or "use this registry").
576    </t>
577    </x:lt>
578    <x:lt>
579    <t>
580      Authentication schemes need to document whether they are usable in
581      origin-server authentication (i.e., using <x:ref>WWW-Authenticate</x:ref>),
582      and/or proxy authentication (i.e., using <x:ref>Proxy-Authenticate</x:ref>).
583    </t>
584    </x:lt>
585    <x:lt>
586    <t>
587      The credentials carried in an <x:ref>Authorization</x:ref> header field are specific to
588      the User Agent, and therefore have the same effect on HTTP caches as the
589      "private" Cache-Control response directive (&caching-rsd-private;),
590      within the scope of the request they appear in.
591    </t>
592    <t>
593      Therefore, new authentication schemes that choose not to carry
594      credentials in the <x:ref>Authorization</x:ref> header field (e.g., using a newly defined
595      header field) will need to explicitly disallow caching, by mandating the use of
596      either Cache-Control request directives (e.g., "no-store",
597      &caching-rqd-no-store;) or response directives (e.g., "private").
598    </t>
599    </x:lt>
600  </list>
601</t>
602</section>
603</section>
604
605<section title="Status Code Registration" anchor="status.code.registration">
606<t>
607   The HTTP Status Code Registry located at <eref target="http://www.iana.org/assignments/http-status-codes"/>
608   shall be updated with the registrations below:
609</t>
610<?BEGININC p7-auth.iana-status-codes ?>
611<!--AUTOGENERATED FROM extract-status-code-defs.xslt, do not edit manually-->
612<texttable align="left" suppress-title="true" anchor="iana.status.code.registration.table">
613   <ttcol>Value</ttcol>
614   <ttcol>Description</ttcol>
615   <ttcol>Reference</ttcol>
616   <c>401</c>
617   <c>Unauthorized</c>
618   <c>
619      <xref target="status.401"/>
620   </c>
621   <c>407</c>
622   <c>Proxy Authentication Required</c>
623   <c>
624      <xref target="status.407"/>
625   </c>
626</texttable>
627<!--(END)-->
628<?ENDINC p7-auth.iana-status-codes ?>
629</section>
630
631<section title="Header Field Registration" anchor="header.field.registration">
632<t>
633   HTTP header fields are registered within the Message Header Field Registry
634   maintained at
635   <eref target="http://www.iana.org/assignments/message-headers/message-header-index.html"/>.
636</t>
637<t>
638   This document defines the following HTTP header fields, so their
639   associated registry entries shall be updated according to the permanent
640   registrations below (see <xref target="BCP90"/>):
641</t>
642<?BEGININC p7-auth.iana-headers ?>
643<!--AUTOGENERATED FROM extract-header-defs.xslt, do not edit manually-->
644<texttable align="left" suppress-title="true" anchor="iana.header.registration.table">
645   <ttcol>Header Field Name</ttcol>
646   <ttcol>Protocol</ttcol>
647   <ttcol>Status</ttcol>
648   <ttcol>Reference</ttcol>
649
650   <c>Authorization</c>
651   <c>http</c>
652   <c>standard</c>
653   <c>
654      <xref target="header.authorization"/>
655   </c>
656   <c>Proxy-Authenticate</c>
657   <c>http</c>
658   <c>standard</c>
659   <c>
660      <xref target="header.proxy-authenticate"/>
661   </c>
662   <c>Proxy-Authorization</c>
663   <c>http</c>
664   <c>standard</c>
665   <c>
666      <xref target="header.proxy-authorization"/>
667   </c>
668   <c>WWW-Authenticate</c>
669   <c>http</c>
670   <c>standard</c>
671   <c>
672      <xref target="header.www-authenticate"/>
673   </c>
674</texttable>
675<!--(END)-->
676<?ENDINC p7-auth.iana-headers ?>
677<t>
678   The change controller is: "IETF (iesg@ietf.org) - Internet Engineering Task Force".
679</t>
680</section>
681</section>
682
683<section title="Security Considerations" anchor="security.considerations">
684<t>
685   This section is meant to inform developers, information providers, and
686   users of known security concerns specific to HTTP authentication.
687   More general security considerations are addressed in HTTP messaging
688   &messaging; and semantics &semantics;.
689</t>
690<t>
691   Everything about the topic of HTTP authentication is a security
692   consideration, so the list of considerations below is not exhaustive.
693   Furthermore, it is limited to security considerations regarding the
694   authentication framework, in general, rather than discussing all of the
695   potential considerations for specific authentication schemes (which ought
696   to be documented in the specifications that define those schemes).
697   Various organizations maintain topical information and links to current
698   research on Web application security (e.g., <xref target="OWASP"/>),
699   including common pitfalls for implementing and using the authentication
700   schemes found in practice.
701</t>
702
703<section title="Confidentiality of Credentials" anchor="confidentiality.of.credentials">
704<t>
705   The HTTP authentication framework does not define a single mechanism for
706   maintaining the confidentiality of credentials; instead, each
707   authentication scheme defines how the credentials are encoded prior to
708   transmission. While this provides flexibility for the development of future
709   authentication schemes, it is inadequate for the protection of existing
710   schemes that provide no confidentiality on their own, or that do not
711   sufficiently protect against replay attacks. Furthermore, if the server
712   expects credentials that are specific to each individual user, the exchange
713   of those credentials will have the effect of identifying that user even if
714   the content within credentials remains confidential.
715</t>
716<t>
717   HTTP depends on the security properties of the underlying transport or
718   session-level connection to provide confidential transmission of header
719   fields. In other words, if a server limits access to authenticated users
720   using this framework, the server needs to ensure that the connection is
721   properly secured in accordance with the nature of the authentication
722   scheme used. For example, services that depend on individual user
723   authentication often require a connection to be secured with TLS
724   ("Transport Layer Security", <xref target="RFC5246"/>) prior to exchanging
725   any credentials.
726</t>
727</section>
728
729<section title="Authentication Credentials and Idle Clients" anchor="auth.credentials.and.idle.clients">
730<t>
731   Existing HTTP clients and user agents typically retain authentication
732   information indefinitely. HTTP does not provide a mechanism for the
733   origin server to direct clients to discard these cached credentials, since
734   the protocol has no awareness of how credentials are obtained or managed
735   by the user agent. The mechanisms for expiring or revoking credentials can
736   be specified as part of an authentication scheme definition.
737</t>
738<t>
739   Circumstances under which credential caching can interfere with the
740   application's security model include but are not limited to:
741  <list style="symbols">
742     <t>Clients that have been idle for an extended period, following
743        which the server might wish to cause the client to re-prompt the
744        user for credentials.</t>
745
746     <t>Applications that include a session termination indication
747        (such as a "logout" or "commit" button on a page) after which
748        the server side of the application "knows" that there is no
749        further reason for the client to retain the credentials.</t>
750  </list>
751</t>
752<t>
753   User agents that cache credentials are encouraged to provide a readily
754   accessible mechanism for discarding cached credentials under user control.
755</t>
756</section>
757
758<section title="Protection Spaces" anchor="protection.spaces">
759<t>
760  Authentication schemes that solely rely on the "realm" mechanism for
761  establishing a protection space will expose credentials to all resources on
762  an origin server. Clients that have successfully made authenticated requests
763  with a resource can use the same authentication credentials for other
764  resources on the same origin server. This makes it possible for a different
765  resource to harvest authentication credentials for other resources.
766</t>
767<t>
768  This is of particular concern when an origin server hosts resources for multiple
769  parties under the same canonical root URI (<xref target="protection.space"/>).
770  Possible mitigation strategies include restricting direct access to
771  authentication credentials (i.e., not making the content of the
772  <x:ref>Authorization</x:ref> request header field available), and separating protection
773  spaces by using a different host name (or port number) for each party.
774</t>
775</section>
776</section>
777
778<section title="Acknowledgments" anchor="acks">
779<t>
780  This specification takes over the definition of the HTTP Authentication
781  Framework, previously defined in <xref target="RFC2617" x:fmt="none">RFC 2617</xref>.
782  We thank John Franks, Phillip M. Hallam-Baker, Jeffery L. Hostetler, Scott D. Lawrence,
783  Paul J. Leach, Ari Luotonen, and Lawrence C. Stewart for their work
784  on that specification. See <xref target="RFC2617" x:fmt="of" x:sec="6"/>
785  for further acknowledgements. 
786</t>
787<t>
788  See &acks; for the Acknowledgments related to this document revision.
789</t>
790</section>
791</middle>
792
793<back>
794
795<references title="Normative References">
796
797<reference anchor="Part1">
798  <front>
799    <title>Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing</title>
800    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
801      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
802      <address><email>fielding@gbiv.com</email></address>
803    </author>
804    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
805      <organization abbrev="greenbytes">greenbytes GmbH</organization>
806      <address><email>julian.reschke@greenbytes.de</email></address>
807    </author>
808    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
809  </front>
810  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p1-messaging-&ID-VERSION;"/>
811  <x:source href="p1-messaging.xml" basename="p1-messaging"/>
812</reference>
813
814<reference anchor="Part2">
815  <front>
816    <title>Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content</title>
817    <author fullname="Roy T. Fielding" initials="R." role="editor" surname="Fielding">
818      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
819      <address><email>fielding@gbiv.com</email></address>
820    </author>
821    <author fullname="Julian F. Reschke" initials="J. F." role="editor" surname="Reschke">
822      <organization abbrev="greenbytes">greenbytes GmbH</organization>
823      <address><email>julian.reschke@greenbytes.de</email></address>
824    </author>
825    <date month="&ID-MONTH;" year="&ID-YEAR;" />
826  </front>
827  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p2-semantics-&ID-VERSION;" />
828  <x:source basename="p2-semantics" href="p2-semantics.xml">
829    <x:defines>403 (Forbidden)</x:defines>
830    <x:defines>Location</x:defines>
831  </x:source>
832</reference>
833
834<reference anchor="Part6">
835  <front>
836    <title>Hypertext Transfer Protocol (HTTP/1.1): Caching</title>
837    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
838      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
839      <address><email>fielding@gbiv.com</email></address>
840    </author>
841    <author initials="M." surname="Nottingham" fullname="Mark Nottingham" role="editor">
842      <organization>Akamai</organization>
843      <address><email>mnot@mnot.net</email></address>
844    </author>
845    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
846      <organization abbrev="greenbytes">greenbytes GmbH</organization>
847      <address><email>julian.reschke@greenbytes.de</email></address>
848    </author>
849    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
850  </front>
851  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p6-cache-&ID-VERSION;"/>
852  <x:source href="p6-cache.xml" basename="p6-cache"/>
853</reference>
854
855<reference anchor="RFC2119">
856  <front>
857    <title>Key words for use in RFCs to Indicate Requirement Levels</title>
858    <author initials="S." surname="Bradner" fullname="Scott Bradner">
859      <organization>Harvard University</organization>
860      <address><email>sob@harvard.edu</email></address>
861    </author>
862    <date month="March" year="1997"/>
863  </front>
864  <seriesInfo name="BCP" value="14"/>
865  <seriesInfo name="RFC" value="2119"/>
866</reference>
867
868<reference anchor="RFC5234">
869  <front>
870    <title abbrev="ABNF for Syntax Specifications">Augmented BNF for Syntax Specifications: ABNF</title>
871    <author initials="D." surname="Crocker" fullname="Dave Crocker" role="editor">
872      <organization>Brandenburg InternetWorking</organization>
873      <address>
874        <email>dcrocker@bbiw.net</email>
875      </address> 
876    </author>
877    <author initials="P." surname="Overell" fullname="Paul Overell">
878      <organization>THUS plc.</organization>
879      <address>
880        <email>paul.overell@thus.net</email>
881      </address>
882    </author>
883    <date month="January" year="2008"/>
884  </front>
885  <seriesInfo name="STD" value="68"/>
886  <seriesInfo name="RFC" value="5234"/>
887</reference>
888
889</references>
890
891<references title="Informative References">
892
893<reference anchor="RFC2616">
894  <front>
895    <title>Hypertext Transfer Protocol -- HTTP/1.1</title>
896    <author initials="R." surname="Fielding" fullname="R. Fielding">
897      <organization>University of California, Irvine</organization>
898      <address><email>fielding@ics.uci.edu</email></address>
899    </author>
900    <author initials="J." surname="Gettys" fullname="J. Gettys">
901      <organization>W3C</organization>
902      <address><email>jg@w3.org</email></address>
903    </author>
904    <author initials="J." surname="Mogul" fullname="J. Mogul">
905      <organization>Compaq Computer Corporation</organization>
906      <address><email>mogul@wrl.dec.com</email></address>
907    </author>
908    <author initials="H." surname="Frystyk" fullname="H. Frystyk">
909      <organization>MIT Laboratory for Computer Science</organization>
910      <address><email>frystyk@w3.org</email></address>
911    </author>
912    <author initials="L." surname="Masinter" fullname="L. Masinter">
913      <organization>Xerox Corporation</organization>
914      <address><email>masinter@parc.xerox.com</email></address>
915    </author>
916    <author initials="P." surname="Leach" fullname="P. Leach">
917      <organization>Microsoft Corporation</organization>
918      <address><email>paulle@microsoft.com</email></address>
919    </author>
920    <author initials="T." surname="Berners-Lee" fullname="T. Berners-Lee">
921      <organization>W3C</organization>
922      <address><email>timbl@w3.org</email></address>
923    </author>
924    <date month="June" year="1999"/>
925  </front>
926  <seriesInfo name="RFC" value="2616"/>
927</reference>
928
929<reference anchor="RFC2617">
930  <front>
931    <title abbrev="HTTP Authentication">HTTP Authentication: Basic and Digest Access Authentication</title>
932    <author initials="J." surname="Franks" fullname="John Franks">
933      <organization>Northwestern University, Department of Mathematics</organization>
934      <address><email>john@math.nwu.edu</email></address>
935    </author>
936    <author initials="P.M." surname="Hallam-Baker" fullname="Phillip M. Hallam-Baker">
937      <organization>Verisign Inc.</organization>
938      <address><email>pbaker@verisign.com</email></address>
939    </author>
940    <author initials="J.L." surname="Hostetler" fullname="Jeffery L. Hostetler">
941      <organization>AbiSource, Inc.</organization>
942      <address><email>jeff@AbiSource.com</email></address>
943    </author>
944    <author initials="S.D." surname="Lawrence" fullname="Scott D. Lawrence">
945      <organization>Agranat Systems, Inc.</organization>
946      <address><email>lawrence@agranat.com</email></address>
947    </author>
948    <author initials="P.J." surname="Leach" fullname="Paul J. Leach">
949      <organization>Microsoft Corporation</organization>
950      <address><email>paulle@microsoft.com</email></address>
951    </author>
952    <author initials="A." surname="Luotonen" fullname="Ari Luotonen">
953      <organization>Netscape Communications Corporation</organization>
954    </author>
955    <author initials="L." surname="Stewart" fullname="Lawrence C. Stewart">
956      <organization>Open Market, Inc.</organization>
957      <address><email>stewart@OpenMarket.com</email></address>
958    </author>
959    <date month="June" year="1999"/>
960  </front>
961  <seriesInfo name="RFC" value="2617"/>
962</reference>
963
964<reference anchor='BCP90'>
965  <front>
966    <title>Registration Procedures for Message Header Fields</title>
967    <author initials='G.' surname='Klyne' fullname='G. Klyne'>
968      <organization>Nine by Nine</organization>
969      <address><email>GK-IETF@ninebynine.org</email></address>
970    </author>
971    <author initials='M.' surname='Nottingham' fullname='M. Nottingham'>
972      <organization>BEA Systems</organization>
973      <address><email>mnot@pobox.com</email></address>
974    </author>
975    <author initials='J.' surname='Mogul' fullname='J. Mogul'>
976      <organization>HP Labs</organization>
977      <address><email>JeffMogul@acm.org</email></address>
978    </author>
979    <date year='2004' month='September' />
980  </front>
981  <seriesInfo name='BCP' value='90' />
982  <seriesInfo name='RFC' value='3864' />
983</reference>
984
985<reference anchor="RFC3986">
986 <front>
987  <title abbrev='URI Generic Syntax'>Uniform Resource Identifier (URI): Generic Syntax</title>
988  <author initials='T.' surname='Berners-Lee' fullname='Tim Berners-Lee'>
989    <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
990    <address>
991       <email>timbl@w3.org</email>
992       <uri>http://www.w3.org/People/Berners-Lee/</uri>
993    </address>
994  </author>
995  <author initials='R.' surname='Fielding' fullname='Roy T. Fielding'>
996    <organization abbrev="Day Software">Day Software</organization>
997    <address>
998      <email>fielding@gbiv.com</email>
999      <uri>http://roy.gbiv.com/</uri>
1000    </address>
1001  </author>
1002  <author initials='L.' surname='Masinter' fullname='Larry Masinter'>
1003    <organization abbrev="Adobe Systems">Adobe Systems Incorporated</organization>
1004    <address>
1005      <email>LMM@acm.org</email>
1006      <uri>http://larry.masinter.net/</uri>
1007    </address>
1008  </author>
1009  <date month='January' year='2005'></date>
1010 </front>
1011 <seriesInfo name="STD" value="66"/>
1012 <seriesInfo name="RFC" value="3986"/>
1013</reference>
1014
1015<reference anchor="RFC4648">
1016  <front>
1017    <title>The Base16, Base32, and Base64 Data Encodings</title>
1018    <author fullname="S. Josefsson" initials="S." surname="Josefsson"/>
1019    <date year="2006" month="October"/>
1020  </front>
1021  <seriesInfo value="4648" name="RFC"/>
1022</reference>
1023
1024<reference anchor='RFC5226'>
1025  <front>
1026    <title>Guidelines for Writing an IANA Considerations Section in RFCs</title>
1027    <author initials='T.' surname='Narten' fullname='T. Narten'>
1028      <organization>IBM</organization>
1029      <address><email>narten@us.ibm.com</email></address>
1030    </author>
1031    <author initials='H.' surname='Alvestrand' fullname='H. Alvestrand'>
1032      <organization>Google</organization>
1033      <address><email>Harald@Alvestrand.no</email></address>
1034    </author>
1035    <date year='2008' month='May' />
1036  </front>
1037  <seriesInfo name='BCP' value='26' />
1038  <seriesInfo name='RFC' value='5226' />
1039</reference>
1040
1041<reference anchor="OWASP" target="https://www.owasp.org/">
1042        <front>
1043    <title abbrev="OWASP">A Guide to Building Secure Web Applications and Web Services</title>
1044    <author role="editor" initials="A." surname="van der Stock"
1045            fullname="Andrew van der Stock"/>
1046    <date month="July" day="27" year="2005"/>
1047  </front>
1048  <seriesInfo name="The Open Web Application Security Project (OWASP)" value="2.0.1"/>
1049</reference>
1050
1051<reference anchor='RFC5246'>
1052   <front>
1053      <title>The Transport Layer Security (TLS) Protocol Version 1.2</title>
1054      <author initials='T.' surname='Dierks' fullname='T. Dierks'/>
1055      <author initials='E.' surname='Rescorla' fullname='E. Rescorla'>
1056         <organization>RTFM, Inc.</organization>
1057      </author>
1058      <date year='2008' month='August' />
1059   </front>
1060   <seriesInfo name='RFC' value='5246' />
1061</reference>
1062
1063</references>
1064
1065<section title="Changes from RFCs 2616 and 2617" anchor="changes.from.rfc.2616">
1066<t>
1067  The framework for HTTP Authentication is now defined by this document,
1068  rather than RFC 2617.
1069</t>
1070<t>
1071  The "realm" parameter is no longer always required on challenges;
1072  consequently, the ABNF allows challenges without any auth parameters.
1073  (<xref target="access.authentication.framework"/>)
1074</t>
1075<t>
1076  The "token68" alternative to auth-param lists has been added for consistency
1077  with legacy authentication schemes such as "Basic".
1078  (<xref target="access.authentication.framework"/>)
1079</t>
1080<t>
1081  This specification introduces the Authentication Scheme Registry, along with
1082  considerations for new authentication schemes.
1083  (<xref target="authentication.scheme.registry"/>)
1084</t>
1085</section>
1086 
1087<section title="Imported ABNF" anchor="imported.abnf">
1088  <x:anchor-alias value="ALPHA"/>
1089  <x:anchor-alias value="CR"/>
1090  <x:anchor-alias value="DIGIT"/>
1091  <x:anchor-alias value="LF"/>
1092  <x:anchor-alias value="OCTET"/>
1093  <x:anchor-alias value="VCHAR"/>
1094  <x:anchor-alias value="SP"/>
1095  <x:anchor-alias value="quoted-string"/>
1096  <x:anchor-alias value="token"/>
1097  <x:anchor-alias value="BWS"/>
1098  <x:anchor-alias value="OWS"/>
1099<t>
1100  The following core rules are included by
1101  reference, as defined in <xref target="RFC5234" x:fmt="of" x:sec="B.1"/>:
1102  ALPHA (letters), CR (carriage return), CRLF (CR LF), CTL (controls),
1103  DIGIT (decimal 0-9), DQUOTE (double quote),
1104  HEXDIG (hexadecimal 0-9/A-F/a-f), LF (line feed),
1105  OCTET (any 8-bit sequence of data), SP (space), and
1106  VCHAR (any visible US-ASCII character).
1107</t>
1108<t>
1109   The rules below are defined in <xref target="Part1"/>:
1110</t>
1111<figure><artwork type="abnf2616">
1112  <x:ref>BWS</x:ref>           = &lt;BWS, defined in &whitespace;&gt;
1113  <x:ref>OWS</x:ref>           = &lt;OWS, defined in &whitespace;&gt;
1114  <x:ref>quoted-string</x:ref> = &lt;quoted-string, defined in &field-components;&gt;
1115  <x:ref>token</x:ref>         = &lt;token, defined in &field-components;&gt;
1116</artwork></figure>
1117</section>
1118
1119<?BEGININC p7-auth.abnf-appendix ?>
1120<section xmlns:x="http://purl.org/net/xml2rfc/ext" title="Collected ABNF" anchor="collected.abnf">
1121<t>
1122  In the collected ABNF below, list rules are expanded as per <xref target="Part1" x:rel="#notation"/>.
1123</t><figure>
1124<artwork type="abnf" name="p7-auth.parsed-abnf">
1125<x:ref>Authorization</x:ref> = credentials
1126
1127<x:ref>BWS</x:ref> = &lt;BWS, defined in [Part1], Section 3.2.3&gt;
1128
1129<x:ref>OWS</x:ref> = &lt;OWS, defined in [Part1], Section 3.2.3&gt;
1130
1131<x:ref>Proxy-Authenticate</x:ref> = *( "," OWS ) challenge *( OWS "," [ OWS
1132 challenge ] )
1133<x:ref>Proxy-Authorization</x:ref> = credentials
1134
1135<x:ref>WWW-Authenticate</x:ref> = *( "," OWS ) challenge *( OWS "," [ OWS challenge
1136 ] )
1137
1138<x:ref>auth-param</x:ref> = token BWS "=" BWS ( token / quoted-string )
1139<x:ref>auth-scheme</x:ref> = token
1140
1141<x:ref>challenge</x:ref> = auth-scheme [ 1*SP ( token68 / [ ( "," / auth-param ) *(
1142 OWS "," [ OWS auth-param ] ) ] ) ]
1143<x:ref>credentials</x:ref> = auth-scheme [ 1*SP ( token68 / [ ( "," / auth-param )
1144 *( OWS "," [ OWS auth-param ] ) ] ) ]
1145
1146<x:ref>quoted-string</x:ref> = &lt;quoted-string, defined in [Part1], Section 3.2.6&gt;
1147
1148<x:ref>token</x:ref> = &lt;token, defined in [Part1], Section 3.2.6&gt;
1149<x:ref>token68</x:ref> = 1*( ALPHA / DIGIT / "-" / "." / "_" / "~" / "+" / "/" )
1150 *"="
1151</artwork>
1152</figure>
1153</section>
1154<?ENDINC p7-auth.abnf-appendix ?>
1155
1156<section title="Change Log (to be removed by RFC Editor before publication)"  anchor="change.log">
1157<t>
1158  Changes up to the IETF Last Call draft are summarized
1159  in <eref target="http://trac.tools.ietf.org/html/draft-ietf-httpbis-p7-auth-24#appendix-D"/>.
1160</t>
1161
1162<section title="Since draft-ietf-httpbis-p7-auth-24" anchor="changes.since.24">
1163<t>
1164  Closed issues:
1165  <list style="symbols">
1166    <t>
1167      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/510"/>:
1168      "SECDIR review of draft-ietf-httpbis-p7-auth-24"
1169    </t>
1170    <t>
1171      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/513"/>:
1172      "APPSDIR review of draft-ietf-httpbis-p7-auth-24"
1173    </t>
1174    <t>
1175      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/516"/>:
1176      "note about WWW-A parsing potentially misleading"
1177    </t>
1178  </list>
1179</t>
1180</section>
1181
1182<section title="Since draft-ietf-httpbis-p7-auth-25" anchor="changes.since.25">
1183<t>
1184  Closed issues:
1185  <list style="symbols">
1186    <t>
1187      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/522"/>:
1188      "Gen-art review of draft-ietf-httpbis-p7-auth-25"
1189    </t>
1190    <t>
1191      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/536"/>:
1192      "IESG ballot on draft-ietf-httpbis-p7-auth-25"
1193    </t>
1194    <t>
1195      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/538"/>:
1196      "add 'stateless' to Abstract"
1197    </t>
1198    <t>
1199      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/539"/>:
1200      "mention TLS vs plain text passwords or dict attacks?"
1201    </t>
1202    <t>
1203      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/542"/>:
1204      "improve introduction of list rule"
1205    </t>
1206    <t>
1207      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/549"/>:
1208      "augment security considerations with pointers to current research"
1209    </t>
1210  </list>
1211</t>
1212</section>
1213</section>
1214
1215</back>
1216</rfc>
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