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4HTTPbis Working Group                                   R. Fielding, Ed.
5Internet-Draft                                                     Adobe
6Obsoletes: 2616 (if approved)                            J. Reschke, Ed.
7Updates: 2617 (if approved)                                   greenbytes
8Intended status: Standards Track                      September 25, 2013
9Expires: March 29, 2014
10
11
12         Hypertext Transfer Protocol (HTTP/1.1): Authentication
13                     draft-ietf-httpbis-p7-auth-24
14
15Abstract
16
17   The Hypertext Transfer Protocol (HTTP) is an application-level
18   protocol for distributed, collaborative, hypermedia information
19   systems.  This document defines the HTTP Authentication framework.
20
21Editorial Note (To be removed by RFC Editor)
22
23   Discussion of this draft takes place on the HTTPBIS working group
24   mailing list (ietf-http-wg@w3.org), which is archived at
25   <http://lists.w3.org/Archives/Public/ietf-http-wg/>.
26
27   The current issues list is at
28   <http://tools.ietf.org/wg/httpbis/trac/report/3> and related
29   documents (including fancy diffs) can be found at
30   <http://tools.ietf.org/wg/httpbis/>.
31
32   The changes in this draft are summarized in Appendix D.5.
33
34Status of This Memo
35
36   This Internet-Draft is submitted in full conformance with the
37   provisions of BCP 78 and BCP 79.
38
39   Internet-Drafts are working documents of the Internet Engineering
40   Task Force (IETF).  Note that other groups may also distribute
41   working documents as Internet-Drafts.  The list of current Internet-
42   Drafts is at http://datatracker.ietf.org/drafts/current/.
43
44   Internet-Drafts are draft documents valid for a maximum of six months
45   and may be updated, replaced, or obsoleted by other documents at any
46   time.  It is inappropriate to use Internet-Drafts as reference
47   material or to cite them other than as "work in progress."
48
49   This Internet-Draft will expire on March 29, 2014.
50
51Copyright Notice
52
53
54
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57Internet-Draft           HTTP/1.1 Authentication          September 2013
58
59
60   Copyright (c) 2013 IETF Trust and the persons identified as the
61   document authors.  All rights reserved.
62
63   This document is subject to BCP 78 and the IETF Trust's Legal
64   Provisions Relating to IETF Documents
65   (http://trustee.ietf.org/license-info) in effect on the date of
66   publication of this document.  Please review these documents
67   carefully, as they describe your rights and restrictions with respect
68   to this document.  Code Components extracted from this document must
69   include Simplified BSD License text as described in Section 4.e of
70   the Trust Legal Provisions and are provided without warranty as
71   described in the Simplified BSD License.
72
73   This document may contain material from IETF Documents or IETF
74   Contributions published or made publicly available before November
75   10, 2008.  The person(s) controlling the copyright in some of this
76   material may not have granted the IETF Trust the right to allow
77   modifications of such material outside the IETF Standards Process.
78   Without obtaining an adequate license from the person(s) controlling
79   the copyright in such materials, this document may not be modified
80   outside the IETF Standards Process, and derivative works of it may
81   not be created outside the IETF Standards Process, except to format
82   it for publication as an RFC or to translate it into languages other
83   than English.
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113Internet-Draft           HTTP/1.1 Authentication          September 2013
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115
116Table of Contents
117
118   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
119     1.1.  Conformance and Error Handling . . . . . . . . . . . . . .  4
120     1.2.  Syntax Notation  . . . . . . . . . . . . . . . . . . . . .  4
121   2.  Access Authentication Framework  . . . . . . . . . . . . . . .  4
122     2.1.  Challenge and Response . . . . . . . . . . . . . . . . . .  4
123     2.2.  Protection Space (Realm) . . . . . . . . . . . . . . . . .  6
124   3.  Status Code Definitions  . . . . . . . . . . . . . . . . . . .  7
125     3.1.  401 Unauthorized . . . . . . . . . . . . . . . . . . . . .  7
126     3.2.  407 Proxy Authentication Required  . . . . . . . . . . . .  7
127   4.  Header Field Definitions . . . . . . . . . . . . . . . . . . .  7
128     4.1.  Authorization  . . . . . . . . . . . . . . . . . . . . . .  8
129     4.2.  Proxy-Authenticate . . . . . . . . . . . . . . . . . . . .  8
130     4.3.  Proxy-Authorization  . . . . . . . . . . . . . . . . . . .  8
131     4.4.  WWW-Authenticate . . . . . . . . . . . . . . . . . . . . .  9
132   5.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 10
133     5.1.  Authentication Scheme Registry . . . . . . . . . . . . . . 10
134       5.1.1.  Procedure  . . . . . . . . . . . . . . . . . . . . . . 10
135       5.1.2.  Considerations for New Authentication Schemes  . . . . 10
136     5.2.  Status Code Registration . . . . . . . . . . . . . . . . . 11
137     5.3.  Header Field Registration  . . . . . . . . . . . . . . . . 12
138   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 12
139     6.1.  Authentication Credentials and Idle Clients  . . . . . . . 12
140     6.2.  Protection Spaces  . . . . . . . . . . . . . . . . . . . . 13
141   7.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 13
142   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 14
143     8.1.  Normative References . . . . . . . . . . . . . . . . . . . 14
144     8.2.  Informative References . . . . . . . . . . . . . . . . . . 14
145   Appendix A.  Changes from RFCs 2616 and 2617 . . . . . . . . . . . 15
146   Appendix B.  Imported ABNF . . . . . . . . . . . . . . . . . . . . 15
147   Appendix C.  Collected ABNF  . . . . . . . . . . . . . . . . . . . 15
148   Appendix D.  Change Log (to be removed by RFC Editor before
149                publication)  . . . . . . . . . . . . . . . . . . . . 16
150     D.1.  Since draft-ietf-httpbis-p7-auth-19  . . . . . . . . . . . 16
151     D.2.  Since draft-ietf-httpbis-p7-auth-20  . . . . . . . . . . . 17
152     D.3.  Since draft-ietf-httpbis-p7-auth-21  . . . . . . . . . . . 17
153     D.4.  Since draft-ietf-httpbis-p7-auth-22  . . . . . . . . . . . 17
154     D.5.  Since draft-ietf-httpbis-p7-auth-23  . . . . . . . . . . . 17
155   Index  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
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171
1721.  Introduction
173
174   This document defines HTTP/1.1 access control and authentication.  It
175   includes the relevant parts of RFC 2616 with only minor changes
176   ([RFC2616]), plus the general framework for HTTP authentication, as
177   previously defined in "HTTP Authentication: Basic and Digest Access
178   Authentication" ([RFC2617]).
179
180   HTTP provides several OPTIONAL challenge-response authentication
181   schemes that can be used by a server to challenge a client request
182   and by a client to provide authentication information.  The "basic"
183   and "digest" authentication schemes continue to be specified in RFC
184   2617.
185
1861.1.  Conformance and Error Handling
187
188   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
189   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
190   document are to be interpreted as described in [RFC2119].
191
192   Conformance criteria and considerations regarding error handling are
193   defined in Section 2.5 of [Part1].
194
1951.2.  Syntax Notation
196
197   This specification uses the Augmented Backus-Naur Form (ABNF)
198   notation of [RFC5234] with the list rule extension defined in Section
199   7 of [Part1].  Appendix B describes rules imported from other
200   documents.  Appendix C shows the collected ABNF with the list rule
201   expanded.
202
2032.  Access Authentication Framework
204
2052.1.  Challenge and Response
206
207   HTTP provides a simple challenge-response authentication framework
208   that can be used by a server to challenge a client request and by a
209   client to provide authentication information.  It uses a case-
210   insensitive token as a means to identify the authentication scheme,
211   followed by additional information necessary for achieving
212   authentication via that scheme.  The latter can either be a comma-
213   separated list of parameters or a single sequence of characters
214   capable of holding base64-encoded information.
215
216   Parameters are name-value pairs where the name is matched case-
217   insensitively, and each parameter name MUST only occur once per
218   challenge.
219
220
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227
228     auth-scheme    = token
229
230     auth-param     = token BWS "=" BWS ( token / quoted-string )
231
232     token68        = 1*( ALPHA / DIGIT /
233                          "-" / "." / "_" / "~" / "+" / "/" ) *"="
234
235   The "token68" syntax allows the 66 unreserved URI characters
236   ([RFC3986]), plus a few others, so that it can hold a base64,
237   base64url (URL and filename safe alphabet), base32, or base16 (hex)
238   encoding, with or without padding, but excluding whitespace
239   ([RFC4648]).
240
241   The 401 (Unauthorized) response message is used by an origin server
242   to challenge the authorization of a user agent.  This response MUST
243   include a WWW-Authenticate header field containing at least one
244   challenge applicable to the requested resource.
245
246   The 407 (Proxy Authentication Required) response message is used by a
247   proxy to challenge the authorization of a client and MUST include a
248   Proxy-Authenticate header field containing at least one challenge
249   applicable to the proxy for the requested resource.
250
251     challenge   = auth-scheme [ 1*SP ( token68 / #auth-param ) ]
252
253      Note: User agents will need to take special care in parsing the
254      WWW-Authenticate and Proxy-Authenticate header field values
255      because they can contain more than one challenge, or if more than
256      one of each is provided, since the contents of a challenge can
257      itself contain a comma-separated list of authentication
258      parameters.
259
260      Note: Many clients fail to parse challenges containing unknown
261      schemes.  A workaround for this problem is to list well-supported
262      schemes (such as "basic") first.
263
264   A user agent that wishes to authenticate itself with an origin server
265   -- usually, but not necessarily, after receiving a 401 (Unauthorized)
266   -- can do so by including an Authorization header field with the
267   request.
268
269   A client that wishes to authenticate itself with a proxy -- usually,
270   but not necessarily, after receiving a 407 (Proxy Authentication
271   Required) -- can do so by including a Proxy-Authorization header
272   field with the request.
273
274   Both the Authorization field value and the Proxy-Authorization field
275   value contain the client's credentials for the realm of the resource
276
277
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283
284   being requested, based upon a challenge received in a response
285   (possibly at some point in the past).  When creating their values,
286   the user agent ought to do so by selecting the challenge with what it
287   considers to be the most secure auth-scheme that it understands,
288   obtaining credentials from the user as appropriate.
289
290     credentials = auth-scheme [ 1*SP ( token68 / #auth-param ) ]
291
292   Upon a request for a protected resource that omits credentials,
293   contains invalid credentials (e.g., a bad password) or partial
294   credentials (e.g., when the authentication scheme requires more than
295   one round trip), an origin server SHOULD send a 401 (Unauthorized)
296   response that contains a WWW-Authenticate header field with at least
297   one (possibly new) challenge applicable to the requested resource.
298
299   Likewise, upon a request that requires authentication by proxies that
300   omit credentials or contain invalid or partial credentials, a proxy
301   SHOULD send a 407 (Proxy Authentication Required) response that
302   contains a Proxy-Authenticate header field with a (possibly new)
303   challenge applicable to the proxy.
304
305   A server receiving credentials that are valid, but not adequate to
306   gain access, ought to respond with the 403 (Forbidden) status code
307   (Section 6.5.3 of [Part2]).
308
309   The HTTP protocol does not restrict applications to this simple
310   challenge-response framework for access authentication.  Additional
311   mechanisms MAY be used, such as encryption at the transport level or
312   via message encapsulation, and with additional header fields
313   specifying authentication information.  However, such additional
314   mechanisms are not defined by this specification.
315
316   A proxy MUST forward the WWW-Authenticate and Authorization header
317   fields unmodified and follow the rules found in Section 4.1.
318
3192.2.  Protection Space (Realm)
320
321   The authentication parameter realm is reserved for use by
322   authentication schemes that wish to indicate the scope of protection.
323
324   A protection space is defined by the canonical root URI (the scheme
325   and authority components of the effective request URI; see Section
326   5.5 of [Part1]) of the server being accessed, in combination with the
327   realm value if present.  These realms allow the protected resources
328   on a server to be partitioned into a set of protection spaces, each
329   with its own authentication scheme and/or authorization database.
330   The realm value is a string, generally assigned by the origin server,
331   which can have additional semantics specific to the authentication
332
333
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339
340   scheme.  Note that a response can have multiple challenges with the
341   same auth-scheme but different realms.
342
343   The protection space determines the domain over which credentials can
344   be automatically applied.  If a prior request has been authorized,
345   the user agent MAY reuse the same credentials for all other requests
346   within that protection space for a period of time determined by the
347   authentication scheme, parameters, and/or user preference.  Unless
348   specifically allowed by the authentication scheme, a single
349   protection space cannot extend outside the scope of its server.
350
351   For historical reasons, a sender MUST only generate the quoted-string
352   syntax.  Recipients might have to support both token and quoted-
353   string syntax for maximum interoperability with existing clients that
354   have been accepting both notations for a long time.
355
3563.  Status Code Definitions
357
3583.1.  401 Unauthorized
359
360   The 401 (Unauthorized) status code indicates that the request has not
361   been applied because it lacks valid authentication credentials for
362   the target resource.  The origin server MUST send a WWW-Authenticate
363   header field (Section 4.4) containing at least one challenge
364   applicable to the target resource.  If the request included
365   authentication credentials, then the 401 response indicates that
366   authorization has been refused for those credentials.  The user agent
367   MAY repeat the request with a new or replaced Authorization header
368   field (Section 4.1).  If the 401 response contains the same challenge
369   as the prior response, and the user agent has already attempted
370   authentication at least once, then the user agent SHOULD present the
371   enclosed representation to the user, since it usually contains
372   relevant diagnostic information.
373
3743.2.  407 Proxy Authentication Required
375
376   The 407 (Proxy Authentication Required) status code is similar to 401
377   (Unauthorized), but indicates that the client needs to authenticate
378   itself in order to use a proxy.  The proxy MUST send a Proxy-
379   Authenticate header field (Section 4.2) containing a challenge
380   applicable to that proxy for the target resource.  The client MAY
381   repeat the request with a new or replaced Proxy-Authorization header
382   field (Section 4.3).
383
3844.  Header Field Definitions
385
386   This section defines the syntax and semantics of HTTP/1.1 header
387   fields related to authentication.
388
389
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395
3964.1.  Authorization
397
398   The "Authorization" header field allows a user agent to authenticate
399   itself with an origin server -- usually, but not necessarily, after
400   receiving a 401 (Unauthorized) response.  Its value consists of
401   credentials containing the authentication information of the user
402   agent for the realm of the resource being requested.
403
404     Authorization = credentials
405
406   If a request is authenticated and a realm specified, the same
407   credentials are presumed to be valid for all other requests within
408   this realm (assuming that the authentication scheme itself does not
409   require otherwise, such as credentials that vary according to a
410   challenge value or using synchronized clocks).
411
412   See Section 3.2 of [Part6] for details of and requirements pertaining
413   to handling of the Authorization field by HTTP caches.
414
4154.2.  Proxy-Authenticate
416
417   The "Proxy-Authenticate" header field consists of at least one
418   challenge that indicates the authentication scheme(s) and parameters
419   applicable to the proxy for this effective request URI (Section 5.5
420   of [Part1]).  It MUST be included as part of a 407 (Proxy
421   Authentication Required) response.
422
423     Proxy-Authenticate = 1#challenge
424
425   Unlike WWW-Authenticate, the Proxy-Authenticate header field applies
426   only to the next outbound client on the response chain that chose to
427   direct its request to the responding proxy.  If that recipient is
428   also a proxy, it will generally consume the Proxy-Authenticate header
429   field (and generate an appropriate Proxy-Authorization in a
430   subsequent request) rather than forward the header field to its own
431   outbound clients.  However, if a recipient proxy needs to obtain its
432   own credentials by requesting them from a further outbound client, it
433   will generate its own 407 response, which might have the appearance
434   of forwarding the Proxy-Authenticate header field if both proxies use
435   the same challenge set.
436
437   Note that the parsing considerations for WWW-Authenticate apply to
438   this header field as well; see Section 4.4 for details.
439
4404.3.  Proxy-Authorization
441
442   The "Proxy-Authorization" header field allows the client to identify
443   itself (or its user) to a proxy that requires authentication.  Its
444
445
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451
452   value consists of credentials containing the authentication
453   information of the client for the proxy and/or realm of the resource
454   being requested.
455
456     Proxy-Authorization = credentials
457
458   Unlike Authorization, the Proxy-Authorization header field applies
459   only to the next inbound proxy that demanded authentication using the
460   Proxy-Authenticate field.  When multiple proxies are used in a chain,
461   the Proxy-Authorization header field is consumed by the first inbound
462   proxy that was expecting to receive credentials.  A proxy MAY relay
463   the credentials from the client request to the next proxy if that is
464   the mechanism by which the proxies cooperatively authenticate a given
465   request.
466
4674.4.  WWW-Authenticate
468
469   The "WWW-Authenticate" header field consists of at least one
470   challenge that indicates the authentication scheme(s) and parameters
471   applicable to the effective request URI (Section 5.5 of [Part1]).
472
473   It MUST be included in 401 (Unauthorized) response messages and MAY
474   be included in other response messages to indicate that supplying
475   credentials (or different credentials) might affect the response.
476
477     WWW-Authenticate = 1#challenge
478
479   User agents are advised to take special care in parsing the WWW-
480   Authenticate field value as it might contain more than one challenge,
481   or if more than one WWW-Authenticate header field is provided, the
482   contents of a challenge itself can contain a comma-separated list of
483   authentication parameters.
484
485   For instance:
486
487     WWW-Authenticate: Newauth realm="apps", type=1,
488                       title="Login to \"apps\"", Basic realm="simple"
489
490   This header field contains two challenges; one for the "Newauth"
491   scheme with a realm value of "apps", and two additional parameters
492   "type" and "title", and another one for the "Basic" scheme with a
493   realm value of "simple".
494
495      Note: The challenge grammar production uses the list syntax as
496      well.  Therefore, a sequence of comma, whitespace, and comma can
497      be considered both as applying to the preceding challenge, or to
498      be an empty entry in the list of challenges.  In practice, this
499      ambiguity does not affect the semantics of the header field value
500
501
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507
508      and thus is harmless.
509
5105.  IANA Considerations
511
5125.1.  Authentication Scheme Registry
513
514   The HTTP Authentication Scheme Registry defines the name space for
515   the authentication schemes in challenges and credentials.  It will be
516   created and maintained at
517   <http://www.iana.org/assignments/http-authschemes>.
518
5195.1.1.  Procedure
520
521   Registrations MUST include the following fields:
522
523   o  Authentication Scheme Name
524
525   o  Pointer to specification text
526
527   o  Notes (optional)
528
529   Values to be added to this name space require IETF Review (see
530   [RFC5226], Section 4.1).
531
5325.1.2.  Considerations for New Authentication Schemes
533
534   There are certain aspects of the HTTP Authentication Framework that
535   put constraints on how new authentication schemes can work:
536
537   o  HTTP authentication is presumed to be stateless: all of the
538      information necessary to authenticate a request MUST be provided
539      in the request, rather than be dependent on the server remembering
540      prior requests.  Authentication based on, or bound to, the
541      underlying connection is outside the scope of this specification
542      and inherently flawed unless steps are taken to ensure that the
543      connection cannot be used by any party other than the
544      authenticated user (see Section 2.3 of [Part1]).
545
546   o  The authentication parameter "realm" is reserved for defining
547      Protection Spaces as defined in Section 2.2.  New schemes MUST NOT
548      use it in a way incompatible with that definition.
549
550   o  The "token68" notation was introduced for compatibility with
551      existing authentication schemes and can only be used once per
552      challenge or credential.  New schemes thus ought to use the "auth-
553      param" syntax instead, because otherwise future extensions will be
554      impossible.
555
556
557
558
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562
563
564   o  The parsing of challenges and credentials is defined by this
565      specification, and cannot be modified by new authentication
566      schemes.  When the auth-param syntax is used, all parameters ought
567      to support both token and quoted-string syntax, and syntactical
568      constraints ought to be defined on the field value after parsing
569      (i.e., quoted-string processing).  This is necessary so that
570      recipients can use a generic parser that applies to all
571      authentication schemes.
572
573      Note: The fact that the value syntax for the "realm" parameter is
574      restricted to quoted-string was a bad design choice not to be
575      repeated for new parameters.
576
577   o  Definitions of new schemes ought to define the treatment of
578      unknown extension parameters.  In general, a "must-ignore" rule is
579      preferable over "must-understand", because otherwise it will be
580      hard to introduce new parameters in the presence of legacy
581      recipients.  Furthermore, it's good to describe the policy for
582      defining new parameters (such as "update the specification", or
583      "use this registry").
584
585   o  Authentication schemes need to document whether they are usable in
586      origin-server authentication (i.e., using WWW-Authenticate),
587      and/or proxy authentication (i.e., using Proxy-Authenticate).
588
589   o  The credentials carried in an Authorization header field are
590      specific to the User Agent, and therefore have the same effect on
591      HTTP caches as the "private" Cache-Control response directive
592      (Section 5.2.2.6 of [Part6]), within the scope of the request they
593      appear in.
594
595      Therefore, new authentication schemes that choose not to carry
596      credentials in the Authorization header field (e.g., using a newly
597      defined header field) will need to explicitly disallow caching, by
598      mandating the use of either Cache-Control request directives
599      (e.g., "no-store", Section 5.2.1.5 of [Part6]) or response
600      directives (e.g., "private").
601
6025.2.  Status Code Registration
603
604   The HTTP Status Code Registry located at
605   <http://www.iana.org/assignments/http-status-codes> shall be updated
606   with the registrations below:
607
608
609
610
611
612
613
614
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618
619
620   +-------+-------------------------------+-------------+
621   | Value | Description                   | Reference   |
622   +-------+-------------------------------+-------------+
623   | 401   | Unauthorized                  | Section 3.1 |
624   | 407   | Proxy Authentication Required | Section 3.2 |
625   +-------+-------------------------------+-------------+
626
6275.3.  Header Field Registration
628
629   HTTP header fields are registered within the Message Header Field
630   Registry maintained at <http://www.iana.org/assignments/
631   message-headers/message-header-index.html>.
632
633   This document defines the following HTTP header fields, so their
634   associated registry entries shall be updated according to the
635   permanent registrations below (see [BCP90]):
636
637   +---------------------+----------+----------+-------------+
638   | Header Field Name   | Protocol | Status   | Reference   |
639   +---------------------+----------+----------+-------------+
640   | Authorization       | http     | standard | Section 4.1 |
641   | Proxy-Authenticate  | http     | standard | Section 4.2 |
642   | Proxy-Authorization | http     | standard | Section 4.3 |
643   | WWW-Authenticate    | http     | standard | Section 4.4 |
644   +---------------------+----------+----------+-------------+
645
646   The change controller is: "IETF (iesg@ietf.org) - Internet
647   Engineering Task Force".
648
6496.  Security Considerations
650
651   This section is meant to inform developers, information providers,
652   and users of known security concerns specific to HTTP/1.1
653   authentication.  More general security considerations are addressed
654   in HTTP messaging [Part1] and semantics [Part2].
655
6566.1.  Authentication Credentials and Idle Clients
657
658   Existing HTTP clients and user agents typically retain authentication
659   information indefinitely.  HTTP does not provide a mechanism for the
660   origin server to direct clients to discard these cached credentials,
661   since the protocol has no awareness of how credentials are obtained
662   or managed by the user agent.  The mechanisms for expiring or
663   revoking credentials can be specified as part of an authentication
664   scheme definition.
665
666   Circumstances under which credential caching can interfere with the
667   application's security model include but are not limited to:
668
669
670
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674
675
676   o  Clients that have been idle for an extended period, following
677      which the server might wish to cause the client to re-prompt the
678      user for credentials.
679
680   o  Applications that include a session termination indication (such
681      as a "logout" or "commit" button on a page) after which the server
682      side of the application "knows" that there is no further reason
683      for the client to retain the credentials.
684
685   User agents that cache credentials are encouraged to provide a
686   readily accessible mechanism for discarding cached credentials under
687   user control.
688
6896.2.  Protection Spaces
690
691   Authentication schemes that solely rely on the "realm" mechanism for
692   establishing a protection space will expose credentials to all
693   resources on an origin server.  Clients that have successfully made
694   authenticated requests with a resource can use the same
695   authentication credentials for other resources on the same origin
696   server.  This makes it possible for a different resource to harvest
697   authentication credentials for other resources.
698
699   This is of particular concern when an origin server hosts resources
700   for multiple parties under the same canonical root URI (Section 2.2).
701   Possible mitigation strategies include restricting direct access to
702   authentication credentials (i.e., not making the content of the
703   Authorization request header field available), and separating
704   protection spaces by using a different host name (or port number) for
705   each party.
706
7077.  Acknowledgments
708
709   This specification takes over the definition of the HTTP
710   Authentication Framework, previously defined in RFC 2617.  We thank
711   John Franks, Phillip M. Hallam-Baker, Jeffery L. Hostetler, Scott D.
712   Lawrence, Paul J. Leach, Ari Luotonen, and Lawrence C. Stewart for
713   their work on that specification.  See Section 6 of [RFC2617] for
714   further acknowledgements.
715
716   See Section 10 of [Part1] for the Acknowledgments related to this
717   document revision.
718
7198.  References
720
721
722
723
724
725
726
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730
731
7328.1.  Normative References
733
734   [Part1]    Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
735              Protocol (HTTP/1.1): Message Syntax and Routing",
736              draft-ietf-httpbis-p1-messaging-24 (work in progress),
737              September 2013.
738
739   [Part2]    Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
740              Protocol (HTTP/1.1): Semantics and Content",
741              draft-ietf-httpbis-p2-semantics-24 (work in progress),
742              September 2013.
743
744   [Part6]    Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
745              Ed., "Hypertext Transfer Protocol (HTTP/1.1): Caching",
746              draft-ietf-httpbis-p6-cache-24 (work in progress),
747              September 2013.
748
749   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
750              Requirement Levels", BCP 14, RFC 2119, March 1997.
751
752   [RFC5234]  Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
753              Specifications: ABNF", STD 68, RFC 5234, January 2008.
754
7558.2.  Informative References
756
757   [BCP90]    Klyne, G., Nottingham, M., and J. Mogul, "Registration
758              Procedures for Message Header Fields", BCP 90, RFC 3864,
759              September 2004.
760
761   [RFC2616]  Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
762              Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
763              Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
764
765   [RFC2617]  Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S.,
766              Leach, P., Luotonen, A., and L. Stewart, "HTTP
767              Authentication: Basic and Digest Access Authentication",
768              RFC 2617, June 1999.
769
770   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
771              Resource Identifier (URI): Generic Syntax", STD 66,
772              RFC 3986, January 2005.
773
774   [RFC4648]  Josefsson, S., "The Base16, Base32, and Base64 Data
775              Encodings", RFC 4648, October 2006.
776
777   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
778              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
779              May 2008.
780
781
782
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786
787
788Appendix A.  Changes from RFCs 2616 and 2617
789
790   The framework for HTTP Authentication is now defined by this
791   document, rather than RFC 2617.
792
793   The "realm" parameter is no longer always required on challenges;
794   consequently, the ABNF allows challenges without any auth parameters.
795   (Section 2)
796
797   The "token68" alternative to auth-param lists has been added for
798   consistency with legacy authentication schemes such as "Basic".
799   (Section 2)
800
801   This specification introduces the Authentication Scheme Registry,
802   along with considerations for new authentication schemes.
803   (Section 5.1)
804
805Appendix B.  Imported ABNF
806
807   The following core rules are included by reference, as defined in
808   Appendix B.1 of [RFC5234]: ALPHA (letters), CR (carriage return),
809   CRLF (CR LF), CTL (controls), DIGIT (decimal 0-9), DQUOTE (double
810   quote), HEXDIG (hexadecimal 0-9/A-F/a-f), LF (line feed), OCTET (any
811   8-bit sequence of data), SP (space), and VCHAR (any visible US-ASCII
812   character).
813
814   The rules below are defined in [Part1]:
815
816     BWS           = <BWS, defined in [Part1], Section 3.2.3>
817     OWS           = <OWS, defined in [Part1], Section 3.2.3>
818     quoted-string = <quoted-string, defined in [Part1], Section 3.2.6>
819     token         = <token, defined in [Part1], Section 3.2.6>
820
821Appendix C.  Collected ABNF
822
823   In the collected ABNF below, list rules are expanded as per Section
824   1.2 of [Part1].
825
826
827
828
829
830
831
832
833
834
835
836
837
838
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842
843
844   Authorization = credentials
845
846   BWS = <BWS, defined in [Part1], Section 3.2.3>
847
848   OWS = <OWS, defined in [Part1], Section 3.2.3>
849
850   Proxy-Authenticate = *( "," OWS ) challenge *( OWS "," [ OWS
851    challenge ] )
852   Proxy-Authorization = credentials
853
854   WWW-Authenticate = *( "," OWS ) challenge *( OWS "," [ OWS challenge
855    ] )
856
857   auth-param = token BWS "=" BWS ( token / quoted-string )
858   auth-scheme = token
859
860   challenge = auth-scheme [ 1*SP ( token68 / [ ( "," / auth-param ) *(
861    OWS "," [ OWS auth-param ] ) ] ) ]
862   credentials = auth-scheme [ 1*SP ( token68 / [ ( "," / auth-param )
863    *( OWS "," [ OWS auth-param ] ) ] ) ]
864
865   quoted-string = <quoted-string, defined in [Part1], Section 3.2.6>
866
867   token = <token, defined in [Part1], Section 3.2.6>
868   token68 = 1*( ALPHA / DIGIT / "-" / "." / "_" / "~" / "+" / "/" )
869    *"="
870
871Appendix D.  Change Log (to be removed by RFC Editor before publication)
872
873   Changes up to the first Working Group Last Call draft are summarized
874   in <http://trac.tools.ietf.org/html/
875   draft-ietf-httpbis-p7-auth-19#appendix-C>.
876
877D.1.  Since draft-ietf-httpbis-p7-auth-19
878
879   Closed issues:
880
881   o  <http://tools.ietf.org/wg/httpbis/trac/ticket/348>: "Realms and
882      scope"
883
884   o  <http://tools.ietf.org/wg/httpbis/trac/ticket/349>: "Strength"
885
886   o  <http://tools.ietf.org/wg/httpbis/trac/ticket/357>:
887      "Authentication exchanges"
888
889   o  <http://tools.ietf.org/wg/httpbis/trac/ticket/361>: "ABNF
890      requirements for recipients"
891
892
893
894
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898
899
900   o  <http://tools.ietf.org/wg/httpbis/trac/ticket/368>: "note
901      introduction of new IANA registries as normative changes"
902
903D.2.  Since draft-ietf-httpbis-p7-auth-20
904
905   Closed issues:
906
907   o  <http://tools.ietf.org/wg/httpbis/trac/ticket/376>: "rename
908      b64token for clarity"
909
910   Other changes:
911
912   o  Conformance criteria and considerations regarding error handling
913      are now defined in Part 1.
914
915D.3.  Since draft-ietf-httpbis-p7-auth-21
916
917   Closed issues:
918
919   o  <http://tools.ietf.org/wg/httpbis/trac/ticket/403>:
920      "Authentication and caching - max-age"
921
922D.4.  Since draft-ietf-httpbis-p7-auth-22
923
924   Closed issues:
925
926   o  <http://tools.ietf.org/wg/httpbis/trac/ticket/436>: "explain list
927      expansion in ABNF appendices"
928
929   o  <http://tools.ietf.org/wg/httpbis/trac/ticket/439>: "terminology:
930      mechanism vs framework vs scheme"
931
932   o  <http://tools.ietf.org/wg/httpbis/trac/ticket/463>: "Editorial
933      suggestions"
934
935   o  <http://tools.ietf.org/wg/httpbis/trac/ticket/464>: "placement of
936      extension point considerations"
937
938D.5.  Since draft-ietf-httpbis-p7-auth-23
939
940   Closed issues:
941
942   o  <http://tools.ietf.org/wg/httpbis/trac/ticket/473>: "Forwarding
943      Proxy-*"
944
945
946
947
948
949
950
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954
955
956Index
957
958   4
959      401 Unauthorized (status code)  7
960      407 Proxy Authentication Required (status code)  7
961
962   A
963      Authorization header field  8
964
965   C
966      Canonical Root URI  6
967
968   G
969      Grammar
970         auth-param  5
971         auth-scheme  5
972         Authorization  8
973         challenge  5
974         credentials  6
975         Proxy-Authenticate  8
976         Proxy-Authorization  9
977         token68  5
978         WWW-Authenticate  9
979
980   P
981      Protection Space  6
982      Proxy-Authenticate header field  8
983      Proxy-Authorization header field  8
984
985   R
986      Realm  6
987
988   W
989      WWW-Authenticate header field  9
990
991Authors' Addresses
992
993   Roy T. Fielding (editor)
994   Adobe Systems Incorporated
995   345 Park Ave
996   San Jose, CA  95110
997   USA
998
999   EMail: fielding@gbiv.com
1000   URI:   http://roy.gbiv.com/
1001
1002
1003
1004
1005
1006
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1010
1011
1012   Julian F. Reschke (editor)
1013   greenbytes GmbH
1014   Hafenweg 16
1015   Muenster, NW  48155
1016   Germany
1017
1018   EMail: julian.reschke@greenbytes.de
1019   URI:   http://greenbytes.de/tech/webdav/
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
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