idnits 2.17.1
draft-ietf-httpbis-p7-auth-19.txt:
Checking boilerplate required by RFC 5378 and the IETF Trust (see
https://trustee.ietf.org/license-info):
----------------------------------------------------------------------------
No issues found here.
Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt:
----------------------------------------------------------------------------
No issues found here.
Checking nits according to https://www.ietf.org/id-info/checklist :
----------------------------------------------------------------------------
-- The draft header indicates that this document updates RFC2617, but the
abstract doesn't seem to mention this, which it should.
Miscellaneous warnings:
----------------------------------------------------------------------------
== The copyright year in the IETF Trust and authors Copyright Line does not
match the current year
(Using the creation date from RFC2617, updated by this document, for
RFC5378 checks: 1997-12-01)
-- The document seems to contain a disclaimer for pre-RFC5378 work, and may
have content which was first submitted before 10 November 2008. The
disclaimer is necessary when there are original authors that you have
been unable to contact, or if some do not wish to grant the BCP78 rights
to the IETF Trust. If you are able to get all authors (current and
original) to grant those rights, you can and should remove the
disclaimer; otherwise, the disclaimer is needed and you can ignore this
comment. (See the Legal Provisions document at
https://trustee.ietf.org/license-info for more information.)
-- The document date (March 12, 2012) is 4429 days in the past. Is this
intentional?
Checking references for intended status: Proposed Standard
----------------------------------------------------------------------------
(See RFCs 3967 and 4897 for information about using normative references
to lower-maturity documents in RFCs)
== Outdated reference: A later version (-26) exists of
draft-ietf-httpbis-p1-messaging-19
== Outdated reference: A later version (-26) exists of
draft-ietf-httpbis-p6-cache-19
-- Obsolete informational reference (is this intentional?): RFC 2616
(Obsoleted by RFC 7230, RFC 7231, RFC 7232, RFC 7233, RFC 7234, RFC 7235)
-- Obsolete informational reference (is this intentional?): RFC 2617
(Obsoleted by RFC 7235, RFC 7615, RFC 7616, RFC 7617)
-- Obsolete informational reference (is this intentional?): RFC 5226
(Obsoleted by RFC 8126)
Summary: 0 errors (**), 0 flaws (~~), 3 warnings (==), 6 comments (--).
Run idnits with the --verbose option for more detailed information about
the items above.
--------------------------------------------------------------------------------
2 HTTPbis Working Group R. Fielding, Ed.
3 Internet-Draft Adobe
4 Obsoletes: 2616 (if approved) Y. Lafon, Ed.
5 Updates: 2617 (if approved) W3C
6 Intended status: Standards Track J. Reschke, Ed.
7 Expires: September 13, 2012 greenbytes
8 March 12, 2012
10 HTTP/1.1, part 7: Authentication
11 draft-ietf-httpbis-p7-auth-19
13 Abstract
15 The Hypertext Transfer Protocol (HTTP) is an application-level
16 protocol for distributed, collaborative, hypermedia information
17 systems. HTTP has been in use by the World Wide Web global
18 information initiative since 1990. This document is Part 7 of the
19 seven-part specification that defines the protocol referred to as
20 "HTTP/1.1" and, taken together, obsoletes RFC 2616.
22 Part 7 defines the HTTP Authentication framework.
24 Editorial Note (To be removed by RFC Editor)
26 Discussion of this draft should take place on the HTTPBIS working
27 group mailing list (ietf-http-wg@w3.org), which is archived at
28 .
30 The current issues list is at
31 and related
32 documents (including fancy diffs) can be found at
33 .
35 The changes in this draft are summarized in Appendix C.20.
37 Status of This Memo
39 This Internet-Draft is submitted in full conformance with the
40 provisions of BCP 78 and BCP 79.
42 Internet-Drafts are working documents of the Internet Engineering
43 Task Force (IETF). Note that other groups may also distribute
44 working documents as Internet-Drafts. The list of current Internet-
45 Drafts is at http://datatracker.ietf.org/drafts/current/.
47 Internet-Drafts are draft documents valid for a maximum of six months
48 and may be updated, replaced, or obsoleted by other documents at any
49 time. It is inappropriate to use Internet-Drafts as reference
50 material or to cite them other than as "work in progress."
52 This Internet-Draft will expire on September 13, 2012.
54 Copyright Notice
56 Copyright (c) 2012 IETF Trust and the persons identified as the
57 document authors. All rights reserved.
59 This document is subject to BCP 78 and the IETF Trust's Legal
60 Provisions Relating to IETF Documents
61 (http://trustee.ietf.org/license-info) in effect on the date of
62 publication of this document. Please review these documents
63 carefully, as they describe your rights and restrictions with respect
64 to this document. Code Components extracted from this document must
65 include Simplified BSD License text as described in Section 4.e of
66 the Trust Legal Provisions and are provided without warranty as
67 described in the Simplified BSD License.
69 This document may contain material from IETF Documents or IETF
70 Contributions published or made publicly available before November
71 10, 2008. The person(s) controlling the copyright in some of this
72 material may not have granted the IETF Trust the right to allow
73 modifications of such material outside the IETF Standards Process.
74 Without obtaining an adequate license from the person(s) controlling
75 the copyright in such materials, this document may not be modified
76 outside the IETF Standards Process, and derivative works of it may
77 not be created outside the IETF Standards Process, except to format
78 it for publication as an RFC or to translate it into languages other
79 than English.
81 Table of Contents
83 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
84 1.1. Conformance and Error Handling . . . . . . . . . . . . . . 4
85 1.2. Syntax Notation . . . . . . . . . . . . . . . . . . . . . 4
86 1.2.1. Core Rules . . . . . . . . . . . . . . . . . . . . . . 5
87 2. Access Authentication Framework . . . . . . . . . . . . . . . 5
88 2.1. Challenge and Response . . . . . . . . . . . . . . . . . . 5
89 2.2. Protection Space (Realm) . . . . . . . . . . . . . . . . . 7
90 2.3. Authentication Scheme Registry . . . . . . . . . . . . . . 7
91 2.3.1. Considerations for New Authentication Schemes . . . . 8
92 3. Status Code Definitions . . . . . . . . . . . . . . . . . . . 9
93 3.1. 401 Unauthorized . . . . . . . . . . . . . . . . . . . . . 9
94 3.2. 407 Proxy Authentication Required . . . . . . . . . . . . 9
95 4. Header Field Definitions . . . . . . . . . . . . . . . . . . . 10
96 4.1. Authorization . . . . . . . . . . . . . . . . . . . . . . 10
97 4.2. Proxy-Authenticate . . . . . . . . . . . . . . . . . . . . 11
98 4.3. Proxy-Authorization . . . . . . . . . . . . . . . . . . . 11
99 4.4. WWW-Authenticate . . . . . . . . . . . . . . . . . . . . . 11
100 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
101 5.1. Authenticaton Scheme Registry . . . . . . . . . . . . . . 12
102 5.2. Status Code Registration . . . . . . . . . . . . . . . . . 12
103 5.3. Header Field Registration . . . . . . . . . . . . . . . . 13
104 6. Security Considerations . . . . . . . . . . . . . . . . . . . 13
105 6.1. Authentication Credentials and Idle Clients . . . . . . . 13
106 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 14
107 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14
108 8.1. Normative References . . . . . . . . . . . . . . . . . . . 14
109 8.2. Informative References . . . . . . . . . . . . . . . . . . 14
110 Appendix A. Changes from RFCs 2616 and 2617 . . . . . . . . . . . 15
111 Appendix B. Collected ABNF . . . . . . . . . . . . . . . . . . . 16
112 Appendix C. Change Log (to be removed by RFC Editor before
113 publication) . . . . . . . . . . . . . . . . . . . . 16
114 C.1. Since RFC 2616 . . . . . . . . . . . . . . . . . . . . . . 16
115 C.2. Since draft-ietf-httpbis-p7-auth-00 . . . . . . . . . . . 16
116 C.3. Since draft-ietf-httpbis-p7-auth-01 . . . . . . . . . . . 17
117 C.4. Since draft-ietf-httpbis-p7-auth-02 . . . . . . . . . . . 17
118 C.5. Since draft-ietf-httpbis-p7-auth-03 . . . . . . . . . . . 17
119 C.6. Since draft-ietf-httpbis-p7-auth-04 . . . . . . . . . . . 17
120 C.7. Since draft-ietf-httpbis-p7-auth-05 . . . . . . . . . . . 17
121 C.8. Since draft-ietf-httpbis-p7-auth-06 . . . . . . . . . . . 18
122 C.9. Since draft-ietf-httpbis-p7-auth-07 . . . . . . . . . . . 18
123 C.10. Since draft-ietf-httpbis-p7-auth-08 . . . . . . . . . . . 18
124 C.11. Since draft-ietf-httpbis-p7-auth-09 . . . . . . . . . . . 18
125 C.12. Since draft-ietf-httpbis-p7-auth-10 . . . . . . . . . . . 18
126 C.13. Since draft-ietf-httpbis-p7-auth-11 . . . . . . . . . . . 18
127 C.14. Since draft-ietf-httpbis-p7-auth-12 . . . . . . . . . . . 19
128 C.15. Since draft-ietf-httpbis-p7-auth-13 . . . . . . . . . . . 19
129 C.16. Since draft-ietf-httpbis-p7-auth-14 . . . . . . . . . . . 19
130 C.17. Since draft-ietf-httpbis-p7-auth-15 . . . . . . . . . . . 19
131 C.18. Since draft-ietf-httpbis-p7-auth-16 . . . . . . . . . . . 19
132 C.19. Since draft-ietf-httpbis-p7-auth-17 . . . . . . . . . . . 20
133 C.20. Since draft-ietf-httpbis-p7-auth-18 . . . . . . . . . . . 20
134 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
136 1. Introduction
138 This document defines HTTP/1.1 access control and authentication. It
139 includes the relevant parts of RFC 2616 with only minor changes, plus
140 the general framework for HTTP authentication, as previously defined
141 in "HTTP Authentication: Basic and Digest Access Authentication"
142 ([RFC2617]).
144 HTTP provides several OPTIONAL challenge-response authentication
145 mechanisms which can be used by a server to challenge a client
146 request and by a client to provide authentication information. The
147 "basic" and "digest" authentication schemes continue to be specified
148 in RFC 2617.
150 1.1. Conformance and Error Handling
152 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
153 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
154 document are to be interpreted as described in [RFC2119].
156 This document defines conformance criteria for several roles in HTTP
157 communication, including Senders, Recipients, Clients, Servers, User-
158 Agents, Origin Servers, Intermediaries, Proxies and Gateways. See
159 Section 2 of [Part1] for definitions of these terms.
161 An implementation is considered conformant if it complies with all of
162 the requirements associated with its role(s). Note that SHOULD-level
163 requirements are relevant here, unless one of the documented
164 exceptions is applicable.
166 This document also uses ABNF to define valid protocol elements
167 (Section 1.2). In addition to the prose requirements placed upon
168 them, Senders MUST NOT generate protocol elements that are invalid.
170 Unless noted otherwise, Recipients MAY take steps to recover a usable
171 protocol element from an invalid construct. However, HTTP does not
172 define specific error handling mechanisms, except in cases where it
173 has direct impact on security. This is because different uses of the
174 protocol require different error handling strategies; for example, a
175 Web browser may wish to transparently recover from a response where
176 the Location header field doesn't parse according to the ABNF,
177 whereby in a systems control protocol using HTTP, this type of error
178 recovery could lead to dangerous consequences.
180 1.2. Syntax Notation
182 This specification uses the Augmented Backus-Naur Form (ABNF)
183 notation of [RFC5234] with the list rule extension defined in Section
184 1.2 of [Part1]. Appendix B shows the collected ABNF with the list
185 rule expanded.
187 The following core rules are included by reference, as defined in
188 [RFC5234], Appendix B.1: ALPHA (letters), CR (carriage return), CRLF
189 (CR LF), CTL (controls), DIGIT (decimal 0-9), DQUOTE (double quote),
190 HEXDIG (hexadecimal 0-9/A-F/a-f), LF (line feed), OCTET (any 8-bit
191 sequence of data), SP (space), and VCHAR (any visible US-ASCII
192 character).
194 1.2.1. Core Rules
196 The core rules below are defined in [Part1]:
198 BWS =
199 OWS =
200 quoted-string =
201 token =
203 2. Access Authentication Framework
205 2.1. Challenge and Response
207 HTTP provides a simple challenge-response authentication mechanism
208 that can be used by a server to challenge a client request and by a
209 client to provide authentication information. It uses an extensible,
210 case-insensitive token 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.
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.
220 auth-scheme = token
222 auth-param = token BWS "=" BWS ( token / quoted-string )
224 b64token = 1*( ALPHA / DIGIT /
225 "-" / "." / "_" / "~" / "+" / "/" ) *"="
227 The "b64token" syntax allows the 66 unreserved URI characters
228 ([RFC3986]), plus a few others, so that it can hold a base64,
229 base64url (URL and filename safe alphabet), base32, or base16 (hex)
230 encoding, with or without padding, but excluding whitespace
231 ([RFC4648]).
233 The 401 (Unauthorized) response message is used by an origin server
234 to challenge the authorization of a user agent. This response MUST
235 include a WWW-Authenticate header field containing at least one
236 challenge applicable to the requested resource.
238 The 407 (Proxy Authentication Required) response message is used by a
239 proxy to challenge the authorization of a client and MUST include a
240 Proxy-Authenticate header field containing at least one challenge
241 applicable to the proxy for the requested resource.
243 challenge = auth-scheme [ 1*SP ( b64token / #auth-param ) ]
245 Note: User agents will need to take special care in parsing the
246 WWW-Authenticate and Proxy-Authenticate header field values
247 because they can contain more than one challenge, or if more than
248 one of each is provided, since the contents of a challenge can
249 itself contain a comma-separated list of authentication
250 parameters.
252 Note: Many browsers fail to parse challenges containing unknown
253 schemes. A workaround for this problem is to list well-supported
254 schemes (such as "basic") first.
256 A user agent that wishes to authenticate itself with an origin server
257 -- usually, but not necessarily, after receiving a 401 (Unauthorized)
258 -- MAY do so by including an Authorization header field with the
259 request.
261 A client that wishes to authenticate itself with a proxy -- usually,
262 but not necessarily, after receiving a 407 (Proxy Authentication
263 Required) -- MAY do so by including a Proxy-Authorization header
264 field with the request.
266 Both the Authorization field value and the Proxy-Authorization field
267 value consist of credentials containing the authentication
268 information of the client for the realm of the resource being
269 requested. The user agent MUST choose to use one of the challenges
270 with the strongest auth-scheme it understands and request credentials
271 from the user based upon that challenge.
273 credentials = auth-scheme [ 1*SP ( b64token / #auth-param ) ]
275 If the origin server does not wish to accept the credentials sent
276 with a request, it SHOULD return a 401 (Unauthorized) response. The
277 response MUST include a WWW-Authenticate header field containing at
278 least one (possibly new) challenge applicable to the requested
279 resource.
281 If a proxy does not accept the credentials sent with a request, it
282 SHOULD return a 407 (Proxy Authentication Required). The response
283 MUST include a Proxy-Authenticate header field containing a (possibly
284 new) challenge applicable to the proxy for the requested resource.
286 The HTTP protocol does not restrict applications to this simple
287 challenge-response mechanism for access authentication. Additional
288 mechanisms MAY be used, such as encryption at the transport level or
289 via message encapsulation, and with additional header fields
290 specifying authentication information. However, such additional
291 mechanisms are not defined by this specification.
293 Proxies MUST forward the WWW-Authenticate and Authorization headers
294 unmodified and follow the rules found in Section 4.1.
296 2.2. Protection Space (Realm)
298 The authentication parameter realm is reserved for use by
299 authentication schemes that wish to indicate the scope of protection.
301 A protection space is defined by the canonical root URI (the scheme
302 and authority components of the effective request URI; see Section
303 5.5 of [Part1]) of the server being accessed, in combination with the
304 realm value if present. These realms allow the protected resources
305 on a server to be partitioned into a set of protection spaces, each
306 with its own authentication scheme and/or authorization database.
307 The realm value is a string, generally assigned by the origin server,
308 which can have additional semantics specific to the authentication
309 scheme. Note that there can be multiple challenges with the same
310 auth-scheme but different realms.
312 The protection space determines the domain over which credentials can
313 be automatically applied. If a prior request has been authorized,
314 the same credentials MAY be reused for all other requests within that
315 protection space for a period of time determined by the
316 authentication scheme, parameters, and/or user preference. Unless
317 otherwise defined by the authentication scheme, a single protection
318 space cannot extend outside the scope of its server.
320 For historical reasons, senders MUST only use the quoted-string
321 syntax. Recipients might have to support both token and quoted-
322 string syntax for maximum interoperability with existing clients that
323 have been accepting both notations for a long time.
325 2.3. Authentication Scheme Registry
327 The HTTP Authentication Scheme Registry defines the name space for
328 the authentication schemes in challenges and credentials.
330 Registrations MUST include the following fields:
332 o Authentication Scheme Name
334 o Pointer to specification text
336 o Notes (optional)
338 Values to be added to this name space require IETF Review (see
339 [RFC5226], Section 4.1).
341 The registry itself is maintained at
342 .
344 2.3.1. Considerations for New Authentication Schemes
346 There are certain aspects of the HTTP Authentication Framework that
347 put constraints on how new authentication schemes can work:
349 o HTTP authentication is presumed to be stateless: all of the
350 information necessary to authenticate a request MUST be provided
351 in the request, rather than be dependent on the server remembering
352 prior requests. Authentication based on, or bound to, the
353 underlying connection is outside the scope of this specification
354 and inherently flawed unless steps are taken to ensure that the
355 connection cannot be used by any party other than the
356 authenticated user (see Section 2.3 of [Part1]).
358 o The authentication parameter "realm" is reserved for defining
359 Protection Spaces as defined in Section 2.2. New schemes MUST NOT
360 use it in a way incompatible with that definition.
362 o The "b64token" notation was introduced for compatibility with
363 existing authentication schemes and can only be used once per
364 challenge/credentials. New schemes thus ought to use the "auth-
365 param" syntax instead, because otherwise future extensions will be
366 impossible.
368 o The parsing of challenges and credentials is defined by this
369 specification, and cannot be modified by new authentication
370 schemes. When the auth-param syntax is used, all parameters ought
371 to support both token and quoted-string syntax, and syntactical
372 constraints ought to be defined on the field value after parsing
373 (i.e., quoted-string processing). This is necessary so that
374 recipients can use a generic parser that applies to all
375 authentication schemes.
377 Note: the fact that the value syntax for the "realm" parameter is
378 restricted to quoted-string was a bad design choice not to be
379 repeated for new parameters.
381 o Definitions of new schemes ought to define the treatment of
382 unknown extension parameters. In general, a "must-ignore" rule is
383 preferable over "must-understand", because otherwise it will be
384 hard to introduce new parameters in the presence of legacy
385 recipients. Furthermore, it's good to describe the policy for
386 defining new parameters (such as "update the specification", or
387 "use this registry").
389 o Authentication schemes need to document whether they are usable in
390 origin-server authentication (i.e., using WWW-Authenticate),
391 and/or proxy authentication (i.e., using Proxy-Authenticate).
393 o The credentials carried in an Authorization header field are
394 specific to the User Agent, and therefore have the same effect on
395 HTTP caches as the "private" Cache-Control response directive,
396 within the scope of the request they appear in.
398 Therefore, new authentication schemes which choose not to carry
399 credentials in the Authorization header (e.g., using a newly
400 defined header) will need to explicitly disallow caching, by
401 mandating the use of either Cache-Control request directives
402 (e.g., "no-store") or response directives (e.g., "private").
404 3. Status Code Definitions
406 3.1. 401 Unauthorized
408 The request requires user authentication. The response MUST include
409 a WWW-Authenticate header field (Section 4.4) containing a challenge
410 applicable to the target resource. The client MAY repeat the request
411 with a suitable Authorization header field (Section 4.1). If the
412 request already included Authorization credentials, then the 401
413 response indicates that authorization has been refused for those
414 credentials. If the 401 response contains the same challenge as the
415 prior response, and the user agent has already attempted
416 authentication at least once, then the user SHOULD be presented the
417 representation that was given in the response, since that
418 representation might include relevant diagnostic information.
420 3.2. 407 Proxy Authentication Required
422 This code is similar to 401 (Unauthorized), but indicates that the
423 client ought to first authenticate itself with the proxy. The proxy
424 MUST return a Proxy-Authenticate header field (Section 4.2)
425 containing a challenge applicable to the proxy for the target
426 resource. The client MAY repeat the request with a suitable Proxy-
427 Authorization header field (Section 4.3).
429 4. Header Field Definitions
431 This section defines the syntax and semantics of HTTP/1.1 header
432 fields related to authentication.
434 4.1. Authorization
436 The "Authorization" header field allows a user agent to authenticate
437 itself with a server -- usually, but not necessarily, after receiving
438 a 401 (Unauthorized) response. Its value consists of credentials
439 containing information of the user agent for the realm of the
440 resource being requested.
442 Authorization = credentials
444 If a request is authenticated and a realm specified, the same
445 credentials SHOULD be valid for all other requests within this realm
446 (assuming that the authentication scheme itself does not require
447 otherwise, such as credentials that vary according to a challenge
448 value or using synchronized clocks).
450 When a shared cache (see Section 1.2 of [Part6]) receives a request
451 containing an Authorization field, it MUST NOT return the
452 corresponding response as a reply to any other request, unless one of
453 the following specific exceptions holds:
455 1. If the response includes the "s-maxage" cache-control directive,
456 the cache MAY use that response in replying to a subsequent
457 request. But (if the specified maximum age has passed) a proxy
458 cache MUST first revalidate it with the origin server, using the
459 header fields from the new request to allow the origin server to
460 authenticate the new request. (This is the defined behavior for
461 s-maxage.) If the response includes "s-maxage=0", the proxy MUST
462 always revalidate it before re-using it.
464 2. If the response includes the "must-revalidate" cache-control
465 directive, the cache MAY use that response in replying to a
466 subsequent request. But if the response is stale, all caches
467 MUST first revalidate it with the origin server, using the header
468 fields from the new request to allow the origin server to
469 authenticate the new request.
471 3. If the response includes the "public" cache-control directive, it
472 MAY be returned in reply to any subsequent request.
474 4.2. Proxy-Authenticate
476 The "Proxy-Authenticate" header field consists of a challenge that
477 indicates the authentication scheme and parameters applicable to the
478 proxy for this effective request URI (Section 5.5 of [Part1]). It
479 MUST be included as part of a 407 (Proxy Authentication Required)
480 response.
482 Proxy-Authenticate = 1#challenge
484 Unlike WWW-Authenticate, the Proxy-Authenticate header field applies
485 only to the current connection and SHOULD NOT be passed on to
486 downstream clients. However, an intermediate proxy might need to
487 obtain its own credentials by requesting them from the downstream
488 client, which in some circumstances will appear as if the proxy is
489 forwarding the Proxy-Authenticate header field.
491 Note that the parsing considerations for WWW-Authenticate apply to
492 this header field as well; see Section 4.4 for details.
494 4.3. Proxy-Authorization
496 The "Proxy-Authorization" header field allows the client to identify
497 itself (or its user) to a proxy which requires authentication. Its
498 value consists of credentials containing the authentication
499 information of the user agent for the proxy and/or realm of the
500 resource being requested.
502 Proxy-Authorization = credentials
504 Unlike Authorization, the Proxy-Authorization header field applies
505 only to the next outbound proxy that demanded authentication using
506 the Proxy-Authenticate field. When multiple proxies are used in a
507 chain, the Proxy-Authorization header field is consumed by the first
508 outbound proxy that was expecting to receive credentials. A proxy
509 MAY relay the credentials from the client request to the next proxy
510 if that is the mechanism by which the proxies cooperatively
511 authenticate a given request.
513 4.4. WWW-Authenticate
515 The "WWW-Authenticate" header field consists of at least one
516 challenge that indicates the authentication scheme(s) and parameters
517 applicable to the effective request URI (Section 5.5 of [Part1]).
519 It MUST be included in 401 (Unauthorized) response messages and MAY
520 be included in other response messages to indicate that supplying
521 credentials (or different credentials) might affect the response.
523 WWW-Authenticate = 1#challenge
525 User agents are advised to take special care in parsing the WWW-
526 Authenticate field value as it might contain more than one challenge,
527 or if more than one WWW-Authenticate header field is provided, the
528 contents of a challenge itself can contain a comma-separated list of
529 authentication parameters.
531 For instance:
533 WWW-Authenticate: Newauth realm="apps", type=1,
534 title="Login to \"apps\"", Basic realm="simple"
536 This header field contains two challenges; one for the "Newauth"
537 scheme with a realm value of "apps", and two additional parameters
538 "type" and "title", and another one for the "Basic" scheme with a
539 realm value of "simple".
541 Note: The challenge grammar production uses the list syntax as
542 well. Therefore, a sequence of comma, whitespace, and comma can
543 be considered both as applying to the preceding challenge, or to
544 be an empty entry in the list of challenges. In practice, this
545 ambiguity does not affect the semantics of the header field value
546 and thus is harmless.
548 5. IANA Considerations
550 5.1. Authenticaton Scheme Registry
552 The registration procedure for HTTP Authentication Schemes is defined
553 by Section 2.3 of this document.
555 The HTTP Method Authentication Scheme shall be created at
556 .
558 5.2. Status Code Registration
560 The HTTP Status Code Registry located at
561 shall be updated
562 with the registrations below:
564 +-------+-------------------------------+-------------+
565 | Value | Description | Reference |
566 +-------+-------------------------------+-------------+
567 | 401 | Unauthorized | Section 3.1 |
568 | 407 | Proxy Authentication Required | Section 3.2 |
569 +-------+-------------------------------+-------------+
571 5.3. Header Field Registration
573 The Message Header Field Registry located at shall be
575 updated with the permanent registrations below (see [RFC3864]):
577 +---------------------+----------+----------+-------------+
578 | Header Field Name | Protocol | Status | Reference |
579 +---------------------+----------+----------+-------------+
580 | Authorization | http | standard | Section 4.1 |
581 | Proxy-Authenticate | http | standard | Section 4.2 |
582 | Proxy-Authorization | http | standard | Section 4.3 |
583 | WWW-Authenticate | http | standard | Section 4.4 |
584 +---------------------+----------+----------+-------------+
586 The change controller is: "IETF (iesg@ietf.org) - Internet
587 Engineering Task Force".
589 6. Security Considerations
591 This section is meant to inform application developers, information
592 providers, and users of the security limitations in HTTP/1.1 as
593 described by this document. The discussion does not include
594 definitive solutions to the problems revealed, though it does make
595 some suggestions for reducing security risks.
597 6.1. Authentication Credentials and Idle Clients
599 Existing HTTP clients and user agents typically retain authentication
600 information indefinitely. HTTP/1.1 does not provide a method for a
601 server to direct clients to discard these cached credentials. This
602 is a significant defect that requires further extensions to HTTP.
603 Circumstances under which credential caching can interfere with the
604 application's security model include but are not limited to:
606 o Clients which have been idle for an extended period following
607 which the server might wish to cause the client to reprompt the
608 user for credentials.
610 o Applications which include a session termination indication (such
611 as a "logout" or "commit" button on a page) after which the server
612 side of the application "knows" that there is no further reason
613 for the client to retain the credentials.
615 This is currently under separate study. There are a number of work-
616 arounds to parts of this problem, and we encourage the use of
617 password protection in screen savers, idle time-outs, and other
618 methods which mitigate the security problems inherent in this
619 problem. In particular, user agents which cache credentials are
620 encouraged to provide a readily accessible mechanism for discarding
621 cached credentials under user control.
623 7. Acknowledgments
625 This specification takes over the definition of the HTTP
626 Authentication Framework, previously defined in RFC 2617. We thank
627 John Franks, Phillip M. Hallam-Baker, Jeffery L. Hostetler, Scott D.
628 Lawrence, Paul J. Leach, Ari Luotonen, and Lawrence C. Stewart for
629 their work on that specification. See Section 6 of [RFC2617] for
630 further acknowledgements.
632 See Section 9 of [Part1] for the Acknowledgments related to this
633 document revision.
635 8. References
637 8.1. Normative References
639 [Part1] Fielding, R., Ed., Lafon, Y., Ed., and J. Reschke, Ed.,
640 "HTTP/1.1, part 1: URIs, Connections, and Message
641 Parsing", draft-ietf-httpbis-p1-messaging-19 (work in
642 progress), March 2012.
644 [Part6] Fielding, R., Ed., Lafon, Y., Ed., Nottingham, M., Ed.,
645 and J. Reschke, Ed., "HTTP/1.1, part 6: Caching",
646 draft-ietf-httpbis-p6-cache-19 (work in progress),
647 March 2012.
649 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
650 Requirement Levels", BCP 14, RFC 2119, March 1997.
652 [RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
653 Specifications: ABNF", STD 68, RFC 5234, January 2008.
655 8.2. Informative References
657 [RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
658 Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
659 Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
661 [RFC2617] Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S.,
662 Leach, P., Luotonen, A., and L. Stewart, "HTTP
663 Authentication: Basic and Digest Access Authentication",
664 RFC 2617, June 1999.
666 [RFC3864] Klyne, G., Nottingham, M., and J. Mogul, "Registration
667 Procedures for Message Header Fields", BCP 90, RFC 3864,
668 September 2004.
670 [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
671 Resource Identifier (URI): Generic Syntax", STD 66,
672 RFC 3986, January 2005.
674 [RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data
675 Encodings", RFC 4648, October 2006.
677 [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
678 IANA Considerations Section in RFCs", BCP 26, RFC 5226,
679 May 2008.
681 Appendix A. Changes from RFCs 2616 and 2617
683 The "realm" parameter isn't required anymore in general;
684 consequently, the ABNF allows challenges without any auth parameters.
685 (Section 2)
687 The "b64token" alternative to auth-param lists has been added for
688 consistency with legacy authentication schemes such as "Basic".
689 (Section 2)
691 Change ABNF productions for header fields to only define the field
692 value. (Section 4)
694 Appendix B. Collected ABNF
696 Authorization = credentials
698 BWS =
700 OWS =
702 Proxy-Authenticate = *( "," OWS ) challenge *( OWS "," [ OWS
703 challenge ] )
704 Proxy-Authorization = credentials
706 WWW-Authenticate = *( "," OWS ) challenge *( OWS "," [ OWS challenge
707 ] )
709 auth-param = token BWS "=" BWS ( token / quoted-string )
710 auth-scheme = token
712 b64token = 1*( ALPHA / DIGIT / "-" / "." / "_" / "~" / "+" / "/" )
713 *"="
715 challenge = auth-scheme [ 1*SP ( b64token / [ ( "," / auth-param ) *(
716 OWS "," [ OWS auth-param ] ) ] ) ]
717 credentials = auth-scheme [ 1*SP ( b64token / [ ( "," / auth-param )
718 *( OWS "," [ OWS auth-param ] ) ] ) ]
720 quoted-string =
722 token =
724 ABNF diagnostics:
726 ; Authorization defined but not used
727 ; Proxy-Authenticate defined but not used
728 ; Proxy-Authorization defined but not used
729 ; WWW-Authenticate defined but not used
731 Appendix C. Change Log (to be removed by RFC Editor before publication)
733 C.1. Since RFC 2616
735 Extracted relevant partitions from [RFC2616].
737 C.2. Since draft-ietf-httpbis-p7-auth-00
739 Closed issues:
741 o : "Normative and
742 Informative references"
744 C.3. Since draft-ietf-httpbis-p7-auth-01
746 Ongoing work on ABNF conversion
747 ():
749 o Explicitly import BNF rules for "challenge" and "credentials" from
750 RFC2617.
752 o Add explicit references to BNF syntax and rules imported from
753 other parts of the specification.
755 C.4. Since draft-ietf-httpbis-p7-auth-02
757 Ongoing work on IANA Message Header Field Registration
758 ():
760 o Reference RFC 3984, and update header field registrations for
761 header fields defined in this document.
763 C.5. Since draft-ietf-httpbis-p7-auth-03
765 None.
767 C.6. Since draft-ietf-httpbis-p7-auth-04
769 Ongoing work on ABNF conversion
770 ():
772 o Use "/" instead of "|" for alternatives.
774 o Introduce new ABNF rules for "bad" whitespace ("BWS"), optional
775 whitespace ("OWS") and required whitespace ("RWS").
777 o Rewrite ABNFs to spell out whitespace rules, factor out header
778 field value format definitions.
780 C.7. Since draft-ietf-httpbis-p7-auth-05
782 Final work on ABNF conversion
783 ():
785 o Add appendix containing collected and expanded ABNF, reorganize
786 ABNF introduction.
788 C.8. Since draft-ietf-httpbis-p7-auth-06
790 None.
792 C.9. Since draft-ietf-httpbis-p7-auth-07
794 Closed issues:
796 o : "move IANA
797 registrations for optional status codes"
799 C.10. Since draft-ietf-httpbis-p7-auth-08
801 No significant changes.
803 C.11. Since draft-ietf-httpbis-p7-auth-09
805 Partly resolved issues:
807 o : "Term for the
808 requested resource's URI"
810 C.12. Since draft-ietf-httpbis-p7-auth-10
812 None.
814 C.13. Since draft-ietf-httpbis-p7-auth-11
816 Closed issues:
818 o : "introduction
819 to part 7 is work-in-progress"
821 o : "auth-param
822 syntax"
824 o : "Header
825 Classification"
827 o : "absorbing the
828 auth framework from 2617"
830 Partly resolved issues:
832 o : "should we
833 have an auth scheme registry"
835 C.14. Since draft-ietf-httpbis-p7-auth-12
837 None.
839 C.15. Since draft-ietf-httpbis-p7-auth-13
841 Closed issues:
843 o : "untangle
844 ABNFs for header fields"
846 C.16. Since draft-ietf-httpbis-p7-auth-14
848 None.
850 C.17. Since draft-ietf-httpbis-p7-auth-15
852 Closed issues:
854 o : "Relationship
855 between 401, Authorization and WWW-Authenticate"
857 o : "Realm
858 required on challenges"
860 o : "auth-param
861 syntax"
863 o :
864 "Considerations for new authentications schemes"
866 o : "LWS in auth-
867 param ABNF"
869 o : "credentials
870 ABNF missing SP (still using implied LWS?)"
872 C.18. Since draft-ietf-httpbis-p7-auth-16
874 Closed issues:
876 o : "Document
877 HTTP's error-handling philosophy"
879 o : "add advice on
880 defining auth scheme parameters"
882 C.19. Since draft-ietf-httpbis-p7-auth-17
884 Closed issues:
886 o : "allow
887 unquoted realm parameters"
889 o : "Repeating
890 auth-params"
892 C.20. Since draft-ietf-httpbis-p7-auth-18
894 Closed issues:
896 o : "recipient
897 behavior for new auth parameters"
899 o : "WWW-
900 Authenticate ABNF slightly ambiguous"
902 Index
904 4
905 401 Unauthorized (status code) 9
906 407 Proxy Authentication Required (status code) 9
908 A
909 auth-param 5
910 auth-scheme 5
911 Authorization header field 10
913 B
914 b64token 5
916 C
917 challenge 6
918 credentials 6
920 G
921 Grammar
922 auth-param 5
923 auth-scheme 5
924 Authorization 10
925 b64token 5
926 challenge 6
927 credentials 6
928 Proxy-Authenticate 11
929 Proxy-Authorization 11
930 WWW-Authenticate 12
932 H
933 Header Fields
934 Authorization 10
935 Proxy-Authenticate 11
936 Proxy-Authorization 11
937 WWW-Authenticate 11
939 P
940 Protection Space 7
941 Proxy-Authenticate header field 11
942 Proxy-Authorization header field 11
944 R
945 Realm 7
947 S
948 Status Codes
949 401 Unauthorized 9
950 407 Proxy Authentication Required 9
952 W
953 WWW-Authenticate header field 11
955 Authors' Addresses
957 Roy T. Fielding (editor)
958 Adobe Systems Incorporated
959 345 Park Ave
960 San Jose, CA 95110
961 USA
963 EMail: fielding@gbiv.com
964 URI: http://roy.gbiv.com/
966 Yves Lafon (editor)
967 World Wide Web Consortium
968 W3C / ERCIM
969 2004, rte des Lucioles
970 Sophia-Antipolis, AM 06902
971 France
973 EMail: ylafon@w3.org
974 URI: http://www.raubacapeu.net/people/yves/
975 Julian F. Reschke (editor)
976 greenbytes GmbH
977 Hafenweg 16
978 Muenster, NW 48155
979 Germany
981 Phone: +49 251 2807760
982 Fax: +49 251 2807761
983 EMail: julian.reschke@greenbytes.de
984 URI: http://greenbytes.de/tech/webdav/