anil.recoil.org
An OCaml webserver, but the allocating version (vs httpz which doesnt)
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7Internet Engineering Task Force (IETF) R. Fielding, Ed.
8Request for Comments: 7235 Adobe
9Obsoletes: 2616 J. Reschke, Ed.
10Updates: 2617 greenbytes
11Category: Standards Track June 2014
12ISSN: 2070-1721
13
14
15 Hypertext Transfer Protocol (HTTP/1.1): Authentication
16
17Abstract
18
19 The Hypertext Transfer Protocol (HTTP) is a stateless application-
20 level protocol for distributed, collaborative, hypermedia information
21 systems. This document defines the HTTP Authentication framework.
22
23Status of This Memo
24
25 This is an Internet Standards Track document.
26
27 This document is a product of the Internet Engineering Task Force
28 (IETF). It represents the consensus of the IETF community. It has
29 received public review and has been approved for publication by the
30 Internet Engineering Steering Group (IESG). Further information on
31 Internet Standards is available in Section 2 of RFC 5741.
32
33 Information about the current status of this document, any errata,
34 and how to provide feedback on it may be obtained at
35 http://www.rfc-editor.org/info/rfc7235.
36
37Copyright Notice
38
39 Copyright (c) 2014 IETF Trust and the persons identified as the
40 document authors. All rights reserved.
41
42 This document is subject to BCP 78 and the IETF Trust's Legal
43 Provisions Relating to IETF Documents
44 (http://trustee.ietf.org/license-info) in effect on the date of
45 publication of this document. Please review these documents
46 carefully, as they describe your rights and restrictions with respect
47 to this document. Code Components extracted from this document must
48 include Simplified BSD License text as described in Section 4.e of
49 the Trust Legal Provisions and are provided without warranty as
50 described in the Simplified BSD License.
51
52 This document may contain material from IETF Documents or IETF
53 Contributions published or made publicly available before November
54 10, 2008. The person(s) controlling the copyright in some of this
55
56
57
58Fielding & Reschke Standards Track [Page 1]
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60RFC 7235 HTTP/1.1 Authentication June 2014
61
62
63 material may not have granted the IETF Trust the right to allow
64 modifications of such material outside the IETF Standards Process.
65 Without obtaining an adequate license from the person(s) controlling
66 the copyright in such materials, this document may not be modified
67 outside the IETF Standards Process, and derivative works of it may
68 not be created outside the IETF Standards Process, except to format
69 it for publication as an RFC or to translate it into languages other
70 than English.
71
72Table of Contents
73
74 1. Introduction ....................................................3
75 1.1. Conformance and Error Handling .............................3
76 1.2. Syntax Notation ............................................3
77 2. Access Authentication Framework .................................3
78 2.1. Challenge and Response .....................................3
79 2.2. Protection Space (Realm) ...................................5
80 3. Status Code Definitions .........................................6
81 3.1. 401 Unauthorized ...........................................6
82 3.2. 407 Proxy Authentication Required ..........................6
83 4. Header Field Definitions ........................................7
84 4.1. WWW-Authenticate ...........................................7
85 4.2. Authorization ..............................................8
86 4.3. Proxy-Authenticate .........................................8
87 4.4. Proxy-Authorization ........................................9
88 5. IANA Considerations .............................................9
89 5.1. Authentication Scheme Registry .............................9
90 5.1.1. Procedure ...........................................9
91 5.1.2. Considerations for New Authentication Schemes ......10
92 5.2. Status Code Registration ..................................11
93 5.3. Header Field Registration .................................11
94 6. Security Considerations ........................................12
95 6.1. Confidentiality of Credentials ............................12
96 6.2. Authentication Credentials and Idle Clients ...............12
97 6.3. Protection Spaces .........................................13
98 7. Acknowledgments ................................................14
99 8. References .....................................................14
100 8.1. Normative References ......................................14
101 8.2. Informative References ....................................14
102 Appendix A. Changes from RFCs 2616 and 2617 .......................16
103 Appendix B. Imported ABNF .........................................16
104 Appendix C. Collected ABNF ........................................17
105 Index .............................................................18
106
107
108
109
110
111
112
113
114Fielding & Reschke Standards Track [Page 2]
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116RFC 7235 HTTP/1.1 Authentication June 2014
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118
1191. Introduction
120
121 HTTP provides a general framework for access control and
122 authentication, via an extensible set of challenge-response
123 authentication schemes, which can be used by a server to challenge a
124 client request and by a client to provide authentication information.
125 This document defines HTTP/1.1 authentication in terms of the
126 architecture defined in "Hypertext Transfer Protocol (HTTP/1.1):
127 Message Syntax and Routing" [RFC7230], including the general
128 framework previously described in "HTTP Authentication: Basic and
129 Digest Access Authentication" [RFC2617] and the related fields and
130 status codes previously defined in "Hypertext Transfer Protocol --
131 HTTP/1.1" [RFC2616].
132
133 The IANA Authentication Scheme Registry (Section 5.1) lists
134 registered authentication schemes and their corresponding
135 specifications, including the "basic" and "digest" authentication
136 schemes previously defined by RFC 2617.
137
1381.1. Conformance and Error Handling
139
140 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
141 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
142 document are to be interpreted as described in [RFC2119].
143
144 Conformance criteria and considerations regarding error handling are
145 defined in Section 2.5 of [RFC7230].
146
1471.2. Syntax Notation
148
149 This specification uses the Augmented Backus-Naur Form (ABNF)
150 notation of [RFC5234] with a list extension, defined in Section 7 of
151 [RFC7230], that allows for compact definition of comma-separated
152 lists using a '#' operator (similar to how the '*' operator indicates
153 repetition). Appendix B describes rules imported from other
154 documents. Appendix C shows the collected grammar with all list
155 operators expanded to standard ABNF notation.
156
1572. Access Authentication Framework
158
1592.1. Challenge and Response
160
161 HTTP provides a simple challenge-response authentication framework
162 that can be used by a server to challenge a client request and by a
163 client to provide authentication information. It uses a case-
164 insensitive token as a means to identify the authentication scheme,
165 followed by additional information necessary for achieving
166
167
168
169
170Fielding & Reschke Standards Track [Page 3]
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172RFC 7235 HTTP/1.1 Authentication June 2014
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174
175 authentication via that scheme. The latter can be either a comma-
176 separated list of parameters or a single sequence of characters
177 capable of holding base64-encoded information.
178
179 Authentication parameters are name=value pairs, where the name token
180 is matched case-insensitively, and each parameter name MUST only
181 occur once per challenge.
182
183 auth-scheme = token
184
185 auth-param = token BWS "=" BWS ( token / quoted-string )
186
187 token68 = 1*( ALPHA / DIGIT /
188 "-" / "." / "_" / "~" / "+" / "/" ) *"="
189
190 The token68 syntax allows the 66 unreserved URI characters
191 ([RFC3986]), plus a few others, so that it can hold a base64,
192 base64url (URL and filename safe alphabet), base32, or base16 (hex)
193 encoding, with or without padding, but excluding whitespace
194 ([RFC4648]).
195
196 A 401 (Unauthorized) response message is used by an origin server to
197 challenge the authorization of a user agent, including a
198 WWW-Authenticate header field containing at least one challenge
199 applicable to the requested resource.
200
201 A 407 (Proxy Authentication Required) response message is used by a
202 proxy to challenge the authorization of a client, including a
203 Proxy-Authenticate header field containing at least one challenge
204 applicable to the proxy for the requested resource.
205
206 challenge = auth-scheme [ 1*SP ( token68 / #auth-param ) ]
207
208 Note: Many clients fail to parse a challenge that contains an
209 unknown scheme. A workaround for this problem is to list well-
210 supported schemes (such as "basic") first.
211
212 A user agent that wishes to authenticate itself with an origin server
213 -- usually, but not necessarily, after receiving a 401 (Unauthorized)
214 -- can do so by including an Authorization header field with the
215 request.
216
217 A client that wishes to authenticate itself with a proxy -- usually,
218 but not necessarily, after receiving a 407 (Proxy Authentication
219 Required) -- can do so by including a Proxy-Authorization header
220 field with the request.
221
222
223
224
225
226Fielding & Reschke Standards Track [Page 4]
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228RFC 7235 HTTP/1.1 Authentication June 2014
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230
231 Both the Authorization field value and the Proxy-Authorization field
232 value contain the client's credentials for the realm of the resource
233 being requested, based upon a challenge received in a response
234 (possibly at some point in the past). When creating their values,
235 the user agent ought to do so by selecting the challenge with what it
236 considers to be the most secure auth-scheme that it understands,
237 obtaining credentials from the user as appropriate. Transmission of
238 credentials within header field values implies significant security
239 considerations regarding the confidentiality of the underlying
240 connection, as described in Section 6.1.
241
242 credentials = auth-scheme [ 1*SP ( token68 / #auth-param ) ]
243
244 Upon receipt of a request for a protected resource that omits
245 credentials, contains invalid credentials (e.g., a bad password) or
246 partial credentials (e.g., when the authentication scheme requires
247 more than one round trip), an origin server SHOULD send a 401
248 (Unauthorized) response that contains a WWW-Authenticate header field
249 with at least one (possibly new) challenge applicable to the
250 requested resource.
251
252 Likewise, upon receipt of a request that omits proxy credentials or
253 contains invalid or partial proxy credentials, a proxy that requires
254 authentication SHOULD generate a 407 (Proxy Authentication Required)
255 response that contains a Proxy-Authenticate header field with at
256 least one (possibly new) challenge applicable to the proxy.
257
258 A server that receives valid credentials that are not adequate to
259 gain access ought to respond with the 403 (Forbidden) status code
260 (Section 6.5.3 of [RFC7231]).
261
262 HTTP does not restrict applications to this simple challenge-response
263 framework for access authentication. Additional mechanisms can be
264 used, such as authentication at the transport level or via message
265 encapsulation, and with additional header fields specifying
266 authentication information. However, such additional mechanisms are
267 not defined by this specification.
268
2692.2. Protection Space (Realm)
270
271 The "realm" authentication parameter is reserved for use by
272 authentication schemes that wish to indicate a scope of protection.
273
274 A protection space is defined by the canonical root URI (the scheme
275 and authority components of the effective request URI; see Section
276 5.5 of [RFC7230]) of the server being accessed, in combination with
277 the realm value if present. These realms allow the protected
278 resources on a server to be partitioned into a set of protection
279
280
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282Fielding & Reschke Standards Track [Page 5]
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284RFC 7235 HTTP/1.1 Authentication June 2014
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286
287 spaces, each with its own authentication scheme and/or authorization
288 database. The realm value is a string, generally assigned by the
289 origin server, that can have additional semantics specific to the
290 authentication scheme. Note that a response can have multiple
291 challenges with the same auth-scheme but with different realms.
292
293 The protection space determines the domain over which credentials can
294 be automatically applied. If a prior request has been authorized,
295 the user agent MAY reuse the same credentials for all other requests
296 within that protection space for a period of time determined by the
297 authentication scheme, parameters, and/or user preferences (such as a
298 configurable inactivity timeout). Unless specifically allowed by the
299 authentication scheme, a single protection space cannot extend
300 outside the scope of its server.
301
302 For historical reasons, a sender MUST only generate the quoted-string
303 syntax. Recipients might have to support both token and
304 quoted-string syntax for maximum interoperability with existing
305 clients that have been accepting both notations for a long time.
306
3073. Status Code Definitions
308
3093.1. 401 Unauthorized
310
311 The 401 (Unauthorized) status code indicates that the request has not
312 been applied because it lacks valid authentication credentials for
313 the target resource. The server generating a 401 response MUST send
314 a WWW-Authenticate header field (Section 4.1) containing at least one
315 challenge applicable to the target resource.
316
317 If the request included authentication credentials, then the 401
318 response indicates that authorization has been refused for those
319 credentials. The user agent MAY repeat the request with a new or
320 replaced Authorization header field (Section 4.2). If the 401
321 response contains the same challenge as the prior response, and the
322 user agent has already attempted authentication at least once, then
323 the user agent SHOULD present the enclosed representation to the
324 user, since it usually contains relevant diagnostic information.
325
3263.2. 407 Proxy Authentication Required
327
328 The 407 (Proxy Authentication Required) status code is similar to 401
329 (Unauthorized), but it indicates that the client needs to
330 authenticate itself in order to use a proxy. The proxy MUST send a
331 Proxy-Authenticate header field (Section 4.3) containing a challenge
332 applicable to that proxy for the target resource. The client MAY
333 repeat the request with a new or replaced Proxy-Authorization header
334 field (Section 4.4).
335
336
337
338Fielding & Reschke Standards Track [Page 6]
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340RFC 7235 HTTP/1.1 Authentication June 2014
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342
3434. Header Field Definitions
344
345 This section defines the syntax and semantics of header fields
346 related to the HTTP authentication framework.
347
3484.1. WWW-Authenticate
349
350 The "WWW-Authenticate" header field indicates the authentication
351 scheme(s) and parameters applicable to the target resource.
352
353 WWW-Authenticate = 1#challenge
354
355 A server generating a 401 (Unauthorized) response MUST send a
356 WWW-Authenticate header field containing at least one challenge. A
357 server MAY generate a WWW-Authenticate header field in other response
358 messages to indicate that supplying credentials (or different
359 credentials) might affect the response.
360
361 A proxy forwarding a response MUST NOT modify any WWW-Authenticate
362 fields in that response.
363
364 User agents are advised to take special care in parsing the field
365 value, as it might contain more than one challenge, and each
366 challenge can contain a comma-separated list of authentication
367 parameters. Furthermore, the header field itself can occur multiple
368 times.
369
370 For instance:
371
372 WWW-Authenticate: Newauth realm="apps", type=1,
373 title="Login to \"apps\"", Basic realm="simple"
374
375 This header field contains two challenges; one for the "Newauth"
376 scheme with a realm value of "apps", and two additional parameters
377 "type" and "title", and another one for the "Basic" scheme with a
378 realm value of "simple".
379
380 Note: The challenge grammar production uses the list syntax as
381 well. Therefore, a sequence of comma, whitespace, and comma can
382 be considered either as applying to the preceding challenge, or to
383 be an empty entry in the list of challenges. In practice, this
384 ambiguity does not affect the semantics of the header field value
385 and thus is harmless.
386
387
388
389
390
391
392
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394Fielding & Reschke Standards Track [Page 7]
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396RFC 7235 HTTP/1.1 Authentication June 2014
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398
3994.2. Authorization
400
401 The "Authorization" header field allows a user agent to authenticate
402 itself with an origin server -- usually, but not necessarily, after
403 receiving a 401 (Unauthorized) response. Its value consists of
404 credentials containing the authentication information of the user
405 agent for the realm of the resource being requested.
406
407 Authorization = credentials
408
409 If a request is authenticated and a realm specified, the same
410 credentials are presumed to be valid for all other requests within
411 this realm (assuming that the authentication scheme itself does not
412 require otherwise, such as credentials that vary according to a
413 challenge value or using synchronized clocks).
414
415 A proxy forwarding a request MUST NOT modify any Authorization fields
416 in that request. See Section 3.2 of [RFC7234] for details of and
417 requirements pertaining to handling of the Authorization field by
418 HTTP caches.
419
4204.3. Proxy-Authenticate
421
422 The "Proxy-Authenticate" header field consists of at least one
423 challenge that indicates the authentication scheme(s) and parameters
424 applicable to the proxy for this effective request URI (Section 5.5
425 of [RFC7230]). A proxy MUST send at least one Proxy-Authenticate
426 header field in each 407 (Proxy Authentication Required) response
427 that it generates.
428
429 Proxy-Authenticate = 1#challenge
430
431 Unlike WWW-Authenticate, the Proxy-Authenticate header field applies
432 only to the next outbound client on the response chain. This is
433 because only the client that chose a given proxy is likely to have
434 the credentials necessary for authentication. However, when multiple
435 proxies are used within the same administrative domain, such as
436 office and regional caching proxies within a large corporate network,
437 it is common for credentials to be generated by the user agent and
438 passed through the hierarchy until consumed. Hence, in such a
439 configuration, it will appear as if Proxy-Authenticate is being
440 forwarded because each proxy will send the same challenge set.
441
442 Note that the parsing considerations for WWW-Authenticate apply to
443 this header field as well; see Section 4.1 for details.
444
445
446
447
448
449
450Fielding & Reschke Standards Track [Page 8]
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452RFC 7235 HTTP/1.1 Authentication June 2014
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454
4554.4. Proxy-Authorization
456
457 The "Proxy-Authorization" header field allows the client to identify
458 itself (or its user) to a proxy that requires authentication. Its
459 value consists of credentials containing the authentication
460 information of the client for the proxy and/or realm of the resource
461 being requested.
462
463 Proxy-Authorization = credentials
464
465 Unlike Authorization, the Proxy-Authorization header field applies
466 only to the next inbound proxy that demanded authentication using the
467 Proxy-Authenticate field. When multiple proxies are used in a chain,
468 the Proxy-Authorization header field is consumed by the first inbound
469 proxy that was expecting to receive credentials. A proxy MAY relay
470 the credentials from the client request to the next proxy if that is
471 the mechanism by which the proxies cooperatively authenticate a given
472 request.
473
4745. IANA Considerations
475
4765.1. Authentication Scheme Registry
477
478 The "Hypertext Transfer Protocol (HTTP) Authentication Scheme
479 Registry" defines the namespace for the authentication schemes in
480 challenges and credentials. It has been created and is now
481 maintained at <http://www.iana.org/assignments/http-authschemes>.
482
4835.1.1. Procedure
484
485 Registrations MUST include the following fields:
486
487 o Authentication Scheme Name
488
489 o Pointer to specification text
490
491 o Notes (optional)
492
493 Values to be added to this namespace require IETF Review (see
494 [RFC5226], Section 4.1).
495
496
497
498
499
500
501
502
503
504
505
506Fielding & Reschke Standards Track [Page 9]
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510
5115.1.2. Considerations for New Authentication Schemes
512
513 There are certain aspects of the HTTP Authentication Framework that
514 put constraints on how new authentication schemes can work:
515
516 o HTTP authentication is presumed to be stateless: all of the
517 information necessary to authenticate a request MUST be provided
518 in the request, rather than be dependent on the server remembering
519 prior requests. Authentication based on, or bound to, the
520 underlying connection is outside the scope of this specification
521 and inherently flawed unless steps are taken to ensure that the
522 connection cannot be used by any party other than the
523 authenticated user (see Section 2.3 of [RFC7230]).
524
525 o The authentication parameter "realm" is reserved for defining
526 protection spaces as described in Section 2.2. New schemes MUST
527 NOT use it in a way incompatible with that definition.
528
529 o The "token68" notation was introduced for compatibility with
530 existing authentication schemes and can only be used once per
531 challenge or credential. Thus, new schemes ought to use the
532 auth-param syntax instead, because otherwise future extensions
533 will be impossible.
534
535 o The parsing of challenges and credentials is defined by this
536 specification and cannot be modified by new authentication
537 schemes. When the auth-param syntax is used, all parameters ought
538 to support both token and quoted-string syntax, and syntactical
539 constraints ought to be defined on the field value after parsing
540 (i.e., quoted-string processing). This is necessary so that
541 recipients can use a generic parser that applies to all
542 authentication schemes.
543
544 Note: The fact that the value syntax for the "realm" parameter is
545 restricted to quoted-string was a bad design choice not to be
546 repeated for new parameters.
547
548 o Definitions of new schemes ought to define the treatment of
549 unknown extension parameters. In general, a "must-ignore" rule is
550 preferable to a "must-understand" rule, because otherwise it will
551 be hard to introduce new parameters in the presence of legacy
552 recipients. Furthermore, it's good to describe the policy for
553 defining new parameters (such as "update the specification" or
554 "use this registry").
555
556 o Authentication schemes need to document whether they are usable in
557 origin-server authentication (i.e., using WWW-Authenticate),
558 and/or proxy authentication (i.e., using Proxy-Authenticate).
559
560
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564RFC 7235 HTTP/1.1 Authentication June 2014
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566
567 o The credentials carried in an Authorization header field are
568 specific to the user agent and, therefore, have the same effect on
569 HTTP caches as the "private" Cache-Control response directive
570 (Section 5.2.2.6 of [RFC7234]), within the scope of the request in
571 which they appear.
572
573 Therefore, new authentication schemes that choose not to carry
574 credentials in the Authorization header field (e.g., using a newly
575 defined header field) will need to explicitly disallow caching, by
576 mandating the use of either Cache-Control request directives
577 (e.g., "no-store", Section 5.2.1.5 of [RFC7234]) or response
578 directives (e.g., "private").
579
5805.2. Status Code Registration
581
582 The "Hypertext Transfer Protocol (HTTP) Status Code Registry" located
583 at <http://www.iana.org/assignments/http-status-codes> has been
584 updated with the registrations below:
585
586 +-------+-------------------------------+-------------+
587 | Value | Description | Reference |
588 +-------+-------------------------------+-------------+
589 | 401 | Unauthorized | Section 3.1 |
590 | 407 | Proxy Authentication Required | Section 3.2 |
591 +-------+-------------------------------+-------------+
592
5935.3. Header Field Registration
594
595 HTTP header fields are registered within the "Message Headers"
596 registry maintained at
597 <http://www.iana.org/assignments/message-headers/>.
598
599 This document defines the following HTTP header fields, so the
600 "Permanent Message Header Field Names" registry has been updated
601 accordingly (see [BCP90]).
602
603 +---------------------+----------+----------+-------------+
604 | Header Field Name | Protocol | Status | Reference |
605 +---------------------+----------+----------+-------------+
606 | Authorization | http | standard | Section 4.2 |
607 | Proxy-Authenticate | http | standard | Section 4.3 |
608 | Proxy-Authorization | http | standard | Section 4.4 |
609 | WWW-Authenticate | http | standard | Section 4.1 |
610 +---------------------+----------+----------+-------------+
611
612 The change controller is: "IETF (iesg@ietf.org) - Internet
613 Engineering Task Force".
614
615
616
617
618Fielding & Reschke Standards Track [Page 11]
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620RFC 7235 HTTP/1.1 Authentication June 2014
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622
6236. Security Considerations
624
625 This section is meant to inform developers, information providers,
626 and users of known security concerns specific to HTTP authentication.
627 More general security considerations are addressed in HTTP messaging
628 [RFC7230] and semantics [RFC7231].
629
630 Everything about the topic of HTTP authentication is a security
631 consideration, so the list of considerations below is not exhaustive.
632 Furthermore, it is limited to security considerations regarding the
633 authentication framework, in general, rather than discussing all of
634 the potential considerations for specific authentication schemes
635 (which ought to be documented in the specifications that define those
636 schemes). Various organizations maintain topical information and
637 links to current research on Web application security (e.g.,
638 [OWASP]), including common pitfalls for implementing and using the
639 authentication schemes found in practice.
640
6416.1. Confidentiality of Credentials
642
643 The HTTP authentication framework does not define a single mechanism
644 for maintaining the confidentiality of credentials; instead, each
645 authentication scheme defines how the credentials are encoded prior
646 to transmission. While this provides flexibility for the development
647 of future authentication schemes, it is inadequate for the protection
648 of existing schemes that provide no confidentiality on their own, or
649 that do not sufficiently protect against replay attacks.
650 Furthermore, if the server expects credentials that are specific to
651 each individual user, the exchange of those credentials will have the
652 effect of identifying that user even if the content within
653 credentials remains confidential.
654
655 HTTP depends on the security properties of the underlying transport-
656 or session-level connection to provide confidential transmission of
657 header fields. In other words, if a server limits access to
658 authenticated users using this framework, the server needs to ensure
659 that the connection is properly secured in accordance with the nature
660 of the authentication scheme used. For example, services that depend
661 on individual user authentication often require a connection to be
662 secured with TLS ("Transport Layer Security", [RFC5246]) prior to
663 exchanging any credentials.
664
6656.2. Authentication Credentials and Idle Clients
666
667 Existing HTTP clients and user agents typically retain authentication
668 information indefinitely. HTTP does not provide a mechanism for the
669 origin server to direct clients to discard these cached credentials,
670 since the protocol has no awareness of how credentials are obtained
671
672
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678
679 or managed by the user agent. The mechanisms for expiring or
680 revoking credentials can be specified as part of an authentication
681 scheme definition.
682
683 Circumstances under which credential caching can interfere with the
684 application's security model include but are not limited to:
685
686 o Clients that have been idle for an extended period, following
687 which the server might wish to cause the client to re-prompt the
688 user for credentials.
689
690 o Applications that include a session termination indication (such
691 as a "logout" or "commit" button on a page) after which the server
692 side of the application "knows" that there is no further reason
693 for the client to retain the credentials.
694
695 User agents that cache credentials are encouraged to provide a
696 readily accessible mechanism for discarding cached credentials under
697 user control.
698
6996.3. Protection Spaces
700
701 Authentication schemes that solely rely on the "realm" mechanism for
702 establishing a protection space will expose credentials to all
703 resources on an origin server. Clients that have successfully made
704 authenticated requests with a resource can use the same
705 authentication credentials for other resources on the same origin
706 server. This makes it possible for a different resource to harvest
707 authentication credentials for other resources.
708
709 This is of particular concern when an origin server hosts resources
710 for multiple parties under the same canonical root URI (Section 2.2).
711 Possible mitigation strategies include restricting direct access to
712 authentication credentials (i.e., not making the content of the
713 Authorization request header field available), and separating
714 protection spaces by using a different host name (or port number) for
715 each party.
716
717
718
719
720
721
722
723
724
725
726
727
728
729
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734
7357. Acknowledgments
736
737 This specification takes over the definition of the HTTP
738 Authentication Framework, previously defined in RFC 2617. We thank
739 John Franks, Phillip M. Hallam-Baker, Jeffery L. Hostetler, Scott D.
740 Lawrence, Paul J. Leach, Ari Luotonen, and Lawrence C. Stewart for
741 their work on that specification. See Section 6 of [RFC2617] for
742 further acknowledgements.
743
744 See Section 10 of [RFC7230] for the Acknowledgments related to this
745 document revision.
746
7478. References
748
7498.1. Normative References
750
751 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
752 Requirement Levels", BCP 14, RFC 2119, March 1997.
753
754 [RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
755 Specifications: ABNF", STD 68, RFC 5234, January 2008.
756
757 [RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
758 Protocol (HTTP/1.1): Message Syntax and Routing",
759 RFC 7230, June 2014.
760
761 [RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
762 Protocol (HTTP/1.1): Semantics and Content", RFC 7231,
763 June 2014.
764
765 [RFC7234] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
766 Ed., "Hypertext Transfer Protocol (HTTP/1.1): Caching",
767 RFC 7234, June 2014.
768
7698.2. Informative References
770
771 [BCP90] Klyne, G., Nottingham, M., and J. Mogul, "Registration
772 Procedures for Message Header Fields", BCP 90, RFC 3864,
773 September 2004.
774
775 [OWASP] van der Stock, A., Ed., "A Guide to Building Secure Web
776 Applications and Web Services", The Open Web Application
777 Security Project (OWASP) 2.0.1, July 2005,
778 <https://www.owasp.org/>.
779
780 [RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
781 Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
782 Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
783
784
785
786Fielding & Reschke Standards Track [Page 14]
787
788RFC 7235 HTTP/1.1 Authentication June 2014
789
790
791 [RFC2617] Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S.,
792 Leach, P., Luotonen, A., and L. Stewart, "HTTP
793 Authentication: Basic and Digest Access Authentication",
794 RFC 2617, June 1999.
795
796 [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
797 Resource Identifier (URI): Generic Syntax", STD 66,
798 RFC 3986, January 2005.
799
800 [RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data
801 Encodings", RFC 4648, October 2006.
802
803 [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
804 IANA Considerations Section in RFCs", BCP 26, RFC 5226,
805 May 2008.
806
807 [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
808 (TLS) Protocol Version 1.2", RFC 5246, August 2008.
809
810
811
812
813
814
815
816
817
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819
820
821
822
823
824
825
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827
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834
835
836
837
838
839
840
841
842Fielding & Reschke Standards Track [Page 15]
843
844RFC 7235 HTTP/1.1 Authentication June 2014
845
846
847Appendix A. Changes from RFCs 2616 and 2617
848
849 The framework for HTTP Authentication is now defined by this
850 document, rather than RFC 2617.
851
852 The "realm" parameter is no longer always required on challenges;
853 consequently, the ABNF allows challenges without any auth parameters.
854 (Section 2)
855
856 The "token68" alternative to auth-param lists has been added for
857 consistency with legacy authentication schemes such as "Basic".
858 (Section 2)
859
860 This specification introduces the Authentication Scheme Registry,
861 along with considerations for new authentication schemes.
862 (Section 5.1)
863
864Appendix B. Imported ABNF
865
866 The following core rules are included by reference, as defined in
867 Appendix B.1 of [RFC5234]: ALPHA (letters), CR (carriage return),
868 CRLF (CR LF), CTL (controls), DIGIT (decimal 0-9), DQUOTE (double
869 quote), HEXDIG (hexadecimal 0-9/A-F/a-f), LF (line feed), OCTET (any
870 8-bit sequence of data), SP (space), and VCHAR (any visible US-ASCII
871 character).
872
873 The rules below are defined in [RFC7230]:
874
875 BWS = <BWS, see [RFC7230], Section 3.2.3>
876 OWS = <OWS, see [RFC7230], Section 3.2.3>
877 quoted-string = <quoted-string, see [RFC7230], Section 3.2.6>
878 token = <token, see [RFC7230], Section 3.2.6>
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898Fielding & Reschke Standards Track [Page 16]
899
900RFC 7235 HTTP/1.1 Authentication June 2014
901
902
903Appendix C. Collected ABNF
904
905 In the collected ABNF below, list rules are expanded as per Section
906 1.2 of [RFC7230].
907
908 Authorization = credentials
909
910 BWS = <BWS, see [RFC7230], Section 3.2.3>
911
912 OWS = <OWS, see [RFC7230], Section 3.2.3>
913
914 Proxy-Authenticate = *( "," OWS ) challenge *( OWS "," [ OWS
915 challenge ] )
916 Proxy-Authorization = credentials
917
918 WWW-Authenticate = *( "," OWS ) challenge *( OWS "," [ OWS challenge
919 ] )
920
921 auth-param = token BWS "=" BWS ( token / quoted-string )
922 auth-scheme = token
923
924 challenge = auth-scheme [ 1*SP ( token68 / [ ( "," / auth-param ) *(
925 OWS "," [ OWS auth-param ] ) ] ) ]
926 credentials = auth-scheme [ 1*SP ( token68 / [ ( "," / auth-param )
927 *( OWS "," [ OWS auth-param ] ) ] ) ]
928
929 quoted-string = <quoted-string, see [RFC7230], Section 3.2.6>
930
931 token = <token, see [RFC7230], Section 3.2.6>
932 token68 = 1*( ALPHA / DIGIT / "-" / "." / "_" / "~" / "+" / "/" )
933 *"="
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954Fielding & Reschke Standards Track [Page 17]
955
956RFC 7235 HTTP/1.1 Authentication June 2014
957
958
959Index
960
961 4
962 401 Unauthorized (status code) 6
963 407 Proxy Authentication Required (status code) 6
964
965 A
966 Authorization header field 8
967
968 C
969 Canonical Root URI 5
970
971 G
972 Grammar
973 auth-param 4
974 auth-scheme 4
975 Authorization 8
976 challenge 4
977 credentials 5
978 Proxy-Authenticate 8
979 Proxy-Authorization 9
980 token68 4
981 WWW-Authenticate 7
982
983 P
984 Protection Space 5
985 Proxy-Authenticate header field 8
986 Proxy-Authorization header field 9
987
988 R
989 Realm 5
990
991 W
992 WWW-Authenticate header field 7
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010Fielding & Reschke Standards Track [Page 18]
1011
1012RFC 7235 HTTP/1.1 Authentication June 2014
1013
1014
1015Authors' Addresses
1016
1017 Roy T. Fielding (editor)
1018 Adobe Systems Incorporated
1019 345 Park Ave
1020 San Jose, CA 95110
1021 USA
1022
1023 EMail: fielding@gbiv.com
1024 URI: http://roy.gbiv.com/
1025
1026
1027 Julian F. Reschke (editor)
1028 greenbytes GmbH
1029 Hafenweg 16
1030 Muenster, NW 48155
1031 Germany
1032
1033 EMail: julian.reschke@greenbytes.de
1034 URI: http://greenbytes.de/tech/webdav/
1035
1036
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1049
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1051
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1066Fielding & Reschke Standards Track [Page 19]
1067