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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) J. Gettys 5 Updates: 2617 (if approved) Alcatel-Lucent 6 Intended status: Standards Track J. Mogul 7 Expires: May 3, 2012 HP 8 H. Frystyk 9 Microsoft 10 L. Masinter 11 Adobe 12 P. Leach 13 Microsoft 14 T. Berners-Lee 15 W3C/MIT 16 Y. Lafon, Ed. 17 W3C 18 J. Reschke, Ed. 19 greenbytes 20 October 31, 2011 22 HTTP/1.1, part 7: Authentication 23 draft-ietf-httpbis-p7-auth-17 25 Abstract 27 The Hypertext Transfer Protocol (HTTP) is an application-level 28 protocol for distributed, collaborative, hypermedia information 29 systems. HTTP has been in use by the World Wide Web global 30 information initiative since 1990. This document is Part 7 of the 31 seven-part specification that defines the protocol referred to as 32 "HTTP/1.1" and, taken together, obsoletes RFC 2616. 34 Part 7 defines the HTTP Authentication framework. 36 Editorial Note (To be removed by RFC Editor) 38 Discussion of this draft should take place on the HTTPBIS working 39 group mailing list (ietf-http-wg@w3.org), which is archived at 40 . 42 The current issues list is at 43 and related 44 documents (including fancy diffs) can be found at 45 . 47 The changes in this draft are summarized in Appendix C.18. 49 Status of This Memo 51 This Internet-Draft is submitted in full conformance with the 52 provisions of BCP 78 and BCP 79. 54 Internet-Drafts are working documents of the Internet Engineering 55 Task Force (IETF). Note that other groups may also distribute 56 working documents as Internet-Drafts. The list of current Internet- 57 Drafts is at http://datatracker.ietf.org/drafts/current/. 59 Internet-Drafts are draft documents valid for a maximum of six months 60 and may be updated, replaced, or obsoleted by other documents at any 61 time. It is inappropriate to use Internet-Drafts as reference 62 material or to cite them other than as "work in progress." 64 This Internet-Draft will expire on May 3, 2012. 66 Copyright Notice 68 Copyright (c) 2011 IETF Trust and the persons identified as the 69 document authors. All rights reserved. 71 This document is subject to BCP 78 and the IETF Trust's Legal 72 Provisions Relating to IETF Documents 73 (http://trustee.ietf.org/license-info) in effect on the date of 74 publication of this document. Please review these documents 75 carefully, as they describe your rights and restrictions with respect 76 to this document. Code Components extracted from this document must 77 include Simplified BSD License text as described in Section 4.e of 78 the Trust Legal Provisions and are provided without warranty as 79 described in the Simplified BSD License. 81 This document may contain material from IETF Documents or IETF 82 Contributions published or made publicly available before November 83 10, 2008. The person(s) controlling the copyright in some of this 84 material may not have granted the IETF Trust the right to allow 85 modifications of such material outside the IETF Standards Process. 86 Without obtaining an adequate license from the person(s) controlling 87 the copyright in such materials, this document may not be modified 88 outside the IETF Standards Process, and derivative works of it may 89 not be created outside the IETF Standards Process, except to format 90 it for publication as an RFC or to translate it into languages other 91 than English. 93 Table of Contents 95 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 96 1.1. Conformance and Error Handling . . . . . . . . . . . . . . 4 97 1.2. Syntax Notation . . . . . . . . . . . . . . . . . . . . . 4 98 1.2.1. Core Rules . . . . . . . . . . . . . . . . . . . . . . 5 99 2. Access Authentication Framework . . . . . . . . . . . . . . . 5 100 2.1. Challenge and Response . . . . . . . . . . . . . . . . . . 5 101 2.2. Protection Space (Realm) . . . . . . . . . . . . . . . . . 7 102 2.3. Authentication Scheme Registry . . . . . . . . . . . . . . 7 103 2.3.1. Considerations for New Authentication Schemes . . . . 8 104 3. Status Code Definitions . . . . . . . . . . . . . . . . . . . 9 105 3.1. 401 Unauthorized . . . . . . . . . . . . . . . . . . . . . 9 106 3.2. 407 Proxy Authentication Required . . . . . . . . . . . . 9 107 4. Header Field Definitions . . . . . . . . . . . . . . . . . . . 9 108 4.1. Authorization . . . . . . . . . . . . . . . . . . . . . . 9 109 4.2. Proxy-Authenticate . . . . . . . . . . . . . . . . . . . . 10 110 4.3. Proxy-Authorization . . . . . . . . . . . . . . . . . . . 11 111 4.4. WWW-Authenticate . . . . . . . . . . . . . . . . . . . . . 11 112 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 113 5.1. Authenticaton Scheme Registry . . . . . . . . . . . . . . 12 114 5.2. Status Code Registration . . . . . . . . . . . . . . . . . 12 115 5.3. Header Field Registration . . . . . . . . . . . . . . . . 12 116 6. Security Considerations . . . . . . . . . . . . . . . . . . . 12 117 6.1. Authentication Credentials and Idle Clients . . . . . . . 13 118 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13 119 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13 120 8.1. Normative References . . . . . . . . . . . . . . . . . . . 13 121 8.2. Informative References . . . . . . . . . . . . . . . . . . 14 122 Appendix A. Changes from RFCs 2616 and 2617 . . . . . . . . . . . 14 123 Appendix B. Collected ABNF . . . . . . . . . . . . . . . . . . . 15 124 Appendix C. Change Log (to be removed by RFC Editor before 125 publication) . . . . . . . . . . . . . . . . . . . . 16 126 C.1. Since RFC 2616 . . . . . . . . . . . . . . . . . . . . . . 16 127 C.2. Since draft-ietf-httpbis-p7-auth-00 . . . . . . . . . . . 16 128 C.3. Since draft-ietf-httpbis-p7-auth-01 . . . . . . . . . . . 16 129 C.4. Since draft-ietf-httpbis-p7-auth-02 . . . . . . . . . . . 16 130 C.5. Since draft-ietf-httpbis-p7-auth-03 . . . . . . . . . . . 16 131 C.6. Since draft-ietf-httpbis-p7-auth-04 . . . . . . . . . . . 16 132 C.7. Since draft-ietf-httpbis-p7-auth-05 . . . . . . . . . . . 17 133 C.8. Since draft-ietf-httpbis-p7-auth-06 . . . . . . . . . . . 17 134 C.9. Since draft-ietf-httpbis-p7-auth-07 . . . . . . . . . . . 17 135 C.10. Since draft-ietf-httpbis-p7-auth-08 . . . . . . . . . . . 17 136 C.11. Since draft-ietf-httpbis-p7-auth-09 . . . . . . . . . . . 17 137 C.12. Since draft-ietf-httpbis-p7-auth-10 . . . . . . . . . . . 17 138 C.13. Since draft-ietf-httpbis-p7-auth-11 . . . . . . . . . . . 17 139 C.14. Since draft-ietf-httpbis-p7-auth-12 . . . . . . . . . . . 18 140 C.15. Since draft-ietf-httpbis-p7-auth-13 . . . . . . . . . . . 18 141 C.16. Since draft-ietf-httpbis-p7-auth-14 . . . . . . . . . . . 18 142 C.17. Since draft-ietf-httpbis-p7-auth-15 . . . . . . . . . . . 18 143 C.18. Since draft-ietf-httpbis-p7-auth-16 . . . . . . . . . . . 19 144 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 146 1. Introduction 148 This document defines HTTP/1.1 access control and authentication. It 149 includes the relevant parts of RFC 2616 with only minor changes, plus 150 the general framework for HTTP authentication, as previously defined 151 in "HTTP Authentication: Basic and Digest Access Authentication" 152 ([RFC2617]). 154 HTTP provides several OPTIONAL challenge-response authentication 155 mechanisms which can be used by a server to challenge a client 156 request and by a client to provide authentication information. The 157 "basic" and "digest" authentication schemes continue to be specified 158 in RFC 2617. 160 1.1. Conformance and Error Handling 162 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 163 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 164 document are to be interpreted as described in [RFC2119]. 166 This document defines conformance criteria for several roles in HTTP 167 communication, including Senders, Recipients, Clients, Servers, User- 168 Agents, Origin Servers, Intermediaries, Proxies and Gateways. See 169 Section 2 of [Part1] for definitions of these terms. 171 An implementation is considered conformant if it complies with all of 172 the requirements associated with its role(s). Note that SHOULD-level 173 requirements are relevant here, unless one of the documented 174 exceptions is applicable. 176 This document also uses ABNF to define valid protocol elements 177 (Section 1.2). In addition to the prose requirements placed upon 178 them, Senders MUST NOT generate protocol elements that are invalid. 180 Unless noted otherwise, Recipients MAY take steps to recover a usable 181 protocol element from an invalid construct. However, HTTP does not 182 define specific error handling mechanisms, except in cases where it 183 has direct impact on security. This is because different uses of the 184 protocol require different error handling strategies; for example, a 185 Web browser may wish to transparently recover from a response where 186 the Location header field doesn't parse according to the ABNF, 187 whereby in a systems control protocol using HTTP, this type of error 188 recovery could lead to dangerous consequences. 190 1.2. Syntax Notation 192 This specification uses the ABNF syntax defined in Section 1.2 of 193 [Part1] (which extends the syntax defined in [RFC5234] with a list 194 rule). Appendix B shows the collected ABNF, with the list rule 195 expanded. 197 The following core rules are included by reference, as defined in 198 [RFC5234], Appendix B.1: ALPHA (letters), CR (carriage return), CRLF 199 (CR LF), CTL (controls), DIGIT (decimal 0-9), DQUOTE (double quote), 200 HEXDIG (hexadecimal 0-9/A-F/a-f), LF (line feed), OCTET (any 8-bit 201 sequence of data), SP (space), and VCHAR (any visible US-ASCII 202 character). 204 1.2.1. Core Rules 206 The core rules below are defined in [Part1]: 208 BWS = 209 OWS = 210 quoted-string = 211 token = 213 2. Access Authentication Framework 215 2.1. Challenge and Response 217 HTTP provides a simple challenge-response authentication mechanism 218 that can be used by a server to challenge a client request and by a 219 client to provide authentication information. It uses an extensible, 220 case-insensitive token to identify the authentication scheme, 221 followed by additional information necessary for achieving 222 authentication via that scheme. The latter can either be a comma- 223 separated list of attribute-value pairs or a single sequence of 224 characters capable of holding base64-encoded information. 226 auth-scheme = token 228 auth-param = token BWS "=" BWS ( token / quoted-string ) 230 b64token = 1*( ALPHA / DIGIT / 231 "-" / "." / "_" / "~" / "+" / "/" ) *"=" 233 The "b64token" syntax allows the 66 unreserved URI characters 234 ([RFC3986]), plus a few others, so that it can hold a base64, 235 base64url (URL and filename safe alphabet), base32, or base16 (hex) 236 encoding, with or without padding, but excluding whitespace 237 ([RFC4648]). 239 The 401 (Unauthorized) response message is used by an origin server 240 to challenge the authorization of a user agent. This response MUST 241 include a WWW-Authenticate header field containing at least one 242 challenge applicable to the requested resource. 244 The 407 (Proxy Authentication Required) response message is used by a 245 proxy to challenge the authorization of a client and MUST include a 246 Proxy-Authenticate header field containing at least one challenge 247 applicable to the proxy for the requested resource. 249 challenge = auth-scheme [ 1*SP ( b64token / #auth-param ) ] 251 Note: User agents will need to take special care in parsing the 252 WWW-Authenticate and Proxy-Authenticate header field values 253 because they can contain more than one challenge, or if more than 254 one of each is provided, since the contents of a challenge can 255 itself contain a comma-separated list of authentication 256 parameters. 258 Note: Many browsers fail to parse challenges containing unknown 259 schemes. A workaround for this problem is to list well-supported 260 schemes (such as "basic") first. 262 A user agent that wishes to authenticate itself with an origin server 263 -- usually, but not necessarily, after receiving a 401 (Unauthorized) 264 -- MAY do so by including an Authorization header field with the 265 request. 267 A client that wishes to authenticate itself with a proxy -- usually, 268 but not necessarily, after receiving a 407 (Proxy Authentication 269 Required) -- MAY do so by including a Proxy-Authorization header 270 field with the request. 272 Both the Authorization field value and the Proxy-Authorization field 273 value consist of credentials containing the authentication 274 information of the client for the realm of the resource being 275 requested. The user agent MUST choose to use one of the challenges 276 with the strongest auth-scheme it understands and request credentials 277 from the user based upon that challenge. 279 credentials = auth-scheme [ 1*SP ( b64token / #auth-param ) ] 281 If the origin server does not wish to accept the credentials sent 282 with a request, it SHOULD return a 401 (Unauthorized) response. The 283 response MUST include a WWW-Authenticate header field containing at 284 least one (possibly new) challenge applicable to the requested 285 resource. 287 If a proxy does not accept the credentials sent with a request, it 288 SHOULD return a 407 (Proxy Authentication Required). The response 289 MUST include a Proxy-Authenticate header field containing a (possibly 290 new) challenge applicable to the proxy for the requested resource. 292 The HTTP protocol does not restrict applications to this simple 293 challenge-response mechanism for access authentication. Additional 294 mechanisms MAY be used, such as encryption at the transport level or 295 via message encapsulation, and with additional header fields 296 specifying authentication information. However, such additional 297 mechanisms are not defined by this specification. 299 Proxies MUST forward the WWW-Authenticate and Authorization headers 300 unmodified and follow the rules found in Section 4.1. 302 2.2. Protection Space (Realm) 304 The authentication parameter realm is reserved for use by 305 authentication schemes that wish to indicate the scope of protection: 307 realm = "realm" BWS "=" BWS realm-value 308 realm-value = quoted-string 310 A protection space is defined by the canonical root URI (the scheme 311 and authority components of the effective request URI; see Section 312 4.3 of [Part1]) of the server being accessed, in combination with the 313 realm value if present. These realms allow the protected resources 314 on a server to be partitioned into a set of protection spaces, each 315 with its own authentication scheme and/or authorization database. 316 The realm value is a string, generally assigned by the origin server, 317 which can have additional semantics specific to the authentication 318 scheme. Note that there can be multiple challenges with the same 319 auth-scheme but different realms. 321 The protection space determines the domain over which credentials can 322 be automatically applied. If a prior request has been authorized, 323 the same credentials MAY be reused for all other requests within that 324 protection space for a period of time determined by the 325 authentication scheme, parameters, and/or user preference. Unless 326 otherwise defined by the authentication scheme, a single protection 327 space cannot extend outside the scope of its server. 329 2.3. Authentication Scheme Registry 331 The HTTP Authentication Scheme Registry defines the name space for 332 the authentication schemes in challenges and credentials. 334 Registrations MUST include the following fields: 336 o Authentication Scheme Name 337 o Pointer to specification text 339 o Notes (optional) 341 Values to be added to this name space are subject to IETF review 342 ([RFC5226], Section 4.1). 344 The registry itself is maintained at 345 . 347 2.3.1. Considerations for New Authentication Schemes 349 There are certain aspects of the HTTP Authentication Framework that 350 put constraints on how new authentication schemes can work: 352 o Authentication schemes need to be compatible with the inherent 353 constraints of HTTP; for instance, that messages need to keep 354 their semantics when inspected in isolation, thus an 355 authentication scheme can not bind information to the TCP session 356 over which the message was received (see Section 2.2 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 Authentication schemes need to document whether they are usable in 382 origin-server authentication (i.e., using WWW-Authenticate), 383 and/or proxy authentication (i.e., using Proxy-Authenticate). 385 o The credentials carried in an Authorization header field are 386 specific to the User Agent, and therefore have the same effect on 387 HTTP caches as the "private" Cache-Control response directive, 388 within the scope of the request they appear in. 390 Therefore, new authentication schemes which choose not to carry 391 credentials in the Authorization header (e.g., using a newly 392 defined header) will need to explicitly disallow caching, by 393 mandating the use of either Cache-Control request directives 394 (e.g., "no-store") or response directives (e.g., "private"). 396 3. Status Code Definitions 398 3.1. 401 Unauthorized 400 The request requires user authentication. The response MUST include 401 a WWW-Authenticate header field (Section 4.4) containing a challenge 402 applicable to the target resource. The client MAY repeat the request 403 with a suitable Authorization header field (Section 4.1). If the 404 request already included Authorization credentials, then the 401 405 response indicates that authorization has been refused for those 406 credentials. If the 401 response contains the same challenge as the 407 prior response, and the user agent has already attempted 408 authentication at least once, then the user SHOULD be presented the 409 representation that was given in the response, since that 410 representation might include relevant diagnostic information. 412 3.2. 407 Proxy Authentication Required 414 This code is similar to 401 (Unauthorized), but indicates that the 415 client ought to first authenticate itself with the proxy. The proxy 416 MUST return a Proxy-Authenticate header field (Section 4.2) 417 containing a challenge applicable to the proxy for the target 418 resource. The client MAY repeat the request with a suitable Proxy- 419 Authorization header field (Section 4.3). 421 4. Header Field Definitions 423 This section defines the syntax and semantics of HTTP/1.1 header 424 fields related to authentication. 426 4.1. Authorization 428 The "Authorization" header field allows a user agent to authenticate 429 itself with a server -- usually, but not necessarily, after receiving 430 a 401 (Unauthorized) response. Its value consists of credentials 431 containing information of the user agent for the realm of the 432 resource being requested. 434 Authorization = credentials 436 If a request is authenticated and a realm specified, the same 437 credentials SHOULD be valid for all other requests within this realm 438 (assuming that the authentication scheme itself does not require 439 otherwise, such as credentials that vary according to a challenge 440 value or using synchronized clocks). 442 When a shared cache (see Section 1.2 of [Part6]) receives a request 443 containing an Authorization field, it MUST NOT return the 444 corresponding response as a reply to any other request, unless one of 445 the following specific exceptions holds: 447 1. If the response includes the "s-maxage" cache-control directive, 448 the cache MAY use that response in replying to a subsequent 449 request. But (if the specified maximum age has passed) a proxy 450 cache MUST first revalidate it with the origin server, using the 451 header fields from the new request to allow the origin server to 452 authenticate the new request. (This is the defined behavior for 453 s-maxage.) If the response includes "s-maxage=0", the proxy MUST 454 always revalidate it before re-using it. 456 2. If the response includes the "must-revalidate" cache-control 457 directive, the cache MAY use that response in replying to a 458 subsequent request. But if the response is stale, all caches 459 MUST first revalidate it with the origin server, using the header 460 fields from the new request to allow the origin server to 461 authenticate the new request. 463 3. If the response includes the "public" cache-control directive, it 464 MAY be returned in reply to any subsequent request. 466 4.2. Proxy-Authenticate 468 The "Proxy-Authenticate" header field consists of a challenge that 469 indicates the authentication scheme and parameters applicable to the 470 proxy for this effective request URI (Section 4.3 of [Part1]). It 471 MUST be included as part of a 407 (Proxy Authentication Required) 472 response. 474 Proxy-Authenticate = 1#challenge 476 Unlike WWW-Authenticate, the Proxy-Authenticate header field applies 477 only to the current connection and SHOULD NOT be passed on to 478 downstream clients. However, an intermediate proxy might need to 479 obtain its own credentials by requesting them from the downstream 480 client, which in some circumstances will appear as if the proxy is 481 forwarding the Proxy-Authenticate header field. 483 4.3. Proxy-Authorization 485 The "Proxy-Authorization" header field allows the client to identify 486 itself (or its user) to a proxy which requires authentication. Its 487 value consists of credentials containing the authentication 488 information of the user agent for the proxy and/or realm of the 489 resource being requested. 491 Proxy-Authorization = credentials 493 Unlike Authorization, the Proxy-Authorization header field applies 494 only to the next outbound proxy that demanded authentication using 495 the Proxy-Authenticate field. When multiple proxies are used in a 496 chain, the Proxy-Authorization header field is consumed by the first 497 outbound proxy that was expecting to receive credentials. A proxy 498 MAY relay the credentials from the client request to the next proxy 499 if that is the mechanism by which the proxies cooperatively 500 authenticate a given request. 502 4.4. WWW-Authenticate 504 The "WWW-Authenticate" header field consists of at least one 505 challenge that indicates the authentication scheme(s) and parameters 506 applicable to the effective request URI (Section 4.3 of [Part1]). 508 It MUST be included in 401 (Unauthorized) response messages and MAY 509 be included in other response messages to indicate that supplying 510 credentials (or different credentials) might affect the response. 512 WWW-Authenticate = 1#challenge 514 User agents are advised to take special care in parsing the WWW- 515 Authenticate field value as it might contain more than one challenge, 516 or if more than one WWW-Authenticate header field is provided, the 517 contents of a challenge itself can contain a comma-separated list of 518 authentication parameters. 520 For instance: 522 WWW-Authenticate: Newauth realm="apps", type=1, 523 title="Login to \"apps\"", Basic realm="simple" 525 This header field contains two challenges; one for the "Newauth" 526 scheme with a realm value of "apps", and two additional parameters 527 "type" and "title", and another one for the "Basic" scheme with a 528 realm value of "simple". 530 5. IANA Considerations 532 5.1. Authenticaton Scheme Registry 534 The registration procedure for HTTP Authentication Schemes is defined 535 by Section 2.3 of this document. 537 The HTTP Method Authentication Scheme shall be created at 538 . 540 5.2. Status Code Registration 542 The HTTP Status Code Registry located at 543 shall be updated 544 with the registrations below: 546 +-------+-------------------------------+-------------+ 547 | Value | Description | Reference | 548 +-------+-------------------------------+-------------+ 549 | 401 | Unauthorized | Section 3.1 | 550 | 407 | Proxy Authentication Required | Section 3.2 | 551 +-------+-------------------------------+-------------+ 553 5.3. Header Field Registration 555 The Message Header Field Registry located at shall be 557 updated with the permanent registrations below (see [RFC3864]): 559 +---------------------+----------+----------+-------------+ 560 | Header Field Name | Protocol | Status | Reference | 561 +---------------------+----------+----------+-------------+ 562 | Authorization | http | standard | Section 4.1 | 563 | Proxy-Authenticate | http | standard | Section 4.2 | 564 | Proxy-Authorization | http | standard | Section 4.3 | 565 | WWW-Authenticate | http | standard | Section 4.4 | 566 +---------------------+----------+----------+-------------+ 568 The change controller is: "IETF (iesg@ietf.org) - Internet 569 Engineering Task Force". 571 6. Security Considerations 573 This section is meant to inform application developers, information 574 providers, and users of the security limitations in HTTP/1.1 as 575 described by this document. The discussion does not include 576 definitive solutions to the problems revealed, though it does make 577 some suggestions for reducing security risks. 579 6.1. Authentication Credentials and Idle Clients 581 Existing HTTP clients and user agents typically retain authentication 582 information indefinitely. HTTP/1.1 does not provide a method for a 583 server to direct clients to discard these cached credentials. This 584 is a significant defect that requires further extensions to HTTP. 585 Circumstances under which credential caching can interfere with the 586 application's security model include but are not limited to: 588 o Clients which have been idle for an extended period following 589 which the server might wish to cause the client to reprompt the 590 user for credentials. 592 o Applications which include a session termination indication (such 593 as a "logout" or "commit" button on a page) after which the server 594 side of the application "knows" that there is no further reason 595 for the client to retain the credentials. 597 This is currently under separate study. There are a number of work- 598 arounds to parts of this problem, and we encourage the use of 599 password protection in screen savers, idle time-outs, and other 600 methods which mitigate the security problems inherent in this 601 problem. In particular, user agents which cache credentials are 602 encouraged to provide a readily accessible mechanism for discarding 603 cached credentials under user control. 605 7. Acknowledgments 607 This specification takes over the definition of the HTTP 608 Authentication Framework, previously defined in RFC 2617. We thank 609 John Franks, Phillip M. Hallam-Baker, Jeffery L. Hostetler, Scott D. 610 Lawrence, Paul J. Leach, Ari Luotonen, and Lawrence C. Stewart for 611 their work on that specification. See Section 6 of [RFC2617] for 612 further acknowledgements. 614 See Section 11 of [Part1] for the Acknowledgments related to this 615 document revision. 617 8. References 619 8.1. Normative References 621 [Part1] Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H., 622 Masinter, L., Leach, P., Berners-Lee, T., Lafon, Y., Ed., 623 and J. Reschke, Ed., "HTTP/1.1, part 1: URIs, Connections, 624 and Message Parsing", draft-ietf-httpbis-p1-messaging-17 625 (work in progress), October 2011. 627 [Part6] Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H., 628 Masinter, L., Leach, P., Berners-Lee, T., Lafon, Y., Ed., 629 Nottingham, M., Ed., and J. Reschke, Ed., "HTTP/1.1, part 630 6: Caching", draft-ietf-httpbis-p6-cache-17 (work in 631 progress), October 2011. 633 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 634 Requirement Levels", BCP 14, RFC 2119, March 1997. 636 [RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax 637 Specifications: ABNF", STD 68, RFC 5234, January 2008. 639 8.2. Informative References 641 [RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., 642 Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext 643 Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999. 645 [RFC2617] Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S., 646 Leach, P., Luotonen, A., and L. Stewart, "HTTP 647 Authentication: Basic and Digest Access Authentication", 648 RFC 2617, June 1999. 650 [RFC3864] Klyne, G., Nottingham, M., and J. Mogul, "Registration 651 Procedures for Message Header Fields", BCP 90, RFC 3864, 652 September 2004. 654 [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform 655 Resource Identifier (URI): Generic Syntax", STD 66, 656 RFC 3986, January 2005. 658 [RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data 659 Encodings", RFC 4648, October 2006. 661 [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an 662 IANA Considerations Section in RFCs", BCP 26, RFC 5226, 663 May 2008. 665 Appendix A. Changes from RFCs 2616 and 2617 667 The "realm" parameter isn't required anymore in general; 668 consequently, the ABNF allows challenges without any auth parameters. 669 (Section 2) 671 The "b64token" alternative to auth-param lists has been added for 672 consistency with legacy authentication schemes such as "Basic". 673 (Section 2) 674 Change ABNF productions for header fields to only define the field 675 value. (Section 4) 677 Appendix B. Collected ABNF 679 Authorization = credentials 681 BWS = 683 OWS = 685 Proxy-Authenticate = *( "," OWS ) challenge *( OWS "," [ OWS 686 challenge ] ) 687 Proxy-Authorization = credentials 689 WWW-Authenticate = *( "," OWS ) challenge *( OWS "," [ OWS challenge 690 ] ) 692 auth-param = token BWS "=" BWS ( token / quoted-string ) 693 auth-scheme = token 695 b64token = 1*( ALPHA / DIGIT / "-" / "." / "_" / "~" / "+" / "/" ) 696 *"=" 698 challenge = auth-scheme [ 1*SP ( b64token / [ ( "," / auth-param ) *( 699 OWS "," [ OWS auth-param ] ) ] ) ] 700 credentials = auth-scheme [ 1*SP ( b64token / [ ( "," / auth-param ) 701 *( OWS "," [ OWS auth-param ] ) ] ) ] 703 quoted-string = 705 realm = "realm" BWS "=" BWS realm-value 706 realm-value = quoted-string 708 token = 710 ABNF diagnostics: 712 ; Authorization defined but not used 713 ; Proxy-Authenticate defined but not used 714 ; Proxy-Authorization defined but not used 715 ; WWW-Authenticate defined but not used 716 ; realm defined but not used 718 Appendix C. Change Log (to be removed by RFC Editor before publication) 720 C.1. Since RFC 2616 722 Extracted relevant partitions from [RFC2616]. 724 C.2. Since draft-ietf-httpbis-p7-auth-00 726 Closed issues: 728 o : "Normative and 729 Informative references" 731 C.3. Since draft-ietf-httpbis-p7-auth-01 733 Ongoing work on ABNF conversion 734 (): 736 o Explicitly import BNF rules for "challenge" and "credentials" from 737 RFC2617. 739 o Add explicit references to BNF syntax and rules imported from 740 other parts of the specification. 742 C.4. Since draft-ietf-httpbis-p7-auth-02 744 Ongoing work on IANA Message Header Field Registration 745 (): 747 o Reference RFC 3984, and update header field registrations for 748 header fields defined in this document. 750 C.5. Since draft-ietf-httpbis-p7-auth-03 752 None. 754 C.6. Since draft-ietf-httpbis-p7-auth-04 756 Ongoing work on ABNF conversion 757 (): 759 o Use "/" instead of "|" for alternatives. 761 o Introduce new ABNF rules for "bad" whitespace ("BWS"), optional 762 whitespace ("OWS") and required whitespace ("RWS"). 764 o Rewrite ABNFs to spell out whitespace rules, factor out header 765 field value format definitions. 767 C.7. Since draft-ietf-httpbis-p7-auth-05 769 Final work on ABNF conversion 770 (): 772 o Add appendix containing collected and expanded ABNF, reorganize 773 ABNF introduction. 775 C.8. Since draft-ietf-httpbis-p7-auth-06 777 None. 779 C.9. Since draft-ietf-httpbis-p7-auth-07 781 Closed issues: 783 o : "move IANA 784 registrations for optional status codes" 786 C.10. Since draft-ietf-httpbis-p7-auth-08 788 No significant changes. 790 C.11. Since draft-ietf-httpbis-p7-auth-09 792 Partly resolved issues: 794 o : "Term for the 795 requested resource's URI" 797 C.12. Since draft-ietf-httpbis-p7-auth-10 799 None. 801 C.13. Since draft-ietf-httpbis-p7-auth-11 803 Closed issues: 805 o : "introduction 806 to part 7 is work-in-progress" 808 o : "auth-param 809 syntax" 811 o : "Header 812 Classification" 814 o : "absorbing the 815 auth framework from 2617" 817 Partly resolved issues: 819 o : "should we 820 have an auth scheme registry" 822 C.14. Since draft-ietf-httpbis-p7-auth-12 824 None. 826 C.15. Since draft-ietf-httpbis-p7-auth-13 828 Closed issues: 830 o : "untangle 831 ABNFs for header fields" 833 C.16. Since draft-ietf-httpbis-p7-auth-14 835 None. 837 C.17. Since draft-ietf-httpbis-p7-auth-15 839 Closed issues: 841 o : "Relationship 842 between 401, Authorization and WWW-Authenticate" 844 o : "Realm 845 required on challenges" 847 o : "auth-param 848 syntax" 850 o : 851 "Considerations for new authentications schemes" 853 o : "LWS in auth- 854 param ABNF" 856 o : "credentials 857 ABNF missing SP (still using implied LWS?)" 859 C.18. Since draft-ietf-httpbis-p7-auth-16 861 Closed issues: 863 o : "Document 864 HTTP's error-handling philosophy" 866 o : "add advice on 867 defining auth scheme parameters" 869 Index 871 4 872 401 Unauthorized (status code) 9 873 407 Proxy Authentication Required (status code) 9 875 A 876 auth-param 5 877 auth-scheme 5 878 Authorization header field 9 880 B 881 b64token 5 883 C 884 challenge 6 885 credentials 6 887 G 888 Grammar 889 auth-param 5 890 auth-scheme 5 891 Authorization 10 892 b64token 5 893 challenge 6 894 credentials 6 895 Proxy-Authenticate 10 896 Proxy-Authorization 11 897 realm 7 898 WWW-Authenticate 11 900 H 901 Header Fields 902 Authorization 9 903 Proxy-Authenticate 10 904 Proxy-Authorization 11 905 WWW-Authenticate 11 907 P 908 Protection Space 7 909 Proxy-Authenticate header field 10 910 Proxy-Authorization header field 11 912 R 913 Realm 7 914 realm 7 915 realm-value 7 917 S 918 Status Codes 919 401 Unauthorized 9 920 407 Proxy Authentication Required 9 922 W 923 WWW-Authenticate header field 11 925 Authors' Addresses 927 Roy T. Fielding (editor) 928 Adobe Systems Incorporated 929 345 Park Ave 930 San Jose, CA 95110 931 USA 933 EMail: fielding@gbiv.com 934 URI: http://roy.gbiv.com/ 936 Jim Gettys 937 Alcatel-Lucent Bell Labs 938 21 Oak Knoll Road 939 Carlisle, MA 01741 940 USA 942 EMail: jg@freedesktop.org 943 URI: http://gettys.wordpress.com/ 944 Jeffrey C. Mogul 945 Hewlett-Packard Company 946 HP Labs, Large Scale Systems Group 947 1501 Page Mill Road, MS 1177 948 Palo Alto, CA 94304 949 USA 951 EMail: JeffMogul@acm.org 953 Henrik Frystyk Nielsen 954 Microsoft Corporation 955 1 Microsoft Way 956 Redmond, WA 98052 957 USA 959 EMail: henrikn@microsoft.com 961 Larry Masinter 962 Adobe Systems Incorporated 963 345 Park Ave 964 San Jose, CA 95110 965 USA 967 EMail: LMM@acm.org 968 URI: http://larry.masinter.net/ 970 Paul J. Leach 971 Microsoft Corporation 972 1 Microsoft Way 973 Redmond, WA 98052 975 EMail: paulle@microsoft.com 977 Tim Berners-Lee 978 World Wide Web Consortium 979 MIT Computer Science and Artificial Intelligence Laboratory 980 The Stata Center, Building 32 981 32 Vassar Street 982 Cambridge, MA 02139 983 USA 985 EMail: timbl@w3.org 986 URI: http://www.w3.org/People/Berners-Lee/ 987 Yves Lafon (editor) 988 World Wide Web Consortium 989 W3C / ERCIM 990 2004, rte des Lucioles 991 Sophia-Antipolis, AM 06902 992 France 994 EMail: ylafon@w3.org 995 URI: http://www.raubacapeu.net/people/yves/ 997 Julian F. Reschke (editor) 998 greenbytes GmbH 999 Hafenweg 16 1000 Muenster, NW 48155 1001 Germany 1003 Phone: +49 251 2807760 1004 Fax: +49 251 2807761 1005 EMail: julian.reschke@greenbytes.de 1006 URI: http://greenbytes.de/tech/webdav/