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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: July 7, 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 January 4, 2012 22 HTTP/1.1, part 7: Authentication 23 draft-ietf-httpbis-p7-auth-18 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.19. 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 July 7, 2012. 66 Copyright Notice 68 Copyright (c) 2012 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 . . . . . . . . . . . . . . . . . . . . . . . . . 5 96 1.1. Conformance and Error Handling . . . . . . . . . . . . . . 5 97 1.2. Syntax Notation . . . . . . . . . . . . . . . . . . . . . 5 98 1.2.1. Core Rules . . . . . . . . . . . . . . . . . . . . . . 6 99 2. Access Authentication Framework . . . . . . . . . . . . . . . 6 100 2.1. Challenge and Response . . . . . . . . . . . . . . . . . . 6 101 2.2. Protection Space (Realm) . . . . . . . . . . . . . . . . . 8 102 2.3. Authentication Scheme Registry . . . . . . . . . . . . . . 8 103 2.3.1. Considerations for New Authentication Schemes . . . . 9 104 3. Status Code Definitions . . . . . . . . . . . . . . . . . . . 10 105 3.1. 401 Unauthorized . . . . . . . . . . . . . . . . . . . . . 10 106 3.2. 407 Proxy Authentication Required . . . . . . . . . . . . 10 107 4. Header Field Definitions . . . . . . . . . . . . . . . . . . . 10 108 4.1. Authorization . . . . . . . . . . . . . . . . . . . . . . 11 109 4.2. Proxy-Authenticate . . . . . . . . . . . . . . . . . . . . 11 110 4.3. Proxy-Authorization . . . . . . . . . . . . . . . . . . . 12 111 4.4. WWW-Authenticate . . . . . . . . . . . . . . . . . . . . . 12 112 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 113 5.1. Authenticaton Scheme Registry . . . . . . . . . . . . . . 13 114 5.2. Status Code Registration . . . . . . . . . . . . . . . . . 13 115 5.3. Header Field Registration . . . . . . . . . . . . . . . . 13 116 6. Security Considerations . . . . . . . . . . . . . . . . . . . 14 117 6.1. Authentication Credentials and Idle Clients . . . . . . . 14 118 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 14 119 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 15 120 8.1. Normative References . . . . . . . . . . . . . . . . . . . 15 121 8.2. Informative References . . . . . . . . . . . . . . . . . . 15 122 Appendix A. Changes from RFCs 2616 and 2617 . . . . . . . . . . . 16 123 Appendix B. Collected ABNF . . . . . . . . . . . . . . . . . . . 16 124 Appendix C. Change Log (to be removed by RFC Editor before 125 publication) . . . . . . . . . . . . . . . . . . . . 17 126 C.1. Since RFC 2616 . . . . . . . . . . . . . . . . . . . . . . 17 127 C.2. Since draft-ietf-httpbis-p7-auth-00 . . . . . . . . . . . 17 128 C.3. Since draft-ietf-httpbis-p7-auth-01 . . . . . . . . . . . 17 129 C.4. Since draft-ietf-httpbis-p7-auth-02 . . . . . . . . . . . 17 130 C.5. Since draft-ietf-httpbis-p7-auth-03 . . . . . . . . . . . 17 131 C.6. Since draft-ietf-httpbis-p7-auth-04 . . . . . . . . . . . 17 132 C.7. Since draft-ietf-httpbis-p7-auth-05 . . . . . . . . . . . 18 133 C.8. Since draft-ietf-httpbis-p7-auth-06 . . . . . . . . . . . 18 134 C.9. Since draft-ietf-httpbis-p7-auth-07 . . . . . . . . . . . 18 135 C.10. Since draft-ietf-httpbis-p7-auth-08 . . . . . . . . . . . 18 136 C.11. Since draft-ietf-httpbis-p7-auth-09 . . . . . . . . . . . 18 137 C.12. Since draft-ietf-httpbis-p7-auth-10 . . . . . . . . . . . 18 138 C.13. Since draft-ietf-httpbis-p7-auth-11 . . . . . . . . . . . 18 139 C.14. Since draft-ietf-httpbis-p7-auth-12 . . . . . . . . . . . 19 140 C.15. Since draft-ietf-httpbis-p7-auth-13 . . . . . . . . . . . 19 141 C.16. Since draft-ietf-httpbis-p7-auth-14 . . . . . . . . . . . 19 142 C.17. Since draft-ietf-httpbis-p7-auth-15 . . . . . . . . . . . 19 143 C.18. Since draft-ietf-httpbis-p7-auth-16 . . . . . . . . . . . 20 144 C.19. Since draft-ietf-httpbis-p7-auth-17 . . . . . . . . . . . 20 146 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 148 1. Introduction 150 This document defines HTTP/1.1 access control and authentication. It 151 includes the relevant parts of RFC 2616 with only minor changes, plus 152 the general framework for HTTP authentication, as previously defined 153 in "HTTP Authentication: Basic and Digest Access Authentication" 154 ([RFC2617]). 156 HTTP provides several OPTIONAL challenge-response authentication 157 mechanisms which can be used by a server to challenge a client 158 request and by a client to provide authentication information. The 159 "basic" and "digest" authentication schemes continue to be specified 160 in RFC 2617. 162 1.1. Conformance and Error Handling 164 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 165 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 166 document are to be interpreted as described in [RFC2119]. 168 This document defines conformance criteria for several roles in HTTP 169 communication, including Senders, Recipients, Clients, Servers, User- 170 Agents, Origin Servers, Intermediaries, Proxies and Gateways. See 171 Section 2 of [Part1] for definitions of these terms. 173 An implementation is considered conformant if it complies with all of 174 the requirements associated with its role(s). Note that SHOULD-level 175 requirements are relevant here, unless one of the documented 176 exceptions is applicable. 178 This document also uses ABNF to define valid protocol elements 179 (Section 1.2). In addition to the prose requirements placed upon 180 them, Senders MUST NOT generate protocol elements that are invalid. 182 Unless noted otherwise, Recipients MAY take steps to recover a usable 183 protocol element from an invalid construct. However, HTTP does not 184 define specific error handling mechanisms, except in cases where it 185 has direct impact on security. This is because different uses of the 186 protocol require different error handling strategies; for example, a 187 Web browser may wish to transparently recover from a response where 188 the Location header field doesn't parse according to the ABNF, 189 whereby in a systems control protocol using HTTP, this type of error 190 recovery could lead to dangerous consequences. 192 1.2. Syntax Notation 194 This specification uses the ABNF syntax defined in Section 1.2 of 195 [Part1] (which extends the syntax defined in [RFC5234] with a list 196 rule). Appendix B shows the collected ABNF, with the list rule 197 expanded. 199 The following core rules are included by reference, as defined in 200 [RFC5234], Appendix B.1: ALPHA (letters), CR (carriage return), CRLF 201 (CR LF), CTL (controls), DIGIT (decimal 0-9), DQUOTE (double quote), 202 HEXDIG (hexadecimal 0-9/A-F/a-f), LF (line feed), OCTET (any 8-bit 203 sequence of data), SP (space), and VCHAR (any visible US-ASCII 204 character). 206 1.2.1. Core Rules 208 The core rules below are defined in [Part1]: 210 BWS = 211 OWS = 212 quoted-string = 213 token = 215 2. Access Authentication Framework 217 2.1. Challenge and Response 219 HTTP provides a simple challenge-response authentication mechanism 220 that can be used by a server to challenge a client request and by a 221 client to provide authentication information. It uses an extensible, 222 case-insensitive token to identify the authentication scheme, 223 followed by additional information necessary for achieving 224 authentication via that scheme. The latter can either be a comma- 225 separated list of parameters or a single sequence of characters 226 capable of holding base64-encoded information. 228 Parameters are name-value pairs where the name is matched case- 229 insensitively, and each parameter name MUST only occur once per 230 challenge. 232 auth-scheme = token 234 auth-param = token BWS "=" BWS ( token / quoted-string ) 236 b64token = 1*( ALPHA / DIGIT / 237 "-" / "." / "_" / "~" / "+" / "/" ) *"=" 239 The "b64token" syntax allows the 66 unreserved URI characters 240 ([RFC3986]), plus a few others, so that it can hold a base64, 241 base64url (URL and filename safe alphabet), base32, or base16 (hex) 242 encoding, with or without padding, but excluding whitespace 243 ([RFC4648]). 245 The 401 (Unauthorized) response message is used by an origin server 246 to challenge the authorization of a user agent. This response MUST 247 include a WWW-Authenticate header field containing at least one 248 challenge applicable to the requested resource. 250 The 407 (Proxy Authentication Required) response message is used by a 251 proxy to challenge the authorization of a client and MUST include a 252 Proxy-Authenticate header field containing at least one challenge 253 applicable to the proxy for the requested resource. 255 challenge = auth-scheme [ 1*SP ( b64token / #auth-param ) ] 257 Note: User agents will need to take special care in parsing the 258 WWW-Authenticate and Proxy-Authenticate header field values 259 because they can contain more than one challenge, or if more than 260 one of each is provided, since the contents of a challenge can 261 itself contain a comma-separated list of authentication 262 parameters. 264 Note: Many browsers fail to parse challenges containing unknown 265 schemes. A workaround for this problem is to list well-supported 266 schemes (such as "basic") first. 268 A user agent that wishes to authenticate itself with an origin server 269 -- usually, but not necessarily, after receiving a 401 (Unauthorized) 270 -- MAY do so by including an Authorization header field with the 271 request. 273 A client that wishes to authenticate itself with a proxy -- usually, 274 but not necessarily, after receiving a 407 (Proxy Authentication 275 Required) -- MAY do so by including a Proxy-Authorization header 276 field with the request. 278 Both the Authorization field value and the Proxy-Authorization field 279 value consist of credentials containing the authentication 280 information of the client for the realm of the resource being 281 requested. The user agent MUST choose to use one of the challenges 282 with the strongest auth-scheme it understands and request credentials 283 from the user based upon that challenge. 285 credentials = auth-scheme [ 1*SP ( b64token / #auth-param ) ] 287 If the origin server does not wish to accept the credentials sent 288 with a request, it SHOULD return a 401 (Unauthorized) response. The 289 response MUST include a WWW-Authenticate header field containing at 290 least one (possibly new) challenge applicable to the requested 291 resource. 293 If a proxy does not accept the credentials sent with a request, it 294 SHOULD return a 407 (Proxy Authentication Required). The response 295 MUST include a Proxy-Authenticate header field containing a (possibly 296 new) challenge applicable to the proxy for the requested resource. 298 The HTTP protocol does not restrict applications to this simple 299 challenge-response mechanism for access authentication. Additional 300 mechanisms MAY be used, such as encryption at the transport level or 301 via message encapsulation, and with additional header fields 302 specifying authentication information. However, such additional 303 mechanisms are not defined by this specification. 305 Proxies MUST forward the WWW-Authenticate and Authorization headers 306 unmodified and follow the rules found in Section 4.1. 308 2.2. Protection Space (Realm) 310 The authentication parameter realm is reserved for use by 311 authentication schemes that wish to indicate the scope of protection. 313 A protection space is defined by the canonical root URI (the scheme 314 and authority components of the effective request URI; see Section 315 4.3 of [Part1]) of the server being accessed, in combination with the 316 realm value if present. These realms allow the protected resources 317 on a server to be partitioned into a set of protection spaces, each 318 with its own authentication scheme and/or authorization database. 319 The realm value is a string, generally assigned by the origin server, 320 which can have additional semantics specific to the authentication 321 scheme. Note that there can be multiple challenges with the same 322 auth-scheme but different realms. 324 The protection space determines the domain over which credentials can 325 be automatically applied. If a prior request has been authorized, 326 the same credentials MAY be reused for all other requests within that 327 protection space for a period of time determined by the 328 authentication scheme, parameters, and/or user preference. Unless 329 otherwise defined by the authentication scheme, a single protection 330 space cannot extend outside the scope of its server. 332 For historical reasons, senders MUST only use the quoted-string 333 syntax. Recipients might have to support both token and quoted- 334 string syntax for maximum interoperability with existing clients that 335 have been accepting both notations for a long time. 337 2.3. Authentication Scheme Registry 339 The HTTP Authentication Scheme Registry defines the name space for 340 the authentication schemes in challenges and credentials. 342 Registrations MUST include the following fields: 344 o Authentication Scheme Name 346 o Pointer to specification text 348 o Notes (optional) 350 Values to be added to this name space are subject to IETF review 351 ([RFC5226], Section 4.1). 353 The registry itself is maintained at 354 . 356 2.3.1. Considerations for New Authentication Schemes 358 There are certain aspects of the HTTP Authentication Framework that 359 put constraints on how new authentication schemes can work: 361 o Authentication schemes need to be compatible with the inherent 362 constraints of HTTP; for instance, that messages need to keep 363 their semantics when inspected in isolation, thus an 364 authentication scheme can not bind information to the TCP session 365 over which the message was received (see Section 2.2 of [Part1]). 367 o The authentication parameter "realm" is reserved for defining 368 Protection Spaces as defined in Section 2.2. New schemes MUST NOT 369 use it in a way incompatible with that definition. 371 o The "b64token" notation was introduced for compatibility with 372 existing authentication schemes and can only be used once per 373 challenge/credentials. New schemes thus ought to use the "auth- 374 param" syntax instead, because otherwise future extensions will be 375 impossible. 377 o The parsing of challenges and credentials is defined by this 378 specification, and cannot be modified by new authentication 379 schemes. When the auth-param syntax is used, all parameters ought 380 to support both token and quoted-string syntax, and syntactical 381 constraints ought to be defined on the field value after parsing 382 (i.e., quoted-string processing). This is necessary so that 383 recipients can use a generic parser that applies to all 384 authentication schemes. 386 Note: the fact that the value syntax for the "realm" parameter is 387 restricted to quoted-string was a bad design choice not to be 388 repeated for new parameters. 390 o Authentication schemes need to document whether they are usable in 391 origin-server authentication (i.e., using WWW-Authenticate), 392 and/or proxy authentication (i.e., using Proxy-Authenticate). 394 o The credentials carried in an Authorization header field are 395 specific to the User Agent, and therefore have the same effect on 396 HTTP caches as the "private" Cache-Control response directive, 397 within the scope of the request they appear in. 399 Therefore, new authentication schemes which choose not to carry 400 credentials in the Authorization header (e.g., using a newly 401 defined header) will need to explicitly disallow caching, by 402 mandating the use of either Cache-Control request directives 403 (e.g., "no-store") or response directives (e.g., "private"). 405 3. Status Code Definitions 407 3.1. 401 Unauthorized 409 The request requires user authentication. The response MUST include 410 a WWW-Authenticate header field (Section 4.4) containing a challenge 411 applicable to the target resource. The client MAY repeat the request 412 with a suitable Authorization header field (Section 4.1). If the 413 request already included Authorization credentials, then the 401 414 response indicates that authorization has been refused for those 415 credentials. If the 401 response contains the same challenge as the 416 prior response, and the user agent has already attempted 417 authentication at least once, then the user SHOULD be presented the 418 representation that was given in the response, since that 419 representation might include relevant diagnostic information. 421 3.2. 407 Proxy Authentication Required 423 This code is similar to 401 (Unauthorized), but indicates that the 424 client ought to first authenticate itself with the proxy. The proxy 425 MUST return a Proxy-Authenticate header field (Section 4.2) 426 containing a challenge applicable to the proxy for the target 427 resource. The client MAY repeat the request with a suitable Proxy- 428 Authorization header field (Section 4.3). 430 4. Header Field Definitions 432 This section defines the syntax and semantics of HTTP/1.1 header 433 fields related to authentication. 435 4.1. Authorization 437 The "Authorization" header field allows a user agent to authenticate 438 itself with a server -- usually, but not necessarily, after receiving 439 a 401 (Unauthorized) response. Its value consists of credentials 440 containing information of the user agent for the realm of the 441 resource being requested. 443 Authorization = credentials 445 If a request is authenticated and a realm specified, the same 446 credentials SHOULD be valid for all other requests within this realm 447 (assuming that the authentication scheme itself does not require 448 otherwise, such as credentials that vary according to a challenge 449 value or using synchronized clocks). 451 When a shared cache (see Section 1.2 of [Part6]) receives a request 452 containing an Authorization field, it MUST NOT return the 453 corresponding response as a reply to any other request, unless one of 454 the following specific exceptions holds: 456 1. If the response includes the "s-maxage" cache-control directive, 457 the cache MAY use that response in replying to a subsequent 458 request. But (if the specified maximum age has passed) a proxy 459 cache MUST first revalidate it with the origin server, using the 460 header fields from the new request to allow the origin server to 461 authenticate the new request. (This is the defined behavior for 462 s-maxage.) If the response includes "s-maxage=0", the proxy MUST 463 always revalidate it before re-using it. 465 2. If the response includes the "must-revalidate" cache-control 466 directive, the cache MAY use that response in replying to a 467 subsequent request. But if the response is stale, all caches 468 MUST first revalidate it with the origin server, using the header 469 fields from the new request to allow the origin server to 470 authenticate the new request. 472 3. If the response includes the "public" cache-control directive, it 473 MAY be returned in reply to any subsequent request. 475 4.2. Proxy-Authenticate 477 The "Proxy-Authenticate" header field consists of a challenge that 478 indicates the authentication scheme and parameters applicable to the 479 proxy for this effective request URI (Section 4.3 of [Part1]). It 480 MUST be included as part of a 407 (Proxy Authentication Required) 481 response. 483 Proxy-Authenticate = 1#challenge 485 Unlike WWW-Authenticate, the Proxy-Authenticate header field applies 486 only to the current connection and SHOULD NOT be passed on to 487 downstream clients. However, an intermediate proxy might need to 488 obtain its own credentials by requesting them from the downstream 489 client, which in some circumstances will appear as if the proxy is 490 forwarding the Proxy-Authenticate header field. 492 4.3. Proxy-Authorization 494 The "Proxy-Authorization" header field allows the client to identify 495 itself (or its user) to a proxy which requires authentication. Its 496 value consists of credentials containing the authentication 497 information of the user agent for the proxy and/or realm of the 498 resource being requested. 500 Proxy-Authorization = credentials 502 Unlike Authorization, the Proxy-Authorization header field applies 503 only to the next outbound proxy that demanded authentication using 504 the Proxy-Authenticate field. When multiple proxies are used in a 505 chain, the Proxy-Authorization header field is consumed by the first 506 outbound proxy that was expecting to receive credentials. A proxy 507 MAY relay the credentials from the client request to the next proxy 508 if that is the mechanism by which the proxies cooperatively 509 authenticate a given request. 511 4.4. WWW-Authenticate 513 The "WWW-Authenticate" header field consists of at least one 514 challenge that indicates the authentication scheme(s) and parameters 515 applicable to the effective request URI (Section 4.3 of [Part1]). 517 It MUST be included in 401 (Unauthorized) response messages and MAY 518 be included in other response messages to indicate that supplying 519 credentials (or different credentials) might affect the response. 521 WWW-Authenticate = 1#challenge 523 User agents are advised to take special care in parsing the WWW- 524 Authenticate field value as it might contain more than one challenge, 525 or if more than one WWW-Authenticate header field is provided, the 526 contents of a challenge itself can contain a comma-separated list of 527 authentication parameters. 529 For instance: 531 WWW-Authenticate: Newauth realm="apps", type=1, 532 title="Login to \"apps\"", Basic realm="simple" 534 This header field contains two challenges; one for the "Newauth" 535 scheme with a realm value of "apps", and two additional parameters 536 "type" and "title", and another one for the "Basic" scheme with a 537 realm value of "simple". 539 5. IANA Considerations 541 5.1. Authenticaton Scheme Registry 543 The registration procedure for HTTP Authentication Schemes is defined 544 by Section 2.3 of this document. 546 The HTTP Method Authentication Scheme shall be created at 547 . 549 5.2. Status Code Registration 551 The HTTP Status Code Registry located at 552 shall be updated 553 with the registrations below: 555 +-------+-------------------------------+-------------+ 556 | Value | Description | Reference | 557 +-------+-------------------------------+-------------+ 558 | 401 | Unauthorized | Section 3.1 | 559 | 407 | Proxy Authentication Required | Section 3.2 | 560 +-------+-------------------------------+-------------+ 562 5.3. Header Field Registration 564 The Message Header Field Registry located at shall be 566 updated with the permanent registrations below (see [RFC3864]): 568 +---------------------+----------+----------+-------------+ 569 | Header Field Name | Protocol | Status | Reference | 570 +---------------------+----------+----------+-------------+ 571 | Authorization | http | standard | Section 4.1 | 572 | Proxy-Authenticate | http | standard | Section 4.2 | 573 | Proxy-Authorization | http | standard | Section 4.3 | 574 | WWW-Authenticate | http | standard | Section 4.4 | 575 +---------------------+----------+----------+-------------+ 576 The change controller is: "IETF (iesg@ietf.org) - Internet 577 Engineering Task Force". 579 6. Security Considerations 581 This section is meant to inform application developers, information 582 providers, and users of the security limitations in HTTP/1.1 as 583 described by this document. The discussion does not include 584 definitive solutions to the problems revealed, though it does make 585 some suggestions for reducing security risks. 587 6.1. Authentication Credentials and Idle Clients 589 Existing HTTP clients and user agents typically retain authentication 590 information indefinitely. HTTP/1.1 does not provide a method for a 591 server to direct clients to discard these cached credentials. This 592 is a significant defect that requires further extensions to HTTP. 593 Circumstances under which credential caching can interfere with the 594 application's security model include but are not limited to: 596 o Clients which have been idle for an extended period following 597 which the server might wish to cause the client to reprompt the 598 user for credentials. 600 o Applications which include a session termination indication (such 601 as a "logout" or "commit" button on a page) after which the server 602 side of the application "knows" that there is no further reason 603 for the client to retain the credentials. 605 This is currently under separate study. There are a number of work- 606 arounds to parts of this problem, and we encourage the use of 607 password protection in screen savers, idle time-outs, and other 608 methods which mitigate the security problems inherent in this 609 problem. In particular, user agents which cache credentials are 610 encouraged to provide a readily accessible mechanism for discarding 611 cached credentials under user control. 613 7. Acknowledgments 615 This specification takes over the definition of the HTTP 616 Authentication Framework, previously defined in RFC 2617. We thank 617 John Franks, Phillip M. Hallam-Baker, Jeffery L. Hostetler, Scott D. 618 Lawrence, Paul J. Leach, Ari Luotonen, and Lawrence C. Stewart for 619 their work on that specification. See Section 6 of [RFC2617] for 620 further acknowledgements. 622 See Section 11 of [Part1] for the Acknowledgments related to this 623 document revision. 625 8. References 627 8.1. Normative References 629 [Part1] Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H., 630 Masinter, L., Leach, P., Berners-Lee, T., Lafon, Y., Ed., 631 and J. Reschke, Ed., "HTTP/1.1, part 1: URIs, Connections, 632 and Message Parsing", draft-ietf-httpbis-p1-messaging-18 633 (work in progress), January 2012. 635 [Part6] Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H., 636 Masinter, L., Leach, P., Berners-Lee, T., Lafon, Y., Ed., 637 Nottingham, M., Ed., and J. Reschke, Ed., "HTTP/1.1, part 638 6: Caching", draft-ietf-httpbis-p6-cache-18 (work in 639 progress), January 2012. 641 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 642 Requirement Levels", BCP 14, RFC 2119, March 1997. 644 [RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax 645 Specifications: ABNF", STD 68, RFC 5234, January 2008. 647 8.2. Informative References 649 [RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., 650 Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext 651 Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999. 653 [RFC2617] Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S., 654 Leach, P., Luotonen, A., and L. Stewart, "HTTP 655 Authentication: Basic and Digest Access Authentication", 656 RFC 2617, June 1999. 658 [RFC3864] Klyne, G., Nottingham, M., and J. Mogul, "Registration 659 Procedures for Message Header Fields", BCP 90, RFC 3864, 660 September 2004. 662 [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform 663 Resource Identifier (URI): Generic Syntax", STD 66, 664 RFC 3986, January 2005. 666 [RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data 667 Encodings", RFC 4648, October 2006. 669 [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an 670 IANA Considerations Section in RFCs", BCP 26, RFC 5226, 671 May 2008. 673 Appendix A. Changes from RFCs 2616 and 2617 675 The "realm" parameter isn't required anymore in general; 676 consequently, the ABNF allows challenges without any auth parameters. 677 (Section 2) 679 The "b64token" alternative to auth-param lists has been added for 680 consistency with legacy authentication schemes such as "Basic". 681 (Section 2) 683 Change ABNF productions for header fields to only define the field 684 value. (Section 4) 686 Appendix B. Collected ABNF 688 Authorization = credentials 690 BWS = 692 OWS = 694 Proxy-Authenticate = *( "," OWS ) challenge *( OWS "," [ OWS 695 challenge ] ) 696 Proxy-Authorization = credentials 698 WWW-Authenticate = *( "," OWS ) challenge *( OWS "," [ OWS challenge 699 ] ) 701 auth-param = token BWS "=" BWS ( token / quoted-string ) 702 auth-scheme = token 704 b64token = 1*( ALPHA / DIGIT / "-" / "." / "_" / "~" / "+" / "/" ) 705 *"=" 707 challenge = auth-scheme [ 1*SP ( b64token / [ ( "," / auth-param ) *( 708 OWS "," [ OWS auth-param ] ) ] ) ] 709 credentials = auth-scheme [ 1*SP ( b64token / [ ( "," / auth-param ) 710 *( OWS "," [ OWS auth-param ] ) ] ) ] 712 quoted-string = 714 token = 715 ABNF diagnostics: 717 ; Authorization defined but not used 718 ; Proxy-Authenticate defined but not used 719 ; Proxy-Authorization defined but not used 720 ; WWW-Authenticate defined but not used 722 Appendix C. Change Log (to be removed by RFC Editor before publication) 724 C.1. Since RFC 2616 726 Extracted relevant partitions from [RFC2616]. 728 C.2. Since draft-ietf-httpbis-p7-auth-00 730 Closed issues: 732 o : "Normative and 733 Informative references" 735 C.3. Since draft-ietf-httpbis-p7-auth-01 737 Ongoing work on ABNF conversion 738 (): 740 o Explicitly import BNF rules for "challenge" and "credentials" from 741 RFC2617. 743 o Add explicit references to BNF syntax and rules imported from 744 other parts of the specification. 746 C.4. Since draft-ietf-httpbis-p7-auth-02 748 Ongoing work on IANA Message Header Field Registration 749 (): 751 o Reference RFC 3984, and update header field registrations for 752 header fields defined in this document. 754 C.5. Since draft-ietf-httpbis-p7-auth-03 756 None. 758 C.6. Since draft-ietf-httpbis-p7-auth-04 760 Ongoing work on ABNF conversion 761 (): 763 o Use "/" instead of "|" for alternatives. 765 o Introduce new ABNF rules for "bad" whitespace ("BWS"), optional 766 whitespace ("OWS") and required whitespace ("RWS"). 768 o Rewrite ABNFs to spell out whitespace rules, factor out header 769 field value format definitions. 771 C.7. Since draft-ietf-httpbis-p7-auth-05 773 Final work on ABNF conversion 774 (): 776 o Add appendix containing collected and expanded ABNF, reorganize 777 ABNF introduction. 779 C.8. Since draft-ietf-httpbis-p7-auth-06 781 None. 783 C.9. Since draft-ietf-httpbis-p7-auth-07 785 Closed issues: 787 o : "move IANA 788 registrations for optional status codes" 790 C.10. Since draft-ietf-httpbis-p7-auth-08 792 No significant changes. 794 C.11. Since draft-ietf-httpbis-p7-auth-09 796 Partly resolved issues: 798 o : "Term for the 799 requested resource's URI" 801 C.12. Since draft-ietf-httpbis-p7-auth-10 803 None. 805 C.13. Since draft-ietf-httpbis-p7-auth-11 807 Closed issues: 809 o : "introduction 810 to part 7 is work-in-progress" 812 o : "auth-param 813 syntax" 815 o : "Header 816 Classification" 818 o : "absorbing the 819 auth framework from 2617" 821 Partly resolved issues: 823 o : "should we 824 have an auth scheme registry" 826 C.14. Since draft-ietf-httpbis-p7-auth-12 828 None. 830 C.15. Since draft-ietf-httpbis-p7-auth-13 832 Closed issues: 834 o : "untangle 835 ABNFs for header fields" 837 C.16. Since draft-ietf-httpbis-p7-auth-14 839 None. 841 C.17. Since draft-ietf-httpbis-p7-auth-15 843 Closed issues: 845 o : "Relationship 846 between 401, Authorization and WWW-Authenticate" 848 o : "Realm 849 required on challenges" 851 o : "auth-param 852 syntax" 854 o : 855 "Considerations for new authentications schemes" 857 o : "LWS in auth- 858 param ABNF" 860 o : "credentials 861 ABNF missing SP (still using implied LWS?)" 863 C.18. Since draft-ietf-httpbis-p7-auth-16 865 Closed issues: 867 o : "Document 868 HTTP's error-handling philosophy" 870 o : "add advice on 871 defining auth scheme parameters" 873 C.19. Since draft-ietf-httpbis-p7-auth-17 875 Closed issues: 877 o : "allow 878 unquoted realm parameters" 880 o : "Repeating 881 auth-params" 883 Index 885 4 886 401 Unauthorized (status code) 10 887 407 Proxy Authentication Required (status code) 10 889 A 890 auth-param 6 891 auth-scheme 6 892 Authorization header field 11 894 B 895 b64token 6 897 C 898 challenge 7 899 credentials 7 901 G 902 Grammar 903 auth-param 6 904 auth-scheme 6 905 Authorization 11 906 b64token 6 907 challenge 7 908 credentials 7 909 Proxy-Authenticate 11 910 Proxy-Authorization 12 911 WWW-Authenticate 12 913 H 914 Header Fields 915 Authorization 11 916 Proxy-Authenticate 11 917 Proxy-Authorization 12 918 WWW-Authenticate 12 920 P 921 Protection Space 8 922 Proxy-Authenticate header field 11 923 Proxy-Authorization header field 12 925 R 926 Realm 8 928 S 929 Status Codes 930 401 Unauthorized 10 931 407 Proxy Authentication Required 10 933 W 934 WWW-Authenticate header field 12 936 Authors' Addresses 938 Roy T. Fielding (editor) 939 Adobe Systems Incorporated 940 345 Park Ave 941 San Jose, CA 95110 942 USA 944 EMail: fielding@gbiv.com 945 URI: http://roy.gbiv.com/ 946 Jim Gettys 947 Alcatel-Lucent Bell Labs 948 21 Oak Knoll Road 949 Carlisle, MA 01741 950 USA 952 EMail: jg@freedesktop.org 953 URI: http://gettys.wordpress.com/ 955 Jeffrey C. Mogul 956 Hewlett-Packard Company 957 HP Labs, Large Scale Systems Group 958 1501 Page Mill Road, MS 1177 959 Palo Alto, CA 94304 960 USA 962 EMail: JeffMogul@acm.org 964 Henrik Frystyk Nielsen 965 Microsoft Corporation 966 1 Microsoft Way 967 Redmond, WA 98052 968 USA 970 EMail: henrikn@microsoft.com 972 Larry Masinter 973 Adobe Systems Incorporated 974 345 Park Ave 975 San Jose, CA 95110 976 USA 978 EMail: LMM@acm.org 979 URI: http://larry.masinter.net/ 981 Paul J. Leach 982 Microsoft Corporation 983 1 Microsoft Way 984 Redmond, WA 98052 986 EMail: paulle@microsoft.com 987 Tim Berners-Lee 988 World Wide Web Consortium 989 MIT Computer Science and Artificial Intelligence Laboratory 990 The Stata Center, Building 32 991 32 Vassar Street 992 Cambridge, MA 02139 993 USA 995 EMail: timbl@w3.org 996 URI: http://www.w3.org/People/Berners-Lee/ 998 Yves Lafon (editor) 999 World Wide Web Consortium 1000 W3C / ERCIM 1001 2004, rte des Lucioles 1002 Sophia-Antipolis, AM 06902 1003 France 1005 EMail: ylafon@w3.org 1006 URI: http://www.raubacapeu.net/people/yves/ 1008 Julian F. Reschke (editor) 1009 greenbytes GmbH 1010 Hafenweg 16 1011 Muenster, NW 48155 1012 Germany 1014 Phone: +49 251 2807760 1015 Fax: +49 251 2807761 1016 EMail: julian.reschke@greenbytes.de 1017 URI: http://greenbytes.de/tech/webdav/