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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 1 SIPPING G. Camarillo 2 Internet-Draft Ericsson 3 Intended status: Standards Track April 24, 2007 4 Expires: October 26, 2007 6 A Document Format for Requesting Consent 7 draft-ietf-sipping-consent-format-03.txt 9 Status of this Memo 11 By submitting this Internet-Draft, each author represents that any 12 applicable patent or other IPR claims of which he or she is aware 13 have been or will be disclosed, and any of which he or she becomes 14 aware will be disclosed, in accordance with Section 6 of BCP 79. 16 Internet-Drafts are working documents of the Internet Engineering 17 Task Force (IETF), its areas, and its working groups. Note that 18 other groups may also distribute working documents as Internet- 19 Drafts. 21 Internet-Drafts are draft documents valid for a maximum of six months 22 and may be updated, replaced, or obsoleted by other documents at any 23 time. It is inappropriate to use Internet-Drafts as reference 24 material or to cite them other than as "work in progress." 26 The list of current Internet-Drafts can be accessed at 27 http://www.ietf.org/ietf/1id-abstracts.txt. 29 The list of Internet-Draft Shadow Directories can be accessed at 30 http://www.ietf.org/shadow.html. 32 This Internet-Draft will expire on October 26, 2007. 34 Copyright Notice 36 Copyright (C) The IETF Trust (2007). 38 Abstract 40 This document defines an Extensible Markup Language (XML) format for 41 a permission document used to request consent. A permission document 42 written in this format is used by a relay to request a specific 43 recipient permission to perform a particular routing translation. 45 Table of Contents 47 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 48 2. Definitions and Terminology . . . . . . . . . . . . . . . . . 3 49 3. Permission Document Structure . . . . . . . . . . . . . . . . 3 50 3.1. Conditions . . . . . . . . . . . . . . . . . . . . . . . . 4 51 3.1.1. Identity Condition . . . . . . . . . . . . . . . . . . 4 52 3.1.2. Sender Condition . . . . . . . . . . . . . . . . . . . 5 53 3.1.3. Target Condition . . . . . . . . . . . . . . . . . . . 7 54 3.2. Actions . . . . . . . . . . . . . . . . . . . . . . . . . 7 55 3.2.1. Translation Handling . . . . . . . . . . . . . . . . . 7 56 4. Example Document . . . . . . . . . . . . . . . . . . . . . . . 7 57 5. XML Schema . . . . . . . . . . . . . . . . . . . . . . . . . . 8 58 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 59 6.1. XML Namespace Registration . . . . . . . . . . . . . . . . 9 60 6.2. XML Schema Registration . . . . . . . . . . . . . . . . . 10 61 7. Security Considerations . . . . . . . . . . . . . . . . . . . 10 62 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11 63 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11 64 9.1. Normative References . . . . . . . . . . . . . . . . . . . 11 65 9.2. Informative References . . . . . . . . . . . . . . . . . . 12 66 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 12 67 Intellectual Property and Copyright Statements . . . . . . . . . . 13 69 1. Introduction 71 The framework for consent-based communications in the Session 72 Initiation Protocol (SIP) [9] identifies the need for a format to 73 create permission documents. Such permission documents are used by 74 SIP [3] relays to request permission to perform translations. A 75 relay is defined as any SIP server, be it a proxy, B2BUA (Back-to- 76 Back User Agent), or some hybrid, which receives a request and 77 translates the request URI into one or more next hop URIs to which it 78 then delivers a request. 80 The format for permission documents specified in this document is 81 based on the XML document format for expressing Privacy Preferences 82 [8]. 84 2. Definitions and Terminology 86 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 87 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 88 document are to be interpreted as described in RFC 2119 [1]. 90 Relay: Any SIP server, be it a proxy, B2BUA (Back-to-Back User 91 Agent), or some hybrid, that receives a request, translates its 92 Request-URI into one or more next-hop URIs (i.e., recipient URIs), 93 and delivers the request to those URIs. 95 Recipient URI: The Request-URI of an outgoing request sent by an 96 entity (e.g., a user agent or a proxy). The sending of such 97 request may have been the result of a translation operation. 99 Target URI: The Request-URI of an incoming request that arrives to 100 an entity (e.g., a proxy) that will perform a translation 101 operation. 103 Translation operation: Operation by which an entity (e.g., a proxy) 104 translates the request URI of an incoming request (i.e., the 105 target URI) into one or more URIs (i.e., recipient URIs) which are 106 used as the request URIs of one or more outgoing requests. 108 3. Permission Document Structure 110 A permission document is an XML document, formatted according to the 111 schema defined in [8]. Permission documents inherit the MIME type of 112 common policy documents, 'application/auth-policy+xml'. As described 113 in [8], this type of document is composed of three parts: conditions, 114 actions, and transformations. However, even though permission 115 documents need to have a transformation part to comply to the common 116 policy syntax, effectively, permission documents do not make any use 117 of transformations. 119 This section defines the new conditions and actions defined by this 120 specification. This specification does not define any new 121 transformation. 123 3.1. Conditions 125 Note that, as discussed in [8], a permission document applies to a 126 translation if all the expressions in its conditions part evaluate to 127 TRUE. 129 3.1.1. Identity Condition 131 The identity condition, defined in [8], is matched against the 132 recipient URI of a translation. 134 When performing a translation, a relay matches the identity condition 135 of the permission document that was used to request permission for 136 that translation against the destination URI of the outgoing request. 137 When receiving a request granting or denying permissions (e.g., a SIP 138 PUBLISH request as described in [9]), the relay matches the identity 139 condition of the permission document that was used to request 140 permission against the identity of the entity granting or denying 141 permissions (i.e., the sender of the PUBLISH request). 143 The element is defined in [8], which indicates that the 144 specific usages of the framework document need to define details that 145 are protocol and usage specific. In particular, this section defines 146 acceptable means of authentication. 148 The 'id' attribute in the elements and MUST contain a 149 scheme when these elements appear in a permission document. 151 When used with SIP, a recipient granting or denying a relay 152 permissions is considered authenticated if one of the following 153 techniques is used: 155 SIP Identity [7], as described in [9]. For PUBLISH requests that 156 are authenticated using the SIP Identity mechanism, the identity 157 of the sender of the PUBLISH request is equal to the SIP URI in 158 the From header field of the request, assuming that the signature 159 in the Identity header field has been validated. 161 P-Asserted-Identity [5], as described in [9]. For PUBLISH requests 162 that are authenticated using the P-Asserted-Identity mechanism, 163 the identity of the sender of the PUBLISH request is equal to the 164 P-Asserted-Identity header field of the request. 166 Return Routability Test, as described in [9]. 168 SIP digest, as described in [9]. 170 3.1.2. Sender Condition 172 The sender condition is matched against the URI of the sender of the 173 request that is used as input for a translation. Sender conditions 174 can contain the same elements and attributes as identity conditions. 176 When performing a translation, a relay matches the sender condition 177 against the identity of the sender of the incoming request. 179 The following subsections define acceptable means of authentication, 180 the procedure for representing the identity of the sender as a URI, 181 and the procedure for converting an identifier of the form 182 user@domain, present in the 'id' attribute of the and 183 elements, into a URI. 185 3.1.2.1. Acceptable Means of Authentication 187 When used with SIP, a request sent by a sender is considered 188 authenticated if one of the following techniques is used: 190 SIP Digest: the relay authenticates the sender using SIP digest 191 authentication [2]. However, if the anonymous authentication 192 described on page 194 of RFC 3261 [3] is used, the sender is not 193 considered authenticated. 195 Asserted Identity: if a request contains a P-Asserted-ID header 196 field [5] and the request is coming from a trusted element, the 197 sender is considered authenticated. 199 Cryptographically Verified Identity: if a request contains an 200 Identity header field as defined in [7], and it validates the From 201 header field of the request, the request is considered to be 202 authenticated. Note that this is true even if the request 203 contained a From header field of the form 204 sip:anonymous@example.com. As long as the signature verifies that 205 the request legitimately came from this identity, it is considered 206 authenticated. 208 3.1.2.2. Computing a URI for the Sender 210 For requests that are authenticated using SIP Digest, the identity of 211 the sender is set equal to the SIP Address of Record (AOR) for the 212 user that has authenticated themselves. For example, consider the 213 following "user record" in a database: 215 SIP AOR: sip:alice@example.com 216 digest username: ali 217 digest password: f779ajvvh8a6s6 218 digest realm: example.com 220 If the relay receives a request, challenges it with the realm set to 221 "example.com", and the subsequent request contains an Authorization 222 header field with a username of "ali" and a digest response generated 223 with the password "f779ajvvh8a6s6", the identity used in matching 224 operations is "sip:alice@example.com". 226 For requests that are authenticated using RFC 3325 [5], the identity 227 of the sender is equal to the SIP URI in the P-Asserted-ID header 228 field. If there are multiple values for the P-Asserted-ID header 229 field (there can be one sip URI and one tel URI [10]), then each of 230 them is used for the comparisons outlined in [8], and if either of 231 them match a or element, it is considered a match. 233 For requests that are authenticated using the SIP Identity mechanism 234 [7], identity of the sender is equal to the SIP URI in the From 235 header field of the request, assuming that the signature in the 236 Identity header field has been validated. 238 SIP also allows for anonymous requests. If a request is anonymous 239 because the digest challenge/response used the "anonymous" username, 240 the request is considered unauthenticated and will not match the 241 condition. If a request is anonymous because it contains a 242 Privacy header field [4], but still contains a P-Asserted-ID header 243 field, the identity in the P-Asserted-ID header field is still used 244 in the authorization computations; the fact that the request was 245 anonymous has no impact on the identity processing. However, if the 246 request had traversed a trust boundary and the P-Asserted-ID header 247 field and the Privacy header field had been removed, the request will 248 be considered unauthenticated when it arrives at the presence server, 249 and thus not match the condition. Finally, if a request 250 contained an Identity header field that was validated, and the From 251 header field contained a URI of the form sip:anonymous@example.com, 252 then the watcher is considered authenticated, and it will have an 253 identity equal to sip:anonymous@example.com. Had such an identity 254 been placed into a or element, there will be a match. 256 3.1.2.3. Computing a SIP URI from the id Attribute 258 If the or condition does not contain a scheme, 259 conversion of the value in the 'id' attribute to a SIP URI is done 260 trivially. If the characters in the 'id' attribute are valid 261 characters for the user and hostpart components of the SIP URI, a 262 'sip:' is appended to the contents of the 'id' attribute, and the 263 result is the SIP URI. If the characters in the 'id' attribute are 264 not valid for the user and hostpart components of the SIP URI, 265 conversion is not possible. This happens, for example, when the user 266 portion of the 'id' attribute contain UTF-8 characters. 268 3.1.3. Target Condition 270 The target condition is matched against the target URI of a 271 translation. Target conditions can contain the same elements and 272 attributes as identity conditions. 274 When performing a translation, a relay matches the target condition 275 against the destination of the incoming request, which is typically 276 contained in the Request-URI. 278 3.2. Actions 280 The actions in a permission document provide URIs to grant or deny 281 permission to perform the translation described in the document. 283 3.2.1. Translation Handling 285 The provides URIs for a recipient to grant or deny 286 the relay permission to perform a translation. The defined values 287 are: 289 deny: this action tells the relay not to perform the translation. 291 grant: this action tells the server to perform the translation. 293 The 'perm-uri' attribute in the element provides a 294 URI to grant or deny permission to perform a translation. 296 4. Example Document 298 The following permission document is generated by the relay handling 299 'sip:alices-friends@example.com' in order to ask for permission to 300 relay requests sent to that URI to 'sip:bob@example.org'. 302 303 309 310 311 312 313 314 315 316 317 318 319 320 321 322 grant 324 deny 326 327 328 329 331 5. XML Schema 332 333 341 342 343 345 346 347 348 349 350 351 353 354 355 356 357 359 360 361 362 364 366 6. IANA Considerations 368 This section registers a new XML namespace and a new XML schema per 369 the procedures in [6]. 371 6.1. XML Namespace Registration 373 URI: urn:ietf:params:xml:ns:consent-rules 375 Registrant Contact: IETF SIPPING working group, 376 , Gonzalo Camarillo 377 378 XML: 380 BEGIN 381 382 384 385 386 388 Consent Rules Namespace 389 390 391

Namespace for Permission Documents

392

urn:ietf:params:xml:ns:consent-rules

393

See RFCXXXX 394 [NOTE TO IANA/RFC-EDITOR: 395 Please replace XXXX with the RFC number of this 396 specification.].

397 398 399 END 401 6.2. XML Schema Registration 403 URI: urn:ietf:params:xml:schema:consent-rules 405 Registrant Contact: IETF SIPPING working group, 406 , Gonzalo Camarillo 407 409 XML: The XML schema to be registered is contained in Section 5. 411 7. Security Considerations 413 Permission documents can reveal sensitive information. Additionally, 414 attackers may attempt to modify them in order to have clients grant 415 or deny permissions different to the ones they think are granting or 416 denying. For this reason, it is RECOMMENDED that relays use strong 417 means for information integrity protection and confidentiality when 418 sending permission documents to clients. 420 The mechanism used for conveying information to clients SHOULD ensure 421 the integrity and confidentially of the information. In order to 422 achieve these, an end-to-end SIP encryption mechanism, such as 423 S/MIME, as described in RFC 3261 [3], SHOULD be used. 425 If strong end-to-end security means (such as above) is not available, 426 it is RECOMMENDED that hop-by-hop security based on TLS and SIPS 427 URIs, as described in [3], is used. 429 8. Acknowledgements 431 Jonathan Rosenberg provided useful ideas on this document. Ben 432 Campbell and Mary Barnes performed a thorough review of this 433 document. 435 9. References 437 9.1. Normative References 439 [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement 440 Levels", BCP 14, RFC 2119, March 1997. 442 [2] Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S., 443 Leach, P., Luotonen, A., and L. Stewart, "HTTP Authentication: 444 Basic and Digest Access Authentication", RFC 2617, June 1999. 446 [3] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., 447 Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP: 448 Session Initiation Protocol", RFC 3261, June 2002. 450 [4] Peterson, J., "A Privacy Mechanism for the Session Initiation 451 Protocol (SIP)", RFC 3323, November 2002. 453 [5] Jennings, C., Peterson, J., and M. Watson, "Private Extensions 454 to the Session Initiation Protocol (SIP) for Asserted Identity 455 within Trusted Networks", RFC 3325, November 2002. 457 [6] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, 458 January 2004. 460 [7] Peterson, J. and C. Jennings, "Enhancements for Authenticated 461 Identity Management in the Session Initiation Protocol (SIP)", 462 RFC 4474, August 2006. 464 [8] Schulzrinne, H., Tschofenig, H., Morris, J., Cuellar, J., Polk, 465 J., and J. Rosenberg, "Common Policy: A Document Format for 466 Expressing Privacy Preferences", RFC 4745, February 2007. 468 [9] Rosenberg, J., "A Framework for Consent-Based Communications in 469 the Session Initiation Protocol (SIP)", 470 draft-ietf-sip-consent-framework-01 (work in progress), 471 November 2006. 473 9.2. Informative References 475 [10] Schulzrinne, H., "The tel URI for Telephone Numbers", RFC 3966, 476 December 2004. 478 Author's Address 480 Gonzalo Camarillo 481 Ericsson 482 Hirsalantie 11 483 Jorvas 02420 484 Finland 486 Email: Gonzalo.Camarillo@ericsson.com 488 Full Copyright Statement 490 Copyright (C) The IETF Trust (2007). 492 This document is subject to the rights, licenses and restrictions 493 contained in BCP 78, and except as set forth therein, the authors 494 retain all their rights. 496 This document and the information contained herein are provided on an 497 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS 498 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND 499 THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS 500 OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF 501 THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED 502 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 504 Intellectual Property 506 The IETF takes no position regarding the validity or scope of any 507 Intellectual Property Rights or other rights that might be claimed to 508 pertain to the implementation or use of the technology described in 509 this document or the extent to which any license under such rights 510 might or might not be available; nor does it represent that it has 511 made any independent effort to identify any such rights. 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