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(See the Legal Provisions document at https://trustee.ietf.org/license-info for more information.) -- The document date (June 2, 2007) is 6167 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 3427 (Obsoleted by RFC 5727) ** Obsolete normative reference: RFC 4234 (Obsoleted by RFC 5234) -- Possible downref: Non-RFC (?) normative reference: ref. 'IEEE.1003.1-2004' Summary: 3 errors (**), 0 flaws (~~), 2 warnings (==), 8 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 SIPPING Working Group G. Camarillo 3 Internet-Draft G. Blanco 4 Expires: December 4, 2007 Ericsson 5 June 2, 2007 7 The Session Initiation Protocol (SIP) P-Profile-Key Private Header 8 (P-Header) 9 draft-camarillo-sipping-profile-key-02.txt 11 Status of this Memo 13 By submitting this Internet-Draft, each author represents that any 14 applicable patent or other IPR claims of which he or she is aware 15 have been or will be disclosed, and any of which he or she becomes 16 aware will be disclosed, in accordance with Section 6 of BCP 79. 18 Internet-Drafts are working documents of the Internet Engineering 19 Task Force (IETF), its areas, and its working groups. Note that 20 other groups may also distribute working documents as Internet- 21 Drafts. 23 Internet-Drafts are draft documents valid for a maximum of six months 24 and may be updated, replaced, or obsoleted by other documents at any 25 time. It is inappropriate to use Internet-Drafts as reference 26 material or to cite them other than as "work in progress." 28 The list of current Internet-Drafts can be accessed at 29 http://www.ietf.org/ietf/1id-abstracts.txt. 31 The list of Internet-Draft Shadow Directories can be accessed at 32 http://www.ietf.org/shadow.html. 34 This Internet-Draft will expire on December 4, 2007. 36 Copyright Notice 38 Copyright (C) The IETF Trust (2007). 40 Abstract 42 This document specifies the SIP P-Profile-Key P-header. This header 43 field is used in the 3rd-Generation Partnership Project (3GPP) IMS 44 (IP Multimedia Subsystem) to provide SIP registrars and SIP proxy 45 servers with the key of the profile corresponding to the destination 46 SIP URI of a particular SIP request. 48 Table of Contents 50 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 51 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3 52 3. Scenario . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 53 4. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 4 54 5. P-Profile-Key header field definition . . . . . . . . . . . . . 4 55 6. Applicability . . . . . . . . . . . . . . . . . . . . . . . . . 5 56 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 57 8. Security Considerations . . . . . . . . . . . . . . . . . . . . 6 58 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6 59 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 60 10.1. Normative References . . . . . . . . . . . . . . . . . . . 6 61 10.2. Informative References . . . . . . . . . . . . . . . . . . 7 62 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7 63 Intellectual Property and Copyright Statements . . . . . . . . . . 9 65 1. Introduction 67 The 3rd-Generation Partnership Project (3GPP) IMS (IP Multimedia 68 Subsystem) uses SIP [RFC3261] as its main signalling protocol. (For 69 more information on the IMS, a detailed description can be found in 70 3GPP TS 23.228 [3GPP.23.228] and 3GPP TS 24.229 [3GPP.24.229]). 3GPP 71 has identified a set of requirements that can be met, according to 72 the procedures in [RFC3427], by defining a new SIP P-header. 74 The remainder of this document is organized as follows. Section 3 75 describes the scenario considered by 3GPP and Section 4 discusses the 76 requirements derived from this scenario. Section 5 defines the 77 P-Profile-Key header field, which meets those requirements, and 78 Section 6 discusses the applicability and scope of this new header 79 field. Section 7 registers the P-Profile-Key header field with the 80 IANA and Section 8 discusses the security properties of the 81 environment where this header field is intended to be used. 83 2. Terminology 85 HSS: Home Subscriber Server. 87 I-CSCF: Interrogating - Call/Session Control Function. 89 Public Service Identity: a SIP URI that refers to a service instead 90 of a user. 92 S-CSCF: Serving - Call/Session Control Function. 94 Wildcarded Public Service Identity: a set of Public Service 95 Identities that match a regular expression and share the same 96 profile. 98 3. Scenario 100 In the 3GPP IMS, there are scenarios where a set of proxies handling 101 a request need to consult the same user database, as described in 102 [RFC4457]. Those proxies typically use the destination SIP URI of 103 the request as the key for their database queries. Nevertheless, 104 when a proxy handles a Wildcarded Public Service Identity, the key to 105 be used in its database query is not the destination SIP URI of the 106 request, but a regular expression instead. 108 Public Service Identities are SIP URIs that refer to services instead 109 of users. That is, they address a specific application in an 110 Application Server. Wildcarded Public Service Identities are a set 111 of Public Service Identities that match a regular expression and 112 share the same profile. For example, the Public Service Identities 113 'sip:chatroom-12@example.com' and 'sip:chatroom-657@example.com' 114 would match the Wildcarded Public Service Identity 'sip:chatroom- 115 !.*!@example.com'. For a description of Wildcarded Public Service 116 Identities, see 3GPP TS 23.003 [3GPP.23.003]. 118 When a proxy queries the user database for a Public Service Identity 119 for which there is no profile in the user database, the user database 120 needs to find its matching Wildcarded Public Service Identity. For 121 example, if the user database receives a query for 122 'sip:chatroom-657@example.com', the user database needs to go through 123 all the Wildcarded Public Service Identity it has until it finds a 124 matching one; in this case, 'sip:chatroom-!.*!@example.com'. The 125 process to find a matching Wildcarded Public Service Identity can be 126 computationally expensive, time consuming, or both. 128 When two proxies query the user database for the same Public Service 129 Identity, which matches a Wildcarded Public Service Identity, the 130 user database needs to perform the matching process twice. Having to 131 perform that process twice can be avoided by having the first proxy 132 obtain the Wildcarded Public Service Identity from the user database 133 and transfer it, piggy-backed in the SIP message, to the second 134 proxy. This way, the second proxy can query the user database using 135 the Wildcarded Public Service Identity directly. 137 An alternative, but undesirable, solution would consist of having the 138 user database store every Public Service Identity and its matching 139 Wildcarded Public Service Identity. The scalability and 140 manageability properties of this approach are considerably worse than 141 those of the approach described earlier. 143 4. Requirements 145 This section lists the requirements derived from the previous 146 scenario: 148 1. It is necessary to optimize the response time for session 149 establishment in the 3GPP IMS. 150 2. It is necessary to avoid storing individual Public Service 151 Identities matching a Wildcarded Public Service Identity in the 152 user database. 154 5. P-Profile-Key header field definition 156 This document defines the SIP P-Profile-Key P-header. The P-Profile- 157 Key P-header contains the key to be used by a proxy to query the user 158 database for a given profile. 160 The augmented Backus-Naur Form (BNF) [RFC4234] syntax of the 161 P-Profile-Key header field is the following: 163 P-Profile-Key = "P-Profile-Key" HCOLON (name-addr / addr-spec) 164 *( SEMI generic-param ) 166 The format of HCOLON, name-addr, addr-spec, and generic-param are 167 defined in [RFC3261]. The format of Wildcarded Public Service 168 Identities is defined in 3GPP TS 23.003 [3GPP.23.003]. They take the 169 form of Extended Regular Expressions (ERE) as defined in Chapter 9 of 170 IEEE 1003.1-2004 Part 1 [IEEE.1003.1-2004]. 172 The following is an example of a P-Profile-Key header field that 173 contains a Wildcarded Public Service Identity: 175 P-Profile-Key: 177 6. Applicability 179 According to [RFC3427], P-headers have a limited applicability. 180 Specifications of P-headers such as this RFC need to clearly document 181 the useful scope of the proposal, and explain its limitations and why 182 it is not suitable for the general use of SIP on the Internet. 184 The P-Profile-Key header field is intended to be used in 3GPP IMS 185 networks. This header field carries the key of a service profile, 186 that is stored in a user database referred to as HSS, between two 187 proxies, which are referred to as I-CSCF and S-CSCF. The I-CSCF and 188 the S-CSCF belong to the same administrative domain and share a 189 common frame of reference to the user database. The I-CSCF inserts 190 the P-Profile-Key header field into a SIP request and the S-CSCF 191 removes it before routing the request further. (For a description of 192 how an I-CSCF and an S-CSCF query the same user database for a single 193 request, see [RFC4457].) 195 Typically, when SIP is used on the Internet, there are not multiple 196 proxies with a trust relationship between them querying the same user 197 database. Consequently, the P-Profile-Key header field does not seem 198 useful in a general Internet environment. 200 7. IANA Considerations 202 This document defines a new SIP header field: P-Profile-Key. This 203 header field needs to be registered by the IANA in the SIP Parameters 204 registry under the Header Fields subregistry. 206 8. Security Considerations 208 The P-Profile-Key defined in this document is to be used in an 209 environment where elements are trusted and where attackers are not 210 supposed to have access to the protocol messages between those 211 elements. Traffic protection between network elements is sometimes 212 achieved by using IPsec and sometimes by physically protecting the 213 network. In any case, the environment where the P-Profile-Key header 214 field will be used ensures the integrity and the confidentiality of 215 the contents of this header field. 217 The P-Profile-Key header field needs to be integrity protected to 218 keep attackers from modifying its contents. An attacker able to 219 modify the contents of this header field could make the network apply 220 a different service than the one corresponding to the request 221 carrying the P-Profile-Key header field. 223 The contents of the P-Profile-Key field need to be kept confidential. 224 An attacker able to access the contents of this header field would 225 obtain certain knowledge about the way services are structured in a 226 given domain. 228 9. Acknowledgements 230 Alf Heidermark and Timo Forsman provided input to this document. 231 Miguel Angel Gacia-Martin performed an expert review on this document 232 on behalf of the SIPPING working group. Jon Peterson provided 233 comments on this document. 235 10. References 237 10.1. Normative References 239 [3GPP.23.003] 240 3GPP, "Numbering, addressing and identification", 3GPP 241 TS 23.003 3.15.0, October 2006. 243 [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, 244 A., Peterson, J., Sparks, R., Handley, M., and E. 246 Schooler, "SIP: Session Initiation Protocol", RFC 3261, 247 June 2002. 249 [RFC3427] Mankin, A., Bradner, S., Mahy, R., Willis, D., Ott, J., 250 and B. Rosen, "Change Process for the Session Initiation 251 Protocol (SIP)", BCP 67, RFC 3427, December 2002. 253 [RFC4234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax 254 Specifications: ABNF", RFC 4234, October 2005. 256 [IEEE.1003.1-2004] 257 "Standard for information technology - portable operating 258 system interface (POSIX). Base definitions", IEEE 1003.1- 259 2004, 2004. 261 10.2. Informative References 263 [3GPP.23.228] 264 3GPP, "IP Multimedia Subsystem (IMS); Stage 2", 3GPP 265 TS 23.228 5.15.0, June 2006. 267 [3GPP.24.229] 268 3GPP, "Internet Protocol (IP) multimedia call control 269 protocol based on Session Initiation Protocol (SIP) and 270 Session Description Protocol (SDP); Stage 3", 3GPP 271 TS 24.229 5.18.0, October 2006. 273 [RFC4457] Camarillo, G. and G. Blanco, "The Session Initiation 274 Protocol (SIP) P-User-Database Private-Header (P-Header)", 275 RFC 4457, April 2006. 277 Authors' Addresses 279 Gonzalo Camarillo 280 Ericsson 281 Hirsalantie 11 282 Jorvas 02420 283 Finland 285 Email: Gonzalo.Camarillo@ericsson.com 286 German Blanco 287 Ericsson 288 Via de los Poblados 13 289 Madrid 28033 290 Spain 292 Email: German.Blanco@ericsson.com 294 Full Copyright Statement 296 Copyright (C) The IETF Trust (2007). 298 This document is subject to the rights, licenses and restrictions 299 contained in BCP 78, and except as set forth therein, the authors 300 retain all their rights. 302 This document and the information contained herein are provided on an 303 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS 304 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND 305 THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS 306 OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF 307 THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED 308 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 310 Intellectual Property 312 The IETF takes no position regarding the validity or scope of any 313 Intellectual Property Rights or other rights that might be claimed to 314 pertain to the implementation or use of the technology described in 315 this document or the extent to which any license under such rights 316 might or might not be available; nor does it represent that it has 317 made any independent effort to identify any such rights. Information 318 on the procedures with respect to rights in RFC documents can be 319 found in BCP 78 and BCP 79. 321 Copies of IPR disclosures made to the IETF Secretariat and any 322 assurances of licenses to be made available, or the result of an 323 attempt made to obtain a general license or permission for the use of 324 such proprietary rights by implementers or users of this 325 specification can be obtained from the IETF on-line IPR repository at 326 http://www.ietf.org/ipr. 328 The IETF invites any interested party to bring to its attention any 329 copyrights, patents or patent applications, or other proprietary 330 rights that may cover technology that may be required to implement 331 this standard. Please address the information to the IETF at 332 ietf-ipr@ietf.org. 334 Acknowledgment 336 Funding for the RFC Editor function is provided by the IETF 337 Administrative Support Activity (IASA).