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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 GEOPRIV J. Winterbottom 3 Internet-Draft Commscope 4 Intended status: Standards Track H. Tschofenig 5 Expires: January 15, 2013 Nokia Siemens Networks 6 H. Schulzrinne 7 Columbia University 8 M. Thomson 9 Microsoft 10 July 14, 2012 12 A Location Dereferencing Protocol Using HELD 13 draft-ietf-geopriv-deref-protocol-07 15 Abstract 17 This document describes how to use the Hypertext Transfer Protocol 18 (HTTP) over Transport Layer Security (TLS) as a dereferencing 19 protocol to resolve a reference to a Presence Information Data Format 20 Location Object (PIDF-LO). The document assumes that a Location 21 Recipient possesses a URI that can be used in conjunction with the 22 HTTP-Enabled Location Delivery (HELD) protocol to request the 23 location of the Target. 25 Status of this Memo 27 This Internet-Draft is submitted in full conformance with the 28 provisions of BCP 78 and BCP 79. 30 Internet-Drafts are working documents of the Internet Engineering 31 Task Force (IETF). Note that other groups may also distribute 32 working documents as Internet-Drafts. The list of current Internet- 33 Drafts is at http://datatracker.ietf.org/drafts/current/. 35 Internet-Drafts are draft documents valid for a maximum of six months 36 and may be updated, replaced, or obsoleted by other documents at any 37 time. It is inappropriate to use Internet-Drafts as reference 38 material or to cite them other than as "work in progress." 40 This Internet-Draft will expire on January 15, 2013. 42 Copyright Notice 44 Copyright (c) 2012 IETF Trust and the persons identified as the 45 document authors. All rights reserved. 47 This document is subject to BCP 78 and the IETF Trust's Legal 48 Provisions Relating to IETF Documents 49 (http://trustee.ietf.org/license-info) in effect on the date of 50 publication of this document. Please review these documents 51 carefully, as they describe your rights and restrictions with respect 52 to this document. Code Components extracted from this document must 53 include Simplified BSD License text as described in Section 4.e of 54 the Trust Legal Provisions and are provided without warranty as 55 described in the Simplified BSD License. 57 Table of Contents 59 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 60 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 61 3. HELD Dereference Protocol . . . . . . . . . . . . . . . . . . 4 62 3.1. HELD Usage Profile . . . . . . . . . . . . . . . . . . . . 4 63 3.2. HTTP GET Behavior . . . . . . . . . . . . . . . . . . . . 5 64 4. Authorization Models . . . . . . . . . . . . . . . . . . . . . 6 65 4.1. Authorization by Possession . . . . . . . . . . . . . . . 7 66 4.2. Authorization via Access Control . . . . . . . . . . . . . 8 67 4.3. Access Control with HELD Deference . . . . . . . . . . . . 8 68 5. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 69 6. Security Considerations . . . . . . . . . . . . . . . . . . . 12 70 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 71 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 14 72 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14 73 9.1. Normative References . . . . . . . . . . . . . . . . . . . 14 74 9.2. Informative references . . . . . . . . . . . . . . . . . . 15 75 Appendix A. GEOPRIV Using Protocol Compliance . . . . . . . . . . 16 76 Appendix B. Compliance to Location Reference Requirements . . . . 19 77 B.1. Requirements for a Location Configuration Protocol . . . . 20 78 B.2. Requirements for a Location Dereference Protocol . . . . . 21 79 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 22 81 1. Introduction 83 A location URI [RFC5808] identifies a resource that contains the 84 location of an entity. This document specifies how a holder of an 85 "http:" or "https:" location URI uses that URI to retrieve location 86 information. 88 A location URI can be acquired using a location configuration 89 protocol, such as HTTP-Enabled Location Delivery (HELD) [RFC5985] or 90 the Dynamic Host Configuration Protocol (DHCP) location URI option 91 [I-D.ietf-geopriv-dhcp-lbyr-uri-option]. 93 A Location Recipient that dereferences a location URI acquires 94 location information in the of a Presence Information Data Format - 95 Location Object (PIDF-LO) document [RFC4119]. HELD parameters allow 96 for specifying the type of location information, though some 97 constraints are placed on allowable parameters. 99 Location URIs compatible with HELD dereferencing use the "https:" or 100 "http:" scheme. HELD can be used by Location Recipients that are 101 aware of the fact that the URI is a location URI. Mandatory support 102 for an HTTP GET request ensures that the URI can be used even if it 103 is not recognized as a location URI. 105 2. Terminology 107 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 108 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 109 document are to be interpreted as described in [RFC2119]. 111 This document uses key terminology from several sources: 113 o terms for the GEOPRIV reference model defined in [RFC6280]; 115 o the term Location Information Server (LIS), from [RFC5687], is a 116 node in the access network that provides location information to 117 an end point; a LIS provides location URIs; 119 o the term Location Server (LS), from [RFC6280], is used to identify 120 the role that responds to a location dereference request; this 121 might be the same entity as the LIS, but the model in [RFC5808] 122 allows for the existence of separate - but related - entities; and 124 o the term location URI is coined in [RFC5808]. 126 3. HELD Dereference Protocol 128 This section describes how HELD can be used to dereference a location 129 URI. This process can be applied when a Location Recipient is in 130 possession of a location URI with a "https:" or "http:" URI scheme. 132 This document does not describe a specific authentication mechanism. 133 This means that authorization policies are unable to specifically 134 identify authorized Location Recipients. 136 A Location Recipient that wishes to dereference an "https:" or 137 "http:" URI performs a HELD request on HTTP to the identified 138 resource. 140 Note: In many cases, an "http:" URI does not provide sufficient 141 security for location URIs. The absence of the security 142 mechanisms provided by TLS means that the Rule Maker has no 143 control over who receives location information and the Location 144 Recipient has no assurance that the information is correct. 146 The Location Recipient establishes a connection to the LS, as 147 described in [RFC2818]. 149 The scheme of a location URI determines whether or not TLS is used on 150 a given dereference transaction. Location Servers MUST be configured 151 to issue only HTTPS URIs and respond to only to HTTPS dereference 152 requests, unless confidentiality and integrity protection are 153 provided by some other mechanism. For example, the server might only 154 accept requests from clients within a trusted network, or via an 155 IPsec-protected channel. When TLS is used, the TLS ciphersuite 156 TLS_NULL_WITH_NULL_NULL MUST NOT be used and the LS MUST be 157 authenticated [RFC6125] to ensure that the correct server is 158 contacted. 160 A Location Server MAY reject a request and request that a Location 161 Recipient provide authentication credentials if authorization is 162 dependent on the Location Recipient identity. Future specifications 163 could define an authentication mechanism and a means by which 164 Location Recipients are identified in authorization policies. This 165 document provides definitions for neither item. 167 3.1. HELD Usage Profile 169 Use of HELD as a location dereference protocol is largely the same as 170 its use as a location configuration protocol. Aside from the 171 restrictions noted in this document, HELD semantics do not differ 172 from those established in [RFC5985]. 174 The HELD "locationRequest" is the only request permitted by this 175 specification. Similarly, request parameters other than the 176 following MUST NOT be accepted by the LS: "responseTime", 177 "locationType" (including the associated "exact" attribute). 179 Parameters and requests that do not have known behaviour for 180 dereference requests MUST NOT be used. The LS MUST ignore any 181 parameters that it does not understand unless it knows the parameters 182 to be invalid. If parameters are understood by the LS and known to 183 be invalid, the LS MAY generate a HELD error response. For instance, 184 those defined in [RFC6155] are always invalid and can be rejected. 186 The LS MUST NOT generate location URIs or provide a "locationUriSet" 187 in response to a dereference request. If the location request 188 contains a "locationType" element that includes "locationURI", this 189 parameter is either ignored or rejected as appropriate, based on the 190 associated "exact" attribute. 192 3.2. HTTP GET Behavior 194 GET is the method assumed by generic HTTP user agents, therefore 195 unless context identifies an "https:" URI as a HELD URI, such a user 196 agent might simply send an HTTP GET. Rather than providing an HTTP 197 405 (Method Not Allowed) response indicating that POST is the only 198 permitted method, a LIS MUST provide a HELD location response if it 199 receives an HTTP GET request. 201 An HTTP GET request to a HELD URI produces a HELD response as if the 202 following HELD request had been sent using HTTP POST: 204 205 206 geodetic civic 207 208 210 Figure 1: GET Request Equivalent Location Request 212 HTTP GET requests MUST be safe and idempotent [RFC2616] - that is, 213 there are no side-effects of making the request and a repeated 214 request has no more effect than a single request. Repeating a HELD 215 request might result in a different location, but only as a result of 216 a change in the state of the resource: the location of the Target. 218 Only the creation of a location URI as a result of receiving a 219 request causes a HELD request to have side-effects. A request to a 220 location URI can be both safe and idempotent, since a location URI 221 cannot be produced in response to a request to a location URI. 223 A Location Recipient MAY infer from a response containing the HELD 224 content type, "application/held+xml", that a URI references a 225 resource that supports HELD. 227 Content negotiation MAY be supported to produce a presence document 228 in place of a HELD location response. Where the presence document 229 would otherwise be included in a "locationResponse" document, it can 230 be included in the body of the HTTP response directly by including an 231 "Accept" header that includes "application/pidf+xml". 233 4. Authorization Models 235 This section discusses two extreme types of authorization models for 236 dereferencing with HELD URIs, namely "Authorization by Possession" 237 and "Authorization by Access Control". In the subsequent subsections 238 we discuss the properties of these two models. Figure 2, from 239 [RFC5808], shows the model applicable to location configuration, 240 conveyance and dereference. 242 +---------+--------+ Location +-----------+ 243 | | | Dereference | Location | 244 | LIS - LS +---------------+ Recipient | 245 | | | Protocol | | 246 +----+----+--------+ (3) +-----+-----+ 247 | `. | 248 | Policy `. | 249 Location | Exchange `. | 250 Configuration | (*) | | 251 Protocol | +----+----+ | 252 (1) | | Rule | Location | 253 | | Maker | Conveyance | 254 +-----+----+ +---------+ Protocol | 255 | | (2) | 256 | Target +------------------------------+ 257 | | 258 +----------+ 260 Figure 2: Communication Model 262 It is important to note that this document does not mandate a 263 specific authorization model. It is possible to combine aspects of 264 both models. However, no authentication framework is provided, which 265 limits the policy options available when the "Authorization by Access 266 Control" model is used. 268 For either authorization model, the overall process is similar. The 269 following steps are followed, with minor alterations: 271 1. The Target acquires a location URI from the LIS. This uses a 272 location configuration protocol (LCP), such as HELD or DHCP. 274 2. The Target then conveys the location URI to a third party, the 275 Location Recipient (for example using SIP as described in 276 [RFC6442]). This step is shown in (2) of Figure 2. 278 3. The Location Recipient then needs to dereference the location URI 279 in order to obtain the Location Object (3). An "https:" or 280 "http:" URI is dereferenced as described in this document; other 281 URI schemes might be dereferenced using another method. 283 In this final step, the Location Server (LS) or LIS makes an 284 authorization decision. How this decision is reached depends on the 285 authorization model. 287 4.1. Authorization by Possession 289 In this model, possession - or knowledge - of the location URI is 290 used to control access to location information. A location URI might 291 be constructed such that it is hard to guess (see C8 of [RFC5808]) 292 and the set of entities that it is disclosed to can be limited. The 293 only authentication this would require by the LS is evidence of 294 possession of the URI. The LS could immediately authorize any 295 request that indicates this URI. 297 Authorization by possession does not require direct interaction with 298 a Rule Maker; it is assumed that the Rule Maker is able to exert 299 control over the distribution of the location URI. Therefore, the 300 LIS can operate with limited policy input from a Rule Maker. 302 Limited disclosure is an important aspect of this authorization 303 model. The location URI is a secret; therefore, ensuring that 304 adversaries are not able to acquire this information is paramount. 305 Encryption, such as might be offered by TLS [RFC5246] or S/MIME 306 [RFC5751], protects the information from eavesdroppers. 308 Use of authorization by possession location URIs in a hop-by-hop 309 protocol such as SIP [RFC3261] adds the possibility of on-path 310 adversaries. Depending on the usage of the location URI for certain 311 location based applications (e.g., emergency services, location based 312 routing) specific treatment is important, as discussed in [RFC6442]. 314 Using possession as a basis for authorization means that, once 315 granted, authorization cannot be easily revoked. Cancellation of a 316 location URI ensures that legitimate users are also affected; 317 application of additional policy is theoretically possible, but could 318 be technically infeasible. Expiration of location URIs limits the 319 usable time for a location URI, requiring that an attacker continue 320 to learn new location URIs to retain access to current location 321 information. 323 A very simple policy might be established at the time that a location 324 URI is created. This policy specifies that the location URI expires 325 after a certain time, which limits any inadvertent exposure of 326 location information to adversaries. The expiration time of the 327 location URI might be negotiated at the time of its creation, or it 328 might be unilaterally set by the LIS. 330 4.2. Authorization via Access Control 332 Use of explicit access control provides a Rule Maker greater control 333 over the behaviour of an LS. In contrast to authorization by 334 possession, possession of this form of location URI does not imply 335 authorization. Since an explicit policy is used to authorize access 336 to location information, the location URI can be distributed to many 337 potential Location Recipients. 339 Either before creation or dissemination of the location URI, the Rule 340 Maker establishes an authorization policy with the LS. In reference 341 to Figure 2, authorization policies might be established at creation 342 (Step 1), and need to be established before the location URI is 343 published (Step 2) to ensure that the policy grants access to the 344 desired Location Recipients. Depending on the mechanism used, it 345 might also be possible to change authorization policies at any time. 347 A possible format for these authorization policies is available with 348 GEOPRIV Common Policy [RFC4745] and Geolocation Policy 349 [I-D.ietf-geopriv-policy]. Additional constraints might be 350 established by other means. 352 The LS enforces the authorization policy when a Location Recipient 353 dereferences the URI. Explicit authorization policies allow a Rule 354 Maker to specify how location information is provided to Location 355 Recipients. 357 4.3. Access Control with HELD Deference 359 This document does not describe a specific authentication mechanism; 360 therefore, the authorization by access control model is not an 361 option. Instead, this document assumes the authorization by 362 possession model. 364 Other policy mechanisms, such as those described in 365 [I-D.ietf-geopriv-policy], can be applied for different Location 366 Recipients if each recipient is given a different location URIs. 368 Each location URI can be assigned different authorization policy. 369 Selective disclosure used in this fashion can be used in place of 370 identity-based authorization. 372 How policy is associated with a location URI is not defined by this 373 document. [I-D.ietf-geopriv-policy-uri] describes one possible 374 mechanism. 376 Use of identity-based authorization policy is not precluded. A 377 Location Server MAY support an authentication mechanism that enables 378 identity-based authorization policies to be used. Future 379 specifications might define means of identifying recipients. 381 Note: Policy frameworks like [RFC4745] degrade in a way that 382 protects privacy if features are not supported. If a policy 383 specifies a rule that is conditional on the identity of a 384 recipient and the protocol does not (or cannot) provide an 385 assertion identity of the recipient, the rule has no effect and 386 the policy defaults to providing less information. 388 5. Examples 390 An example scenario envisioned by this document is shown in Figure 3. 391 This diagram shows how a location dereference protocol fits with 392 location configuration and conveyance. [RFC5808] contains more 393 information on this scenario and others like it. 395 +-------------+ 396 +------------+ | Location | +-----------+ 397 | End Device | | Information | | Location | 398 | (Target) | | Server | | Recipient | 399 +-----+------+ +------+------+ +-----+-----+ 400 | | | 401 .- + - - - - - - - - - - - - + -. | 402 : | locationRequest | : | 403 . |----(for location URI)-->| . | 404 : | | : Location | 405 . | locationResponse | . Configuration | 406 : |<-----(location URI)-----| : | 407 . | | . | 408 `- + - - - - - - - - - - - - + -' | 409 | | | 410 | Location Conveyance | 411 |~ ~ ~ ~ ~ ~ ~ ~ ~ ~(location URI)~ ~ ~ ~ ~ ~ ~ ~ ~>| 412 | | | 413 | .- + - - - - - - - - - - - - + -. 414 | : | locationRequest | : 415 | . |<------(for civic)-------| . 416 | Dereferencing : | | : 417 | . | locationResponse | . 418 | : |--------(PIDF-LO)------->| : 419 | . | | . 420 | `- + - - - - - - - - - - - - + -' 421 | | | 423 Figure 3: Example of Dereference Protocol Exchange 425 The example in Figure 4 shows the simplest form of dereferencing 426 request using HELD to the location URI 427 "https://ls.example.com:49152/uri/w3g61nf5n66p0". The only way that 428 this differs from the example in Section 10.1 of [RFC5985] is in the 429 request URI and the source of the URI. 431 POST /uri/w3g61nf5n66p0 HTTP/1.1 432 Host: ls.example.com:49152 433 Content-Type: application/held+xml 434 Content-Length: 87 436 437 439 Figure 4: Minimal Dereferencing Request 441 Figure 5 shows the response to the previous request listing both 442 civic and geodetic location information of the Target's location. 444 Again, this is identical to the response in Section 10.1 of [RFC5985] 445 - unless policy specifies otherwise, the Location Recipient receives 446 the same information as the Device. 448 HTTP/1.1 200 OK 449 Server: Example LIS 450 Date: Mon, 10 Jan 2011 03:42:29 GMT 451 Expires: Tue, 11 Jan 2011 03:42:29 GMT 452 Cache-control: private 453 Content-Type: application/held+xml 454 Content-Length: 676 456 457 458 460 461 462 464 465 467 -34.407 150.88001 468 469 470 471 472 false 473 474 2011-01-11T03:42:29+00:00 475 476 Wiremap 477 478 479 2006-01-10T03:42:28+00:00 480 481 482 484 Figure 5: Response with Location Information 486 The following GET request is treated in an equivalent fashion. The 487 LS treats this request as though it were a location request of the 488 form shown in Figure 1. The same response might be provided. 490 GET /uri/w3g61nf5n66p0 HTTP/1.1 491 Host: ls.example.com:49152 492 Accept: application/held+xml 494 Figure 6: GET Request 496 The following GET request uses content negotiation to indicate a 497 preference for a presence document. 499 GET /uri/w3g61nf5n66p0 HTTP/1.1 500 Host: ls.example.com:49152 501 Accept: application/pidf+xml,application/held+xml;q=0.5 503 Figure 7: GET Request with Content Negotiation 505 The response only differs from a normal HELD location response to a 506 POST request in that the "locationResponse" element is omitted and 507 the "Content-Type" header reflects the changed content. 509 HTTP/1.1 200 OK 510 Server: Example LIS 511 Date: Mon, 10 Jan 2011 03:42:29 GMT 512 Expires: Tue, 11 Jan 2011 03:42:29 GMT 513 Cache-control: private 514 Content-Type: application/pidf+xml 515 Content-Length: 591 517 518 520 521 523 Figure 8: GET Response with PIDF-LO 525 6. Security Considerations 527 Privacy of location information is the most important security 528 consideration for this document. Two measures in particular are used 529 to protect privacy: TLS and authorization policies. TLS provides a 530 means of ensuring confidentiality of location information through 531 encryption and mutual authentication. An authorization policy allows 532 a Rule Maker to explicitly control how location information is 533 provided to Location Recipients. 535 The process by which a Rule Maker establishes an authorization policy 536 is not covered by this document; several methods are possible, for 537 instance: [I-D.ietf-geopriv-policy-uri], [RFC4825]. 539 TLS MUST be used for dereferencing location URIs unless 540 confidentiality and integrity are provided by some other mechanism, 541 as discussed in Section 3. Location Recipients MUST authenticate the 542 host identity using the domain name included in the location URI, 543 using the procedure described in Section 3.1 of [RFC2818]. Local 544 policy determines what a Location Recipient does if authentication 545 fails or cannot be attempted. 547 The authorization by possession model (Section 4.1) further relies on 548 TLS when transmitting the location URI to protect the secrecy of the 549 URI. Possession of such a URI implies the same privacy 550 considerations as possession of the PIDF-LO document that the URI 551 references. 553 Location URIs MUST only be disclosed to authorized Location 554 Recipients. The GEOPRIV architecture [RFC6280] identifies the Rule 555 Maker role as being the entity that authorizes disclosure of this 556 nature. 558 Protection of the location URI is necessary, since the policy 559 attached to such a location URI permits any who have the URI to view 560 it. This aspect of security is covered in more detail in the 561 specification of location conveyance protocols, such as [RFC6442]. 563 The LS MUST NOT provide any information about the Target except its 564 location, unless policy from a Rule Maker allows otherwise. In 565 particular, the requirements in [RFC5808] mandate this measure to 566 protect the identity of the Target. To this end, an unlinked 567 pseudonym MUST be provided in the "entity" attribute of the PIDF-LO 568 document. 570 Further security considerations and requirements relating to the use 571 of location URIs are described in [RFC5808]. 573 7. IANA Considerations 575 This document makes no request of IANA. 577 [[IANA/RFC-EDITOR: Please remove this section before publication.]] 579 8. Acknowledgements 581 Thanks to Barbara Stark and Guy Caron for providing early comments. 582 Thanks to Rohan Mahy for constructive comments on the scope and 583 format of the document. Thanks to Ted Hardie for his strawman 584 proposal that provided assistance with the security section of this 585 document. Richard Barnes made helpful observations on the 586 application of authorization policy. Bernard Aboba and Julian 587 Reschke contributed constructive reviews. 589 The participants of the GEOPRIV interim meeting 2008 provided 590 significant feedback on this document. 592 James Polk provided input on security in June 2008. 594 Martin Dawson was an original author of this document. Sadly, he 595 passed away prior to its publication. 597 9. References 599 9.1. Normative References 601 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 602 Requirement Levels", BCP 14, RFC 2119, March 1997. 604 [RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., 605 Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext 606 Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999. 608 [RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000. 610 [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform 611 Resource Identifier (URI): Generic Syntax", STD 66, 612 RFC 3986, January 2005. 614 [RFC4119] Peterson, J., "A Presence-based GEOPRIV Location Object 615 Format", RFC 4119, December 2005. 617 [RFC5491] Winterbottom, J., Thomson, M., and H. Tschofenig, "GEOPRIV 618 Presence Information Data Format Location Object (PIDF-LO) 619 Usage Clarification, Considerations, and Recommendations", 620 RFC 5491, March 2009. 622 [RFC5985] Barnes, M., "HTTP-Enabled Location Delivery (HELD)", 623 RFC 5985, September 2010. 625 [RFC6125] Saint-Andre, P. and J. Hodges, "Representation and 626 Verification of Domain-Based Application Service Identity 627 within Internet Public Key Infrastructure Using X.509 628 (PKIX) Certificates in the Context of Transport Layer 629 Security (TLS)", RFC 6125, March 2011. 631 9.2. Informative references 633 [I-D.ietf-geopriv-dhcp-lbyr-uri-option] 634 Polk, J., "Dynamic Host Configuration Protocol (DHCP) IPv4 635 and IPv6 Option for a Location Uniform Resource Identifier 636 (URI)", draft-ietf-geopriv-dhcp-lbyr-uri-option-15 (work 637 in progress), May 2012. 639 [I-D.ietf-geopriv-policy] 640 Schulzrinne, H., Tschofenig, H., Cuellar, J., Polk, J., 641 Morris, J., and M. Thomson, "Geolocation Policy: A 642 Document Format for Expressing Privacy Preferences for 643 Location Information", draft-ietf-geopriv-policy-26 (work 644 in progress), June 2012. 646 [I-D.ietf-geopriv-policy-uri] 647 Thomson, M., Winterbottom, J., Barnes, R., and H. 648 Tschofenig, "Location Configuration Extensions for Policy 649 Management", draft-ietf-geopriv-policy-uri-04 (work in 650 progress), November 2011. 652 [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, 653 A., Peterson, J., Sparks, R., Handley, M., and E. 654 Schooler, "SIP: Session Initiation Protocol", RFC 3261, 655 June 2002. 657 [RFC3693] Cuellar, J., Morris, J., Mulligan, D., Peterson, J., and 658 J. Polk, "Geopriv Requirements", RFC 3693, February 2004. 660 [RFC4745] Schulzrinne, H., Tschofenig, H., Morris, J., Cuellar, J., 661 Polk, J., and J. Rosenberg, "Common Policy: A Document 662 Format for Expressing Privacy Preferences", RFC 4745, 663 February 2007. 665 [RFC4825] Rosenberg, J., "The Extensible Markup Language (XML) 666 Configuration Access Protocol (XCAP)", RFC 4825, May 2007. 668 [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security 669 (TLS) Protocol Version 1.2", RFC 5246, August 2008. 671 [RFC5687] Tschofenig, H. and H. Schulzrinne, "GEOPRIV Layer 7 672 Location Configuration Protocol: Problem Statement and 673 Requirements", RFC 5687, March 2010. 675 [RFC5751] Ramsdell, B. and S. Turner, "Secure/Multipurpose Internet 676 Mail Extensions (S/MIME) Version 3.2 Message 677 Specification", RFC 5751, January 2010. 679 [RFC5808] Marshall, R., "Requirements for a Location-by-Reference 680 Mechanism", RFC 5808, May 2010. 682 [RFC6155] Winterbottom, J., Thomson, M., Tschofenig, H., and R. 683 Barnes, "Use of Device Identity in HTTP-Enabled Location 684 Delivery (HELD)", RFC 6155, March 2011. 686 [RFC6280] Barnes, R., Lepinski, M., Cooper, A., Morris, J., 687 Tschofenig, H., and H. Schulzrinne, "An Architecture for 688 Location and Location Privacy in Internet Applications", 689 BCP 160, RFC 6280, July 2011. 691 [RFC6442] Polk, J., Rosen, B., and J. Peterson, "Location Conveyance 692 for the Session Initiation Protocol", RFC 6442, 693 December 2011. 695 Appendix A. GEOPRIV Using Protocol Compliance 697 This section describes how use of HELD as a location dereference 698 protocol complies with the GEOPRIV requirements described in 699 [RFC3693]. 701 Req. 1. (Location Object generalities): 703 This section relates to the PIDF-LO [RFC4119] document, 704 which is used by HELD. These requirements are addressed by 705 [RFC4119] and [RFC5491]. 707 Req. 2. (Location Object fields): 709 This section relates to the PIDF-LO [RFC4119] document, 710 which is used by HELD. These requirements are addressed by 711 [RFC4119] and [RFC5491]. 713 Req. 3. (Location Data Types): 715 This section relates to the PIDF-LO [RFC4119] document, 716 which is used by HELD. These requirements are addressed by 717 [RFC4119] and [RFC5491]. 719 Section 7.2 of [RFC3693] details the requirements of a "Using 720 Protocol". These requirements are restated, followed by a statement 721 of compliance: 723 Req. 4. "The using protocol has to obey the privacy and security 724 instructions coded in the Location Object and in the 725 corresponding Rules regarding the transmission and storage 726 of the LO." 728 Compliant: This specification describes the use of HTTP over 729 TLS for carring the PIDF-LO from the LS to the Location 730 Recipient. The sending and receiving parties are expected 731 to comply with the instructions carried inside the object. 733 Though discouraged, using unsecured http: URIs is permitted. 734 Using unsecured HTTP is likely to result in non-compliance 735 with this requirement. 737 Req. 5. "The using protocol will typically facilitate that the keys 738 associated with the credentials are transported to the 739 respective parties, that is, key establishment is the 740 responsibility of the using protocol." 742 Compliant: This document specifies that authentication of 743 the LS uses the established public key infrastructure used 744 by HTTP over TLS [RFC2818]. Authentication of Location 745 Recipients is either based on distribution of a secret (the 746 location URI) using a conveyance protocol (for instance, 747 [RFC6442]), allowances are made for later work to define 748 alternative methods. 750 Req. 6. "(Single Message Transfer) In particular, for tracking of 751 small target devices, the design should allow a single 752 message/packet transmission of location as a complete 753 transaction." 755 Not Compliant: The XML encoding specified in [RFC4119] is 756 not suited to single packet transfers. Use of compressed 757 content encoding [RFC2616] might allow this condition to be 758 met. 760 Section 7.3 of [RFC3693] details the requirements of a "Rule based 761 Location Data Transfer". These requirements are restated where they 762 are applicable to this document: 764 Req. 7. "(LS Rules) The decision of a Location Server to provide a 765 Location Recipient access to Location Information MUST be 766 based on Rule Maker-defined Privacy Rules." 768 Compliant: This document describes two alternative methods 769 by which a Rule Maker is able to control access to location 770 information. Rule Maker policy is enforced by the LS when 771 a location URI is dereferenced. However, this document 772 does not describe how a location URI is created, or how a 773 Rule Maker associates policy with a location URI. These 774 are covered by other specifications. 776 Req. 8. (LG Rules) Not Applicable: This relationship between LS and 777 the source of its information (be that Location Generator 778 (LG) or LIS) is out of scope for this document. 780 Req. 9. "(Viewer Rules) A Viewer does not need to be aware of the 781 full Rules defined by the Rule Maker (because a Viewer 782 SHOULD NOT retransmit Location Information), and thus a 783 Viewer SHOULD receive only the subset of Privacy Rules 784 necessary for the Viewer to handle the LO in compliance 785 with the full Privacy Rules (such as, instruction on the 786 time period for which the LO can be retained)." 788 Compliant: The Rule Maker might define (via mechanisms 789 outside the scope of this document) which policy rules are 790 disclosed to other entities. For instance, if [RFC4745] is 791 used to convey authorization policies from Rule Maker to 792 LS, this is possible using the parameters specified in 793 [I-D.ietf-geopriv-policy]. 795 In order to comply with these rules, a Location Recipient 796 MUST NOT redistribute a location URI without express 797 permission. Depending on the access control model, the 798 location URI might be secret (see Section 3.3 of 799 [RFC5808]). 801 Req. 10. (Full Rule language) Not Applicable: Note however that 802 Geopriv has defined a rule language capable of expressing a 803 wide range of privacy rules (see [RFC4745] and 804 [I-D.ietf-geopriv-policy]. 806 Req. 11. (Limited Rule language) Not Applicable: This requirement 807 applies to (and is addressed by) PIDF-LO [RFC4119]. 809 Section 7.4 of [RFC3693] details the requirements of "Location Object 810 Privacy and Security". These requirements are restated where they 811 are applicable to this document: 813 Req. 12. (Identity Protection) Compliant: Identity protection of the 814 Target is provided as long as both of the following 815 conditions are true: 817 (a) the location URI is not associated with the identity 818 of the Target in any context, and 820 (b) the PIDF-LO does not contain information about the 821 identity of the Target. 823 For instance, this requirement is complied with if the 824 protocol that conveys the location URI does not link the 825 identity of the Target to the location URI and the LS 826 doesn't include meaningful identification information in 827 the PIDF-LO document. Section 6 recommends that an 828 unlinked pseudonym is used by the LS. 830 Req. 13. (Credential Requirements) Compliant: The primary security 831 mechanism specified in this document is Transport Layer 832 Security. TLS offers the ability to use different types of 833 credentials, including symmetric, asymmetric credentials or 834 a combination of them. 836 Req. 14. (Security Features) Compliant: Geopriv defines a few 837 security requirements for the protection of Location 838 Objects such as mutual end-point authentication, data 839 object integrity, data object confidentiality and replay 840 protection. The ability to use Transport Layer security 841 fulfills most of these requirements. Authentication of 842 Location Recipients in this document relies on proof of a 843 shared secret - the location URI. This does not preclude 844 the addition of more robust authentication procedures. 846 Req. 15. (Minimal Crypto) Compliant: The mandatory to implement 847 ciphersuite is provided in the TLS layer security 848 specification. 850 Appendix B. Compliance to Location Reference Requirements 852 This section describes how HELD complies to the location reference 853 requirements stipulated in [RFC5808]. Compliance of [RFC5985] to the 854 Location Configuration Protocol is included. 856 Note that use of HELD as a location dereference protocol does not 857 necessarily imply that HELD is the corresponding LCP. This 858 document is still applicable to HTTP location URIs that are 859 acquired by other means. 861 B.1. Requirements for a Location Configuration Protocol 863 C1. "Location URI support: The location configuration protocol MUST 864 support a location reference in URI form." 866 Compliant: HELD only provides location references in URI form. 868 C2. "Location URI expiration: When a location URI has a limited 869 validity interval, its lifetime MUST be indicated." 871 Compliant: HELD indicates the expiry time of location URIs using 872 the "expires" attribute. [I-D.ietf-geopriv-policy-uri] provides 873 a way to control expiration of a location URI. 875 C3. "Location URI cancellation: The location configuration protocol 876 MUST support the ability to request a cancellation of a specific 877 location URI." 879 Compliant with Extension: [I-D.ietf-geopriv-policy-uri] 880 describes how a location URI can be cancelled through the 881 application of policy. Without extensions, HELD does not 882 provide a method for cancelling location URIs. 884 C4. "Location Information Masking: The location URI MUST ensure, by 885 default, through randomization and uniqueness, that the location 886 URI does not contain location information specific components." 888 Compliant: The HELD specification explicitly references this 889 requirement in providing guidance on the format of the location 890 URI. 892 C5. "Target Identity Protection: The location URI MUST NOT contain 893 information that identifies the Target (e.g., user or device)." 895 Compliant: The HELD specification provides specific guidance on 896 the anonymity of the Target with regards to the generation of 897 location URIs. Section 6 expands on this guidance. 899 C6. "Reuse indicator: There SHOULD be a way to allow a Target to 900 control whether a location URI can be resolved once only, or 901 multiple times." 903 Not Compliant: Specific extensions to the protocol or 904 authorization policy formats is needed to alter the default 905 behavior, which allows unlimited resolution of the location URI. 907 C7. "Selective disclosure: The location configuration protocol MUST 908 provide a mechanism that allows the Rule Maker to control what 909 information is being disclosed about the Target." 911 Compliant with Extension: Use of policy mechanisms and 912 [I-D.ietf-geopriv-policy-uri] enable this capability. Note that 913 this document recommends that only location information be 914 provided. 916 C8. "Location URI Not guessable: As a default, the location 917 configuration protocol MUST return location URIs that are random 918 and unique throughout the indicated lifetime. A location URI 919 with 128-bits of randomness is RECOMMENDED." 921 Compliant: HELD specifies that location URIs conform to this 922 requirement. The amount of randomness is not specifically 923 identified since it depends on a number of factors that change 924 over time, such as the number of valid location URIs, the 925 validity period of those URIs and the rate that guesses can be 926 made. 928 C9. "Location URI Options: In the case of user-provided 929 authorization policies, where anonymous or non-guessable 930 location URIs are not warranted, the location configuration 931 protocol MAY support a variety of optional location URI 932 conventions, as requested by a Target to a location 933 configuration server, (e.g., embedded location information 934 within the location URI)." 936 Not Compliant: HELD does not support Device-specified location 937 URI forms. 939 B.2. Requirements for a Location Dereference Protocol 941 D1. "Location URI support: The location dereference protocol MUST 942 support a location reference in URI form." 944 Compliant: HELD only provides location references in URI form. 946 D2. "Authentication: The location dereference protocol MUST include 947 mechanisms to authenticate both the client and the server." 949 Partially Compliant: TLS provides means for mutual 950 authentication. This document only specifies the required 951 mechanism for server authentication. Client authentication is 952 not precluded. 954 D3. "Dereferenced Location Form: The value returned by the 955 dereference protocol MUST contain a well-formed PIDF-LO 956 document." 958 Compliant: HELD requires that location objects are in the form 959 of a PIDF-LO that complies with [RFC5491]. 961 D4. "Location URI Repeated Use: The location dereference protocol 962 MUST support the ability for the same location URI to be 963 resolved more than once, based on dereference server 964 configuration." 966 Compliant: A Location Recipient may access and use a location 967 URI as many times as desired until URI expiration results in the 968 URI being invalidated. Authorization policies might include 969 rules that modify this behavior. 971 D5. "The location dereference protocol MUST support confidentiality 972 protection of messages sent between the Location Recipient and 973 the location server." 975 Compliant: This document strongly recommends the use of TLS for 976 confidentiality and HELD mandates its implementation. Unsecured 977 HTTP is permitted: the associated risks are described in 978 Section 3. 980 Authors' Addresses 982 James Winterbottom 983 Commscope 984 Andrew Building (39) 985 Wollongong University Campus 986 Northfields Avenue 987 Wollongong, NSW 2522 988 AU 990 Phone: +61 242 212938 991 Email: james.winterbottom@commscope.com 992 Hannes Tschofenig 993 Nokia Siemens Networks 994 Linnoitustie 6 995 Espoo 02600 996 Finland 998 Phone: +358 (50) 4871445 999 Email: Hannes.Tschofenig@gmx.net 1000 URI: http://www.tschofenig.priv.at 1002 Henning Schulzrinne 1003 Columbia University 1004 Department of Computer Science 1005 450 Computer Science Building, New York, NY 10027 1006 US 1008 Phone: +1 212 939 7004 1009 Email: hgs@cs.columbia.edu 1010 URI: http://www.cs.columbia.edu 1012 Martin Thomson 1013 Microsoft 1014 3210 Porter Drive 1015 Palo Alto, CA 94304 1016 US 1018 Phone: +1 650-353-1925 1019 Email: martin.thomson@skype.net