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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 5226 (Obsoleted by RFC 8126) ** Obsolete normative reference: RFC 7049 (Obsoleted by RFC 8949) ** Obsolete normative reference: RFC 8152 (Obsoleted by RFC 9052, RFC 9053) == Outdated reference: A later version (-46) exists of draft-ietf-ace-oauth-authz-16 -- Obsolete informational reference (is this intentional?): RFC 7159 (Obsoleted by RFC 8259) Summary: 4 errors (**), 0 flaws (~~), 2 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 ACE M. Jones 3 Internet-Draft Microsoft 4 Intended status: Standards Track L. Seitz 5 Expires: May 10, 2019 RISE SICS 6 G. Selander 7 Ericsson AB 8 S. Erdtman 9 Spotify 10 H. Tschofenig 11 ARM Ltd. 12 November 6, 2018 14 Proof-of-Possession Key Semantics for CBOR Web Tokens (CWTs) 15 draft-ietf-ace-cwt-proof-of-possession-04 17 Abstract 19 This specification describes how to declare in a CBOR Web Token (CWT) 20 that the presenter of the CWT possesses a particular proof-of- 21 possession key. Being able to prove possession of a key is also 22 sometimes described as being the holder-of-key. This specification 23 provides equivalent functionality to "Proof-of-Possession Key 24 Semantics for JSON Web Tokens (JWTs)" (RFC 7800), but using CBOR and 25 CWTs rather than JSON and JWTs. 27 Status of This Memo 29 This Internet-Draft is submitted in full conformance with the 30 provisions of BCP 78 and BCP 79. 32 Internet-Drafts are working documents of the Internet Engineering 33 Task Force (IETF). Note that other groups may also distribute 34 working documents as Internet-Drafts. The list of current Internet- 35 Drafts is at https://datatracker.ietf.org/drafts/current/. 37 Internet-Drafts are draft documents valid for a maximum of six months 38 and may be updated, replaced, or obsoleted by other documents at any 39 time. It is inappropriate to use Internet-Drafts as reference 40 material or to cite them other than as "work in progress." 42 This Internet-Draft will expire on May 10, 2019. 44 Copyright Notice 46 Copyright (c) 2018 IETF Trust and the persons identified as the 47 document authors. All rights reserved. 49 This document is subject to BCP 78 and the IETF Trust's Legal 50 Provisions Relating to IETF Documents 51 (https://trustee.ietf.org/license-info) in effect on the date of 52 publication of this document. Please review these documents 53 carefully, as they describe your rights and restrictions with respect 54 to this document. Code Components extracted from this document must 55 include Simplified BSD License text as described in Section 4.e of 56 the Trust Legal Provisions and are provided without warranty as 57 described in the Simplified BSD License. 59 Table of Contents 61 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 62 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 63 3. Representations for Proof-of-Possession Keys . . . . . . . . 3 64 3.1. Confirmation Claim . . . . . . . . . . . . . . . . . . . 4 65 3.2. Representation of an Asymmetric Proof-of-Possession Key . 5 66 3.3. Representation of an Encrypted Symmetric Proof-of- 67 Possession Key . . . . . . . . . . . . . . . . . . . . . 5 68 3.4. Representation of a Key ID for a Proof-of-Possession Key 6 69 3.5. Specifics Intentionally Not Specified . . . . . . . . . . 7 70 4. Security Considerations . . . . . . . . . . . . . . . . . . . 7 71 5. Privacy Considerations . . . . . . . . . . . . . . . . . . . 8 72 6. Operational Considerations . . . . . . . . . . . . . . . . . 8 73 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 74 7.1. CBOR Web Token Claims Registration . . . . . . . . . . . 10 75 7.1.1. Registry Contents . . . . . . . . . . . . . . . . . . 10 76 7.2. CWT Confirmation Methods Registry . . . . . . . . . . . . 10 77 7.2.1. Registration Template . . . . . . . . . . . . . . . . 10 78 7.2.2. Initial Registry Contents . . . . . . . . . . . . . . 11 79 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 11 80 8.1. Normative References . . . . . . . . . . . . . . . . . . 11 81 8.2. Informative References . . . . . . . . . . . . . . . . . 12 82 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 13 83 Document History . . . . . . . . . . . . . . . . . . . . . . . . 13 84 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14 86 1. Introduction 88 This specification describes how a CBOR Web Token (CWT) [RFC8392] can 89 declare that the presenter of the CWT possesses a particular proof- 90 of-possession (PoP) key. Proof of possession of a key is also 91 sometimes described as being the holder-of-key. This specification 92 provides equivalent functionality to "Proof-of-Possession Key 93 Semantics for JSON Web Tokens (JWTs)" [RFC7800], but using CBOR 94 [RFC7049] and CWTs [RFC8392] rather than JSON [RFC7159] and JWTs 95 [JWT]. 97 2. Terminology 99 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 100 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 101 "OPTIONAL" in this document are to be interpreted as described in BCP 102 14 [RFC2119] [RFC8174] when, and only when, they appear in all 103 capitals, as shown here. 105 This specification uses terms defined in the CBOR Web Token (CWT) 106 [RFC8392], CBOR Object Signing and Encryption (COSE) [RFC8152], and 107 Concise Binary Object Representation (CBOR) [RFC7049] specifications. 109 These terms are defined by this specification: 111 Issuer 112 Party that creates the CWT and binds the claims about the subject 113 to the proof-of-possession key. 115 Presenter 116 Party that proves possession of a private key (for asymmetric key 117 cryptography) or secret key (for symmetric key cryptography) to a 118 recipient. 119 In context of OAuth this party is also called OAuth Client. 121 Recipient 122 Party that receives the CWT containing the proof-of-possession key 123 information from the presenter. 124 In context of OAuth this party is also called OAuth Resource 125 Server. 127 3. Representations for Proof-of-Possession Keys 129 By including a "cnf" (confirmation) claim in a CWT, the issuer of the 130 CWT declares that the presenter possesses a particular key and that 131 the recipient can cryptographically confirm that the presenter has 132 possession of that key. The value of the "cnf" claim is a CBOR map 133 and the members of that map identify the proof-of-possession key. 135 The presenter can be identified in one of several ways by the CWT, 136 depending upon the application requirements. For instance, some 137 applications may use the CWT "sub" (subject) claim [RFC8392], to 138 identify the presenter. Other applications may use the "iss" claim 139 to identify the presenter. In some applications, the subject 140 identifier might be relative to the issuer identified by the "iss" 141 (issuer) claim [RFC8392]. The actual mechanism used is dependent 142 upon the application. The case in which the presenter is the subject 143 of the CWT is analogous to Security Assertion Markup Language (SAML) 144 2.0 [OASIS.saml-core-2.0-os] SubjectConfirmation usage. 146 3.1. Confirmation Claim 148 The "cnf" claim in the CWT is used to carry confirmation methods. 149 Some of them use proof-of-possession keys while others do not. This 150 design is analogous to the SAML 2.0 [OASIS.saml-core-2.0-os] 151 SubjectConfirmation element in which a number of different subject 152 confirmation methods can be included (including proof-of-possession 153 key information). 155 The set of confirmation members that a CWT must contain to be 156 considered valid is context dependent and is outside the scope of 157 this specification. Specific applications of CWTs will require 158 implementations to understand and process some confirmation members 159 in particular ways. However, in the absence of such requirements, 160 all confirmation members that are not understood by implementations 161 MUST be ignored. 163 This specification establishes the IANA "CWT Confirmation Methods" 164 registry for these members in Section 7.2 and registers the members 165 defined by this specification. Other specifications can register 166 other members used for confirmation, including other members for 167 conveying proof-of-possession keys using different key 168 representations. 170 The "cnf" claim value MUST represent only a single proof-of- 171 possession key. At most one of the "COSE_Key" and 172 "Encrypted_COSE_Key" confirmation values defined in Figure 1 may be 173 present. Note that if an application needs to represent multiple 174 proof-of-possession keys in the same CWT, one way for it to achieve 175 this is to use other claim names, in addition to "cnf", to hold the 176 additional proof-of-possession key information. These claims could 177 use the same syntax and semantics as the "cnf" claim. Those claims 178 would be defined by applications or other specifications and could be 179 registered in the IANA "CBOR Web Token Claims" registry 180 [IANA.CWT.Claims]. 182 /--------------------+-----+-------------------------------\ 183 | Name | Key | Value type | 184 |--------------------+-----+-------------------------------| 185 | COSE_Key | 1 | COSE_Key | 186 | Encrypted_COSE_Key | 2 | COSE_Encrypt or COSE_Encrypt0 | 187 | kid | 3 | binary string | 188 \--------------------+-----+-------------------------------/ 190 Figure 1: Summary of the cnf names, keys, and value types 192 3.2. Representation of an Asymmetric Proof-of-Possession Key 194 When the key held by the presenter is an asymmetric private key, the 195 "COSE_Key" member is a COSE_Key [RFC8152] representing the 196 corresponding asymmetric public key. The following example (using 197 CBOR diagnostic notation) demonstrates such a declaration in the CWT 198 Claims Set of a CWT: 200 { 201 /iss/ 1 : "coaps://server.example.com", 202 /aud/ 3 : "coaps://client.example.org", 203 /exp/ 4 : 1361398824, 204 /cnf/ 8 :{ 205 /COSE_Key/ 1 :{ 206 /kty/ 1 : /EC/ 2, 207 /crv/ -1 : /P-256/ 1, 208 /x/ -2 : h'd7cc072de2205bdc1537a543d53c60a6acb62eccd890c7fa27c9 209 e354089bbe13', 210 /y/ -3 : h'f95e1d4b851a2cc80fff87d8e23f22afb725d535e515d020731e 211 79a3b4e47120' 212 } 213 } 214 } 216 The COSE_Key MUST contain the required key members for a COSE_Key of 217 that key type and MAY contain other COSE_Key members, including the 218 "kid" (Key ID) member. 220 The "COSE_Key" member MAY also be used for a COSE_Key representing a 221 symmetric key, provided that the CWT is encrypted so that the key is 222 not revealed to unintended parties. The means of encrypting a CWT is 223 explained in [RFC8392]. If the CWT is not encrypted, the symmetric 224 key MUST be encrypted as described in Section 3.3. 226 3.3. Representation of an Encrypted Symmetric Proof-of-Possession Key 228 When the key held by the presenter is a symmetric key, the 229 "Encrypted_COSE_Key" member is an encrypted COSE_Key [RFC8152] 230 representing the symmetric key encrypted to a key known to the 231 recipient using COSE_Encrypt or COSE_Encrypt0. 233 The following example (using CBOR diagnostic notation, with 234 linebreaks for readability) illustrates a symmetric key that could 235 subsequently be encrypted for use in the "Encrypted_COSE_Key" member: 237 { 238 /kty/ 1 : /Symmetric/ 4, 239 /alg/ 3 : /HMAC256/ 5, 240 /k/ -1 : h'6684523ab17337f173500e5728c628547cb37df 241 e68449c65f885d1b73b49eae1A0B0C0D0E0F10' 242 } 244 The COSE_Key representation is used as the plaintext when encrypting 245 the key. 247 The following example CWT Claims Set of a CWT (using CBOR diagnostic 248 notation, with linebreaks for readability) illustrates the use of an 249 encrypted symmetric key as the "Encrypted_COSE_Key" member value: 251 { 252 /iss/ 1 : "coaps://server.example.com", 253 /sub/ 2 : "24400320", 254 /aud/ 3: "s6BhdRkqt3", 255 /exp/ 4 : 1311281970, 256 /iat/ 5 : 1311280970, 257 /cnf/ 8 : { 258 /COSE_Encrypt0/ 2 : [ 259 /protected header / h'A1010A' /{ \alg\ 1:10 \AES-CCM-16-64-128\}/, 260 /unprotected header/ { / iv / 5: h'636898994FF0EC7BFCF6D3F95B'}, 261 /ciphertext/ h'0573318A3573EB983E55A7C2F06CADD0796C9E584F1D0E3E 262 A8C5B052592A8B2694BE9654F0431F38D5BBC8049FA7F13F' 263 ] 264 } 265 } 267 The example above was generated with the key: 269 h'6162630405060708090a0b0c0d0e0f10' 271 3.4. Representation of a Key ID for a Proof-of-Possession Key 273 The proof-of-possession key can also be identified by the use of a 274 Key ID instead of communicating the actual key, provided the 275 recipient is able to obtain the identified key using the Key ID. In 276 this case, the issuer of a CWT declares that the presenter possesses 277 a particular key and that the recipient can cryptographically confirm 278 proof of possession of the key by the presenter by including a "cnf" 279 claim in the CWT whose value is a CBOR map with the CBOR map 280 containing a "kid" member identifying the key. 282 The following example (using CBOR diagnostic notation) demonstrates 283 such a declaration in the CWT Claims Set of a CWT: 285 { 286 /iss/ 1 : "coaps://server.example.com", 287 /aud/ 3 : "coaps://client.example.org", 288 /exp/ 4 : 1361398824, 289 /cnf/ 8 : { 290 /kid/ 2 : h'dfd1aa976d8d4575a0fe34b96de2bfad' 291 } 292 } 294 The content of the "kid" value is application specific. For 295 instance, some applications may choose to use a cryptographic hash of 296 the public key value as the "kid" value. 298 3.5. Specifics Intentionally Not Specified 300 Proof of possession is often demonstrated by having the presenter 301 sign a value determined by the recipient using the key possessed by 302 the presenter. This value is sometimes called a "nonce" or a 303 "challenge". 305 The means of communicating the nonce and the nature of its contents 306 are intentionally not described in this specification, as different 307 protocols will communicate this information in different ways. 308 Likewise, the means of communicating the signed nonce is also not 309 specified, as this is also protocol specific. 311 Note that another means of proving possession of the key when it is a 312 symmetric key is to encrypt the key to the recipient. The means of 313 obtaining a key for the recipient is likewise protocol specific. 315 4. Security Considerations 317 All of the security considerations that are discussed in [RFC8392] 318 also apply here. In addition, proof of possession introduces its own 319 unique security issues. Possessing a key is only valuable if it is 320 kept secret. Appropriate means must be used to ensure that 321 unintended parties do not learn private key or symmetric key values. 323 Applications utilizing proof of possession SHOULD also utilize 324 audience restriction, as described in Section 4.1.3 of [JWT], as it 325 provides additional protections. Audience restriction can be used by 326 recipients to reject messages intended for different recipients. 328 A recipient might not understand the "cnf" claim. Applications that 329 require the proof-of-possession keys communicated with it to be 330 understood and processed MUST ensure that the parts of this 331 specification that they use are implemented. 333 CBOR Web Tokens with proof-of-possession keys are used in context of 334 an architecture, such as the ACE OAuth Framework 335 [I-D.ietf-ace-oauth-authz], in which protocols are used by a 336 presenter to request these tokens and to subsequently use them with 337 recipients. To avoid replay attacks when the proof-of-possession 338 tokens are sent to presenters, a security protocol, which uses 339 mechansims such as nonces or timestamps, has to be utilized. Note 340 that a discussion of the architecture or specific protocols that CWT 341 proof-of-possession tokens are used with is beyond the scope of this 342 specification. 344 As is the case with other information included in a CWT, it is 345 necessary to apply data origin authentication and integrity 346 protection (via a keyed message digest or a digital signature). Data 347 origin authentication ensures that the recipient of the CWT learns 348 about the entity that created the CWT since this will be important 349 for any policy decisions. Integrity protection prevents an adversary 350 from changing any elements conveyed within the CWT payload. Special 351 care has to be applied when carrying symmetric keys inside the CWT 352 since those not only require integrity protection but also 353 confidentiality protection. 355 As described in Section 6 (Key Identification) and Appendix D (Notes 356 on Key Selection) of [JWS], it is important to make explicit trust 357 decisions about the keys. Proof-of-possession signatures made with 358 keys not meeting the application's trust criteria MUST NOT be relied 359 upon. 361 5. Privacy Considerations 363 A proof-of-possession key can be used as a correlation handle if the 364 same key is used with multiple parties. Thus, for privacy reasons, 365 it is recommended that different proof-of-possession keys be used 366 when interacting with different parties. 368 6. Operational Considerations 370 The use of CWTs with proof-of-possession keys requires additional 371 information to be shared between the involved parties in order to 372 ensure correct processing. The recipient needs to be able to use 373 credentials to verify the authenticity, integrity, and potentially 374 the confidentiality of the CWT and its content. This requires the 375 recipient to know information about the issuer. Likewise, there 376 needs to be agreement between the issuer and the recipient about the 377 claims being used (which is also true of CWTs in general). 379 When an issuer creates a CWT containing a Key ID claim, it needs to 380 make sure that it does not issue another CWT containing the same Key 381 ID with a different content, or for a different subject, within the 382 lifetime of the CWTs, unless intentionally desired. Failure to do so 383 may allow one party to impersonate another party, with the potential 384 to gain additional privileges. Likewise, if PoP keys are used for 385 multiple different kinds of CWTs in an application and the PoP keys 386 are identified by Key IDs, care must be taken to keep the keys for 387 the different kinds of CWTs segregated so that an attacker cannot 388 cause the wrong PoP key to be used by using a valid Key ID for the 389 wrong kind of CWT. 391 7. IANA Considerations 393 The following registration procedure is used for all the registries 394 established by this specification. 396 Values are registered on a Specification Required [RFC5226] basis 397 after a three-week review period on the cwt-reg-review@ietf.org 398 mailing list, on the advice of one or more Designated Experts. 399 However, to allow for the allocation of values prior to publication, 400 the Designated Experts may approve registration once they are 401 satisfied that such a specification will be published. [[ Note to 402 the RFC Editor: The name of the mailing list should be determined in 403 consultation with the IESG and IANA. Suggested name: cwt-reg- 404 review@ietf.org. ]] 406 Registration requests sent to the mailing list for review should use 407 an appropriate subject (e.g., "Request to Register CWT Confirmation 408 Method: example"). Registration requests that are undetermined for a 409 period longer than 21 days can be brought to the IESG's attention 410 (using the iesg@ietf.org mailing list) for resolution. 412 Criteria that should be applied by the Designated Experts include 413 determining whether the proposed registration duplicates existing 414 functionality, determining whether it is likely to be of general 415 applicability or whether it is useful only for a single application, 416 and evaluating the security properties of the item being registered 417 and whether the registration makes sense. 419 It is suggested that multiple Designated Experts be appointed who are 420 able to represent the perspectives of different applications using 421 this specification in order to enable broadly informed review of 422 registration decisions. In cases where a registration decision could 423 be perceived as creating a conflict of interest for a particular 424 Expert, that Expert should defer to the judgment of the other 425 Experts. 427 7.1. CBOR Web Token Claims Registration 429 This specification registers the "cnf" claim in the IANA "CBOR Web 430 Token Claims" registry [IANA.CWT.Claims] established by [RFC8392]. 432 7.1.1. Registry Contents 434 o Claim Name: "cnf" 435 o Claim Description: Confirmation 436 o JWT Claim Name: "cnf" 437 o Claim Key: TBD (maybe 8) 438 o Claim Value Type(s): map 439 o Change Controller: IESG 440 o Specification Document(s): Section 3.1 of [[ this document ]] 442 7.2. CWT Confirmation Methods Registry 444 This specification establishes the IANA "CWT Confirmation Methods" 445 registry for CWT "cnf" member values. The registry records the 446 confirmation method member and a reference to the specification that 447 defines it. 449 7.2.1. Registration Template 451 Confirmation Method Name: 452 The human-readable name requested (e.g., "kid"). 454 Confirmation Method Description: 455 Brief description of the confirmation method (e.g., "Key 456 Identifier"). 458 JWT Confirmation Method Name: 459 Claim Name of the equivalent JWT confirmation method value, as 460 registered in [IANA.JWT.Claims]. CWT claims should normally have 461 a corresponding JWT claim. If a corresponding JWT claim would not 462 make sense, the Designated Experts can choose to accept 463 registrations for which the JWT Claim Name is listed as "N/A". 465 Confirmation Key: 466 CBOR map key value for the confirmation method. 468 Confirmation Value Type(s): 469 CBOR types that can be used for the confirmation method value. 471 Change Controller: 472 For Standards Track RFCs, list the "IESG". For others, give the 473 name of the responsible party. Other details (e.g., postal 474 address, email address, home page URI) may also be included. 476 Specification Document(s): 477 Reference to the document or documents that specify the parameter, 478 preferably including URIs that can be used to retrieve copies of 479 the documents. An indication of the relevant sections may also be 480 included but is not required. 482 7.2.2. Initial Registry Contents 484 o Confirmation Method Name: "COSE_Key" 485 o Confirmation Method Description: COSE_Key Representing Public Key 486 o JWT Confirmation Method Name: "jwk" 487 o Confirmation Key: 1 488 o Confirmation Value Type(s): COSE_Key structure 489 o Change Controller: IESG 490 o Specification Document(s): Section 3.2 of [[ this document ]] 492 o Confirmation Method Name: "Encrypted_COSE_Key" 493 o Confirmation Method Description: Encrypted COSE_Key 494 o JWT Confirmation Method Name: "jwe" 495 o Confirmation Key: 2 496 o Confirmation Value Type(s): COSE_Encrypt or COSE_Encrypt0 497 structure (with an optional corresponding COSE_Encrypt or 498 COSE_Encrypt0 tag) 499 o Change Controller: IESG 500 o Specification Document(s): Section 3.3 of [[ this document ]] 502 o Confirmation Method Name: "kid" 503 o Confirmation Method Description: Key Identifier 504 o JWT Confirmation Method Name: "kid" 505 o Confirmation Key: 3 506 o Confirmation Value Type(s): binary string 507 o Change Controller: IESG 508 o Specification Document(s): Section 3.4 of [[ this document ]] 510 8. References 512 8.1. Normative References 514 [IANA.CWT.Claims] 515 IANA, "CBOR Web Token Claims", 516 . 518 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 519 Requirement Levels", BCP 14, RFC 2119, 520 DOI 10.17487/RFC2119, March 1997, 521 . 523 [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an 524 IANA Considerations Section in RFCs", RFC 5226, 525 DOI 10.17487/RFC5226, May 2008, 526 . 528 [RFC7049] Bormann, C. and P. Hoffman, "Concise Binary Object 529 Representation (CBOR)", RFC 7049, DOI 10.17487/RFC7049, 530 October 2013, . 532 [RFC8152] Schaad, J., "CBOR Object Signing and Encryption (COSE)", 533 RFC 8152, DOI 10.17487/RFC8152, July 2017, 534 . 536 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 537 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 538 May 2017, . 540 [RFC8392] Jones, M., Wahlstroem, E., Erdtman, S., and H. Tschofenig, 541 "CBOR Web Token (CWT)", RFC 8392, DOI 10.17487/RFC8392, 542 May 2018, . 544 8.2. Informative References 546 [I-D.ietf-ace-oauth-authz] 547 Seitz, L., Selander, G., Wahlstroem, E., Erdtman, S., and 548 H. Tschofenig, "Authentication and Authorization for 549 Constrained Environments (ACE) using the OAuth 2.0 550 Framework (ACE-OAuth)", draft-ietf-ace-oauth-authz-16 551 (work in progress), October 2018. 553 [IANA.JWT.Claims] 554 IANA, "JSON Web Token Claims", 555 . 557 [JWS] Jones, M., Bradley, J., and N. Sakimura, "JSON Web 558 Signature (JWS)", RFC 7515, May 2015, 559 . 561 [JWT] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token 562 (JWT)", RFC 7519, DOI 10.17487/RFC7159, May 2015, 563 . 565 [OASIS.saml-core-2.0-os] 566 Cantor, S., Kemp, J., Philpott, R., and E. Maler, 567 "Assertions and Protocol for the OASIS Security Assertion 568 Markup Language (SAML) V2.0", OASIS Standard saml-core- 569 2.0-os, March 2005, 570 . 572 [RFC7159] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data 573 Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March 574 2014, . 576 [RFC7800] Jones, M., Bradley, J., and H. Tschofenig, "Proof-of- 577 Possession Key Semantics for JSON Web Tokens (JWTs)", 578 RFC 7800, DOI 10.17487/RFC7800, April 2016, 579 . 581 Acknowledgements 583 Thanks to the following people for their reviews of the 584 specification: Roman Danyliw, Michael Richardson, and Jim Schaad. 586 Ludwig Seitz and Goeran Selander worked on this document as part of 587 the CelticPlus project CyberWI, with funding from Vinnova. 589 Document History 591 [[ to be removed by the RFC Editor before publication as an RFC ]] 593 -04 595 o Addressed additional WGLC comments by Jim Schaad and Roman 596 Danyliw. 598 -03 600 o Addressed review comments by Jim Schaad, see https://www.ietf.org/ 601 mail-archive/web/ace/current/msg02798.html 603 o Removed unnecessary sentence in the introduction regarding the use 604 any strings that could be case-sensitive. 606 o Clarified the terms Presenter and Recipient. 608 o Clarified text about the confirmation claim. 610 -02 612 o Changed "typically" to "often" when describing ways of performing 613 proof of possession. 615 o Changed b64 to hex encoding in an example. 617 o Changed to using the RFC 8174 boilerplate instead of the RFC 2119 618 boilerplate. 620 -01 622 o Now uses CBOR diagnostic notation for the examples. 624 o Added a table summarizing the "cnf" names, keys, and value types. 626 o Addressed some of Jim Schaad's feedback on -00. 628 -00 630 o Created the initial working group draft from draft-jones-ace-cwt- 631 proof-of-possession-01. 633 Authors' Addresses 635 Michael B. Jones 636 Microsoft 638 Email: mbj@microsoft.com 639 URI: http://self-issued.info/ 641 Ludwig Seitz 642 RISE SICS 643 Scheelevaegen 17 644 Lund 223 70 645 Sweden 647 Email: ludwig@ri.se 649 Goeran Selander 650 Ericsson AB 651 Faeroegatan 6 652 Kista 164 80 653 Sweden 655 Email: goran.selander@ericsson.com 657 Samuel Erdtman 658 Spotify 660 Email: erdtman@spotify.com 661 Hannes Tschofenig 662 ARM Ltd. 663 Hall in Tirol 6060 664 Austria 666 Email: Hannes.Tschofenig@arm.com