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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references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 7049 (Obsoleted by RFC 8949) == Outdated reference: A later version (-46) exists of draft-ietf-ace-oauth-authz-21 Summary: 1 error (**), 0 flaws (~~), 2 warnings (==), 1 comment (--). 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: April 20, 2020 RISE SICS 6 G. Selander 7 Ericsson AB 8 S. Erdtman 9 Spotify 10 H. Tschofenig 11 Arm Ltd. 12 October 18, 2019 14 Proof-of-Possession Key Semantics for CBOR Web Tokens (CWTs) 15 draft-ietf-ace-cwt-proof-of-possession-09 17 Abstract 19 This specification describes how to declare in a CBOR Web Token (CWT) 20 (which is defined by RFC 8392) that the presenter of the CWT 21 possesses a particular proof-of-possession key. Being able to prove 22 possession of a key is also sometimes described as being the holder- 23 of-key. This specification provides equivalent functionality to 24 "Proof-of-Possession Key Semantics for JSON Web Tokens (JWTs)" (RFC 25 7800) but using Concise Binary Object Representation (CBOR) and CWTs 26 rather than JavaScript Object Notation (JSON) and JSON Web Tokens 27 (JWTs). 29 Status of This Memo 31 This Internet-Draft is submitted in full conformance with the 32 provisions of BCP 78 and BCP 79. 34 Internet-Drafts are working documents of the Internet Engineering 35 Task Force (IETF). Note that other groups may also distribute 36 working documents as Internet-Drafts. The list of current Internet- 37 Drafts is at https://datatracker.ietf.org/drafts/current/. 39 Internet-Drafts are draft documents valid for a maximum of six months 40 and may be updated, replaced, or obsoleted by other documents at any 41 time. It is inappropriate to use Internet-Drafts as reference 42 material or to cite them other than as "work in progress." 44 This Internet-Draft will expire on April 20, 2020. 46 Copyright Notice 48 Copyright (c) 2019 IETF Trust and the persons identified as the 49 document authors. All rights reserved. 51 This document is subject to BCP 78 and the IETF Trust's Legal 52 Provisions Relating to IETF Documents 53 (https://trustee.ietf.org/license-info) in effect on the date of 54 publication of this document. Please review these documents 55 carefully, as they describe your rights and restrictions with respect 56 to this document. Code Components extracted from this document must 57 include Simplified BSD License text as described in Section 4.e of 58 the Trust Legal Provisions and are provided without warranty as 59 described in the Simplified BSD License. 61 Table of Contents 63 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 64 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 65 3. Representations for Proof-of-Possession Keys . . . . . . . . 3 66 3.1. Confirmation Claim . . . . . . . . . . . . . . . . . . . 4 67 3.2. Representation of an Asymmetric Proof-of-Possession Key . 5 68 3.3. Representation of an Encrypted Symmetric Proof-of- 69 Possession Key . . . . . . . . . . . . . . . . . . . . . 6 70 3.4. Representation of a Key ID for a Proof-of-Possession Key 7 71 3.5. Specifics Intentionally Not Specified . . . . . . . . . . 8 72 4. Security Considerations . . . . . . . . . . . . . . . . . . . 8 73 5. Privacy Considerations . . . . . . . . . . . . . . . . . . . 9 74 6. Operational Considerations . . . . . . . . . . . . . . . . . 9 75 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 76 7.1. CBOR Web Token Claims Registration . . . . . . . . . . . 11 77 7.1.1. Registry Contents . . . . . . . . . . . . . . . . . . 11 78 7.2. CWT Confirmation Methods Registry . . . . . . . . . . . . 11 79 7.2.1. Registration Template . . . . . . . . . . . . . . . . 11 80 7.2.2. Initial Registry Contents . . . . . . . . . . . . . . 12 81 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 82 8.1. Normative References . . . . . . . . . . . . . . . . . . 12 83 8.2. Informative References . . . . . . . . . . . . . . . . . 13 84 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 14 85 Document History . . . . . . . . . . . . . . . . . . . . . . . . 14 86 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16 88 1. Introduction 90 This specification describes how a CBOR Web Token (CWT) [RFC8392] can 91 declare that the presenter of the CWT possesses a particular proof- 92 of-possession (PoP) key. Proof of possession of a key is also 93 sometimes described as being the holder-of-key. This specification 94 provides equivalent functionality to "Proof-of-Possession Key 95 Semantics for JSON Web Tokens (JWTs)" [RFC7800] but using Concise 96 Binary Object Representation (CBOR) [RFC7049] and CWTs [RFC8392] 97 rather than JavaScript Object Notation (JSON) [RFC8259] and JSON Web 98 Tokens (JWTs) [JWT]. 100 2. Terminology 102 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 103 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 104 "OPTIONAL" in this document are to be interpreted as described in BCP 105 14 [RFC2119] [RFC8174] when, and only when, they appear in all 106 capitals, as shown here. 108 This specification uses terms defined in the CBOR Web Token (CWT) 109 [RFC8392], CBOR Object Signing and Encryption (COSE) [RFC8152], and 110 Concise Binary Object Representation (CBOR) [RFC7049] specifications. 112 These terms are defined by this specification: 114 Issuer 115 Party that creates the CWT and binds the claims about the subject 116 to the proof-of-possession key. 118 Presenter 119 Party that proves possession of a private key (for asymmetric key 120 cryptography) or secret key (for symmetric key cryptography) to a 121 recipient of a CWT. 122 In the context of OAuth, this party is also called the OAuth 123 Client. 125 Recipient 126 Party that receives the CWT containing the proof-of-possession key 127 information from the presenter. 128 In the context of OAuth, this party is also called the OAuth 129 Resource Server. 131 This specification provides examples in CBOR extended diagnostic 132 notation, as defined in Appendix G of [RFC8610]. The examples 133 include line breaks for readability. 135 3. Representations for Proof-of-Possession Keys 137 By including a "cnf" (confirmation) claim in a CWT, the issuer of the 138 CWT declares that the presenter possesses a particular key and that 139 the recipient can cryptographically confirm that the presenter has 140 possession of that key. The value of the "cnf" claim is a CBOR map 141 (which is defined in Section 2.1 of [RFC7049]) and the members of 142 that map identify the proof-of-possession key. 144 The presenter can be identified in one of several ways by the CWT, 145 depending upon the application requirements. For instance, some 146 applications may use the CWT "sub" (subject) claim [RFC8392], to 147 identify the presenter. Other applications may use the "iss" claim 148 to identify the presenter. In some applications, the subject 149 identifier might be relative to the issuer identified by the "iss" 150 (issuer) claim [RFC8392]. The actual mechanism used is dependent 151 upon the application. The case in which the presenter is the subject 152 of the CWT is analogous to Security Assertion Markup Language (SAML) 153 2.0 [OASIS.saml-core-2.0-os] SubjectConfirmation usage. 155 3.1. Confirmation Claim 157 The "cnf" claim in the CWT is used to carry confirmation methods. 158 Some of them use proof-of-possession keys while others do not. This 159 design is analogous to the SAML 2.0 [OASIS.saml-core-2.0-os] 160 SubjectConfirmation element in which a number of different subject 161 confirmation methods can be included (including proof-of-possession 162 key information). 164 The set of confirmation members that a CWT must contain to be 165 considered valid is context dependent and is outside the scope of 166 this specification. Specific applications of CWTs will require 167 implementations to understand and process some confirmation members 168 in particular ways. However, in the absence of such requirements, 169 all confirmation members that are not understood by implementations 170 MUST be ignored. 172 This specification establishes the IANA "CWT Confirmation Methods" 173 registry for these members in Section 7.2 and registers the members 174 defined by this specification. Other specifications can register 175 other members used for confirmation, including other members for 176 conveying proof-of-possession keys using different key 177 representations. 179 The "cnf" claim value MUST represent only a single proof-of- 180 possession key. At most one of the "COSE_Key" and 181 "Encrypted_COSE_Key" confirmation values defined in Figure 1 may be 182 present. Note that if an application needs to represent multiple 183 proof-of-possession keys in the same CWT, one way for it to achieve 184 this is to use other claim names, in addition to "cnf", to hold the 185 additional proof-of-possession key information. These claims could 186 use the same syntax and semantics as the "cnf" claim. Those claims 187 would be defined by applications or other specifications and could be 188 registered in the IANA "CBOR Web Token Claims" registry 189 [IANA.CWT.Claims]. 191 /--------------------+-----+-------------------------------\ 192 | Name | Key | Value type | 193 |--------------------+-----+-------------------------------| 194 | COSE_Key | 1 | COSE_Key | 195 | Encrypted_COSE_Key | 2 | COSE_Encrypt or COSE_Encrypt0 | 196 | kid | 3 | binary string | 197 \--------------------+-----+-------------------------------/ 199 Figure 1: Summary of the cnf names, keys, and value types 201 3.2. Representation of an Asymmetric Proof-of-Possession Key 203 When the key held by the presenter is an asymmetric private key, the 204 "COSE_Key" member is a COSE_Key [RFC8152] representing the 205 corresponding asymmetric public key. The following example 206 demonstrates such a declaration in the CWT Claims Set of a CWT: 208 { 209 /iss/ 1 : "coaps://server.example.com", 210 /aud/ 3 : "coaps://client.example.org", 211 /exp/ 4 : 1879067471, 212 /cnf/ 8 :{ 213 /COSE_Key/ 1 :{ 214 /kty/ 1 : /EC2/ 2, 215 /crv/ -1 : /P-256/ 1, 216 /x/ -2 : h'd7cc072de2205bdc1537a543d53c60a6acb62eccd890c7fa27c9 217 e354089bbe13', 218 /y/ -3 : h'f95e1d4b851a2cc80fff87d8e23f22afb725d535e515d020731e 219 79a3b4e47120' 220 } 221 } 222 } 224 The COSE_Key MUST contain the required key members for a COSE_Key of 225 that key type and MAY contain other COSE_Key members, including the 226 "kid" (Key ID) member. 228 The "COSE_Key" member MAY also be used for a COSE_Key representing a 229 symmetric key, provided that the CWT is encrypted so that the key is 230 not revealed to unintended parties. The means of encrypting a CWT is 231 explained in [RFC8392]. If the CWT is not encrypted, the symmetric 232 key MUST be encrypted as described in Section 3.3. This procedure is 233 equivalent to the one defined in section 3.3 of [RFC7800]. 235 3.3. Representation of an Encrypted Symmetric Proof-of-Possession Key 237 When the key held by the presenter is a symmetric key, the 238 "Encrypted_COSE_Key" member is an encrypted COSE_Key [RFC8152] 239 representing the symmetric key encrypted to a key known to the 240 recipient using COSE_Encrypt or COSE_Encrypt0. 242 The following example illustrates a symmetric key that could 243 subsequently be encrypted for use in the "Encrypted_COSE_Key" member: 245 { 246 /kty/ 1 : /Symmetric/ 4, 247 /alg/ 3 : /HMAC256//256/ 5, 248 /k/ -1 : h'6684523ab17337f173500e5728c628547cb37df 249 e68449c65f885d1b73b49eae1' 250 } 252 The COSE_Key representation is used as the plaintext when encrypting 253 the key. 255 The following example CWT Claims Set of a CWT illustrates the use of 256 an encrypted symmetric key as the "Encrypted_COSE_Key" member value: 258 { 259 /iss/ 1 : "coaps://server.example.com", 260 /sub/ 2 : "24400320", 261 /aud/ 3: "s6BhdRkqt3", 262 /exp/ 4 : 1311281970, 263 /iat/ 5 : 1311280970, 264 /cnf/ 8 : { 265 /Encrypted_COSE_Key/ 2 : [ 266 /protected header/ h'A1010A' /{ \alg\ 1:10 \AES-CCM-16-64-128\}/, 267 /unprotected header/ { / iv / 5: h'636898994FF0EC7BFCF6D3F95B'}, 268 /ciphertext/ h'0573318A3573EB983E55A7C2F06CADD0796C9E584F1D0E3E 269 A8C5B052592A8B2694BE9654F0431F38D5BBC8049FA7F13F' 270 ] 271 } 272 } 274 The example above was generated with the key: 276 h'6162630405060708090a0b0c0d0e0f10' 278 3.4. Representation of a Key ID for a Proof-of-Possession Key 280 The proof-of-possession key can also be identified using a Key ID 281 instead of communicating the actual key, provided the recipient is 282 able to obtain the identified key using the Key ID. In this case, 283 the issuer of a CWT declares that the presenter possesses a 284 particular key and that the recipient can cryptographically confirm 285 proof of possession of the key by the presenter by including a "cnf" 286 claim in the CWT whose value is a CBOR map with the CBOR map 287 containing a "kid" member identifying the key. 289 The following example demonstrates such a declaration in the CWT 290 Claims Set of a CWT: 292 { 293 /iss/ 1 : "coaps://as.example.com", 294 /aud/ 3 : "coaps://resource.example.org", 295 /exp/ 4 : 1361398824, 296 /cnf/ 8 : { 297 /kid/ 3 : h'dfd1aa976d8d4575a0fe34b96de2bfad' 298 } 299 } 301 The content of the "kid" value is application specific. For 302 instance, some applications may choose to use a cryptographic hash of 303 the public key value as the "kid" value. 305 Note that the use of a Key ID to identify a proof-of-possession key 306 needs to be carefully circumscribed, as described below and in 307 Section 6. In cases where the Key ID is not a cryptographic value 308 derived from the key or where not all of the parties involved are 309 validating the cryptographic derivation, implementers should expect 310 collisions, where different keys are assigned the same Key ID. 311 Recipients of a CWT with a PoP key linked through only a Key ID 312 should be prepared to handle such situations. 314 In the world of constrained Internet of Things (IoT) devices, there 315 is frequently a restriction on the size of Key IDs, either because of 316 table constraints or a desire to keep message sizes small. 318 Note that the value of a Key ID for a specific key is not necessarily 319 the same for different parties. When sending a COSE encrypted 320 message with a shared key, the Key ID may be different on both sides 321 of the conversation, with the appropriate one being included in the 322 message based on the recipient of the message. 324 3.5. Specifics Intentionally Not Specified 326 Proof of possession is often demonstrated by having the presenter 327 sign a value determined by the recipient using the key possessed by 328 the presenter. This value is sometimes called a "nonce" or a 329 "challenge". There are, however, also other means to demonstrate 330 freshness of the exchange and to link the proof-of-possession key to 331 the participating parties, as demonstrated by various authentication 332 and key exchange protocols. 334 The means of communicating the nonce and the nature of its contents 335 are intentionally not described in this specification, as different 336 protocols will communicate this information in different ways. 337 Likewise, the means of communicating the signed nonce is also not 338 specified, as this is also protocol specific. 340 Note that other means of proving possession of the key exist, which 341 could be used in conjunction with a CWT's confirmation key. 342 Applications making use of such alternate means are encouraged to 343 register them in the IANA "CWT Confirmation Methods" registry 344 established in Section 7.2. 346 4. Security Considerations 348 All the security considerations that are discussed in [RFC8392] also 349 apply here. In addition, proof of possession introduces its own 350 unique security issues. Possessing a key is only valuable if it is 351 kept secret. Appropriate means must be used to ensure that 352 unintended parties do not learn private key or symmetric key values. 354 Applications utilizing proof of possession SHOULD also utilize 355 audience restriction, as described in Section 3.1.3 of [RFC8392], as 356 it provides additional protections. Audience restriction can be used 357 by recipients to reject messages intended for different recipients. 358 (Of course, applications not using proof of possession can also 359 benefit from using audience restriction to reject messages intended 360 for different recipients.) 362 CBOR Web Tokens with proof-of-possession keys are used in context of 363 an architecture, such as the ACE OAuth Framework 364 [I-D.ietf-ace-oauth-authz], in which protocols are used by a 365 presenter to request these tokens and to subsequently use them with 366 recipients. Proof of possession only provides the intended security 367 gains when the proof is known to be current and not subject to replay 368 attacks; security protocols using mechanisms such as nonces and 369 timestamps can be used to avoid the risk of replay when performing 370 proof of possession for a token. Note that a discussion of the 371 architecture or specific protocols that CWT proof-of-possession 372 tokens are used with is beyond the scope of this specification. 374 As is the case with other information included in a CWT, it is 375 necessary to apply data origin authentication and integrity 376 protection (via a keyed message digest or a digital signature). Data 377 origin authentication ensures that the recipient of the CWT learns 378 about the entity that created the CWT since this will be important 379 for any policy decisions. Integrity protection prevents an adversary 380 from changing any elements conveyed within the CWT payload. Special 381 care has to be applied when carrying symmetric keys inside the CWT 382 since those not only require integrity protection but also 383 confidentiality protection. 385 As described in Section 6 (Key Identification) and Appendix D (Notes 386 on Key Selection) of [JWS], it is important to make explicit trust 387 decisions about the keys. Proof-of-possession signatures made with 388 keys not meeting the application's trust criteria MUST NOT be relied 389 upon. 391 5. Privacy Considerations 393 A proof-of-possession key can be used as a correlation handle if the 394 same key is used on multiple occasions. Thus, for privacy reasons, 395 it is recommended that different proof-of-possession keys be used 396 when interacting with different parties. 398 6. Operational Considerations 400 The use of CWTs with proof-of-possession keys requires additional 401 information to be shared between the involved parties in order to 402 ensure correct processing. The recipient needs to be able to use 403 credentials to verify the authenticity and integrity of the CWT. 404 Furthermore, the recipient may need to be able to decrypt either the 405 whole CWT or the encrypted parts thereof (see Section 3.3). This 406 requires the recipient to know information about the issuer. 407 Likewise, there needs to be agreement between the issuer and the 408 recipient about the claims being used (which is also true of CWTs in 409 general). 411 When an issuer creates a CWT containing a Key ID claim, it needs to 412 make sure that it does not issue another CWT with different claims 413 containing the same Key ID within the lifetime of the CWTs, unless 414 intentionally desired. Failure to do so may allow one party to 415 impersonate another party, with the potential to gain additional 416 privileges. A case where such reuse of a Key ID would be intentional 417 is when a presenter obtains a CWT with different claims (e.g., 418 extended scope) for the same recipient, but wants to continue using 419 an existing security association (e.g., a DTLS session) bound to the 420 key identified by the Key ID. Likewise, if PoP keys are used for 421 multiple different kinds of CWTs in an application and the PoP keys 422 are identified by Key IDs, care must be taken to keep the keys for 423 the different kinds of CWTs segregated so that an attacker cannot 424 cause the wrong PoP key to be used by using a valid Key ID for the 425 wrong kind of CWT. Using an audience restriction for the CWT would 426 be one strategy to mitigate this risk. 428 7. IANA Considerations 430 The following registration procedure is used for all the registries 431 established by this specification. 433 Values are registered on a Specification Required [RFC8126] basis 434 after a three-week review period on the cwt-reg-review@ietf.org 435 mailing list, on the advice of one or more Designated Experts. 436 However, to allow for the allocation of values prior to publication, 437 the Designated Experts may approve registration once they are 438 satisfied that such a specification will be published. [[ Note to 439 the RFC Editor: The name of the mailing list should be determined in 440 consultation with the IESG and IANA. Suggested name: cwt-reg- 441 review@ietf.org. ]] 443 Registration requests sent to the mailing list for review should use 444 an appropriate subject (e.g., "Request to Register CWT Confirmation 445 Method: example"). Registration requests that are undetermined for a 446 period longer than 21 days can be brought to the IESG's attention 447 (using the iesg@ietf.org mailing list) for resolution. 449 Designated Experts should determine whether a registration request 450 contains enough information for the registry to be populated with the 451 new values and whether the proposed new functionality already exists. 452 In the case of an incomplete registration or an attempt to register 453 already existing functionality, the Designated Experts should ask for 454 corrections or reject the registration. 456 It is suggested that multiple Designated Experts be appointed who are 457 able to represent the perspectives of different applications using 458 this specification in order to enable broadly informed review of 459 registration decisions. In cases where a registration decision could 460 be perceived as creating a conflict of interest for a particular 461 Expert, that Expert should defer to the judgment of the other 462 Experts. 464 7.1. CBOR Web Token Claims Registration 466 This specification registers the "cnf" claim in the IANA "CBOR Web 467 Token Claims" registry [IANA.CWT.Claims] established by [RFC8392]. 469 7.1.1. Registry Contents 471 o Claim Name: "cnf" 472 o Claim Description: Confirmation 473 o JWT Claim Name: "cnf" 474 o Claim Key: TBD (maybe 8) 475 o Claim Value Type(s): map 476 o Change Controller: IESG 477 o Specification Document(s): Section 3.1 of [[ this document ]] 479 7.2. CWT Confirmation Methods Registry 481 This specification establishes the IANA "CWT Confirmation Methods" 482 registry for CWT "cnf" member values. The registry records the 483 confirmation method member and a reference to the specification that 484 defines it. 486 7.2.1. Registration Template 488 Confirmation Method Name: 489 The human-readable name requested (e.g., "kid"). 491 Confirmation Method Description: 492 Brief description of the confirmation method (e.g., "Key 493 Identifier"). 495 JWT Confirmation Method Name: 496 Claim Name of the equivalent JWT confirmation method value, as 497 registered in [IANA.JWT.Claims]. CWT claims should normally have 498 a corresponding JWT claim. If a corresponding JWT claim would not 499 make sense, the Designated Experts can choose to accept 500 registrations for which the JWT Claim Name is listed as "N/A". 502 Confirmation Key: 503 CBOR map key value for the confirmation method. 505 Confirmation Value Type(s): 506 CBOR types that can be used for the confirmation method value. 508 Change Controller: 509 For Standards Track RFCs, list the "IESG". For others, give the 510 name of the responsible party. 512 Specification Document(s): 513 Reference to the document or documents that specify the parameter, 514 preferably including URIs that can be used to retrieve copies of 515 the documents. An indication of the relevant sections may also be 516 included but is not required. Note that the Designated Experts 517 and IANA must be able to obtain copies of the specification 518 document(s) to perform their work. 520 7.2.2. Initial Registry Contents 522 o Confirmation Method Name: "COSE_Key" 523 o Confirmation Method Description: COSE_Key Representing Public Key 524 o JWT Confirmation Method Name: "jwk" 525 o Confirmation Key: 1 526 o Confirmation Value Type(s): COSE_Key structure 527 o Change Controller: IESG 528 o Specification Document(s): Section 3.2 of [[ this document ]] 530 o Confirmation Method Name: "Encrypted_COSE_Key" 531 o Confirmation Method Description: Encrypted COSE_Key 532 o JWT Confirmation Method Name: "jwe" 533 o Confirmation Key: 2 534 o Confirmation Value Type(s): COSE_Encrypt or COSE_Encrypt0 535 structure (with an optional corresponding COSE_Encrypt or 536 COSE_Encrypt0 tag) 537 o Change Controller: IESG 538 o Specification Document(s): Section 3.3 of [[ this document ]] 540 o Confirmation Method Name: "kid" 541 o Confirmation Method Description: Key Identifier 542 o JWT Confirmation Method Name: "kid" 543 o Confirmation Key: 3 544 o Confirmation Value Type(s): binary string 545 o Change Controller: IESG 546 o Specification Document(s): Section 3.4 of [[ this document ]] 548 8. References 550 8.1. Normative References 552 [IANA.CWT.Claims] 553 IANA, "CBOR Web Token Claims", 554 . 556 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 557 Requirement Levels", BCP 14, RFC 2119, 558 DOI 10.17487/RFC2119, March 1997, 559 . 561 [RFC7049] Bormann, C. and P. Hoffman, "Concise Binary Object 562 Representation (CBOR)", RFC 7049, DOI 10.17487/RFC7049, 563 October 2013, . 565 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 566 Writing an IANA Considerations Section in RFCs", BCP 26, 567 RFC 8126, DOI 10.17487/RFC8126, June 2017, 568 . 570 [RFC8152] Schaad, J., "CBOR Object Signing and Encryption (COSE)", 571 RFC 8152, DOI 10.17487/RFC8152, July 2017, 572 . 574 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 575 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 576 May 2017, . 578 [RFC8392] Jones, M., Wahlstroem, E., Erdtman, S., and H. Tschofenig, 579 "CBOR Web Token (CWT)", RFC 8392, DOI 10.17487/RFC8392, 580 May 2018, . 582 8.2. Informative References 584 [I-D.ietf-ace-oauth-authz] 585 Seitz, L., Selander, G., Wahlstroem, E., Erdtman, S., and 586 H. Tschofenig, "Authentication and Authorization for 587 Constrained Environments (ACE) using the OAuth 2.0 588 Framework (ACE-OAuth)", draft-ietf-ace-oauth-authz-21 589 (work in progress), February 2019. 591 [IANA.JWT.Claims] 592 IANA, "JSON Web Token Claims", 593 . 595 [JWS] Jones, M., Bradley, J., and N. Sakimura, "JSON Web 596 Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May 597 2015, . 599 [JWT] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token 600 (JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015, 601 . 603 [OASIS.saml-core-2.0-os] 604 Cantor, S., Kemp, J., Philpott, R., and E. Maler, 605 "Assertions and Protocol for the OASIS Security Assertion 606 Markup Language (SAML) V2.0", OASIS Standard saml-core- 607 2.0-os, March 2005, 608 . 610 [RFC7800] Jones, M., Bradley, J., and H. Tschofenig, "Proof-of- 611 Possession Key Semantics for JSON Web Tokens (JWTs)", 612 RFC 7800, DOI 10.17487/RFC7800, April 2016, 613 . 615 [RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data 616 Interchange Format", STD 90, RFC 8259, 617 DOI 10.17487/RFC8259, December 2017, 618 . 620 [RFC8610] Birkholz, H., Vigano, C., and C. Bormann, "Concise Data 621 Definition Language (CDDL): A Notational Convention to 622 Express Concise Binary Object Representation (CBOR) and 623 JSON Data Structures", RFC 8610, DOI 10.17487/RFC8610, 624 June 2019, . 626 Acknowledgements 628 Thanks to the following people for their reviews of the 629 specification: Roman Danyliw, Christer Holmberg, Benjamin Kaduk, Yoav 630 Nir, Michael Richardson, and Jim Schaad. 632 Ludwig Seitz and Goeran Selander worked on this document as part of 633 the CelticPlus projects CyberWI and CRITISEC, with funding from 634 Vinnova. 636 Document History 638 [[ to be removed by the RFC Editor before publication as an RFC ]] 640 -09 642 o Addressed Gen-ART review comments by Christer Holmberg and SecDir 643 review comments by Yoav Nir. 645 -08 647 o Addressed remaining Area Director review comments by Benjamin 648 Kaduk. 650 -07 652 o Addressed Area Director review by Benjamin Kaduk. 654 -06 656 o Corrected nits identified by Roman Danyliw. 658 -05 660 o Added text suggested by Jim Schaad describing considerations when 661 using the Key ID confirmation method. 663 -04 665 o Addressed additional WGLC comments by Jim Schaad and Roman 666 Danyliw. 668 -03 670 o Addressed review comments by Jim Schaad, see https://www.ietf.org/ 671 mail-archive/web/ace/current/msg02798.html 673 o Removed unnecessary sentence in the introduction regarding the use 674 any strings that could be case-sensitive. 676 o Clarified the terms Presenter and Recipient. 678 o Clarified text about the confirmation claim. 680 -02 682 o Changed "typically" to "often" when describing ways of performing 683 proof of possession. 685 o Changed b64 to hex encoding in an example. 687 o Changed to using the RFC 8174 boilerplate instead of the RFC 2119 688 boilerplate. 690 -01 692 o Now uses CBOR diagnostic notation for the examples. 694 o Added a table summarizing the "cnf" names, keys, and value types. 696 o Addressed some of Jim Schaad's feedback on -00. 698 -00 700 o Created the initial working group draft from draft-jones-ace-cwt- 701 proof-of-possession-01. 703 Authors' Addresses 705 Michael B. Jones 706 Microsoft 708 Email: mbj@microsoft.com 709 URI: http://self-issued.info/ 711 Ludwig Seitz 712 RISE SICS 713 Scheelevaegen 17 714 Lund 223 70 715 Sweden 717 Email: ludwig@ri.se 719 Goeran Selander 720 Ericsson AB 721 Faeroegatan 6 722 Kista 164 80 723 Sweden 725 Email: goran.selander@ericsson.com 727 Samuel Erdtman 728 Spotify 730 Email: erdtman@spotify.com 732 Hannes Tschofenig 733 Arm Ltd. 734 Hall in Tirol 6060 735 Austria 737 Email: Hannes.Tschofenig@arm.com