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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) == Missing Reference: 'RFC 7519' is mentioned on line 752, but not defined ** Obsolete normative reference: RFC 5226 (Obsoleted by RFC 8126) ** Obsolete normative reference: RFC 5246 (Obsoleted by RFC 8446) == Outdated reference: A later version (-08) exists of draft-ietf-oauth-pop-architecture-05 Summary: 2 errors (**), 0 flaws (~~), 3 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 OAuth Working Group M. Jones 3 Internet-Draft Microsoft 4 Intended status: Standards Track J. Bradley 5 Expires: June 20, 2016 Ping Identity 6 H. Tschofenig 7 ARM Limited 8 December 18, 2015 10 Proof-of-Possession Key Semantics for JSON Web Tokens (JWTs) 11 draft-ietf-oauth-proof-of-possession-11 13 Abstract 15 This specification defines how to declare in a JSON Web Token (JWT) 16 that the presenter of the JWT possesses a particular proof-of- 17 possession key and that the recipient can cryptographically confirm 18 proof-of-possession of the key by the presenter. Being able to prove 19 possession of a key is also sometimes described as the presenter 20 being a holder-of-key. 22 Status of this Memo 24 This Internet-Draft is submitted in full conformance with the 25 provisions of BCP 78 and BCP 79. 27 Internet-Drafts are working documents of the Internet Engineering 28 Task Force (IETF). Note that other groups may also distribute 29 working documents as Internet-Drafts. The list of current Internet- 30 Drafts is at http://datatracker.ietf.org/drafts/current/. 32 Internet-Drafts are draft documents valid for a maximum of six months 33 and may be updated, replaced, or obsoleted by other documents at any 34 time. It is inappropriate to use Internet-Drafts as reference 35 material or to cite them other than as "work in progress." 37 This Internet-Draft will expire on June 20, 2016. 39 Copyright Notice 41 Copyright (c) 2015 IETF Trust and the persons identified as the 42 document authors. All rights reserved. 44 This document is subject to BCP 78 and the IETF Trust's Legal 45 Provisions Relating to IETF Documents 46 (http://trustee.ietf.org/license-info) in effect on the date of 47 publication of this document. Please review these documents 48 carefully, as they describe your rights and restrictions with respect 49 to this document. Code Components extracted from this document must 50 include Simplified BSD License text as described in Section 4.e of 51 the Trust Legal Provisions and are provided without warranty as 52 described in the Simplified BSD License. 54 Table of Contents 56 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 57 1.1. Notational Conventions . . . . . . . . . . . . . . . . . . 5 58 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 59 3. Representations for Proof-of-Possession Keys . . . . . . . . . 6 60 3.1. Confirmation Claim . . . . . . . . . . . . . . . . . . . . 6 61 3.2. Representation of an Asymmetric Proof-of-Possession Key . 7 62 3.3. Representation of an Encrypted Symmetric 63 Proof-of-Possession Key . . . . . . . . . . . . . . . . . 8 64 3.4. Representation of a Key ID for a Proof-of-Possession 65 Key . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 66 3.5. Representation of a URL for a Proof-of-Possession Key . . 9 67 3.6. Specifics Intentionally Not Specified . . . . . . . . . . 10 68 4. Security Considerations . . . . . . . . . . . . . . . . . . . 10 69 5. Privacy Considerations . . . . . . . . . . . . . . . . . . . . 11 70 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 71 6.1. JSON Web Token Claims Registration . . . . . . . . . . . . 12 72 6.1.1. Registry Contents . . . . . . . . . . . . . . . . . . 12 73 6.2. JWT Confirmation Methods Registry . . . . . . . . . . . . 12 74 6.2.1. Registration Template . . . . . . . . . . . . . . . . 12 75 6.2.2. Initial Registry Contents . . . . . . . . . . . . . . 13 76 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13 77 7.1. Normative References . . . . . . . . . . . . . . . . . . . 13 78 7.2. Informative References . . . . . . . . . . . . . . . . . . 14 79 Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 15 80 Appendix B. Document History . . . . . . . . . . . . . . . . . . 15 81 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17 83 1. Introduction 85 This specification defines how a JSON Web Token [JWT] can declare 86 that the presenter of the JWT possesses a particular proof-of- 87 possession (PoP) key and that the recipient can cryptographically 88 confirm proof-of-possession of the key by the presenter. Proof-of- 89 possession of a key is also sometimes described as the presenter 90 being a holder-of-key. The [I-D.ietf-oauth-pop-architecture] 91 specification describes key confirmation, among other confirmation 92 mechanisms. This specification defines how to communicate key 93 confirmation key information in JWTs. 95 Envision the following two use cases. The first use case employs a 96 symmetric proof-of-possession key and the second use case employs an 97 asymmetric proof-of-possession key. 99 +--------------+ 100 | | +--------------+ 101 | |--(3) Presentation of -->| | 102 | | JWT w/ Encrypted | | 103 | Presenter | PoP Key | | 104 | | | | 105 | |<-(4) Communication ---->| | 106 | | Authenticated by | | 107 +--------------+ PoP Key | | 108 ^ ^ | | 109 | | | | 110 (1) Sym. (2) JWT w/ | Recipient | 111 | PoP | Encrypted | | 112 | Key | PoP Key | | 113 v | | | 114 +--------------+ | | 115 | | | | 116 | | | | 117 | |<-(0) Key Exchange for ->| | 118 | Issuer | Key Encryption Key | | 119 | | | | 120 | | | | 121 | | +--------------+ 122 +--------------+ 124 Figure 1: Proof-of-Possession with a Symmetric Key 126 In the case illustrated in Figure 1, either the presenter generates a 127 symmetric key and privately sends it to the issuer (1) or the issuer 128 generates a symmetric key and privately sends it to the presenter 129 (1). The issuer generates a JWT with an encrypted copy of this 130 symmetric key in the confirmation claim. This symmetric key is 131 encrypted with a key known only to the issuer and the recipient, 132 which was previously established in step (0). The entire JWT is 133 integrity protected by the issuer. The JWT is then (2) sent to the 134 presenter. Now, the presenter is in possession of the symmetric key 135 as well as the JWT (which includes the confirmation claim). When the 136 presenter (3) presents the JWT to the recipient, it also needs to 137 demonstrate possession of the symmetric key; the presenter, for 138 example, (4) uses the symmetric key in a challenge/response protocol 139 with the recipient. The recipient is then able to verify that it is 140 interacting with the genuine presenter by decrypting the key in the 141 confirmation claim of the JWT. By doing this, the recipient obtains 142 the symmetric key, which it then uses to verify cryptographically 143 protected messages exchanged with the presenter (4). This symmetric 144 key mechanism described above is conceptually similar to the use of 145 Kerberos tickets. 147 Note that for simplicity, the diagram above and associated text 148 describe the direct use of symmetric keys without the use of derived 149 keys. A more secure practice is to derive the symmetric keys 150 actually used from secrets exchanged, such as the key exchanged in 151 step (0), using a Key Derivation Function (KDF) and use the derived 152 keys, rather than directly using the secrets exchanged. 154 +--------------+ 155 | | +--------------+ 156 | |--(3) Presentation of -->| | 157 | | JWT w/ Public | | 158 | Presenter | PoP Key | | 159 | | | | 160 | |<-(4) Communication ---->| | 161 | | Authenticated by | | 162 +--------------+ PoP Key | | 163 | ^ | | 164 | | | | 165 (1) Public (2) JWT w/ | Recipient | 166 | PoP | Public | | 167 | Key | PoP Key | | 168 v | | | 169 +--------------+ | | 170 | | | | 171 | | | | 172 | | | | 173 | Issuer | | | 174 | | | | 175 | | | | 176 | | +--------------+ 177 +--------------+ 178 Figure 2: Proof-of-Possession with an Asymmetric Key 180 In the case illustrated in Figure 2, the presenter generates a 181 public/private key pair and (1) sends the public key to the issuer, 182 which creates a JWT that contains the public key (or an identifier 183 for it) in the confirmation claim. The entire JWT is integrity 184 protected using a digital signature to protect it against 185 modifications. The JWT is then (2) sent to the presenter. When the 186 presenter (3) presents the JWT to the recipient, it also needs to 187 demonstrate possession of the private key. The presenter, for 188 example, (4) uses the private key in a TLS exchange with the 189 recipient or (4) signs a nonce with the private key. The recipient 190 is able to verify that it is interacting with the genuine presenter 191 by extracting the public key from the confirmation claim of the JWT 192 (after verifying the digital signature of the JWT) and utilizing it 193 with the private key in the TLS exchange or by checking the nonce 194 signature. 196 In both cases, the JWT may contain other claims that are needed by 197 the application. 199 1.1. Notational Conventions 201 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 202 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 203 "OPTIONAL" in this document are to be interpreted as described in RFC 204 2119 [RFC2119]. 206 Unless otherwise noted, all the protocol parameter names and values 207 are case sensitive. 209 2. Terminology 211 This specification uses terms defined in the JSON Web Token [JWT], 212 JSON Web Key [JWK], and JSON Web Encryption [JWE] specifications. 214 These terms are defined by this specification: 216 Issuer 217 Party that creates the JWT and binds the proof-of-possession key 218 to it. 220 Presenter 221 Party that proves possession of a private key (for asymmetric key 222 cryptography) or secret key (for symmetric key cryptography) to a 223 recipient. 225 Recipient 226 Party that receives the JWT containing the proof-of-possession key 227 information from the presenter. 229 3. Representations for Proof-of-Possession Keys 231 By including a "cnf" (confirmation) claim in a JWT, the issuer of the 232 JWT declares that the presenter possesses a particular key, and that 233 the recipient can cryptographically confirm that the presenter has 234 possession of that key. The value of the "cnf" claim is a JSON 235 object and the members of that object identify the proof-of- 236 possession key. 238 The presenter can be identified in one of several ways by the JWT, 239 depending upon the application requirements. If the JWT contains a 240 "sub" (subject) claim [JWT], the presenter is normally the subject 241 identified by the JWT. (In some applications, the subject identifier 242 will be relative to the issuer identified by the "iss" (issuer) claim 243 [JWT].) If the JWT contains no "sub" (subject) claim, the presenter 244 is normally the issuer identified by the JWT using the "iss" (issuer) 245 claim. The case in which the presenter is the subject of the JWT is 246 analogous to SAML 2.0 [OASIS.saml-core-2.0-os] SubjectConfirmation 247 usage. At least one of the "sub" and "iss" claims MUST be present in 248 the JWT. Some use cases may require that both be present. 250 Another means used by some applications to identify the presenter is 251 an explicit claim, such as the "azp" (authorized party) claim defined 252 by OpenID Connect [OpenID.Core]. Ultimately, the means of 253 identifying the presenter is application-specific, as is the means of 254 confirming possession of the key that is communicated. 256 3.1. Confirmation Claim 258 The "cnf" (confirmation) claim is used in the JWT to contain members 259 used to identify the proof-of-possession key. Other members of the 260 "cnf" object may be defined because a proof-of-possession key may not 261 be the only means of confirming the authenticity of the token. This 262 is analogous to the SAML 2.0 [OASIS.saml-core-2.0-os] 263 SubjectConfirmation element, in which a number of different subject 264 confirmation methods can be included, including proof-of-possession 265 key information. 267 The set of confirmation members that a JWT must contain to be 268 considered valid is context dependent and is outside the scope of 269 this specification. Specific applications of JWTs will require 270 implementations to understand and process some confirmation members 271 in particular ways. However, in the absence of such requirements, 272 all confirmation members that are not understood by implementations 273 MUST be ignored. 275 This specification establishes the IANA "JWT Confirmation Methods" 276 registry for these members in Section 6.2 and registers the members 277 defined by this specification. Other specifications can register 278 other members used for confirmation, including other members for 279 conveying proof-of-possession keys, possibly using different key 280 representations. 282 The "cnf" claim value MUST represent only a single proof-of- 283 possession key; thus, at most one of the "jwk", "jwe", and "jku" 284 confirmation values defined below may be present. Note that if an 285 application needs to represent multiple proof-of-possession keys in 286 the same JWT, one way for it to achieve this is to use other claim 287 names, in addition to "cnf", to hold the additional proof-of- 288 possession key information. These claims could use the same syntax 289 and semantics as the "cnf" claim. Those claims would be defined by 290 applications or other specifications and could be registered in the 291 IANA "JSON Web Token Claims" registry [IANA.JWT.Claims]. 293 3.2. Representation of an Asymmetric Proof-of-Possession Key 295 When the key held by the presenter is an asymmetric private key, the 296 "jwk" member is a JSON Web Key [JWK] representing the corresponding 297 asymmetric public key. The following example demonstrates such a 298 declaration in the JWT Claims Set of a JWT: 300 { 301 "iss": "https://server.example.com", 302 "aud": "https://client.example.org", 303 "exp": 1361398824, 304 "cnf":{ 305 "jwk":{ 306 "kty": "EC", 307 "use": "sig", 308 "crv": "P-256", 309 "x": "18wHLeIgW9wVN6VD1Txgpqy2LszYkMf6J8njVAibvhM", 310 "y": "-V4dS4UaLMgP_4fY4j8ir7cl1TXlFdAgcx55o7TkcSA" 311 } 312 } 313 } 315 The JWK MUST contain the required key members for a JWK of that key 316 type and MAY contain other JWK members, including the "kid" (key ID) 317 member. 319 The "jwk" member MAY also be used for a JWK representing a symmetric 320 key, provided that the JWT is encrypted so that the key is not 321 revealed to unintended parties. If the JWT is not encrypted, the 322 symmetric key MUST be encrypted as described below. 324 3.3. Representation of an Encrypted Symmetric Proof-of-Possession Key 326 When the key held by the presenter is a symmetric key, the "jwe" 327 member is an encrypted JSON Web Key [JWK] encrypted to a key known to 328 the recipient using the JWE Compact Serialization containing the 329 symmetric key. The rules for encrypting a JWK are found in Section 7 330 of the JSON Web Key [JWK] specification. 332 The following example illustrates a symmetric key that could 333 subsequently be encrypted for use in the "jwe" member: 335 { 336 "kty": "oct", 337 "alg": "HS256", 338 "k": "ZoRSOrFzN_FzUA5XKMYoVHyzff5oRJxl-IXRtztJ6uE" 339 } 341 The UTF-8 [RFC3629] encoding of this JWK is used as the JWE Plaintext 342 when encrypting the key. 344 The following example is a JWE Header that could be used when 345 encrypting this key: 347 { 348 "alg": "RSA-OAEP", 349 "enc": "A128CBC-HS256" 350 } 352 The following example JWT Claims Set of a JWT illustrates the use of 353 an encrypted symmetric key as the "jwe" member value: 355 { 356 "iss": "https://server.example.com", 357 "sub": "24400320", 358 "aud": "s6BhdRkqt3", 359 "nonce": "n-0S6_WzA2Mj", 360 "exp": 1311281970, 361 "iat": 1311280970, 362 "cnf":{ 363 "jwe": 364 "eyJhbGciOiJSU0EtT0FFUCIsImVuYyI6IkExMjhDQkMtSFMyNTYifQ. 365 (remainder of JWE omitted for brevity)" 366 } 367 } 369 3.4. Representation of a Key ID for a Proof-of-Possession Key 371 The proof-of-possession key can also be identified by the use of a 372 Key ID instead of communicating the actual key, provided the 373 recipient is able to obtain the identified key using the Key ID. In 374 this case, the issuer of a JWT declares that the presenter possesses 375 a particular key and that the recipient can cryptographically confirm 376 proof-of-possession of the key by the presenter by including a "cnf" 377 (confirmation) claim in the JWT whose value is a JSON object, with 378 the JSON object containing a "kid" (key ID) member identifying the 379 key. 381 The following example demonstrates such a declaration in the JWT 382 Claims Set of a JWT: 384 { 385 "iss": "https://server.example.com", 386 "aud": "https://client.example.org", 387 "exp": 1361398824, 388 "cnf":{ 389 "kid": "dfd1aa97-6d8d-4575-a0fe-34b96de2bfad" 390 } 391 } 393 The content of the "kid" value is application specific. For 394 instance, some applications may choose to use a JWK Thumbprint 395 [JWK.Thumbprint] value as the "kid" value. 397 3.5. Representation of a URL for a Proof-of-Possession Key 399 The proof-of-possession key can be passed by reference instead of 400 being passed by value. This is done using the "jku" (JWK Set URL) 401 member. Its value is a URI [RFC3986] that refers to a resource for a 402 set of JSON-encoded public keys represented as a JWK Set [JWK], one 403 of which is the proof-of-possession key. If there are multiple keys 404 in the referenced JWK Set document, a "kid" member MUST also be 405 included, with the referenced key's JWK also containing the same 406 "kid" value. 408 The protocol used to acquire the resource MUST provide integrity 409 protection. An HTTP GET request to retrieve the JWK Set MUST use 410 Transport Layer Security (TLS) [RFC5246] and the identity of the 411 server MUST be validated, as per Section 6 of RFC 6125 [RFC6125]. 413 The following example demonstrates such a declaration in the JWT 414 Claims Set of a JWT: 416 { 417 "iss": "https://server.example.com", 418 "sub": "17760704", 419 "aud": "https://client.example.org", 420 "exp": 1440804813, 421 "cnf":{ 422 "jku": "https://keys.example.net/pop-keys.json", 423 "kid": "2015-08-28" 424 } 425 } 427 3.6. Specifics Intentionally Not Specified 429 Proof-of-possession is typically demonstrated by having the presenter 430 sign a value determined by the recipient using the key possessed by 431 the presenter. This value is sometimes called a "nonce" or a 432 "challenge". 434 The means of communicating the nonce and the nature of its contents 435 are intentionally not described in this specification, as different 436 protocols will communicate this information in different ways. 437 Likewise, the means of communicating the signed nonce is also not 438 specified, as this is also protocol-specific. 440 Note that another means of proving possession of the key when it is a 441 symmetric key is to encrypt the key to the recipient. The means of 442 obtaining a key for the recipient is likewise protocol-specific. 444 For examples using the mechanisms defined in this specification, see 445 [I-D.ietf-oauth-pop-architecture]. 447 4. Security Considerations 449 All of the security considerations that are discussed in [JWT] also 450 apply here. In addition, proof-of-possession introduces its own 451 unique security issues. Possessing a key is only valuable if it is 452 kept secret. Appropriate means must be used to ensure that 453 unintended parties do not learn private key or symmetric key values. 455 Applications utilizing proof-of-possession should also utilize 456 audience restriction, as described in Section 4.1.3 of [JWT], as it 457 provides different protections. Proof-of-possession can be used by 458 recipients to reject messages from unauthorized senders. Audience 459 restriction can be used by recipients to reject messages intended for 460 different recipients. 462 A recipient might not understand the "cnf" claim. Applications that 463 require the proof-of-possession keys communicated with it to be 464 understood and processed must ensure that the parts of this 465 specification that they use are implemented. 467 Proof-of-possession via encrypted symmetric secrets is subject to 468 replay attacks. This attack can be avoided when a signed nonce or 469 challenge is used, since the recipient can use a distinct nonce or 470 challenge for each interaction. Replay can also be avoided if a sub- 471 key is derived from a shared secret that is specific to the instance 472 of the PoP demonstration. 474 Similarly to other information included in a JWT, it is necessary to 475 apply data origin authentication and integrity protection (via a 476 keyed message digest or a digital signature). Data origin 477 authentication ensures that the recipient of the JWT learns about the 478 entity that created the JWT, since this will be important for any 479 policy decisions. Integrity protection prevents an adversary from 480 changing any elements conveyed within the JWT payload. Special care 481 has to be applied when carrying symmetric keys inside the JWT, since 482 those not only require integrity protection, but also confidentiality 483 protection. 485 5. Privacy Considerations 487 A proof-of-possession key can be used as a correlation handle if the 488 same key is used with multiple parties. Thus, for privacy reasons, 489 it is recommended that different proof-of-possession keys be used 490 when interacting with different parties. 492 6. IANA Considerations 494 The following registration procedure is used for all the registries 495 established by this specification. 497 Values are registered on a Specification Required [RFC5226] basis 498 after a three-week review period on the oauth-pop-reg-review@ietf.org 499 mailing list, on the advice of one or more Designated Experts. 500 However, to allow for the allocation of values prior to publication, 501 the Designated Experts may approve registration once they are 502 satisfied that such a specification will be published. [[ Note to the 503 RFC Editor: The name of the mailing list should be determined in 504 consultation with the IESG and IANA. Suggested name: 505 oauth-pop-reg-review@ietf.org. ]] 507 Registration requests sent to the mailing list for review should use 508 an appropriate subject (e.g., "Request to register JWT Confirmation 509 Method: example"). Registration requests that are undetermined for a 510 period longer than 21 days can be brought to the IESG's attention 511 (using the iesg@ietf.org mailing list) for resolution. 513 Criteria that should be applied by the Designated Experts include 514 determining whether the proposed registration duplicates existing 515 functionality, determining whether it is likely to be of general 516 applicability or whether it is useful only for a single application, 517 evaluating the security properties of the item being registered, and 518 whether the registration makes sense. 520 It is suggested that multiple Designated Experts be appointed who are 521 able to represent the perspectives of different applications using 522 this specification, in order to enable broadly-informed review of 523 registration decisions. In cases where a registration decision could 524 be perceived as creating a conflict of interest for a particular 525 Expert, that Expert should defer to the judgment of the other 526 Experts. 528 6.1. JSON Web Token Claims Registration 530 This specification registers the "cnf" claim in the IANA "JSON Web 531 Token Claims" registry [IANA.JWT.Claims] established by [JWT]. 533 6.1.1. Registry Contents 535 o Claim Name: "cnf" 536 o Claim Description: Confirmation 537 o Change Controller: IESG 538 o Specification Document(s): Section 3.1 of [[ this document ]] 540 6.2. JWT Confirmation Methods Registry 542 This specification establishes the IANA "JWT Confirmation Methods" 543 registry for JWT "cnf" member values. The registry records the 544 confirmation method member and a reference to the specification that 545 defines it. 547 6.2.1. Registration Template 549 Confirmation Method Value: 550 The name requested (e.g., "kid"). Because a core goal of this 551 specification is for the resulting representations to be compact, 552 it is RECOMMENDED that the name be short -- not to exceed 8 553 characters without a compelling reason to do so. This name is 554 case-sensitive. Names may not match other registered names in a 555 case-insensitive manner unless the Designated Experts state that 556 there is a compelling reason to allow an exception. 558 Confirmation Method Description: 559 Brief description of the confirmation method (e.g., "Key 560 Identifier"). 562 Change Controller: 563 For Standards Track RFCs, list the "IESG". For others, give the 564 name of the responsible party. Other details (e.g., postal 565 address, email address, home page URI) may also be included. 567 Specification Document(s): 568 Reference to the document or documents that specify the parameter, 569 preferably including URIs that can be used to retrieve copies of 570 the documents. An indication of the relevant sections may also be 571 included but is not required. 573 6.2.2. Initial Registry Contents 575 o Confirmation Method Value: "jwk" 576 o Confirmation Method Description: JSON Web Key Representing Public 577 Key 578 o Change Controller: IESG 579 o Specification Document(s): Section 3.2 of [[ this document ]] 581 o Confirmation Method Value: "jwe" 582 o Confirmation Method Description: Encrypted JSON Web Key 583 o Change Controller: IESG 584 o Specification Document(s): Section 3.3 of [[ this document ]] 586 o Confirmation Method Value: "kid" 587 o Confirmation Method Description: Key Identifier 588 o Change Controller: IESG 589 o Specification Document(s): Section 3.4 of [[ this document ]] 591 o Confirmation Method Value: "jku" 592 o Confirmation Method Description: JWK Set URL 593 o Change Controller: IESG 594 o Specification Document(s): Section 3.5 of [[ this document ]] 596 7. References 598 7.1. Normative References 600 [IANA.JWT.Claims] 601 IANA, "JSON Web Token Claims", 602 . 604 [JWE] Jones, M. and J. Hildebrand, "JSON Web Encryption (JWE)", 605 RFC 7516, DOI 10.17487/RFC7156, May 2015, 606 . 608 [JWK] Jones, M., "JSON Web Key (JWK)", RFC 7517, DOI 10.17487/ 609 RFC7157, May 2015, 610 . 612 [JWT] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token 613 (JWT)", RFC 7519, DOI 10.17487/RFC7159, May 2015, 614 . 616 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 617 Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/ 618 RFC2119, March 1997, 619 . 621 [RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO 622 10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, 623 November 2003, . 625 [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform 626 Resource Identifier (URI): Generic Syntax", STD 66, 627 RFC 3986, DOI 10.17487/RFC3986, January 2005, 628 . 630 [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an 631 IANA Considerations Section in RFCs", BCP 26, RFC 5226, 632 DOI 10.17487/RFC5226, May 2008, 633 . 635 [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security 636 (TLS) Protocol Version 1.2", RFC 5246, DOI 10.17487/ 637 RFC5246, August 2008, 638 . 640 [RFC6125] Saint-Andre, P. and J. Hodges, "Representation and 641 Verification of Domain-Based Application Service Identity 642 within Internet Public Key Infrastructure Using X.509 643 (PKIX) Certificates in the Context of Transport Layer 644 Security (TLS)", RFC 6125, DOI 10.17487/RFC6125, 645 March 2011, . 647 7.2. Informative References 649 [I-D.ietf-oauth-pop-architecture] 650 Hunt, P., Richer, J., Mills, W., Mishra, P., and H. 651 Tschofenig, "OAuth 2.0 Proof-of-Possession (PoP) Security 652 Architecture", draft-ietf-oauth-pop-architecture-05 (work 653 in progress), October 2015. 655 [JWK.Thumbprint] 656 Jones, M. and N. Sakimura, "JSON Web Key (JWK) 657 Thumbprint", RFC 7638, DOI 10.17487/RFC7638, 658 September 2015, . 660 [OASIS.saml-core-2.0-os] 661 Cantor, S., Kemp, J., Philpott, R., and E. Maler, 662 "Assertions and Protocol for the OASIS Security Assertion 663 Markup Language (SAML) V2.0", OASIS Standard saml-core- 664 2.0-os, March 2005. 666 [OpenID.Core] 667 Sakimura, N., Bradley, J., Jones, M., de Medeiros, B., and 668 C. Mortimore, "OpenID Connect Core 1.0", November 2014, 669 . 671 Appendix A. Acknowledgements 673 The authors wish to thank Brian Campbell, Stephen Farrell, Barry 674 Leiba, Kepeng Li, Chris Lonvick, James Manger, Kathleen Moriarty, 675 Justin Richer, and Nat Sakimura for their reviews of the 676 specification. 678 Appendix B. Document History 680 [[ to be removed by the RFC Editor before publication as an RFC ]] 682 -11 684 o Addressed Sec-Dir review comments by Chris Lonvick and ballot 685 comments by Stephen Farrell. 687 -10 689 o Addressed ballot comments by Barry Leiba. 691 -09 693 o Removed erroneous quotation marks around numeric "exp" claim 694 values in examples. 696 -08 697 o Added security consideration about also utilizing audience 698 restriction. 700 -07 702 o Addressed review comments by Hannes Tschofenig, Kathleen Moriarty, 703 and Justin Richer. Changes were: 705 o Clarified that symmetric proof-of-possession keys can be generated 706 by either the presenter or the issuer. 708 o Clarified that confirmation members that are not understood must 709 be ignored unless otherwise specified by the application. 711 -06 713 o Added diagrams to the introduction. 715 -05 717 o Addressed review comments by Kepeng Li. 719 -04 721 o Allowed the use of "jwk" for symmetric keys when the JWT is 722 encrypted. 724 o Added the "jku" (JWK Set URL) member. 726 o Added privacy considerations. 728 o Reordered sections so that the "cnf" (confirmation) claim is 729 defined before it is used. 731 o Noted that applications can define new claim names, in addition to 732 "cnf", to represent additional proof-of-possession keys, using the 733 same representation as "cnf". 735 o Applied wording clarifications suggested by Nat Sakimura. 737 -03 739 o Separated the "jwk" and "jwe" confirmation members; the former 740 represents a public key as a JWK and the latter represents a 741 symmetric key as a JWE encrypted JWK. 743 o Changed the title to indicate that a proof-of-possession key is 744 being communicated. 746 o Updated language that formerly assumed that the issuer was an 747 OAuth 2.0 authorization server. 749 o Described ways that applications can choose to identify the 750 presenter, including use of the "iss", "sub", and "azp" claims. 752 o Harmonized the registry language with that used in JWT [RFC 7519]. 754 o Addressed other issues identified during working group last call. 756 o Referenced the JWT and JOSE RFCs. 758 -02 760 o Defined the terms Issuer, Presenter, and Recipient and updated 761 their usage within the document. 763 o Added a description of a use case using an asymmetric proof-of- 764 possession key to the introduction. 766 o Added the "kid" (key ID) confirmation method. 768 o These changes address the open issues identified in the previous 769 draft. 771 -01 773 o Updated references. 775 -00 777 o Created the initial working group draft from 778 draft-jones-oauth-proof-of-possession-02. 780 Authors' Addresses 782 Michael B. Jones 783 Microsoft 785 Email: mbj@microsoft.com 786 URI: http://self-issued.info/ 787 John Bradley 788 Ping Identity 790 Email: ve7jtb@ve7jtb.com 791 URI: http://www.thread-safe.com/ 793 Hannes Tschofenig 794 ARM Limited 795 Austria 797 Email: Hannes.Tschofenig@gmx.net 798 URI: http://www.tschofenig.priv.at