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Checking references for intended status: Best Current Practice ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) ** Downref: Normative reference to an Informational RFC: RFC 6979 == Outdated reference: A later version (-13) exists of draft-ietf-secevent-token-10 Summary: 1 error (**), 0 flaws (~~), 2 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 OAuth Working Group Y. Sheffer 3 Internet-Draft Intuit 4 Intended status: Best Current Practice D. Hardt 5 Expires: November 9, 2018 Amazon 6 M. Jones 7 Microsoft 8 May 08, 2018 10 JSON Web Token Best Current Practices 11 draft-ietf-oauth-jwt-bcp-03 13 Abstract 15 JSON Web Tokens, also known as JWTs, are URL-safe JSON-based security 16 tokens that contain a set of claims that can be signed and/or 17 encrypted. JWTs are being widely used and deployed as a simple 18 security token format in numerous protocols and applications, both in 19 the area of digital identity, and in other application areas. The 20 goal of this Best Current Practices document is to provide actionable 21 guidance leading to secure implementation and deployment of JWTs. 23 Status of This Memo 25 This Internet-Draft is submitted in full conformance with the 26 provisions of BCP 78 and BCP 79. 28 Internet-Drafts are working documents of the Internet Engineering 29 Task Force (IETF). Note that other groups may also distribute 30 working documents as Internet-Drafts. The list of current Internet- 31 Drafts is at https://datatracker.ietf.org/drafts/current/. 33 Internet-Drafts are draft documents valid for a maximum of six months 34 and may be updated, replaced, or obsoleted by other documents at any 35 time. It is inappropriate to use Internet-Drafts as reference 36 material or to cite them other than as "work in progress." 38 This Internet-Draft will expire on November 9, 2018. 40 Copyright Notice 42 Copyright (c) 2018 IETF Trust and the persons identified as the 43 document authors. All rights reserved. 45 This document is subject to BCP 78 and the IETF Trust's Legal 46 Provisions Relating to IETF Documents 47 (https://trustee.ietf.org/license-info) in effect on the date of 48 publication of this document. Please review these documents 49 carefully, as they describe your rights and restrictions with respect 50 to this document. Code Components extracted from this document must 51 include Simplified BSD License text as described in Section 4.e of 52 the Trust Legal Provisions and are provided without warranty as 53 described in the Simplified BSD License. 55 Table of Contents 57 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 58 1.1. Target Audience . . . . . . . . . . . . . . . . . . . . . 3 59 1.2. Conventions used in this document . . . . . . . . . . . . 4 60 2. Threats and Vulnerabilities . . . . . . . . . . . . . . . . . 4 61 2.1. Weak Signatures and Insufficient Signature Validation . . 4 62 2.2. Weak symmetric keys . . . . . . . . . . . . . . . . . . . 4 63 2.3. Multiplicity of JSON encodings . . . . . . . . . . . . . 5 64 2.4. Incorrect Composition of Encryption and Signature . . . . 5 65 2.5. Insecure Use of Elliptic Curve Encryption . . . . . . . . 5 66 2.6. Substitution Attacks . . . . . . . . . . . . . . . . . . 5 67 2.7. Cross-JWT Confusion . . . . . . . . . . . . . . . . . . . 5 68 3. Best Practices . . . . . . . . . . . . . . . . . . . . . . . 6 69 3.1. Perform Algorithm Verification . . . . . . . . . . . . . 6 70 3.2. Use Appropriate Algorithms . . . . . . . . . . . . . . . 6 71 3.3. Validate All Cryptographic Operations . . . . . . . . . . 7 72 3.4. Validate Cryptographic Inputs . . . . . . . . . . . . . . 7 73 3.5. Ensure Cryptographic Keys have Sufficient Entropy . . . . 7 74 3.6. Avoid Length-Dependent Encryption Inputs . . . . . . . . 7 75 3.7. Use UTF-8 . . . . . . . . . . . . . . . . . . . . . . . . 8 76 3.8. Validate Issuer and Subject . . . . . . . . . . . . . . . 8 77 3.9. Use and Validate Audience . . . . . . . . . . . . . . . . 8 78 3.10. Do Not Trust Received Claims . . . . . . . . . . . . . . 8 79 3.11. Use Explicit Typing . . . . . . . . . . . . . . . . . . . 9 80 3.12. Use Mutually Exclusive Validation Rules for Different 81 Kinds of JWTs . . . . . . . . . . . . . . . . . . . . . . 9 82 4. Security Considerations . . . . . . . . . . . . . . . . . . . 10 83 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 84 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10 85 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 11 86 7.1. Normative References . . . . . . . . . . . . . . . . . . 11 87 7.2. Informative References . . . . . . . . . . . . . . . . . 11 88 Appendix A. Document History . . . . . . . . . . . . . . . . . . 13 89 A.1. draft-ietf-oauth-jwt-bcp-03 . . . . . . . . . . . . . . . 13 90 A.2. draft-ietf-oauth-jwt-bcp-02 . . . . . . . . . . . . . . . 13 91 A.3. draft-ietf-oauth-jwt-bcp-01 . . . . . . . . . . . . . . . 13 92 A.4. draft-ietf-oauth-jwt-bcp-00 . . . . . . . . . . . . . . . 13 93 A.5. draft-sheffer-oauth-jwt-bcp-01 . . . . . . . . . . . . . 13 94 A.6. draft-sheffer-oauth-jwt-bcp-00 . . . . . . . . . . . . . 13 95 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13 97 1. Introduction 99 JSON Web Tokens, also known as JWTs [RFC7519], are URL-safe JSON- 100 based security tokens that contain a set of claims that can be signed 101 and/or encrypted. The JWT specification has seen rapid adoption 102 because it encapsulates security-relevant information in one, easy to 103 protect location, and because it is easy to implement using widely- 104 available tools. One application area in which JWTs are commonly 105 used is representing digital identity information, such as OpenID 106 Connect ID Tokens [OpenID.Core] and OAuth 2.0 [RFC6749] access tokens 107 and refresh tokens, the details of which are deployment-specific. 109 Since the JWT specification was published, there have been several 110 widely published attacks on implementations and deployments. Such 111 attacks are the result of under-specified security mechanisms, as 112 well as incomplete implementations and incorrect usage by 113 applications. 115 The goal of this document is to facilitate secure implementation and 116 deployment of JWTs. Many of the recommendations in this document 117 will actually be about implementation and use of the cryptographic 118 mechanisms underlying JWTs that are defined by JSON Web Signature 119 (JWS) [RFC7515], JSON Web Encryption (JWE) [RFC7516], and JSON Web 120 Algorithms (JWA) [RFC7518]. Others will be about use of the JWT 121 claims themselves. 123 These are intended to be minimum recommendations for the use of JWTs 124 in the vast majority of implementation and deployment scenarios. 125 Other specifications that reference this document can have stricter 126 requirements related to one or more aspects of the format, based on 127 their particular circumstances; when that is the case, implementers 128 are advised to adhere to those stricter requirements. Furthermore, 129 this document provides a floor, not a ceiling, so stronger options 130 are always allowed (e.g., depending on differing evaluations of the 131 importance of cryptographic strength vs. computational load). 133 Community knowledge about the strength of various algorithms and 134 feasible attacks can change quickly, and experience shows that a Best 135 Current Practice (BCP) document about security is a point-in-time 136 statement. Readers are advised to seek out any errata or updates 137 that apply to this document. 139 1.1. Target Audience 141 The targets of this document are: 143 - Implementers of JWT libraries (and the JWS and JWE libraries used 144 by them), 146 - Implementers of code that uses such libraries (to the extent that 147 some mechanisms may not be provided by libraries, or until they 148 are), and 150 - Developers of specifications that rely on JWTs, both inside and 151 outside the IETF. 153 1.2. Conventions used in this document 155 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 156 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 157 "OPTIONAL" in this document are to be interpreted as described in 158 [RFC2119]. 160 2. Threats and Vulnerabilities 162 This section lists some known and possible problems with JWT 163 implementations and deployments. Each problem description is 164 followed by references to one or more mitigations to those problems. 166 2.1. Weak Signatures and Insufficient Signature Validation 168 Signed JSON Web Tokens carry an explicit indication of the signing 169 algorithm, in the form of the "alg" header parameter, to facilitate 170 cryptographic agility. This, in conjunction with design flaws in 171 some libraries and applications, have led to several attacks: 173 - The algorithm can be changed to "none" by an attacker, and some 174 libraries would trust this value and "validate" the JWT without 175 checking any signature. 177 - An "RS256" (RSA, 2048 bit) parameter value can be changed into 178 "HS256" (HMAC, SHA-256), and some libraries would try to validate 179 the signature using HMAC-SHA256 and using the RSA public key as 180 the HMAC shared secret. 182 For mitigations, see Section 3.1 and Section 3.2. 184 2.2. Weak symmetric keys 186 In addition, some applications sign tokens using a weak symmetric key 187 and a keyed MAC algorithm such as "HS256". In most cases, these keys 188 are human memorable passwords that are vulnerable to dictionary 189 attacks [Langkemper]. 191 For mitigations, see Section 3.5. 193 2.3. Multiplicity of JSON encodings 195 Previous versions of the JSON format [RFC8259] allowed several 196 different character encodings: UTF-8, UTF-16 and UTF-32. This is not 197 the case anymore, with the latest standard only allowing UTF-8. 198 However older implementations may result in the JWT being 199 misinterpreted by its recipient. 201 For mitigations, see Section 3.7. 203 2.4. Incorrect Composition of Encryption and Signature 205 Some libraries that decrypt a JWE-encrypted JWT to obtain a JWS- 206 signed object do not always validate the internal signature. 208 For mitigations, see Section 3.3. 210 2.5. Insecure Use of Elliptic Curve Encryption 212 Per [Sanso], several JOSE libraries fail to validate their inputs 213 correctly when performing elliptic curve key agreement (the "ECDH-ES" 214 algorithm). An attacker that is able to send JWEs of its choosing 215 that use invalid curve points and observe the cleartext outputs 216 resulting from decryption with the invalid curve points can use this 217 vulnerability to recover the recipient's private key. 219 For mitigations, see Section 3.4. 221 2.6. Substitution Attacks 223 There are attacks in which one recipient will have a JWT intended for 224 it and attempt to use it at a different recipient that it was not 225 intended for. If not caught, these attacks can result in the 226 attacker gaining access to resources that it is not entitled to 227 access. 229 For mitigations, see Section 3.8 and Section 3.9. 231 2.7. Cross-JWT Confusion 233 As JWTs are being used by more different protocols in diverse 234 application areas, it becomes increasingly important to prevent cases 235 of JWT tokens that have been issued for one purpose being subverted 236 and used for another. Note that this is a specific type of 237 substitution attack. If the JWT could be used in an application 238 context in which it could be confused with other kinds of JWTs, then 239 mitigations MUST be employed to prevent these substitution attacks. 241 For mitigations, see Section 3.8, Section 3.9, Section 3.11, and 242 Section 3.12. 244 3. Best Practices 246 The best practices listed below should be applied by practitioners to 247 mitigate the threats listed in the preceding section. 249 3.1. Perform Algorithm Verification 251 Libraries MUST enable the caller to specify a supported set of 252 algorithms and MUST NOT use any other algorithms when performing 253 cryptographic operations. The library MUST ensure that the "alg" or 254 "enc" header specifies the same algorithm that is used for the 255 cryptographic operation. Moreover, each key MUST be used with 256 exactly one algorithm, and this MUST be checked when the 257 cryptographic operation is performed. 259 3.2. Use Appropriate Algorithms 261 As Section 5.2 of [RFC7515] says, "it is an application decision 262 which algorithms may be used in a given context. Even if a JWS can 263 be successfully validated, unless the algorithm(s) used in the JWS 264 are acceptable to the application, it SHOULD consider the JWS to be 265 invalid." 267 Therefore, applications MUST only allow the use of cryptographically 268 current algorithms that meet the security requirements of the 269 application. This set will vary over time as new algorithms are 270 introduced and existing algorithms are deprecated due to discovered 271 cryptographic weaknesses. Applications must therefore be designed to 272 enable cryptographic agility. 274 That said, if a JWT is cryptographically protected by a transport 275 layer, such as TLS using cryptographically current algorithms, there 276 may be no need to apply another layer of cryptographic protections to 277 the JWT. In such cases, the use of the "none" algorithm can be 278 perfectly acceptable. JWTs using "none" are often used in 279 application contexts in which the content is optionally signed; then 280 the URL-safe claims representation and processing can be the same in 281 both the signed and unsigned cases. 283 Applications SHOULD follow these algorithm-specific recommendations: 285 - Avoid all RSA-PKCS1 v1.5 encryption algorithms, preferring RSA- 286 OAEP. 288 - ECDSA signatures require a unique random value for every message 289 that is signed. If even just a few bits of the random value are 290 predictable across multiple messages then the security of the 291 signature scheme may be compromised. In the worst case, the 292 private key may be recoverable by an attacker. To counter these 293 attacks, JWT libraries SHOULD implement ECDSA using the 294 deterministic approach defined in [RFC6979]. This approach is 295 completely compatible with existing ECDSA verifiers and so can be 296 implemented without new algorithm identifiers being required. 298 3.3. Validate All Cryptographic Operations 300 All cryptographic operations used in the JWT MUST be validated and 301 the entire JWT MUST be rejected if any of them fail to validate. 302 This is true not only of JWTs with a single set of Header Parameters 303 but also for Nested JWTs, in which both outer and inner operations 304 MUST be validated using the keys and algorithms supplied by the 305 application. 307 3.4. Validate Cryptographic Inputs 309 Some cryptographic operations, such as Elliptic Curve Diffie-Hellman 310 key agreement ("ECDH-ES") take inputs that may contain invalid 311 values, such as points not on the specified elliptic curve or other 312 invalid points (see e.g. [Valenta], Sec. 7.1). Either the JWS/JWE 313 library itself must validate these inputs before using them or it 314 must use underlying cryptographic libraries that do so (or both!). 316 ECDH-ES ephemeral public key (epk) inputs should be validated 317 according to the recipient's chosen elliptic curve. For the NIST 318 prime-order curves P-256, P-384 and P-521, validation MUST be 319 performed according to Section 5.6.2.3.4 "ECC Partial Public-Key 320 Validation Routine" of NIST Special Publication 800-56A revision 3 321 [nist-sp-800-56a-r3]. 323 3.5. Ensure Cryptographic Keys have Sufficient Entropy 325 The Key Entropy and Random Values advice in Section 10.1 of [RFC7515] 326 and the Password Considerations in Section 8.8 of [RFC7518] MUST be 327 followed. In particular, human-memorizable passwords MUST NOT be 328 directly used as the key to a keyed-MAC algorithm such as "HS256". 330 3.6. Avoid Length-Dependent Encryption Inputs 332 Many encryption algorithms leak information about the length of the 333 plaintext, with a varying amount of leakage depending on the 334 algorithm and mode of operation. Sensitive information, such as 335 passwords, SHOULD be padded before being encrypted. It is 336 RECOMMENDED to avoid any compression of data before encryption since 337 such compression often reveals information about the plaintext. 339 3.7. Use UTF-8 341 [RFC7515], [RFC7516], and [RFC7519] all specify that UTF-8 be used 342 for encoding and decoding JSON used in Header Parameters and JWT 343 Claims Sets. This is also in line with the latest JSON specification 344 [RFC8259]. Implementations and applications MUST do this, and not 345 use or admit the use of other Unicode encodings for these purposes. 347 3.8. Validate Issuer and Subject 349 When a JWT contains an "iss" (issuer) claim, the application MUST 350 validate that the cryptographic keys used for the cryptographic 351 operations in the JWT belong to the issuer. If they do not, the 352 application MUST reject the JWT. 354 The means of determining the keys owned by an issuer is application- 355 specific. As one example, OpenID Connect [OpenID.Core] issuer values 356 are "https" URLs that reference a JSON metadata document that 357 contains a "jwks_uri" value that is an "https" URL from which the 358 issuer's keys are retrieved as a JWK Set [RFC7517]. This same 359 mechanism is used by [I-D.ietf-oauth-discovery]. Other applications 360 may use different means of binding keys to issuers. 362 Similarly, when the JWT contains a "sub" (subject) claim, the 363 application MUST validate that the subject value corresponds to a 364 valid subject and/or issuer/subject pair at the application. This 365 may include confirming that the issuer is trusted by the application. 366 If the issuer, subject, or the pair are invalid, the application MUST 367 reject the JWT. 369 3.9. Use and Validate Audience 371 If the same issuer can issue JWTs that are intended for use by more 372 than one relying party or application, the JWT MUST contain an "aud" 373 (audience) claim that can be used to determine whether the JWT is 374 being used by an intended party or was substituted by an attacker at 375 an unintended party. Furthermore, the relying party or application 376 MUST validate the audience value and if the audience value is not 377 present or not associated with the recipient, it MUST reject the JWT. 379 3.10. Do Not Trust Received Claims 381 The "kid" (key ID) header is used by the relying application to 382 perform key lookup. Applications should ensure that this does not 383 create SQL or LDAP injection vulnerabilities. 385 Similarly, blindly following a "jku" (JWK set URL) header, which may 386 contain an arbitrary URL, could result in server-side request forgery 387 (SSRF) attacks. 389 3.11. Use Explicit Typing 391 Confusion of one kind of JWT for another can be prevented by having 392 all the kinds of JWTs that could otherwise potentially be confused 393 include an explicit JWT type value and include checking the type 394 value in their validation rules. Explicit JWT typing is accomplished 395 by using the "typ" header parameter. For instance, the 396 [I-D.ietf-secevent-token] specification uses the "application/ 397 secevent+jwt" media type to perform explicit typing of Security Event 398 Tokens (SETs). 400 Per the definition of "typ" in Section 4.1.9 of [RFC7515], it is 401 RECOMMENDED that the "application/" prefix be omitted from the "typ" 402 value. Therefore, for example, the "typ" value used to explicitly 403 include a type for a SET SHOULD be "secevent+jwt". When explicit 404 typing is employed for a JWT, it is RECOMMENDED that a media type 405 name of the format "application/example+jwt" be used, where "example" 406 is replaced by the identifier for the specific kind of JWT. 408 When applying explicit typing to a Nested JWT, the "typ" header 409 parameter containing the explicit type value MUST be present in the 410 inner JWT of the Nested JWT (the JWT whose payload is the JWT Claims 411 Set). The same "typ" header parameter value MAY be present in the 412 outer JWT as well, to explicitly type the entire Nested JWT. 414 Note that the use of explicit typing may not achieve disambiguation 415 from existing kinds of JWTs, as the validation rules for existing 416 kinds JWTs often do not use the "typ" header parameter value. 417 Explicit typing is RECOMMENDED for new uses of JWTs. 419 3.12. Use Mutually Exclusive Validation Rules for Different Kinds of 420 JWTs 422 Each application of JWTs defines a profile specifying the required 423 and optional JWT claims and the validation rules associated with 424 them. If more than one kind of JWT can be issued by the same issuer, 425 the validation rules for those JWTs MUST be written such that they 426 are mutually exclusive, rejecting JWTs of the wrong kind. To prevent 427 substitution of JWTs from one context into another, a number of 428 strategies may be employed: 430 - Use explicit typing for different kinds of JWTs. Then the 431 distinct "typ" values can be used to differentiate between the 432 different kinds of JWTs. 434 - Use different sets of required claims or different required claim 435 values. Then the validation rules for one kind of JWT will reject 436 those with different claims or values. 438 - Use different sets of required header parameters or different 439 required header parameter values. Then the validation rules for 440 one kind of JWT will reject those with different header parameters 441 or values. 443 - Use different keys for different kinds of JWTs. Then the keys 444 used to validate one kind of JWT will fail to validate other kinds 445 of JWTs. 447 - Use different "aud" values for different uses of JWTs from the 448 same issuer. Then audience validation will reject JWTs 449 substituted into inappropriate contexts. 451 - Use different issuers for different kinds of JWTs. Then the 452 distinct "iss" values can be used to segregate the different kinds 453 of JWTs. 455 Given the broad diversity of JWT usage and applications, the best 456 combination of types, required claims, values, header parameters, key 457 usages, and issuers to differentiate among different kinds of JWTs 458 will, in general, be application specific. 460 4. Security Considerations 462 This entire document is about security considerations when 463 implementing and deploying JSON Web Tokens. 465 5. IANA Considerations 467 This document requires no IANA actions. 469 6. Acknowledgements 471 Thanks to Antonio Sanso for bringing the "ECDH-ES" invalid point 472 attack to the attention of JWE and JWT implementers. Tim McLean 473 published the RSA/HMAC confusion attack. Thanks to Nat Sakimura for 474 advocating the use of explicit typing. Thanks to Neil Madden for his 475 numerous comments, and to Carsten Bormann and Brian Campbell for 476 their reviews. 478 7. References 480 7.1. Normative References 482 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 483 Requirement Levels", BCP 14, RFC 2119, 484 DOI 10.17487/RFC2119, March 1997, 485 . 487 [RFC6979] Pornin, T., "Deterministic Usage of the Digital Signature 488 Algorithm (DSA) and Elliptic Curve Digital Signature 489 Algorithm (ECDSA)", RFC 6979, DOI 10.17487/RFC6979, August 490 2013, . 492 [RFC7515] Jones, M., Bradley, J., and N. Sakimura, "JSON Web 493 Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May 494 2015, . 496 [RFC7516] Jones, M. and J. Hildebrand, "JSON Web Encryption (JWE)", 497 RFC 7516, DOI 10.17487/RFC7516, May 2015, 498 . 500 [RFC7518] Jones, M., "JSON Web Algorithms (JWA)", RFC 7518, 501 DOI 10.17487/RFC7518, May 2015, 502 . 504 [RFC7519] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token 505 (JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015, 506 . 508 [RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data 509 Interchange Format", STD 90, RFC 8259, 510 DOI 10.17487/RFC8259, December 2017, 511 . 513 7.2. Informative References 515 [I-D.ietf-oauth-discovery] 516 Jones, M., Sakimura, N., and J. Bradley, "OAuth 2.0 517 Authorization Server Metadata", draft-ietf-oauth- 518 discovery-10 (work in progress), March 2018. 520 [I-D.ietf-secevent-token] 521 Hunt, P., Jones, M., Denniss, W., and M. Ansari, "Security 522 Event Token (SET)", draft-ietf-secevent-token-10 (work in 523 progress), May 2018. 525 [Langkemper] 526 Langkemper, S., "Attacking JWT Authentication", September 527 2016, . 530 [nist-sp-800-56a-r3] 531 Barker, E., Chen, L., Keller, S., Roginsky, A., Vassilev, 532 A., and R. Davis, "Recommendation for Pair-Wise Key 533 Establishment Schemes Using Discrete Logarithm 534 Cryptography, Draft NIST Special Publication 800-56A 535 Revision 3", August 2017, 536 . 539 [OpenID.Core] 540 Sakimura, N., Bradley, J., Jones, M., Medeiros, B., and C. 541 Mortimore, "OpenID Connect Core 1.0", November 2014, 542 . 544 [RFC6749] Hardt, D., Ed., "The OAuth 2.0 Authorization Framework", 545 RFC 6749, DOI 10.17487/RFC6749, October 2012, 546 . 548 [RFC7517] Jones, M., "JSON Web Key (JWK)", RFC 7517, 549 DOI 10.17487/RFC7517, May 2015, 550 . 552 [Sanso] Sanso, A., "Critical Vulnerability Uncovered in JSON 553 Encryption", March 2017, 554 . 557 [Valenta] Valenta, L., Sullivan, N., Sanso, A., and N. Heninger, "In 558 search of CurveSwap: Measuring elliptic curve 559 implementations in the wild", March 2018, 560 . 562 Appendix A. Document History 564 [[ to be removed by the RFC editor before publication as an RFC ]] 566 A.1. draft-ietf-oauth-jwt-bcp-03 568 - Acknowledgements. 570 A.2. draft-ietf-oauth-jwt-bcp-02 572 - Implemented WGLC feedback. 574 A.3. draft-ietf-oauth-jwt-bcp-01 576 - Feedback from Brian Campbell. 578 A.4. draft-ietf-oauth-jwt-bcp-00 580 - Initial WG draft. No change from the latest individual version. 582 A.5. draft-sheffer-oauth-jwt-bcp-01 584 - Added explicit typing. 586 A.6. draft-sheffer-oauth-jwt-bcp-00 588 - Initial version. 590 Authors' Addresses 592 Yaron Sheffer 593 Intuit 595 EMail: yaronf.ietf@gmail.com 597 Dick Hardt 598 Amazon 600 EMail: dick@amazon.com 602 Michael B. Jones 603 Microsoft 605 EMail: mbj@microsoft.com 606 URI: http://self-issued.info/