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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references to lower-maturity documents in RFCs) ** Downref: Normative reference to an Informational RFC: RFC 6979 == Outdated reference: A later version (-13) exists of draft-ietf-secevent-token-10 Summary: 1 error (**), 0 flaws (~~), 2 warnings (==), 1 comment (--).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 3, 2018 Amazon 6 M. Jones 7 Microsoft 8 May 02, 2018 10 JSON Web Token Best Current Practices 11 draft-ietf-oauth-jwt-bcp-02 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 http://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 3, 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 (http://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 . . . . . . . . . . . . . . . . . . . . . . . . . 10 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-02 . . . . . . . . . . . . . . . 13 90 A.2. draft-ietf-oauth-jwt-bcp-01 . . . . . . . . . . . . . . . 13 91 A.3. draft-ietf-oauth-jwt-bcp-00 . . . . . . . . . . . . . . . 13 92 A.4. draft-sheffer-oauth-jwt-bcp-01 . . . . . . . . . . . . . 13 93 A.5. draft-sheffer-oauth-jwt-bcp-00 . . . . . . . . . . . . . 13 94 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13 96 1. Introduction 98 JSON Web Tokens, also known as JWTs [RFC7519], are URL-safe JSON- 99 based security tokens that contain a set of claims that can be signed 100 and/or encrypted. The JWT specification has seen rapid adoption 101 because it encapsulates security-relevant information in one, easy to 102 protect location, and because it is easy to implement using widely- 103 available tools. One application area in which JWTs are commonly 104 used is representing digital identity information, such as OpenID 105 Connect ID Tokens [OpenID.Core] and OAuth 2.0 [RFC6749] access tokens 106 and refresh tokens, the details of which are deployment-specific. 108 Since the JWT specification was published, there have been several 109 widely published attacks on implementations and deployments. Such 110 attacks are the result of under-specified security mechanisms, as 111 well as incomplete implementations and incorrect usage by 112 applications. 114 The goal of this document is to facilitate secure implementation and 115 deployment of JWTs. Many of the recommendations in this document 116 will actually be about implementation and use of the cryptographic 117 mechanisms underlying JWTs that are defined by JSON Web Signature 118 (JWS) [RFC7515], JSON Web Encryption (JWE) [RFC7516], and JSON Web 119 Algorithms (JWA) [RFC7518]. Others will be about use of the JWT 120 claims themselves. 122 These are intended to be minimum recommendations for the use of JWTs 123 in the vast majority of implementation and deployment scenarios. 124 Other specifications that reference this document can have stricter 125 requirements related to one or more aspects of the format, based on 126 their particular circumstances; when that is the case, implementers 127 are advised to adhere to those stricter requirements. Furthermore, 128 this document provides a floor, not a ceiling, so stronger options 129 are always allowed (e.g., depending on differing evaluations of the 130 importance of cryptographic strength vs. computational load). 132 Community knowledge about the strength of various algorithms and 133 feasible attacks can change quickly, and experience shows that a Best 134 Current Practice (BCP) document about security is a point-in-time 135 statement. Readers are advised to seek out any errata or updates 136 that apply to this document. 138 1.1. Target Audience 140 The targets of this document are: 142 - Implementers of JWT libraries (and the JWS and JWE libraries used 143 by them), 145 - Implementers of code that uses such libraries (to the extent that 146 some mechanisms may not be provided by libraries, or until they 147 are), and 149 - Developers of specifications that rely on JWTs, both inside and 150 outside the IETF. 152 1.2. Conventions used in this document 154 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 155 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 156 "OPTIONAL" in this document are to be interpreted as described in 157 [RFC2119]. 159 2. Threats and Vulnerabilities 161 This section lists some known and possible problems with JWT 162 implementations and deployments. Each problem description is 163 followed by references to one or more mitigations to those problems. 165 2.1. Weak Signatures and Insufficient Signature Validation 167 Signed JSON Web Tokens carry an explicit indication of the signing 168 algorithm, in the form of the "alg" header parameter, to facilitate 169 cryptographic agility. This, in conjunction with design flaws in 170 some libraries and applications, have led to several attacks: 172 - The algorithm can be changed to "none" by an attacker, and some 173 libraries would trust this value and "validate" the JWT without 174 checking any signature. 176 - An "RS256" (RSA, 2048 bit) parameter value can be changed into 177 "HS256" (HMAC, SHA-256), and some libraries would try to validate 178 the signature using HMAC-SHA256 and using the RSA public key as 179 the HMAC shared secret. 181 For mitigations, see Section 3.1 and Section 3.2. 183 2.2. Weak symmetric keys 185 In addition, some applications sign tokens using a weak symmetric key 186 and a keyed MAC algorithm such as "HS256". In most cases, these keys 187 are human memorable passwords that are vulnerable to dictionary 188 attacks [Langkemper]. 190 For mitigations, see Section 3.5. 192 2.3. Multiplicity of JSON encodings 194 Previous versions of the JSON format [RFC8259] allowed several 195 different character encodings: UTF-8, UTF-16 and UTF-32. This is not 196 the case anymore, with the latest standard only allowing UTF-8. 197 However older implementations may result in the JWT being 198 misinterpreted by its recipient. 200 For mitigations, see Section 3.7. 202 2.4. Incorrect Composition of Encryption and Signature 204 Some libraries that decrypt a JWE-encrypted JWT to obtain a JWS- 205 signed object do not always validate the internal signature. 207 For mitigations, see Section 3.3. 209 2.5. Insecure Use of Elliptic Curve Encryption 211 Per [Sanso], several JOSE libraries fail to validate their inputs 212 correctly when performing elliptic curve key agreement (the "ECDH-ES" 213 algorithm). An attacker that is able to send JWEs of its choosing 214 that use invalid curve points and observe the cleartext outputs 215 resulting from decryption with the invalid curve points can use this 216 vulnerability to recover the recipient's private key. 218 For mitigations, see Section 3.4. 220 2.6. Substitution Attacks 222 There are attacks in which one recipient will have a JWT intended for 223 it and attempt to use it at a different recipient that it was not 224 intended for. If not caught, these attacks can result in the 225 attacker gaining access to resources that it is not entitled to 226 access. 228 For mitigations, see Section 3.8 and Section 3.9. 230 2.7. Cross-JWT Confusion 232 As JWTs are being used by more different protocols in diverse 233 application areas, it becomes increasingly important to prevent cases 234 of JWT tokens that have been issued for one purpose being subverted 235 and used for another. Note that this is a specific type of 236 substitution attack. If the JWT could be used in an application 237 context in which it could be confused with other kinds of JWTs, then 238 mitigations MUST be employed to prevent these substitution attacks. 240 For mitigations, see Section 3.8, Section 3.9, Section 3.11, and 241 Section 3.12. 243 3. Best Practices 245 The best practices listed below should be applied by practitioners to 246 mitigate the threats listed in the preceding section. 248 3.1. Perform Algorithm Verification 250 Libraries MUST enable the caller to specify a supported set of 251 algorithms and MUST NOT use any other algorithms when performing 252 cryptographic operations. The library MUST ensure that the "alg" or 253 "enc" header specifies the same algorithm that is used for the 254 cryptographic operation. Moreover, each key MUST be used with 255 exactly one algorithm, and this MUST be checked when the 256 cryptographic operation is performed. 258 3.2. Use Appropriate Algorithms 260 As Section 5.2 of [RFC7515] says, "it is an application decision 261 which algorithms may be used in a given context. Even if a JWS can 262 be successfully validated, unless the algorithm(s) used in the JWS 263 are acceptable to the application, it SHOULD consider the JWS to be 264 invalid." 266 Therefore, applications MUST only allow the use of cryptographically 267 current algorithms that meet the security requirements of the 268 application. This set will vary over time as new algorithms are 269 introduced and existing algorithms are deprecated due to discovered 270 cryptographic weaknesses. Applications must therefore be designed to 271 enable cryptographic agility. 273 That said, if a JWT is cryptographically protected by a transport 274 layer, such as TLS using cryptographically current algorithms, there 275 may be no need to apply another layer of cryptographic protections to 276 the JWT. In such cases, the use of the "none" algorithm can be 277 perfectly acceptable. JWTs using "none" are often used in 278 application contexts in which the content is optionally signed; then 279 the URL-safe claims representation and processing can be the same in 280 both the signed and unsigned cases. 282 Applications SHOULD follow these algorithm-specific recommendations: 284 - Avoid all RSA-PKCS1 v1.5 encryption algorithms, preferring RSA- 285 OAEP. 287 - ECDSA signatures require a unique random value for every message 288 that is signed. If even just a few bits of the random value are 289 predictable across multiple messages then the security of the 290 signature scheme may be compromised. In the worst case, the 291 private key may be recoverable by an attacker. To counter these 292 attacks, JWT libraries SHOULD implement ECDSA using the 293 deterministic approach defined in [RFC6979]. This approach is 294 completely compatible with existing ECDSA verifiers and so can be 295 implemented without new algorithm identifiers being required. 297 3.3. Validate All Cryptographic Operations 299 All cryptographic operations used in the JWT MUST be validated and 300 the entire JWT MUST be rejected if any of them fail to validate. 301 This is true not only of JWTs with a single set of Header Parameters 302 but also for Nested JWTs, in which both outer and inner operations 303 MUST be validated using the keys and algorithms supplied by the 304 application. 306 3.4. Validate Cryptographic Inputs 308 Some cryptographic operations, such as Elliptic Curve Diffie-Hellman 309 key agreement ("ECDH-ES") take inputs that may contain invalid 310 values, such as points not on the specified elliptic curve or other 311 invalid points (see e.g. [Valenta], Sec. 7.1). Either the JWS/JWE 312 library itself must validate these inputs before using them or it 313 must use underlying cryptographic libraries that do so (or both!). 315 ECDH-ES ephemeral public key (epk) inputs should be validated 316 according to the recipient's chosen elliptic curve. For the NIST 317 prime-order curves P-256, P-384 and P-521, validation MUST be 318 performed according to Section 5.6.2.3.4 "ECC Partial Public-Key 319 Validation Routine" of NIST Special Publication 800-56A revision 3 320 [nist-sp-800-56a-r3]. 322 3.5. Ensure Cryptographic Keys have Sufficient Entropy 324 The Key Entropy and Random Values advice in Section 10.1 of [RFC7515] 325 and the Password Considerations in Section 8.8 of [RFC7518] MUST be 326 followed. In particular, human-memorizable passwords MUST NOT be 327 directly used as the key to a keyed-MAC algorithm such as "HS256". 329 3.6. Avoid Length-Dependent Encryption Inputs 331 Many encryption algorithms leak information about the length of the 332 plaintext, with a varying amount of leakage depending on the 333 algorithm and mode of operation. Sensitive information, such as 334 passwords, SHOULD be padded before being encrypted. It is 335 RECOMMENDED to avoid any compression of data before encryption since 336 such compression often reveals information about the plaintext. 338 3.7. Use UTF-8 340 [RFC7515], [RFC7516], and [RFC7519] all specify that UTF-8 be used 341 for encoding and decoding JSON used in Header Parameters and JWT 342 Claims Sets. This is also in line with the latest JSON specification 343 [RFC8259]. Implementations and applications MUST do this, and not 344 use or admit the use of other Unicode encodings for these purposes. 346 3.8. Validate Issuer and Subject 348 When a JWT contains an "iss" (issuer) claim, the application MUST 349 validate that the cryptographic keys used for the cryptographic 350 operations in the JWT belong to the issuer. If they do not, the 351 application MUST reject the JWT. 353 The means of determining the keys owned by an issuer is application- 354 specific. As one example, OpenID Connect [OpenID.Core] issuer values 355 are "https" URLs that reference a JSON metadata document that 356 contains a "jwks_uri" value that is an "https" URL from which the 357 issuer's keys are retrieved as a JWK Set [RFC7517]. This same 358 mechanism is used by [I-D.ietf-oauth-discovery]. Other applications 359 may use different means of binding keys to issuers. 361 Similarly, when the JWT contains a "sub" (subject) claim, the 362 application MUST validate that the subject value corresponds to a 363 valid subject and/or issuer/subject pair at the application. This 364 may include confirming that the issuer is trusted by the application. 365 If the issuer, subject, or the pair are invalid, the application MUST 366 reject the JWT. 368 3.9. Use and Validate Audience 370 If the same issuer can issue JWTs that are intended for use by more 371 than one relying party or application, the JWT MUST contain an "aud" 372 (audience) claim that can be used to determine whether the JWT is 373 being used by an intended party or was substituted by an attacker at 374 an unintended party. Furthermore, the relying party or application 375 MUST validate the audience value and if the audience value is not 376 present or not associated with the recipient, it MUST reject the JWT. 378 3.10. Do Not Trust Received Claims 380 The "kid" (key ID) header is used by the relying application to 381 perform key lookup. Applications should ensure that this does not 382 create SQL or LDAP injection vulnerabilities. 384 Similarly, blindly following a "jku" (JWK set URL) header, which may 385 contain an arbitrary URL, could result in server-side request forgery 386 (SSRF) attacks. 388 3.11. Use Explicit Typing 390 Confusion of one kind of JWT for another can be prevented by having 391 all the kinds of JWTs that could otherwise potentially be confused 392 include an explicit JWT type value and include checking the type 393 value in their validation rules. Explicit JWT typing is accomplished 394 by using the "typ" header parameter. For instance, the 395 [I-D.ietf-secevent-token] specification uses the "application/ 396 secevent+jwt" media type to perform explicit typing of Security Event 397 Tokens (SETs). 399 Per the definition of "typ" in Section 4.1.9 of [RFC7515], it is 400 RECOMMENDED that the "application/" prefix be omitted from the "typ" 401 value. Therefore, for example, the "typ" value used to explicitly 402 include a type for a SET SHOULD be "secevent+jwt". When explicit 403 typing is employed for a JWT, it is RECOMMENDED that a media type 404 name of the format "application/example+jwt" be used, where "example" 405 is replaced by the identifier for the specific kind of JWT. 407 When applying explicit typing to a Nested JWT, the "typ" header 408 parameter containing the explicit type value MUST be present in the 409 inner JWT of the Nested JWT (the JWT whose payload is the JWT Claims 410 Set). The same "typ" header parameter value MAY be present in the 411 outer JWT as well, to explicitly type the entire Nested JWT. 413 Note that the use of explicit typing may not achieve disambiguation 414 from existing kinds of JWTs, as the validation rules for existing 415 kinds JWTs often do not use the "typ" header parameter value. 416 Explicit typing is RECOMMENDED for new uses of JWTs. 418 3.12. Use Mutually Exclusive Validation Rules for Different Kinds of 419 JWTs 421 Each application of JWTs defines a profile specifying the required 422 and optional JWT claims and the validation rules associated with 423 them. If more than one kind of JWT can be issued by the same issuer, 424 the validation rules for those JWTs MUST be written such that they 425 are mutually exclusive, rejecting JWTs of the wrong kind. To prevent 426 substitution of JWTs from one context into another, a number of 427 strategies may be employed: 429 - Use explicit typing for different kinds of JWTs. Then the 430 distinct "typ" values can be used to differentiate between the 431 different kinds of JWTs. 433 - Use different sets of required claims or different required claim 434 values. Then the validation rules for one kind of JWT will reject 435 those with different claims or values. 437 - Use different sets of required header parameters or different 438 required header parameter values. Then the validation rules for 439 one kind of JWT will reject those with different header parameters 440 or values. 442 - Use different keys for different kinds of JWTs. Then the keys 443 used to validate one kind of JWT will fail to validate other kinds 444 of JWTs. 446 - Use different "aud" values for different uses of JWTs from the 447 same issuer. Then audience validation will reject JWTs 448 substituted into inappropriate contexts. 450 - Use different issuers for different kinds of JWTs. Then the 451 distinct "iss" values can be used to segregate the different kinds 452 of JWTs. 454 Given the broad diversity of JWT usage and applications, the best 455 combination of types, required claims, values, header parameters, key 456 usages, and issuers to differentiate among different kinds of JWTs 457 will, in general, be application specific. 459 4. Security Considerations 461 This entire document is about security considerations when 462 implementing and deploying JSON Web Tokens. 464 5. IANA Considerations 466 This document requires no IANA actions. 468 6. Acknowledgements 470 Thanks to Antonio Sanso for bringing the "ECDH-ES" invalid point 471 attack to the attention of JWE and JWT implementers. Thanks to Nat 472 Sakimura for advocating the use of explicit typing. Thanks to Neil 473 Madden for his numerous comments, and to Carsten Bormann for his 474 review. 476 7. References 477 7.1. Normative References 479 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 480 Requirement Levels", BCP 14, RFC 2119, 481 DOI 10.17487/RFC2119, March 1997, . 484 [RFC6979] Pornin, T., "Deterministic Usage of the Digital Signature 485 Algorithm (DSA) and Elliptic Curve Digital Signature 486 Algorithm (ECDSA)", RFC 6979, DOI 10.17487/RFC6979, August 487 2013, . 489 [RFC7515] Jones, M., Bradley, J., and N. Sakimura, "JSON Web 490 Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May 491 2015, . 493 [RFC7516] Jones, M. and J. Hildebrand, "JSON Web Encryption (JWE)", 494 RFC 7516, DOI 10.17487/RFC7516, May 2015, 495 . 497 [RFC7518] Jones, M., "JSON Web Algorithms (JWA)", RFC 7518, 498 DOI 10.17487/RFC7518, May 2015, . 501 [RFC7519] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token 502 (JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015, 503 . 505 [RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data 506 Interchange Format", STD 90, RFC 8259, 507 DOI 10.17487/RFC8259, December 2017, . 510 7.2. Informative References 512 [I-D.ietf-oauth-discovery] 513 Jones, M., Sakimura, N., and J. Bradley, "OAuth 2.0 514 Authorization Server Metadata", draft-ietf-oauth- 515 discovery-10 (work in progress), March 2018. 517 [I-D.ietf-secevent-token] 518 Hunt, P., Jones, M., Denniss, W., and M. Ansari, "Security 519 Event Token (SET)", draft-ietf-secevent-token-10 (work in 520 progress), May 2018. 522 [Langkemper] 523 Langkemper, S., "Attacking JWT Authentication", September 524 2016, . 527 [nist-sp-800-56a-r3] 528 Barker, E., Chen, L., Keller, S., Roginsky, A., Vassilev, 529 A., and R. Davis, "Recommendation for Pair-Wise Key 530 Establishment Schemes Using Discrete Logarithm 531 Cryptography, Draft NIST Special Publication 800-56A 532 Revision 3", August 2017, 533 . 536 [OpenID.Core] 537 Sakimura, N., Bradley, J., Jones, M., Medeiros, B., and C. 538 Mortimore, "OpenID Connect Core 1.0", November 2014, 539 . 541 [RFC6749] Hardt, D., Ed., "The OAuth 2.0 Authorization Framework", 542 RFC 6749, DOI 10.17487/RFC6749, October 2012, 543 . 545 [RFC7517] Jones, M., "JSON Web Key (JWK)", RFC 7517, 546 DOI 10.17487/RFC7517, May 2015, . 549 [Sanso] Sanso, A., "Critical Vulnerability Uncovered in JSON 550 Encryption", March 2017, 551 . 554 [Valenta] Valenta, L., Sullivan, N., Sanso, A., and N. Heninger, "In 555 search of CurveSwap: Measuring elliptic curve 556 implementations in the wild", March 2018, 557 . 559 Appendix A. Document History 561 [[ to be removed by the RFC editor before publication as an RFC ]] 563 A.1. draft-ietf-oauth-jwt-bcp-02 565 - Implemented WGLC feedback. 567 A.2. draft-ietf-oauth-jwt-bcp-01 569 - Feedback from Brian Campbell. 571 A.3. draft-ietf-oauth-jwt-bcp-00 573 - Initial WG draft. No change from the latest individual version. 575 A.4. draft-sheffer-oauth-jwt-bcp-01 577 - Added explicit typing. 579 A.5. draft-sheffer-oauth-jwt-bcp-00 581 - Initial version. 583 Authors' Addresses 585 Yaron Sheffer 586 Intuit 588 EMail: yaronf.ietf@gmail.com 590 Dick Hardt 591 Amazon 593 EMail: dick@amazon.com 595 Michael B. Jones 596 Microsoft 598 EMail: mbj@microsoft.com 599 URI: http://self-issued.info/