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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Security Events Working Group A. Backman, Ed. 3 Internet-Draft Amazon 4 Intended status: Standards Track M. Jones, Ed. 5 Expires: December 26, 2020 Microsoft 6 M. Scurtescu 7 Coinbase 8 M. Ansari 9 Cisco 10 A. Nadalin 11 Microsoft 12 June 24, 2020 14 Push-Based Security Event Token (SET) Delivery Using HTTP 15 draft-ietf-secevent-http-push-13 17 Abstract 19 This specification defines how a Security Event Token (SET) can be 20 delivered to an intended recipient using HTTP POST over TLS. The SET 21 is transmitted in the body of an HTTP POST request to an endpoint 22 operated by the recipient, and the recipient indicates successful or 23 failed transmission via the HTTP response. 25 Status of This Memo 27 This Internet-Draft is submitted in full conformance with the 28 provisions of BCP 78 and BCP 79. 30 Internet-Drafts are working documents of the Internet Engineering 31 Task Force (IETF). Note that other groups may also distribute 32 working documents as Internet-Drafts. The list of current Internet- 33 Drafts is at https://datatracker.ietf.org/drafts/current/. 35 Internet-Drafts are draft documents valid for a maximum of six months 36 and may be updated, replaced, or obsoleted by other documents at any 37 time. It is inappropriate to use Internet-Drafts as reference 38 material or to cite them other than as "work in progress." 40 This Internet-Draft will expire on December 26, 2020. 42 Copyright Notice 44 Copyright (c) 2020 IETF Trust and the persons identified as the 45 document authors. All rights reserved. 47 This document is subject to BCP 78 and the IETF Trust's Legal 48 Provisions Relating to IETF Documents 49 (https://trustee.ietf.org/license-info) in effect on the date of 50 publication of this document. Please review these documents 51 carefully, as they describe your rights and restrictions with respect 52 to this document. Code Components extracted from this document must 53 include Simplified BSD License text as described in Section 4.e of 54 the Trust Legal Provisions and are provided without warranty as 55 described in the Simplified BSD License. 57 Table of Contents 59 1. Introduction and Overview . . . . . . . . . . . . . . . . . . 2 60 1.1. Notational Conventions . . . . . . . . . . . . . . . . . 3 61 1.2. Definitions . . . . . . . . . . . . . . . . . . . . . . . 3 62 2. SET Delivery . . . . . . . . . . . . . . . . . . . . . . . . 3 63 2.1. Transmitting a SET . . . . . . . . . . . . . . . . . . . 5 64 2.2. Success Response . . . . . . . . . . . . . . . . . . . . 6 65 2.3. Failure Response . . . . . . . . . . . . . . . . . . . . 6 66 2.4. Security Event Token Delivery Error Codes . . . . . . . . 8 67 3. Authentication and Authorization . . . . . . . . . . . . . . 9 68 4. Delivery Reliability . . . . . . . . . . . . . . . . . . . . 9 69 5. Security Considerations . . . . . . . . . . . . . . . . . . . 10 70 5.1. Authentication Using Signed SETs . . . . . . . . . . . . 10 71 5.2. HTTP Considerations . . . . . . . . . . . . . . . . . . . 10 72 5.3. Confidentiality of SETs . . . . . . . . . . . . . . . . . 10 73 5.4. Denial of Service . . . . . . . . . . . . . . . . . . . . 11 74 5.5. Authenticating Persisted SETs . . . . . . . . . . . . . . 11 75 6. Privacy Considerations . . . . . . . . . . . . . . . . . . . 11 76 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 77 7.1. Security Event Token Delivery Error Codes . . . . . . . . 12 78 7.1.1. Registration Template . . . . . . . . . . . . . . . . 12 79 7.1.2. Initial Registry Contents . . . . . . . . . . . . . . 13 80 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 14 81 8.1. Normative References . . . . . . . . . . . . . . . . . . 14 82 8.2. Informative References . . . . . . . . . . . . . . . . . 15 83 Appendix A. Unencrypted Transport Considerations . . . . . . . . 16 84 Appendix B. Other Streaming Specifications . . . . . . . . . . . 16 85 Appendix C. Acknowledgments . . . . . . . . . . . . . . . . . . 18 86 Appendix D. Change Log . . . . . . . . . . . . . . . . . . . . . 18 87 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23 89 1. Introduction and Overview 91 This specification defines a mechanism by which a transmitter of a 92 Security Event Token (SET) [RFC8417] can deliver the SET to an 93 intended SET Recipient via HTTP POST [RFC7231] over TLS. This is an 94 alternative SET delivery method to the one defined in 95 [I-D.ietf-secevent-http-poll]. 97 Push-based SET delivery over HTTP POST is intended for scenarios 98 where all of the following apply: 100 o The transmitter of the SET is capable of making outbound HTTP 101 requests. 103 o The recipient is capable of hosting a TLS-enabled HTTP endpoint 104 that is accessible to the transmitter. 106 o The transmitter and recipient are willing to exchange data with 107 one another. 109 In some scenarios, either push-based or poll-based delivery could be 110 used, and in others, only one of them would be applicable. 112 A mechanism for exchanging configuration metadata such as endpoint 113 URLs, cryptographic keys, and possible implementation constraints 114 such as buffer size limitations between the transmitter and recipient 115 is out of scope for this specification. How SETs are defined and the 116 process by which security events are identified for SET Recipients 117 are specified in [RFC8417]. 119 1.1. Notational Conventions 121 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 122 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 123 "OPTIONAL" in this document are to be interpreted as described in BCP 124 14 [RFC2119] [RFC8174] when, and only when, they appear in all 125 capitals, as shown here. 127 Throughout this document, all figures may contain spaces and extra 128 line wrapping for readability and due to space limitations. 130 1.2. Definitions 132 This specification utilizes the following terms defined in [RFC8417]: 133 "Security Event Token (SET)", "SET Issuer", "SET Recipient", and 134 "Event Payload", as well as the term defined below: 136 SET Transmitter An entity that delivers SETs in its possession to 137 one or more SET Recipients. 139 2. SET Delivery 141 To deliver a SET to a given SET Recipient, the SET Transmitter makes 142 a SET transmission request to the SET Recipient, with the SET itself 143 contained within the request. The SET Recipient replies to this 144 request with a response either acknowledging successful transmission 145 of the SET or indicating that an error occurred while receiving, 146 parsing, and/or validating the SET. 148 Upon receipt of a SET, the SET Recipient SHALL validate that all of 149 the following are true: 151 o The SET Recipient can parse the SET. 153 o The SET is authentic (i.e., it was issued by the issuer specified 154 within the SET, and if signed, was signed by a key belonging to 155 the issuer). 157 o The SET Recipient is identified as an intended audience of the 158 SET. 160 o The SET Issuer is recognized as an issuer that the SET Recipient 161 is willing to receive SETs from (e.g., the issuer is listed as 162 allowed by the SET Recipient). 164 o The SET Recipient is willing to accept this SET from this SET 165 Transmitter (e.g., the SET Transmitter is expected to send SETs 166 with the issuer and subject of the SET in question). 168 The mechanisms by which the SET Recipient performs this validation 169 are out of scope for this document. SET parsing, issuer 170 identification, and audience identification are defined in [RFC8417]. 171 The mechanism for validating the authenticity of a SET is deployment 172 specific, and may vary depending on the authentication mechanisms in 173 use, and whether the SET is signed and/or encrypted (See Section 3). 175 SET Transmitters MAY transmit SETs issued by another entity. The SET 176 Recipient may accept or reject (i.e., return an error response such 177 as "access_denied") a SET at its own discretion. 179 The SET Recipient persists the SET in a way that is sufficient to 180 meet the SET Recipient's own reliability requirements, and MUST NOT 181 expect or depend on a SET Transmitter to re-transmit or otherwise 182 make available to the SET Recipient a SET once the SET Recipient 183 acknowledges that it was received successfully. The level and method 184 of retention of SETs by SET Recipients is out of scope of this 185 specification. 187 Once the SET has been validated and persisted, the SET Recipient 188 SHOULD immediately return a response indicating that the SET was 189 successfully delivered. The SET Recipient SHOULD NOT perform further 190 processing of the SET beyond the required validation steps prior to 191 sending this response. Any additional steps SHOULD be executed 192 asynchronously from delivery to minimize the time the SET Transmitter 193 is waiting for a response. 195 The SET Transmitter MAY re-transmit a SET if the responses from 196 previous transmissions timed out or indicated potentially recoverable 197 errors (such as server unavailability that may be transient). In all 198 other cases, the SET Transmitter SHOULD NOT re-transmit a SET. The 199 SET Transmitter SHOULD delay retransmission for an appropriate amount 200 of time to avoid overwhelming the SET Recipient (see Section 4). 202 2.1. Transmitting a SET 204 To transmit a SET to a SET Recipient, the SET Transmitter makes an 205 HTTP POST request to a TLS-enabled HTTP endpoint provided by the SET 206 Recipient. The "Content-Type" header field of this request MUST be 207 "application/secevent+jwt" as defined in Sections 2.3 and 7.2 of 208 [RFC8417], and the "Accept" header field MUST be "application/json". 209 The request body MUST consist of the SET itself, represented as a JWT 210 [RFC7519]. 212 The SET Transmitter MAY include in the request an "Accept-Language" 213 header field to indicate to the SET Recipient the preferred 214 language(s) in which to receive error messages. 216 The mechanisms by which the SET Transmitter determines the HTTP 217 endpoint to use when transmitting a SET to a given SET Recipient are 218 not defined by this specification and are deployment specific. 220 The following is a non-normative example of a SET transmission 221 request: 223 POST /Events HTTP/1.1 224 Host: notify.rp.example.com 225 Accept: application/json 226 Accept-Language: en-US, en;q=0.5 227 Content-Type: application/secevent+jwt 229 eyJ0eXAiOiJzZWNldmVudCtqd3QiLCJhbGciOiJIUzI1NiJ9Cg 230 . 231 eyJpc3MiOiJodHRwczovL2lkcC5leGFtcGxlLmNvbS8iLCJqdGkiOiI3NTZFNjk 232 3MTc1NjUyMDY5NjQ2NTZFNzQ2OTY2Njk2NTcyIiwiaWF0IjoxNTA4MTg0ODQ1LC 233 JhdWQiOiI2MzZDNjk2NTZFNzQ1RjY5NjQiLCJldmVudHMiOnsiaHR0cHM6Ly9zY 234 2hlbWFzLm9wZW5pZC5uZXQvc2VjZXZlbnQvcmlzYy9ldmVudC10eXBlL2FjY291 235 bnQtZGlzYWJsZWQiOnsic3ViamVjdCI6eyJzdWJqZWN0X3R5cGUiOiJpc3Mtc3V 236 iIiwiaXNzIjoiaHR0cHM6Ly9pZHAuZXhhbXBsZS5jb20vIiwic3ViIjoiNzM3NT 237 YyNkE2NTYzNzQifSwicmVhc29uIjoiaGlqYWNraW5nIn19fQ 238 . 239 Y4rXxMD406P2edv00cr9Wf3_XwNtLjB9n-jTqN1_lLc 241 Figure 1: Example SET Transmission Request 243 2.2. Success Response 245 If the SET is determined to be valid, the SET Recipient SHALL 246 acknowledge successful transmission by responding with HTTP Response 247 Status Code 202 (Accepted) (see Section 6.3.3 of [RFC7231]). The 248 body of the response MUST be empty. 250 The following is a non-normative example of a successful receipt of a 251 SET. 253 HTTP/1.1 202 Accepted 255 Figure 2: Example Successful Delivery Response 257 2.3. Failure Response 259 In the event of a general HTTP error condition, the SET Recipient 260 responds with the applicable HTTP Status Code, as defined in 261 Section 6 of [RFC7231]. 263 When the SET Recipient detects an error parsing, validating, or 264 authenticating a SET transmitted in a SET Transmission Request, the 265 SET Recipient SHALL respond with an HTTP Response Status Code of 400 266 (Bad Request). The "Content-Type" header field of this response MUST 267 be "application/json", and the body MUST be a UTF-8 encoded JSON 268 [RFC8259] object containing the following name/value pairs: 270 err A Security Event Token Error Code (see Section 2.4). 272 description A UTF-8 string containing a human-readable description 273 of the error that may provide additional diagnostic information. 274 The exact content of this field is implementation specific. 276 The response MUST include a "Content-Language" header field, whose 277 value indicates the language of the error descriptions included in 278 the response body. If the SET Recipient can provide error 279 descriptions in multiple languages, they SHOULD choose the language 280 to use according to the value of the "Accept-Language" header field 281 sent by the SET Transmitter in the transmission request, as described 282 in Section 5.3.5 of [RFC7231]. If the SET Transmitter did not send 283 an "Accept-Language" header field, or if the SET Recipient does not 284 support any of the languages included in the header field, the SET 285 Recipient MUST respond with messages that are understandable by an 286 English-speaking person, as described in Section 4.5 of [RFC2277]. 288 The following is a non-normative example error response indicating 289 that the key used to encrypt the SET has been revoked. 291 HTTP/1.1 400 Bad Request 292 Content-Language: en-US 293 Content-Type: application/json 295 { 296 "err": "invalid_key", 297 "description": "Key ID 12345 has been revoked." 298 } 300 Figure 3: Example Error Response (invalid_key) 302 The following is a non-normative example error response indicating 303 that the access token included in the request is expired. 305 HTTP/1.1 400 Bad Request 306 Content-Language: en-US 307 Content-Type: application/json 309 { 310 "err": "authentication_failed", 311 "description": "Access token has expired." 312 } 314 Figure 4: Example Error Response (authentication_failed) 316 The following is a non-normative example error response indicating 317 that the SET Receiver is not willing to accept SETs issued by the 318 specified issuer from this particular SET Transmitter. 320 HTTP/1.1 400 Bad Request 321 Content-Language: en-US 322 Content-Type: application/json 324 { 325 "err": "invalid_issuer", 326 "description": "Not authorized for issuer https://iss.example.com/." 327 } 329 Figure 5: Example Error Response (access_denied) 331 2.4. Security Event Token Delivery Error Codes 333 Security Event Token Delivery Error Codes are strings that identify a 334 specific category of error that may occur when parsing or validating 335 a SET. Every Security Event Token Delivery Error Code MUST have a 336 unique name registered in the IANA "Security Event Token Delivery 337 Error Codes" registry established by Section 7.1. 339 The following table presents the initial set of Error Codes that are 340 registered in the IANA "Security Event Token Delivery Error Codes" 341 registry: 343 +-----------------------+-------------------------------------------+ 344 | Error Code | Description | 345 +-----------------------+-------------------------------------------+ 346 | invalid_request | The request body cannot be parsed as a | 347 | | SET, or the Event Payload within the SET | 348 | | does not conform to the event's | 349 | | definition. | 350 | invalid_key | One or more keys used to encrypt or sign | 351 | | the SET is invalid or otherwise | 352 | | unacceptable to the SET Recipient | 353 | | (expired, revoked, failed certificate | 354 | | validation, etc.). | 355 | invalid_issuer | The SET issuer is invalid for the SET | 356 | | Recipient. | 357 | invalid_audience | The SET audience does not correspond to | 358 | | the SET Recipient. | 359 | authentication_failed | The SET Recipient could not authenticate | 360 | | the SET Transmitter. | 361 | access_denied | The SET Transmitter is not authorized to | 362 | | transmit the SET to the SET Recipient. | 363 +-----------------------+-------------------------------------------+ 365 Table 1: SET Delivery Error Codes 367 Other Error Codes may also be received, as the set of Error Codes is 368 extensible via the IANA "Security Event Token Delivery Error Codes" 369 registry established in Section 7.1. 371 3. Authentication and Authorization 373 The SET delivery method described in this specification is based upon 374 HTTP over TLS [RFC2818] and standard HTTP authentication and 375 authorization schemes, as per [RFC7235]. The TLS server certificate 376 MUST be validated using DNS-ID [RFC6125] and/or DANE [RFC6698]. 378 Authorization for the eligibility to provide actionable SETs can be 379 determined by using the identity of the SET Issuer, the identity of 380 the SET Transmitter, perhaps using mutual TLS, or via other employed 381 authentication methods. Because SETs are not commands, SET 382 Recipients are free to ignore SETs that are not of interest. 384 4. Delivery Reliability 386 Delivery reliability requirements may vary depending upon the use 387 cases. This specification defines the response from the SET 388 Recipient in such a way as to provide the SET Transmitter with the 389 information necessary to determine what further action is required, 390 if any, in order to meet their requirements. SET Transmitters with 391 high reliability requirements may be tempted to always retry failed 392 transmissions. However, it should be noted that for many types of 393 SET delivery errors, a retry is extremely unlikely to be successful. 394 For example, "invalid_request" indicates a structural error in the 395 content of the request body that is likely to remain when re- 396 transmitting the same SET. Others such as "access_denied" may be 397 transient, for example if the SET Transmitter refreshes expired 398 credentials prior to re-transmission. 400 Implementers SHOULD evaluate the reliability requirements of their 401 use cases and the impact of various retry mechanisms on the 402 performance of their systems to determine an appropriate strategy for 403 handling various error conditions. 405 5. Security Considerations 407 5.1. Authentication Using Signed SETs 409 JWS signed SETs can be used (see [RFC7515] and Section 5 of 410 [RFC8417]) to enable the SET Recipient to validate that the SET 411 Issuer is authorized to provide actionable SETs. 413 5.2. HTTP Considerations 415 SET delivery depends on the use of Hypertext Transfer Protocol and is 416 thus subject to the security considerations of HTTP Section 9 of 417 [RFC7230] and its related specifications. 419 5.3. Confidentiality of SETs 421 SETs may contain sensitive information, including Personally 422 Identifiable Information (PII), or be distributed through third 423 parties. In such cases, SET Transmitters and SET Recipients MUST 424 protect the confidentiality of the SET contents. TLS MUST be used to 425 secure the transmitted SETs. In some use cases, encrypting the SET 426 as described in JWE [RFC7516] will also be required. The Event 427 delivery endpoint MUST support at least TLS version 1.2 [RFC5246] and 428 SHOULD support the newest version of TLS that meets its security 429 requirements, which as of the time of this publication is TLS 1.3 430 [RFC8446]. The client MUST perform a TLS/SSL server certificate 431 check using DNS-ID [RFC6125] and/or DANE [RFC6698]. How a SET 432 Transmitter determines the expected service identity to match the SET 433 Recipient's server certificate against is out of scope for this 434 document. The implementation security considerations for TLS in 435 "Recommendations for Secure Use of TLS and DTLS" [RFC7525] MUST be 436 followed. 438 5.4. Denial of Service 440 The SET Recipient may be vulnerable to a denial-of-service attack 441 where a malicious party makes a high volume of requests containing 442 invalid SETs, causing the endpoint to expend significant resources on 443 cryptographic operations that are bound to fail. This may be 444 mitigated by authenticating SET Transmitters with a mechanism such as 445 mutual TLS. Rate-limiting problematic transmitters is also a 446 possible means of mitigation. 448 5.5. Authenticating Persisted SETs 450 At the time of receipt, the SET Recipient can rely upon TLS 451 mechanisms, HTTP authentication methods, and/or other context from 452 the transmission request to authenticate the SET Transmitter and 453 validate the authenticity of the SET. However, this context is 454 typically unavailable to systems to which the SET Recipient forwards 455 the SET, or to systems that retrieve the SET from storage. If the 456 SET Recipient requires the ability to validate SET authenticity 457 outside of the context of the transmission request, then the SET 458 Recipient SHOULD ensure that such SETs have been signed in accordance 459 with [RFC7515]. Needed context could also be stored with the SET and 460 retrieved with it. 462 6. Privacy Considerations 464 SET Transmitters should attempt to deliver SETs that are targeted to 465 the specific business and protocol needs of subscribers. 467 When sharing personally identifiable information or information that 468 is otherwise considered confidential to affected users, SET 469 Transmitters and Recipients MUST have the appropriate legal 470 agreements and user consent or terms of service in place. 471 Furthermore, data that needs confidentiality protection MUST be 472 encrypted, at least with TLS and sometimes also using JSON Web 473 Encryption (JWE) [RFC7516]. 475 In some cases, subject identifiers themselves may be considered 476 sensitive information, such that their inclusion within a SET may be 477 considered a violation of privacy. SET Issuers and SET Transmitters 478 should consider the ramifications of sharing a particular subject 479 identifier with a SET Recipient (e.g., whether doing so could enable 480 correlation and/or de-anonymization of data) and choose appropriate 481 subject identifiers for their use cases. 483 7. IANA Considerations 485 7.1. Security Event Token Delivery Error Codes 487 This document defines Security Event Token Delivery Error Codes, for 488 which IANA is asked to create and maintain a new registry titled 489 "Security Event Token Delivery Error Codes". Initial values for the 490 Security Event Token Delivery Error Codes registry are defined in 491 Table 1 and registered below. Future assignments are to be made 492 through the Specification Required registration policy ([RFC8126]) 493 and shall follow the template below. 495 Error Codes are intended to be interpreted by automated systems, and 496 therefore SHOULD identify classes of errors to which an automated 497 system could respond in a meaningfully distinct way (e.g., by 498 refreshing authentication credentials and retrying the request). 500 Error Code names are case sensitive. Names may not match other 501 registered names in a case-insensitive manner unless the Designated 502 Experts state that there is a compelling reason to allow an 503 exception. 505 Criteria that should be applied by the Designated Experts includes 506 determining whether the proposed registration duplicates existing 507 functionality, whether it is likely to be of general applicability or 508 whether it is useful only for a single application, and whether the 509 registration description is clear. 511 It is suggested that multiple Designated Experts be appointed who are 512 able to represent the perspectives of different applications using 513 this specification, in order to enable broadly informed review of 514 registration decisions. In cases where a registration decision could 515 be perceived as creating a conflict of interest for a particular 516 Expert, that Expert should defer to the judgment of the other 517 Experts. 519 7.1.1. Registration Template 521 Error Code 522 The name of the Security Event Token Delivery Error Code, as 523 described in Section 2.4. The name MUST be a case-sensitive ASCII 524 string consisting only of letters, digits, and underscore; these 525 are the characters whose codes fall within the inclusive ranges 526 0x30-39, 0x41-5A, 0x5F and 0x61-7A. 528 Description 529 A brief human-readable description of the Security Event Token 530 Delivery Error Code. 532 Change Controller 533 For error codes registered by the IETF or its working groups, list 534 "IETF". For all other error codes, list the name of the party 535 responsible for the registration. Contact information such as 536 mailing address, email address, or phone number may also be 537 provided. 539 Defining Document(s) 540 A reference to the document or documents that define the Security 541 Event Token Delivery Error Code. The definition MUST specify the 542 name and description of the error code and explain under what 543 circumstances the error code may be used. URIs that can be used 544 to retrieve copies of each document at no cost SHOULD be included. 546 7.1.2. Initial Registry Contents 548 Error Code: invalid_request 549 Description: The request body cannot be parsed as a SET or the 550 event payload within the SET does not conform to the event's 551 definition. 552 Change Controller: IETF 553 Defining Document(s): Section 2.4 of [[ this specification ]] 555 Error Code: invalid_key 556 Description: One or more keys used to encrypt or sign the SET is 557 invalid or otherwise unacceptable to the SET Recipient (expired, 558 revoked, failed certificate validation, etc.). 559 Change Controller: IETF 560 Defining Document(s): Section 2.4 of [[ this specification ]] 562 Error Code: invalid_issuer 563 Description: The SET issuer is invalid for the SET Recipient. 564 Change Controller: IETF 565 Defining Document(s): Section 2.4 of [[ this specification ]] 567 Error Code: invalid_audience 568 Description: The SET audience does not correspond to the SET 569 Recipient. 570 Change Controller: IETF 571 Defining Document(s): Section 2.4 of [[ this specification ]] 573 Error Code: authentication_failed 574 Description: The SET Recipient could not authenticate the SET 575 Transmitter. 576 Change Controller: IETF 577 Defining Document(s): Section 2.4 of [[ this specification ]] 579 Error Code: access_denied 580 Description: The SET Transmitter is not authorized to transmit the 581 SET to the SET Recipient. 582 Change Controller: IETF 583 Defining Document(s): Section 2.4 of [[ this specification ]] 585 8. References 587 8.1. Normative References 589 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 590 Requirement Levels", BCP 14, RFC 2119, 591 DOI 10.17487/RFC2119, March 1997, 592 . 594 [RFC2277] Alvestrand, H., "IETF Policy on Character Sets and 595 Languages", BCP 18, RFC 2277, DOI 10.17487/RFC2277, 596 January 1998, . 598 [RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, 599 DOI 10.17487/RFC2818, May 2000, 600 . 602 [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security 603 (TLS) Protocol Version 1.2", RFC 5246, 604 DOI 10.17487/RFC5246, August 2008, 605 . 607 [RFC6125] Saint-Andre, P. and J. Hodges, "Representation and 608 Verification of Domain-Based Application Service Identity 609 within Internet Public Key Infrastructure Using X.509 610 (PKIX) Certificates in the Context of Transport Layer 611 Security (TLS)", RFC 6125, DOI 10.17487/RFC6125, March 612 2011, . 614 [RFC6698] Hoffman, P. and J. Schlyter, "The DNS-Based Authentication 615 of Named Entities (DANE) Transport Layer Security (TLS) 616 Protocol: TLSA", RFC 6698, DOI 10.17487/RFC6698, August 617 2012, . 619 [RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer 620 Protocol (HTTP/1.1): Message Syntax and Routing", 621 RFC 7230, DOI 10.17487/RFC7230, June 2014, 622 . 624 [RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer 625 Protocol (HTTP/1.1): Semantics and Content", RFC 7231, 626 DOI 10.17487/RFC7231, June 2014, 627 . 629 [RFC7515] Jones, M., Bradley, J., and N. Sakimura, "JSON Web 630 Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May 631 2015, . 633 [RFC7516] Jones, M. and J. Hildebrand, "JSON Web Encryption (JWE)", 634 RFC 7516, DOI 10.17487/RFC7516, May 2015, 635 . 637 [RFC7519] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token 638 (JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015, 639 . 641 [RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre, 642 "Recommendations for Secure Use of Transport Layer 643 Security (TLS) and Datagram Transport Layer Security 644 (DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May 645 2015, . 647 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 648 Writing an IANA Considerations Section in RFCs", BCP 26, 649 RFC 8126, DOI 10.17487/RFC8126, June 2017, 650 . 652 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 653 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 654 May 2017, . 656 [RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data 657 Interchange Format", STD 90, RFC 8259, 658 DOI 10.17487/RFC8259, December 2017, 659 . 661 [RFC8417] Hunt, P., Ed., Jones, M., Denniss, W., and M. Ansari, 662 "Security Event Token (SET)", RFC 8417, 663 DOI 10.17487/RFC8417, July 2018, 664 . 666 [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol 667 Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, 668 . 670 8.2. Informative References 672 [I-D.ietf-secevent-http-poll] 673 Backman, A., Jones, M., Scurtescu, M., Ansari, M., and A. 674 Nadalin, "Poll-Based Security Event Token (SET) Delivery 675 Using HTTP", draft-ietf-secevent-http-poll-11 (work in 676 progress), June 2020. 678 [RFC7235] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer 679 Protocol (HTTP/1.1): Authentication", RFC 7235, 680 DOI 10.17487/RFC7235, June 2014, 681 . 683 Appendix A. Unencrypted Transport Considerations 685 Earlier versions of this specification made the use of TLS optional 686 and described security and privacy considerations resulting from use 687 of unencrypted HTTP as the underlying transport. When the working 688 group decided to mandate usage HTTP over TLS, it also decided to 689 preserve the description of these considerations in this non- 690 normative appendix. 692 SETs may contain sensitive information that is considered Personally 693 Identifiable Information (PII). In such cases, SET Transmitters and 694 SET Recipients MUST protect the confidentiality of the SET contents. 695 When TLS is not used, this means that the SET MUST be encrypted as 696 described in JWE [RFC7516]. 698 If SETs were allowed to be transmitted over unencrypted channels, 699 some privacy-sensitive information about them might leak, even though 700 the SETs themselves are encrypted. For instance, an attacker may be 701 able to determine whether or not a SET was accepted and the reason 702 for its rejection or may be able to derive information from being 703 able to observe the size of the encrypted SET. (Note that even when 704 TLS is utilized, some information leakage is still possible; message 705 padding algorithms to prevent side channels remain an open research 706 topic.) 708 Appendix B. Other Streaming Specifications 710 [[ NOTE TO THE RFC EDITOR: This section to be removed prior to 711 publication ]] 713 The following pub/sub, queuing, and streaming systems were reviewed 714 as possible solutions or as input to the current draft: 716 Poll-Based Security Event Token (SET) Delivery Using HTTP 718 In addition to this specification, the WG is defining a polling-based 719 SET delivery protocol. That protocol [I-D.ietf-secevent-http-poll] 720 describes it as: 722 This specification defines how a series of Security Event Tokens 723 (SETs) can be delivered to an intended recipient using HTTP POST over 724 TLS initiated as a poll by the recipient. The specification also 725 defines how delivery can be assured, subject to the SET Recipient's 726 need for assurance. 728 XMPP Events 730 The WG considered XMPP Events and their ability to provide a single 731 messaging solution without the need for both polling and push modes. 732 The feeling was the size and methodology of XMPP was too far apart 733 from the current capabilities of the SECEVENTs community, which 734 focuses in on HTTP based service delivery and authorization. 736 Amazon Simple Notification Service 738 Simple Notification Service is a pub/sub messaging product from AWS. 739 SNS supports a variety of subscriber types: HTTP/HTTPS endpoints, AWS 740 Lambda functions, email addresses (as JSON or plain text), phone 741 numbers (via SMS), and AWS SQS standard queues. It does not directly 742 support pull, but subscribers can get the pull model by creating an 743 SQS queue and subscribing it to the topic. Note that this puts the 744 cost of pull support back onto the subscriber, just as it is in the 745 push model. It is not clear that one way is strictly better than the 746 other; larger, sophisticated developers may be happy to own message 747 persistence so they can have their own internal delivery guarantees. 748 The long tail of OIDC clients may not care about that or may fail to 749 get it right. Regardless, I think we can learn something from the 750 Delivery Policies supported by SNS, as well as the delivery controls 751 that SQS offers (e.g., Visibility Timeout, Dead-Letter Queues). I am 752 not suggesting that we need all of these things in the spec, but they 753 give an idea of what features people have found useful. 755 Other information: 757 o API Reference: 758 http://docs.aws.amazon.com/AWSSimpleQueueService/latest/ 759 APIReference/Welcome.html 761 o Visibility Timeouts: 762 http://docs.aws.amazon.com/AWSSimpleQueueService/latest/ 763 SQSDeveloperGuide/sqs-visibility-timeout.html 765 Apache Kafka 767 Apache Kafka is an Apache open source project based upon TCP for 768 distributed streaming. It prescribes some interesting general- 769 purpose features that seem to extend far beyond the simpler streaming 770 model that SECEVENTs is after. A comment from MS has been that Kafka 771 does an acknowledge with poll combination event which seems to be a 772 performance advantage. See: https://kafka.apache.org/intro 774 Google Pub/Sub 776 The Google Pub Sub system favors a model whereby polling and 777 acknowledgement of events is done with separate endpoints and as 778 separate functions. 780 Information: 782 o Cloud Overview - https://cloud.google.com/pubsub/ 784 o Subscriber Overview - https://cloud.google.com/pubsub/docs/ 785 subscriber 787 o Subscriber Pull(poll) - https://cloud.google.com/pubsub/docs/pull 789 Appendix C. Acknowledgments 791 The editors would like to thank the members of the SCIM working 792 group, which began discussions of provisioning events starting with 793 draft-hunt-scim-notify-00 in 2015. We would like to thank Phil Hunt 794 and the other authors of draft-ietf-secevent-delivery-02, upon which 795 this specification is based. We would like to thank the participants 796 in the SecEvents working group for their contributions to this 797 specification. 799 Additionally, we would like to thank the following individuals for 800 their reviews of the specification: Joe Clarke, Roman Danyliw, Vijay 801 Gurbani, Benjamin Kaduk, Erik Kline, Murray Kucherawy, Barry Leiba, 802 Yaron Sheffer, Robert Sparks, Valery Smyslov, Eric Vyncke, and Robert 803 Wilton. 805 Appendix D. Change Log 807 [[ NOTE TO THE RFC EDITOR: This section to be removed prior to 808 publication ]] 810 Draft 00 - AB - Based on draft-ietf-secevent-delivery-02 with the 811 following changes: 813 o Renamed to "Push-Based SET Token Delivery Using HTTP" 815 o Removed references to the HTTP Polling delivery method. 817 o Removed informative reference to RFC6202. 819 Draft 01 - AB: 821 o Fixed area and workgroup to match secevent. 823 o Removed unused definitions and definitions already covered by SET. 825 o Renamed Event Transmitter and Event Receiver to SET Transmitter 826 and SET Receiver, respectively. 828 o Added IANA registry for SET Delivery Error Codes. 830 o Removed enumeration of HTTP authentication methods. 832 o Removed generally applicable guidance for HTTP, authorization 833 tokens, and bearer tokens. 835 o Moved guidance for using authentication methods as DoS protection 836 to Security Considerations. 838 o Removed redundant instruction to use WWW-Authenticate header. 840 o Removed further generally applicable guidance for authorization 841 tokens. 843 o Removed bearer token from example delivery request, and text 844 referencing it. 846 o Broke delivery method description into separate request/response 847 sections. 849 o Added missing empty line between headers and body in example 850 request. 852 o Removed inapplicable notes about example formatting. 854 o Removed text about SET creation and handling. 856 o Removed duplication in protocol description. 858 o Added "non-normative example" text to example transmission 859 request. 861 o Fixed inconsistencies in use of Error Code term. 863 Draft 02 - AB: 865 o Rewrote abstract and introduction. 867 o Rewrote definitions for SET Transmitter, SET Receiver. 869 o Renamed Event Delivery section to SET Delivery. 871 o Readability edits to Success Response and Failure Response 872 sections. 874 o Consolidated definition of error response under Failure Response 875 section. 877 o Removed Event Delivery Process section and moved its content to 878 parent section. 880 o Readability edits to SET Delivery section and its subsections. 882 o Added callout that SET Receiver HTTP endpoint configuration is 883 out-of-scope. 885 o Added callout that SET verification mechanisms are out-of-scope. 887 o Added retry guidance, notes regarding delivery reliability 888 requirements. 890 o Added guidance around using JWS and/or JWE to authenticate 891 persisted SETs. 893 Draft 03 - mbj: 895 o Addressed problems identified in my 18-Jul-18 review message 896 titled "Issues for both the Push and Poll Specs". 898 o Changes to align terminology with RFC 8417, for instance, by using 899 the already defined term SET Recipient rather than SET Receiver. 901 o Applied editorial and minor normative corrections. 903 o Updated Marius' contact information. 905 Draft 04 - AB: 907 o Replaced Error Codes with smaller set of meaningfully 908 differentiated codes. 910 o Added more error response examples. 912 o Removed un-referenced normative references. 914 o Added normative reference to JSON in error response definition. 916 o Added text clarifying that the value of the "description" 917 attribute in error responses is implementation specific. 919 o Added requirement that error descriptions and responses are UTF-8 920 encoded. 922 o Added error description language preferences and specification via 923 "Accept-Language" and "Content-Language" headers. 925 o Added "recognized issuer" validation requirement in section 2. 927 o Added timeouts as an acceptable reason to resend a SET in section 928 2. 930 o Edited text in section 1 to clarify that configuration is out of 931 scope. 933 o Made minor editorial corrections. 935 Draft 05 - AB: 937 o Made minor editorial corrections. 939 o Updated example request with a correct SET header and signature. 941 o Revised TLS guidance to allow implementers to provide 942 confidentiality protection via JWE. 944 o Revised TLS guidance to require *at least* TLS 1.2. 946 o Revised TLS guidance to recommend supporting the newest version of 947 TLS that meets security requirements. 949 o Revised SET Delivery Error Code format to allow the same set of 950 characters as is allowed in error codes in RFC6749. 952 o Added mention of HTTP Poll spec to list of other streaming specs 953 in appendix. 955 o Added validation step requiring SET Recipient to verify that the 956 SET is one which the SET Transmitter is expected to send to the 957 SET Recipient. 959 o Changed responding to errors with an appropriate HTTP status code 960 from optional to recommended. 962 o Changed Error Codes registry change policy from Expert Review to 963 First Come First Served; added guidance that error codes are meant 964 to be consumed by automated systems. 966 o Added text making clear that it is up to SET Recipients whether or 967 not they will accept SETs where the SET Issuer is different from 968 the SET Transmitter. 970 o Reworded guidance around signing and/or encrypting SETs for 971 integrity protection. 973 o Renamed TLS "Support Considerations" section to "Confidentiality 974 of SETs". 976 o Reworded guidance around subject identifier selection and privacy 977 concerns. 979 Draft 06 - mbj, MS: 981 o Made minor editorial corrections. 983 o Updated to indicate that failure response should be returned if 984 errors occur in authenticating the SET. 986 o Updated reference for JSON from RFC 7159 to RFC 8259. 988 o Fixed Authentication Using Signed SETs to indicate the SET 989 Transmitter must be authorized to deliver the SET, not the SET 990 Issuer. 992 o Fixed Authenticating Persisted SETs to put the responsibility for 993 ensuring the SET is signed on the SET Recipient. 995 o Fixed error code format definition to match error codes defined in 996 doc. 998 Draft 07 - AB: 1000 o Made minor editorial corrections. 1002 o Removed "SET Recipient" definition and added explicit list of 1003 terms used from RFC8417. 1005 Draft 08 - mbj 1007 o Addressed area director review comments by Benjamin Kaduk. 1009 Draft 09 - mbj + AB 1010 o Corrected editorial nits. 1012 Draft 10 - AB 1014 o Addressed area director review comments by Benjamin Kaduk: 1016 * Added reference to 8417 as definition document for SETs. 1018 * Added text clarifying that determining the SET Recipient's 1019 service identity is out of scope. 1021 * Added normative recommendation for transmitters to target SETs 1022 to specific business needs of subscribers. 1024 * Minor editorial corrections. 1026 Draft 11 - mbj 1028 o Addressed SecDir review comments by Valery Smyslov. 1030 o Addressed OpsDir review comments by Joe Clarke. 1032 o Addressed GenArt review comments by Vijay Gurbani. 1034 Draft 12 - mbj 1036 o Revised to unambiguously require the use of TLS, while preserving 1037 descriptions of precautions needed for non-TLS use in an appendix. 1039 Draft 13 - mbj 1041 o Addressed IESG comments. 1043 Authors' Addresses 1045 Annabelle Backman (editor) 1046 Amazon 1048 Email: richanna@amazon.com 1050 Michael B. Jones (editor) 1051 Microsoft 1053 Email: mbj@microsoft.com 1054 URI: https://self-issued.info/ 1055 Marius Scurtescu 1056 Coinbase 1058 Email: marius.scurtescu@coinbase.com 1060 Morteza Ansari 1061 Cisco 1063 Email: morteza.ansari@cisco.com 1065 Anthony Nadalin 1066 Microsoft 1068 Email: tonynad@microsoft.com