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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 28, 2020 Microsoft 6 M. Scurtescu 7 Coinbase 8 M. Ansari 9 Cisco 10 A. Nadalin 11 Microsoft 12 June 26, 2020 14 Push-Based Security Event Token (SET) Delivery Using HTTP 15 draft-ietf-secevent-http-push-14 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 28, 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 . . . . . . . . . . . . . . . . 13 79 7.1.2. Initial Registry Contents . . . . . . . . . . . . . . 13 80 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 14 81 8.1. Normative References . . . . . . . . . . . . . . . . . . 14 82 8.2. Informative References . . . . . . . . . . . . . . . . . 16 83 Appendix A. Unencrypted Transport Considerations . . . . . . . . 16 84 Appendix B. Other Streaming Specifications . . . . . . . . . . . 17 85 Appendix C. Acknowledgments . . . . . . . . . . . . . . . . . . 18 86 Appendix D. Change Log . . . . . . . . . . . . . . . . . . . . . 19 87 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 24 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. The level and 181 method of retention of SETs by SET Recipients is out of scope of this 182 specification. Once the SET has been validated and persisted, the 183 SET Recipient SHOULD immediately return a response indicating that 184 the SET was successfully delivered. The SET Recipient SHOULD NOT 185 perform further processing of the SET beyond the required validation 186 steps prior to sending this response. Any additional steps SHOULD be 187 executed asynchronously from delivery to minimize the time the SET 188 Transmitter is waiting for a response. 190 The SET Transmitter MAY transmit the same SET to the SET Recipient 191 multiple times, regardless of the response from the SET Recipient. 192 The SET Recipient MUST respond as it would if the SET had not been 193 previously received by the SET Recipient. The SET Recipient MUST NOT 194 expect or depend on a SET Transmitter to re-transmit a SET or 195 otherwise make a SET available to the SET Recipient once the SET 196 Recipient acknowledges that it was received successfully. 198 The SET Transmitter should not re-transmit a SET unless the SET 199 Transmitter suspects that previous transmissions may have failed due 200 to potentially recoverable errors (such as network outage or 201 temporary service interruption at either the SET Transmitter or SET 202 Recipient). In all other cases, the SET Transmitter SHOULD NOT re- 203 transmit a SET. The SET Transmitter SHOULD delay retransmission for 204 an appropriate amount of time to avoid overwhelming the SET Recipient 205 (see Section 4). 207 2.1. Transmitting a SET 209 To transmit a SET to a SET Recipient, the SET Transmitter makes an 210 HTTP POST request to a TLS-enabled HTTP endpoint provided by the SET 211 Recipient. The "Content-Type" header field of this request MUST be 212 "application/secevent+jwt" as defined in Sections 2.3 and 7.2 of 213 [RFC8417], and the "Accept" header field MUST be "application/json". 214 The request body MUST consist of the SET itself, represented as a JWT 215 [RFC7519]. 217 The SET Transmitter MAY include in the request an "Accept-Language" 218 header field to indicate to the SET Recipient the preferred 219 language(s) in which to receive error messages. 221 The mechanisms by which the SET Transmitter determines the HTTP 222 endpoint to use when transmitting a SET to a given SET Recipient are 223 not defined by this specification and are deployment specific. 225 The following is a non-normative example of a SET transmission 226 request: 228 POST /Events HTTP/1.1 229 Host: notify.rp.example.com 230 Accept: application/json 231 Accept-Language: en-US, en;q=0.5 232 Content-Type: application/secevent+jwt 234 eyJ0eXAiOiJzZWNldmVudCtqd3QiLCJhbGciOiJIUzI1NiJ9Cg 235 . 236 eyJpc3MiOiJodHRwczovL2lkcC5leGFtcGxlLmNvbS8iLCJqdGkiOiI3NTZFNjk 237 3MTc1NjUyMDY5NjQ2NTZFNzQ2OTY2Njk2NTcyIiwiaWF0IjoxNTA4MTg0ODQ1LC 238 JhdWQiOiI2MzZDNjk2NTZFNzQ1RjY5NjQiLCJldmVudHMiOnsiaHR0cHM6Ly9zY 239 2hlbWFzLm9wZW5pZC5uZXQvc2VjZXZlbnQvcmlzYy9ldmVudC10eXBlL2FjY291 240 bnQtZGlzYWJsZWQiOnsic3ViamVjdCI6eyJzdWJqZWN0X3R5cGUiOiJpc3Mtc3V 241 iIiwiaXNzIjoiaHR0cHM6Ly9pZHAuZXhhbXBsZS5jb20vIiwic3ViIjoiNzM3NT 242 YyNkE2NTYzNzQifSwicmVhc29uIjoiaGlqYWNraW5nIn19fQ 243 . 244 Y4rXxMD406P2edv00cr9Wf3_XwNtLjB9n-jTqN1_lLc 246 Figure 1: Example SET Transmission Request 248 2.2. Success Response 250 If the SET is determined to be valid, the SET Recipient SHALL 251 acknowledge successful transmission by responding with HTTP Response 252 Status Code 202 (Accepted) (see Section 6.3.3 of [RFC7231]). The 253 body of the response MUST be empty. 255 The following is a non-normative example of a successful receipt of a 256 SET. 258 HTTP/1.1 202 Accepted 260 Figure 2: Example Successful Delivery Response 262 2.3. Failure Response 264 In the event of a general HTTP error condition, the SET Recipient 265 responds with the applicable HTTP Status Code, as defined in 266 Section 6 of [RFC7231]. 268 When the SET Recipient detects an error parsing, validating, or 269 authenticating a SET transmitted in a SET Transmission Request, the 270 SET Recipient SHALL respond with an HTTP Response Status Code of 400 271 (Bad Request). The "Content-Type" header field of this response MUST 272 be "application/json", and the body MUST be a UTF-8 encoded JSON 273 [RFC8259] object containing the following name/value pairs: 275 err A Security Event Token Error Code (see Section 2.4). 277 description A UTF-8 string containing a human-readable description 278 of the error that may provide additional diagnostic information. 279 The exact content of this field is implementation specific. 281 The response MUST include a "Content-Language" header field, whose 282 value indicates the language of the error descriptions included in 283 the response body. If the SET Recipient can provide error 284 descriptions in multiple languages, they SHOULD choose the language 285 to use according to the value of the "Accept-Language" header field 286 sent by the SET Transmitter in the transmission request, as described 287 in Section 5.3.5 of [RFC7231]. If the SET Transmitter did not send 288 an "Accept-Language" header field, or if the SET Recipient does not 289 support any of the languages included in the header field, the SET 290 Recipient MUST respond with messages that are understandable by an 291 English-speaking person, as described in Section 4.5 of [RFC2277]. 293 The following is a non-normative example error response indicating 294 that the key used to encrypt the SET has been revoked. 296 HTTP/1.1 400 Bad Request 297 Content-Language: en-US 298 Content-Type: application/json 300 { 301 "err": "invalid_key", 302 "description": "Key ID 12345 has been revoked." 303 } 305 Figure 3: Example Error Response (invalid_key) 307 The following is a non-normative example error response indicating 308 that the access token included in the request is expired. 310 HTTP/1.1 400 Bad Request 311 Content-Language: en-US 312 Content-Type: application/json 314 { 315 "err": "authentication_failed", 316 "description": "Access token has expired." 317 } 319 Figure 4: Example Error Response (authentication_failed) 321 The following is a non-normative example error response indicating 322 that the SET Receiver is not willing to accept SETs issued by the 323 specified issuer from this particular SET Transmitter. 325 HTTP/1.1 400 Bad Request 326 Content-Language: en-US 327 Content-Type: application/json 329 { 330 "err": "invalid_issuer", 331 "description": "Not authorized for issuer https://iss.example.com/." 332 } 334 Figure 5: Example Error Response (access_denied) 336 2.4. Security Event Token Delivery Error Codes 338 Security Event Token Delivery Error Codes are strings that identify a 339 specific category of error that may occur when parsing or validating 340 a SET. Every Security Event Token Delivery Error Code MUST have a 341 unique name registered in the IANA "Security Event Token Delivery 342 Error Codes" registry established by Section 7.1. 344 The following table presents the initial set of Error Codes that are 345 registered in the IANA "Security Event Token Delivery Error Codes" 346 registry: 348 +-----------------------+-------------------------------------------+ 349 | Error Code | Description | 350 +-----------------------+-------------------------------------------+ 351 | invalid_request | The request body cannot be parsed as a | 352 | | SET, or the Event Payload within the SET | 353 | | does not conform to the event's | 354 | | definition. | 355 | invalid_key | One or more keys used to encrypt or sign | 356 | | the SET is invalid or otherwise | 357 | | unacceptable to the SET Recipient | 358 | | (expired, revoked, failed certificate | 359 | | validation, etc.). | 360 | invalid_issuer | The SET issuer is invalid for the SET | 361 | | Recipient. | 362 | invalid_audience | The SET audience does not correspond to | 363 | | the SET Recipient. | 364 | authentication_failed | The SET Recipient could not authenticate | 365 | | the SET Transmitter. | 366 | access_denied | The SET Transmitter is not authorized to | 367 | | transmit the SET to the SET Recipient. | 368 +-----------------------+-------------------------------------------+ 370 Table 1: SET Delivery Error Codes 372 Other Error Codes may also be received, as the set of Error Codes is 373 extensible via the IANA "Security Event Token Delivery Error Codes" 374 registry established in Section 7.1. 376 3. Authentication and Authorization 378 The SET delivery method described in this specification is based upon 379 HTTP over TLS [RFC2818] and standard HTTP authentication and 380 authorization schemes, as per [RFC7235]. The TLS server certificate 381 MUST be validated using DNS-ID [RFC6125] and/or DANE [RFC6698]. 383 Authorization for the eligibility to provide actionable SETs can be 384 determined by using the identity of the SET Issuer, the identity of 385 the SET Transmitter, perhaps using mutual TLS, or via other employed 386 authentication methods. Because SETs are not commands, SET 387 Recipients are free to ignore SETs that are not of interest. 389 4. Delivery Reliability 391 Delivery reliability requirements may vary depending upon the use 392 cases. This specification defines the response from the SET 393 Recipient in such a way as to provide the SET Transmitter with the 394 information necessary to determine what further action is required, 395 if any, in order to meet their requirements. SET Transmitters with 396 high reliability requirements may be tempted to always retry failed 397 transmissions. However, it should be noted that for many types of 398 SET delivery errors, a retry is extremely unlikely to be successful. 399 For example, "invalid_request" indicates a structural error in the 400 content of the request body that is likely to remain when re- 401 transmitting the same SET. Others such as "access_denied" may be 402 transient, for example if the SET Transmitter refreshes expired 403 credentials prior to re-transmission. 405 The SET Transmitter may be unaware of whether or not a SET has been 406 delivered to a SET Recipient. For example, a network interruption 407 could prevent the SET Transmitter from receiving the success 408 response, or a service outage could prevent the SET Transmitter from 409 recording the fact that the SET was delivered. It is left to the 410 implementer to decide how to handle such cases, based on their 411 requirements. For example, it may be appropriate for the SET 412 Transmitter to re-transmit the SET to the SET Recipient, erring on 413 the side of guaranteeing delivery, or it may be appropriate to assume 414 delivery was successful, erring on the side of not spending resources 415 re-transmitting previously delivered SETs. Other options, such as 416 sending the SET to a "dead letter queue" for manual examination may 417 also be appropriate. 419 Implementers SHOULD evaluate the reliability requirements of their 420 use cases and the impact of various retry mechanisms and re- 421 transmission policies on the performance of their systems to 422 determine an appropriate strategy for handling various error 423 conditions. 425 5. Security Considerations 427 5.1. Authentication Using Signed SETs 429 JWS signed SETs can be used (see [RFC7515] and Section 5 of 430 [RFC8417]) to enable the SET Recipient to validate that the SET 431 Issuer is authorized to provide actionable SETs. 433 5.2. HTTP Considerations 435 SET delivery depends on the use of Hypertext Transfer Protocol and is 436 thus subject to the security considerations of HTTP Section 9 of 437 [RFC7230] and its related specifications. 439 5.3. Confidentiality of SETs 441 SETs may contain sensitive information, including Personally 442 Identifiable Information (PII), or be distributed through third 443 parties. In such cases, SET Transmitters and SET Recipients MUST 444 protect the confidentiality of the SET contents. TLS MUST be used to 445 secure the transmitted SETs. In some use cases, encrypting the SET 446 as described in JWE [RFC7516] will also be required. The Event 447 delivery endpoint MUST support at least TLS version 1.2 [RFC5246] and 448 SHOULD support the newest version of TLS that meets its security 449 requirements, which as of the time of this publication is TLS 1.3 450 [RFC8446]. The client MUST perform a TLS/SSL server certificate 451 check using DNS-ID [RFC6125] and/or DANE [RFC6698]. How a SET 452 Transmitter determines the expected service identity to match the SET 453 Recipient's server certificate against is out of scope for this 454 document. The implementation security considerations for TLS in 455 "Recommendations for Secure Use of TLS and DTLS" [RFC7525] MUST be 456 followed. 458 5.4. Denial of Service 460 The SET Recipient may be vulnerable to a denial-of-service attack 461 where a malicious party makes a high volume of requests containing 462 invalid SETs, causing the endpoint to expend significant resources on 463 cryptographic operations that are bound to fail. This may be 464 mitigated by authenticating SET Transmitters with a mechanism such as 465 mutual TLS. Rate-limiting problematic transmitters is also a 466 possible means of mitigation. 468 5.5. Authenticating Persisted SETs 470 At the time of receipt, the SET Recipient can rely upon TLS 471 mechanisms, HTTP authentication methods, and/or other context from 472 the transmission request to authenticate the SET Transmitter and 473 validate the authenticity of the SET. However, this context is 474 typically unavailable to systems to which the SET Recipient forwards 475 the SET, or to systems that retrieve the SET from storage. If the 476 SET Recipient requires the ability to validate SET authenticity 477 outside of the context of the transmission request, then the SET 478 Recipient SHOULD ensure that such SETs have been signed in accordance 479 with [RFC7515]. Needed context could also be stored with the SET and 480 retrieved with it. 482 6. Privacy Considerations 484 SET Transmitters should attempt to deliver SETs that are targeted to 485 the specific business and protocol needs of subscribers. 487 When sharing personally identifiable information or information that 488 is otherwise considered confidential to affected users, SET 489 Transmitters and Recipients MUST have the appropriate legal 490 agreements and user consent or terms of service in place. 491 Furthermore, data that needs confidentiality protection MUST be 492 encrypted, at least with TLS and sometimes also using JSON Web 493 Encryption (JWE) [RFC7516]. 495 In some cases, subject identifiers themselves may be considered 496 sensitive information, such that their inclusion within a SET may be 497 considered a violation of privacy. SET Issuers and SET Transmitters 498 should consider the ramifications of sharing a particular subject 499 identifier with a SET Recipient (e.g., whether doing so could enable 500 correlation and/or de-anonymization of data) and choose appropriate 501 subject identifiers for their use cases. 503 7. IANA Considerations 505 7.1. Security Event Token Delivery Error Codes 507 This document defines Security Event Token Delivery Error Codes, for 508 which IANA is asked to create and maintain a new registry titled 509 "Security Event Token Delivery Error Codes". Initial values for the 510 Security Event Token Delivery Error Codes registry are defined in 511 Table 1 and registered below. Future assignments are to be made 512 through the Specification Required registration policy ([RFC8126]) 513 and shall follow the template below. 515 Error Codes are intended to be interpreted by automated systems, and 516 therefore SHOULD identify classes of errors to which an automated 517 system could respond in a meaningfully distinct way (e.g., by 518 refreshing authentication credentials and retrying the request). 520 Error Code names are case sensitive. Names may not match other 521 registered names in a case-insensitive manner unless the Designated 522 Experts state that there is a compelling reason to allow an 523 exception. 525 Criteria that should be applied by the Designated Experts includes 526 determining whether the proposed registration duplicates existing 527 functionality, whether it is likely to be of general applicability or 528 whether it is useful only for a single application, and whether the 529 registration description is clear. 531 It is suggested that multiple Designated Experts be appointed who are 532 able to represent the perspectives of different applications using 533 this specification, in order to enable broadly informed review of 534 registration decisions. In cases where a registration decision could 535 be perceived as creating a conflict of interest for a particular 536 Expert, that Expert should defer to the judgment of the other 537 Experts. 539 7.1.1. Registration Template 541 Error Code 542 The name of the Security Event Token Delivery Error Code, as 543 described in Section 2.4. The name MUST be a case-sensitive ASCII 544 string consisting only of letters, digits, and underscore; these 545 are the characters whose codes fall within the inclusive ranges 546 0x30-39, 0x41-5A, 0x5F and 0x61-7A. 548 Description 549 A brief human-readable description of the Security Event Token 550 Delivery Error Code. 552 Change Controller 553 For error codes registered by the IETF or its working groups, list 554 "IETF". For all other error codes, list the name of the party 555 responsible for the registration. Contact information such as 556 mailing address, email address, or phone number may also be 557 provided. 559 Defining Document(s) 560 A reference to the document or documents that define the Security 561 Event Token Delivery Error Code. The definition MUST specify the 562 name and description of the error code and explain under what 563 circumstances the error code may be used. URIs that can be used 564 to retrieve copies of each document at no cost SHOULD be included. 566 7.1.2. Initial Registry Contents 568 Error Code: invalid_request 569 Description: The request body cannot be parsed as a SET or the 570 event payload within the SET does not conform to the event's 571 definition. 572 Change Controller: IETF 573 Defining Document(s): Section 2.4 of [[ this specification ]] 575 Error Code: invalid_key 576 Description: One or more keys used to encrypt or sign the SET is 577 invalid or otherwise unacceptable to the SET Recipient (expired, 578 revoked, failed certificate validation, etc.). 579 Change Controller: IETF 580 Defining Document(s): Section 2.4 of [[ this specification ]] 582 Error Code: invalid_issuer 583 Description: The SET issuer is invalid for the SET Recipient. 584 Change Controller: IETF 585 Defining Document(s): Section 2.4 of [[ this specification ]] 586 Error Code: invalid_audience 587 Description: The SET audience does not correspond to the SET 588 Recipient. 589 Change Controller: IETF 590 Defining Document(s): Section 2.4 of [[ this specification ]] 592 Error Code: authentication_failed 593 Description: The SET Recipient could not authenticate the SET 594 Transmitter. 595 Change Controller: IETF 596 Defining Document(s): Section 2.4 of [[ this specification ]] 598 Error Code: access_denied 599 Description: The SET Transmitter is not authorized to transmit the 600 SET to the SET Recipient. 601 Change Controller: IETF 602 Defining Document(s): Section 2.4 of [[ this specification ]] 604 8. References 606 8.1. Normative References 608 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 609 Requirement Levels", BCP 14, RFC 2119, 610 DOI 10.17487/RFC2119, March 1997, 611 . 613 [RFC2277] Alvestrand, H., "IETF Policy on Character Sets and 614 Languages", BCP 18, RFC 2277, DOI 10.17487/RFC2277, 615 January 1998, . 617 [RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, 618 DOI 10.17487/RFC2818, May 2000, 619 . 621 [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security 622 (TLS) Protocol Version 1.2", RFC 5246, 623 DOI 10.17487/RFC5246, August 2008, 624 . 626 [RFC6125] Saint-Andre, P. and J. Hodges, "Representation and 627 Verification of Domain-Based Application Service Identity 628 within Internet Public Key Infrastructure Using X.509 629 (PKIX) Certificates in the Context of Transport Layer 630 Security (TLS)", RFC 6125, DOI 10.17487/RFC6125, March 631 2011, . 633 [RFC6698] Hoffman, P. and J. Schlyter, "The DNS-Based Authentication 634 of Named Entities (DANE) Transport Layer Security (TLS) 635 Protocol: TLSA", RFC 6698, DOI 10.17487/RFC6698, August 636 2012, . 638 [RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer 639 Protocol (HTTP/1.1): Message Syntax and Routing", 640 RFC 7230, DOI 10.17487/RFC7230, June 2014, 641 . 643 [RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer 644 Protocol (HTTP/1.1): Semantics and Content", RFC 7231, 645 DOI 10.17487/RFC7231, June 2014, 646 . 648 [RFC7515] Jones, M., Bradley, J., and N. Sakimura, "JSON Web 649 Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May 650 2015, . 652 [RFC7516] Jones, M. and J. Hildebrand, "JSON Web Encryption (JWE)", 653 RFC 7516, DOI 10.17487/RFC7516, May 2015, 654 . 656 [RFC7519] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token 657 (JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015, 658 . 660 [RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre, 661 "Recommendations for Secure Use of Transport Layer 662 Security (TLS) and Datagram Transport Layer Security 663 (DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May 664 2015, . 666 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 667 Writing an IANA Considerations Section in RFCs", BCP 26, 668 RFC 8126, DOI 10.17487/RFC8126, June 2017, 669 . 671 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 672 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 673 May 2017, . 675 [RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data 676 Interchange Format", STD 90, RFC 8259, 677 DOI 10.17487/RFC8259, December 2017, 678 . 680 [RFC8417] Hunt, P., Ed., Jones, M., Denniss, W., and M. Ansari, 681 "Security Event Token (SET)", RFC 8417, 682 DOI 10.17487/RFC8417, July 2018, 683 . 685 [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol 686 Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, 687 . 689 8.2. Informative References 691 [I-D.ietf-secevent-http-poll] 692 Backman, A., Jones, M., Scurtescu, M., Ansari, M., and A. 693 Nadalin, "Poll-Based Security Event Token (SET) Delivery 694 Using HTTP", draft-ietf-secevent-http-poll-12 (work in 695 progress), June 2020. 697 [RFC7235] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer 698 Protocol (HTTP/1.1): Authentication", RFC 7235, 699 DOI 10.17487/RFC7235, June 2014, 700 . 702 Appendix A. Unencrypted Transport Considerations 704 Earlier versions of this specification made the use of TLS optional 705 and described security and privacy considerations resulting from use 706 of unencrypted HTTP as the underlying transport. When the working 707 group decided to mandate usage HTTP over TLS, it also decided to 708 preserve the description of these considerations in this non- 709 normative appendix. 711 SETs may contain sensitive information that is considered Personally 712 Identifiable Information (PII). In such cases, SET Transmitters and 713 SET Recipients MUST protect the confidentiality of the SET contents. 714 When TLS is not used, this means that the SET MUST be encrypted as 715 described in JWE [RFC7516]. 717 If SETs were allowed to be transmitted over unencrypted channels, 718 some privacy-sensitive information about them might leak, even though 719 the SETs themselves are encrypted. For instance, an attacker may be 720 able to determine whether or not a SET was accepted and the reason 721 for its rejection or may be able to derive information from being 722 able to observe the size of the encrypted SET. (Note that even when 723 TLS is utilized, some information leakage is still possible; message 724 padding algorithms to prevent side channels remain an open research 725 topic.) 727 Appendix B. Other Streaming Specifications 729 [[ NOTE TO THE RFC EDITOR: This section to be removed prior to 730 publication ]] 732 The following pub/sub, queuing, and streaming systems were reviewed 733 as possible solutions or as input to the current draft: 735 Poll-Based Security Event Token (SET) Delivery Using HTTP 737 In addition to this specification, the WG is defining a polling-based 738 SET delivery protocol. That protocol [I-D.ietf-secevent-http-poll] 739 describes it as: 741 This specification defines how a series of Security Event Tokens 742 (SETs) can be delivered to an intended recipient using HTTP POST over 743 TLS initiated as a poll by the recipient. The specification also 744 defines how delivery can be assured, subject to the SET Recipient's 745 need for assurance. 747 XMPP Events 749 The WG considered XMPP Events and their ability to provide a single 750 messaging solution without the need for both polling and push modes. 751 The feeling was the size and methodology of XMPP was too far apart 752 from the current capabilities of the SECEVENTs community, which 753 focuses in on HTTP based service delivery and authorization. 755 Amazon Simple Notification Service 757 Simple Notification Service is a pub/sub messaging product from AWS. 758 SNS supports a variety of subscriber types: HTTP/HTTPS endpoints, AWS 759 Lambda functions, email addresses (as JSON or plain text), phone 760 numbers (via SMS), and AWS SQS standard queues. It does not directly 761 support pull, but subscribers can get the pull model by creating an 762 SQS queue and subscribing it to the topic. Note that this puts the 763 cost of pull support back onto the subscriber, just as it is in the 764 push model. It is not clear that one way is strictly better than the 765 other; larger, sophisticated developers may be happy to own message 766 persistence so they can have their own internal delivery guarantees. 767 The long tail of OIDC clients may not care about that or may fail to 768 get it right. Regardless, I think we can learn something from the 769 Delivery Policies supported by SNS, as well as the delivery controls 770 that SQS offers (e.g., Visibility Timeout, Dead-Letter Queues). I am 771 not suggesting that we need all of these things in the spec, but they 772 give an idea of what features people have found useful. 774 Other information: 776 o API Reference: 777 http://docs.aws.amazon.com/AWSSimpleQueueService/latest/ 778 APIReference/Welcome.html 780 o Visibility Timeouts: 781 http://docs.aws.amazon.com/AWSSimpleQueueService/latest/ 782 SQSDeveloperGuide/sqs-visibility-timeout.html 784 Apache Kafka 786 Apache Kafka is an Apache open source project based upon TCP for 787 distributed streaming. It prescribes some interesting general- 788 purpose features that seem to extend far beyond the simpler streaming 789 model that SECEVENTs is after. A comment from MS has been that Kafka 790 does an acknowledge with poll combination event which seems to be a 791 performance advantage. See: https://kafka.apache.org/intro 793 Google Pub/Sub 795 The Google Pub Sub system favors a model whereby polling and 796 acknowledgement of events is done with separate endpoints and as 797 separate functions. 799 Information: 801 o Cloud Overview - https://cloud.google.com/pubsub/ 803 o Subscriber Overview - https://cloud.google.com/pubsub/docs/ 804 subscriber 806 o Subscriber Pull(poll) - https://cloud.google.com/pubsub/docs/pull 808 Appendix C. Acknowledgments 810 The editors would like to thank the members of the SCIM working 811 group, which began discussions of provisioning events starting with 812 draft-hunt-scim-notify-00 in 2015. We would like to thank Phil Hunt 813 and the other authors of draft-ietf-secevent-delivery-02, upon which 814 this specification is based. We would like to thank the participants 815 in the SecEvents working group for their contributions to this 816 specification. 818 Additionally, we would like to thank the following individuals for 819 their reviews of the specification: Joe Clarke, Roman Danyliw, Vijay 820 Gurbani, Benjamin Kaduk, Erik Kline, Murray Kucherawy, Barry Leiba, 821 Yaron Sheffer, Robert Sparks, Valery Smyslov, Eric Vyncke, and Robert 822 Wilton. 824 Appendix D. Change Log 826 [[ NOTE TO THE RFC EDITOR: This section to be removed prior to 827 publication ]] 829 Draft 00 - AB - Based on draft-ietf-secevent-delivery-02 with the 830 following changes: 832 o Renamed to "Push-Based SET Token Delivery Using HTTP" 834 o Removed references to the HTTP Polling delivery method. 836 o Removed informative reference to RFC6202. 838 Draft 01 - AB: 840 o Fixed area and workgroup to match secevent. 842 o Removed unused definitions and definitions already covered by SET. 844 o Renamed Event Transmitter and Event Receiver to SET Transmitter 845 and SET Receiver, respectively. 847 o Added IANA registry for SET Delivery Error Codes. 849 o Removed enumeration of HTTP authentication methods. 851 o Removed generally applicable guidance for HTTP, authorization 852 tokens, and bearer tokens. 854 o Moved guidance for using authentication methods as DoS protection 855 to Security Considerations. 857 o Removed redundant instruction to use WWW-Authenticate header. 859 o Removed further generally applicable guidance for authorization 860 tokens. 862 o Removed bearer token from example delivery request, and text 863 referencing it. 865 o Broke delivery method description into separate request/response 866 sections. 868 o Added missing empty line between headers and body in example 869 request. 871 o Removed inapplicable notes about example formatting. 873 o Removed text about SET creation and handling. 875 o Removed duplication in protocol description. 877 o Added "non-normative example" text to example transmission 878 request. 880 o Fixed inconsistencies in use of Error Code term. 882 Draft 02 - AB: 884 o Rewrote abstract and introduction. 886 o Rewrote definitions for SET Transmitter, SET Receiver. 888 o Renamed Event Delivery section to SET Delivery. 890 o Readability edits to Success Response and Failure Response 891 sections. 893 o Consolidated definition of error response under Failure Response 894 section. 896 o Removed Event Delivery Process section and moved its content to 897 parent section. 899 o Readability edits to SET Delivery section and its subsections. 901 o Added callout that SET Receiver HTTP endpoint configuration is 902 out-of-scope. 904 o Added callout that SET verification mechanisms are out-of-scope. 906 o Added retry guidance, notes regarding delivery reliability 907 requirements. 909 o Added guidance around using JWS and/or JWE to authenticate 910 persisted SETs. 912 Draft 03 - mbj: 914 o Addressed problems identified in my 18-Jul-18 review message 915 titled "Issues for both the Push and Poll Specs". 917 o Changes to align terminology with RFC 8417, for instance, by using 918 the already defined term SET Recipient rather than SET Receiver. 920 o Applied editorial and minor normative corrections. 922 o Updated Marius' contact information. 924 Draft 04 - AB: 926 o Replaced Error Codes with smaller set of meaningfully 927 differentiated codes. 929 o Added more error response examples. 931 o Removed un-referenced normative references. 933 o Added normative reference to JSON in error response definition. 935 o Added text clarifying that the value of the "description" 936 attribute in error responses is implementation specific. 938 o Added requirement that error descriptions and responses are UTF-8 939 encoded. 941 o Added error description language preferences and specification via 942 "Accept-Language" and "Content-Language" headers. 944 o Added "recognized issuer" validation requirement in section 2. 946 o Added timeouts as an acceptable reason to resend a SET in section 947 2. 949 o Edited text in section 1 to clarify that configuration is out of 950 scope. 952 o Made minor editorial corrections. 954 Draft 05 - AB: 956 o Made minor editorial corrections. 958 o Updated example request with a correct SET header and signature. 960 o Revised TLS guidance to allow implementers to provide 961 confidentiality protection via JWE. 963 o Revised TLS guidance to require *at least* TLS 1.2. 965 o Revised TLS guidance to recommend supporting the newest version of 966 TLS that meets security requirements. 968 o Revised SET Delivery Error Code format to allow the same set of 969 characters as is allowed in error codes in RFC6749. 971 o Added mention of HTTP Poll spec to list of other streaming specs 972 in appendix. 974 o Added validation step requiring SET Recipient to verify that the 975 SET is one which the SET Transmitter is expected to send to the 976 SET Recipient. 978 o Changed responding to errors with an appropriate HTTP status code 979 from optional to recommended. 981 o Changed Error Codes registry change policy from Expert Review to 982 First Come First Served; added guidance that error codes are meant 983 to be consumed by automated systems. 985 o Added text making clear that it is up to SET Recipients whether or 986 not they will accept SETs where the SET Issuer is different from 987 the SET Transmitter. 989 o Reworded guidance around signing and/or encrypting SETs for 990 integrity protection. 992 o Renamed TLS "Support Considerations" section to "Confidentiality 993 of SETs". 995 o Reworded guidance around subject identifier selection and privacy 996 concerns. 998 Draft 06 - mbj, MS: 1000 o Made minor editorial corrections. 1002 o Updated to indicate that failure response should be returned if 1003 errors occur in authenticating the SET. 1005 o Updated reference for JSON from RFC 7159 to RFC 8259. 1007 o Fixed Authentication Using Signed SETs to indicate the SET 1008 Transmitter must be authorized to deliver the SET, not the SET 1009 Issuer. 1011 o Fixed Authenticating Persisted SETs to put the responsibility for 1012 ensuring the SET is signed on the SET Recipient. 1014 o Fixed error code format definition to match error codes defined in 1015 doc. 1017 Draft 07 - AB: 1019 o Made minor editorial corrections. 1021 o Removed "SET Recipient" definition and added explicit list of 1022 terms used from RFC8417. 1024 Draft 08 - mbj 1026 o Addressed area director review comments by Benjamin Kaduk. 1028 Draft 09 - mbj + AB 1030 o Corrected editorial nits. 1032 Draft 10 - AB 1034 o Addressed area director review comments by Benjamin Kaduk: 1036 * Added reference to 8417 as definition document for SETs. 1038 * Added text clarifying that determining the SET Recipient's 1039 service identity is out of scope. 1041 * Added normative recommendation for transmitters to target SETs 1042 to specific business needs of subscribers. 1044 * Minor editorial corrections. 1046 Draft 11 - mbj 1048 o Addressed SecDir review comments by Valery Smyslov. 1050 o Addressed OpsDir review comments by Joe Clarke. 1052 o Addressed GenArt review comments by Vijay Gurbani. 1054 Draft 12 - mbj 1056 o Revised to unambiguously require the use of TLS, while preserving 1057 descriptions of precautions needed for non-TLS use in an appendix. 1059 Draft 13 - mbj 1061 o Addressed IESG comments. 1063 Draft 14 - AB 1065 o Revised normative requirements for SET re-transmission to clarify 1066 "at least once" delivery expectiations. 1068 o Added non-normative text to Section 4 - Delivery Reliability 1069 describing conditions where re-transmission of successfully 1070 delivered SETs may occur. 1072 Authors' Addresses 1074 Annabelle Backman (editor) 1075 Amazon 1077 Email: richanna@amazon.com 1079 Michael B. Jones (editor) 1080 Microsoft 1082 Email: mbj@microsoft.com 1083 URI: https://self-issued.info/ 1085 Marius Scurtescu 1086 Coinbase 1088 Email: marius.scurtescu@coinbase.com 1090 Morteza Ansari 1091 Cisco 1093 Email: morteza.ansari@cisco.com 1095 Anthony Nadalin 1096 Microsoft 1098 Email: tonynad@microsoft.com