idnits 2.17.1 draft-ietf-secevent-http-poll-04.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- == There are 5 instances of lines with non-RFC2606-compliant FQDNs in the document. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (November 1, 2019) is 1632 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Unused Reference: 'RFC3986' is defined on line 651, but no explicit reference was found in the text == Unused Reference: 'RFC7519' is defined on line 681, but no explicit reference was found in the text == Unused Reference: 'RFC3339' is defined on line 707, but no explicit reference was found in the text == Unused Reference: 'RFC6750' is defined on line 721, but no explicit reference was found in the text == Outdated reference: A later version (-14) exists of draft-ietf-secevent-http-push-06 ** Obsolete normative reference: RFC 5246 (Obsoleted by RFC 8446) ** Obsolete normative reference: RFC 6125 (Obsoleted by RFC 9525) ** Obsolete normative reference: RFC 7231 (Obsoleted by RFC 9110) ** Obsolete normative reference: RFC 7525 (Obsoleted by RFC 9325) -- Obsolete informational reference (is this intentional?): RFC 7230 (Obsoleted by RFC 9110, RFC 9112) -- Obsolete informational reference (is this intentional?): RFC 7235 (Obsoleted by RFC 9110) Summary: 4 errors (**), 0 flaws (~~), 7 warnings (==), 3 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group A. Backman, Ed. 3 Internet-Draft Amazon 4 Intended status: Standards Track M. Jones, Ed. 5 Expires: May 4, 2020 Microsoft 6 M. Scurtescu 7 Coinbase 8 M. Ansari 9 Cisco 10 A. Nadalin 11 Microsoft 12 November 1, 2019 14 Poll-Based Security Event Token (SET) Delivery Using HTTP 15 draft-ietf-secevent-http-poll-04 17 Abstract 19 This specification defines how a series of Security Event Tokens 20 (SETs) may be delivered to an intended recipient using HTTP POST over 21 TLS initiated as a poll by the recipient. The specification also 22 defines how delivery can be assured, subject to the SET Recipient's 23 need for assurance. 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 May 4, 2020. 42 Copyright Notice 44 Copyright (c) 2019 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. Polling Delivery using HTTP . . . . . . . . . . . . . . . 4 64 2.2. Polling HTTP Request . . . . . . . . . . . . . . . . . . 4 65 2.3. Polling HTTP Response . . . . . . . . . . . . . . . . . . 5 66 2.4. Poll Request . . . . . . . . . . . . . . . . . . . . . . 6 67 2.4.1. Poll Only Request . . . . . . . . . . . . . . . . . . 7 68 2.4.2. Acknowledge Only Request . . . . . . . . . . . . . . 7 69 2.4.3. Poll with Acknowledgement . . . . . . . . . . . . . . 8 70 2.4.4. Poll with Acknowledgement and Errors . . . . . . . . 9 71 2.5. Poll Response . . . . . . . . . . . . . . . . . . . . . . 9 72 2.6. Error Response Handling . . . . . . . . . . . . . . . . . 11 73 3. Authentication and Authorization . . . . . . . . . . . . . . 12 74 3.1. Use of Tokens as Authorizations . . . . . . . . . . . . . 12 75 4. Security Considerations . . . . . . . . . . . . . . . . . . . 12 76 4.1. Authentication Using Signed SETs . . . . . . . . . . . . 13 77 4.2. HTTP Considerations . . . . . . . . . . . . . . . . . . . 13 78 4.3. Confidentiality of SETs . . . . . . . . . . . . . . . . . 13 79 4.4. Access Token Considerations . . . . . . . . . . . . . . . 13 80 4.4.1. Bearer Token Considerations . . . . . . . . . . . . . 13 81 5. Privacy Considerations . . . . . . . . . . . . . . . . . . . 14 82 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 83 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 14 84 7.1. Normative References . . . . . . . . . . . . . . . . . . 14 85 7.2. Informative References . . . . . . . . . . . . . . . . . 16 86 Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . 17 87 Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 17 88 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19 90 1. Introduction and Overview 92 This specification defines how a stream of Security Event Tokens 93 (SETs) [RFC8417] can be transmitted to an intended SET Recipient 94 using HTTP [RFC7231] over TLS. The specification defines a method to 95 poll for SETs using HTTP POST. 97 A mechanism for exchanging configuration metadata such as endpoint 98 URLs and cryptographic key parameters between the transmitter and 99 recipient is out of scope for this specification. How SETs are 100 defined and the process by which events are identified for SET 101 Recipients is also out of scope for this specification. 103 1.1. Notational Conventions 105 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 106 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 107 "OPTIONAL" in this document are to be interpreted as described in BCP 108 14 [RFC2119] [RFC8174] when, and only when, they appear in all 109 capitals, as shown here. 111 Throughout this document, all figures MAY contain spaces and extra 112 line wrapping for readability and due to space limitations. 114 1.2. Definitions 116 This specification utilizes terminology defined in [RFC8417] and 117 [I-D.ietf-secevent-http-push]. 119 2. SET Delivery 121 When a SET is available for a SET Recipient, the SET Transmitter 122 attempts to deliver the SET by queueing the SET in a buffer so that a 123 SET Recipient can poll for SETs using HTTP/1.1 POST. 125 In Poll-Based SET Delivery Using HTTP, zero or more SETs are 126 delivered in a JSON [RFC8259] document to a SET Recipient in response 127 to an HTTP POST request to the SET Transmitter. Then in a following 128 request, the SET Recipient acknowledges received SETs and can poll 129 for more. All requests and responses are JSON documents and use a 130 "Content-Type" of "application/json", as described in Section 2.1. 132 After successful (acknowledged) SET delivery, SET Transmitters are 133 not required to retain or record SETs for retransmission. Once a SET 134 is acknowledged, the SET Recipient SHALL be responsible for 135 retention, if needed. 137 Transmitted SETs SHOULD be self-validating (signed) if there is a 138 requirement to verify they were issued by the SET Transmitter at a 139 later date when de-coupled from the original delivery where 140 authenticity could be checked via the HTTP or TLS mutual 141 authentication. 143 Upon receiving a SET, the SET Recipient reads the SET and validates 144 it in the manner described in Section 2 of 146 [I-D.ietf-secevent-http-push]. The SET Recipient MUST acknowledge 147 receipt to the SET Transmitter. The SET Recipient SHALL NOT use the 148 event acknowledgement mechanism to report event errors other than 149 those relating to the parsing and validation of the SET. 151 2.1. Polling Delivery using HTTP 153 This method allows a SET Recipient to use HTTP POST (Section 4.3.3 of 154 [RFC7231]) to acknowledge SETs and to check for and receive zero or 155 more SETs. Requests MAY be made at a periodic interval (short 156 polling) or requests MAY wait, pending availability of new SETs using 157 long polling, per Section 2 of [RFC6202]. 159 The delivery of SETs in this method is facilitated by HTTP POST 160 requests initiated by the SET Recipient in which: 162 o The SET Recipient makes a request for available SETs using an HTTP 163 POST to a pre-arranged endpoint provided by the SET Transmitter 164 or, 166 o after validating previously received SETs, the SET Recipient 167 initiates another poll request using HTTP POST that includes 168 acknowledgement of previous SETs and waits for the next batch of 169 SETs. 171 The purpose of the acknowledgement is to inform the SET Transmitter 172 that delivery has succeeded and redelivery is no longer required. 173 Before acknowledgement, SET Recipients SHOULD ensure that received 174 SETs have been validated and retained in a manner appropriate to the 175 recipient's requirements. The level and method of retention of SETs 176 by SET Recipients is out of scope of this specification. 178 2.2. Polling HTTP Request 180 When initiating a poll request, the SET Recipient constructs a JSON 181 document that consists of polling request parameters and SET 182 acknowledgement parameters in the form of JSON objects. The request 183 payloads are delivered in a JSON document, as described in 184 Section 2.4 and Section 2.5. 186 When making a request, the HTTP header "Content-Type" is set to 187 "application/json". 189 The following JSON object members are used in a polling request: 191 Request Processing Parameters 193 maxEvents 194 An OPTIONAL JSON integer value indicating the maximum number of 195 unacknowledged SETs that SHOULD be returned. If more than the 196 maximum number of SETs are available, the oldest SETs available 197 SHOULD be returned first. A value of "0" MAY be used by SET 198 Recipients that would like to perform an acknowledge only 199 request. This enables the Recipient to use separate HTTP 200 requests for acknowledgement and reception of SETs. If this 201 parameter is omitted, no limit is placed on the number of SETs 202 to be returned. 204 returnImmediately 205 An OPTIONAL JSON boolean value that indicates the SET 206 Transmitter SHOULD return an immediate response even if no 207 results are available (short polling). The default value is 208 "false", which indicates the request is to be treated as an 209 HTTP Long Poll, per Section 2 of [RFC6202]. The timeout for 210 the request is part of the configuration between the 211 participants, which is out of scope of this specification. 213 SET Acknowledgment Parameters 215 ack 216 An array of strings that each corresponds to the "jti" of a 217 successfully received SET. If there are no outstanding SETs to 218 acknowledge, the member MAY be omitted. When acknowledging a 219 SET, the SET Transmitter is released from any obligation to 220 retain the SET. 222 setErrs 223 A JSON Object that contains one or more nested JSON object 224 members that correspond to the "jti" of each invalid SET 225 received. The value of each is a JSON object whose contents is 226 an "err" member and "description" member, whose values 227 correspond to the errors described in Section 2.6. 229 2.3. Polling HTTP Response 231 In response to a poll request, the SET Transmitter checks for 232 available SETs and responds with a JSON document containing the 233 following JSON object members: 235 sets 236 A JSON object that contains zero or more nested JSON objects. 237 Each nested JSON object's key corresponds to the "jti" of a SET to 238 be delivered, and its value is a JSON string containing the value 239 of the encoded corresponding SET. If there are no outstanding 240 SETs to be transmitted, the JSON object SHALL be empty. 242 moreAvailable 243 A JSON boolean value that indicates if more unacknowledged SETs 244 are available to be returned. 246 When making a response, the HTTP header "Content-Type" is set to 247 "application/json". 249 2.4. Poll Request 251 The SET Recipient performs an HTTP POST (see Section 4.3.4 of 252 [RFC7231]) to a pre-arranged polling endpoint URI to check for SETs 253 that are available. Because the SET Recipient has no prior SETs to 254 acknowledge, the "ack" and "errs" request parameters are omitted. 256 If after a period of time, negotiated between the SET Transmitter and 257 Recipient, a SET Transmitter MAY redeliver SETs it has previously 258 delivered. The SET Recipient SHOULD accept repeat SETs and 259 acknowledge the SETs regardless of whether the Recipient believes it 260 has already acknowledged the SETs previously. A SET Transmitter MAY 261 limit the number of times it attempts to deliver a SET. 263 If the SET Recipient has received SETs from the SET Transmitter, the 264 SET Recipient SHOULD parse and validate received SETs to meet its own 265 requirements and SHOULD acknowledge receipt in a timely fashion 266 (e.g., seconds or minutes) so that the SET Transmitter can mark the 267 SETs as received. SET Recipients SHOULD acknowledge receipt before 268 taking any local actions based on the SETs to avoid unnecessary delay 269 in acknowledgement, where possible. 271 Poll requests have three variations: 273 Poll Only 274 In which a SET Recipient asks for the next set of events where no 275 previous SET deliveries are acknowledged (such as in the initial 276 poll request). 278 Acknowledge Only 279 In which a SET Recipient sets the "maxEvents" value to "0" along 280 with "ack" and "err" members indicating the SET Recipient is 281 acknowledging previously received SETs and does not want to 282 receive any new SETs in response to the request. 284 Combined Acknowledge and Poll 285 In which a SET Recipient is both acknowledging previously received 286 SETs using the "ack" and "err" members and will wait for the next 287 group of SETs in the SET Transmitters response. 289 2.4.1. Poll Only Request 291 In the case where no SETs were received in a previous poll (see 292 Figure 7), the SET Recipient simply polls without acknowledgement 293 parameters ("sets" and "setErrs"). 295 The following is an example request made by a SET Recipient that has 296 no outstanding SETs to acknowledge and is polling for available SETs 297 at the endpoint "https://nofity.exampleidp.com/Events": 299 POST /Events HTTP/1.1 300 Host: notify.exampleidp.com 301 Content-Type: application/json 303 { 304 "returnImmediately": true 305 } 307 Figure 1: Example Initial Poll Request 309 A SET Recipient can poll using default parameter values by passing an 310 empty JSON object. 312 The following is a non-normative example default poll request to the 313 endpoint "https://nofity.exampleidp.com/Events": 315 POST /Events HTTP/1.1 316 Host: notify.exampleidp.com 317 Content-Type: application/json 319 {} 321 Figure 2: Example Default Poll Request 323 2.4.2. Acknowledge Only Request 325 In this variation, the SET Recipient acknowledges previously received 326 SETs and indicates it does not want to receive SETs in response by 327 setting the "maxEvents" value to "0". 329 This variation might be used, for instance, when a SET Recipient 330 needs to acknowledge received SETs independently (e.g., on separate 331 threads) from the process of receiving SETs. 333 The following is a non-normative example poll request with 334 acknowledgement of SETs received (for example as shown in Figure 6): 336 POST /Events HTTP/1.1 337 Host: notify.exampleidp.com 338 Content-Type: application/json 340 { 341 "ack": [ 342 "4d3559ec67504aaba65d40b0363faad8", 343 "3d0c3cf797584bd193bd0fb1bd4e7d30" 344 ], 345 "maxEvents": 0, 346 "returnImmediately": true 347 } 349 Figure 3: Example Acknowledge Only Request 351 2.4.3. Poll with Acknowledgement 353 This variation allows a recipient thread to simultaneously 354 acknowledge previously received SETs and wait for the next group of 355 SETs in a single request. 357 The following is a non-normative example poll with acknowledgement of 358 the SETs received in Figure 6: 360 POST /Events HTTP/1.1 361 Host: notify.exampleidp.com 362 Content-Type: application/json 364 { 365 "ack": [ 366 "4d3559ec67504aaba65d40b0363faad8", 367 "3d0c3cf797584bd193bd0fb1bd4e7d30" 368 ], 369 "returnImmediately": false 370 } 372 Figure 4: Example Poll with Acknowledgement and No Errors 374 In the above acknowledgement, the SET Recipient has acknowledged 375 receipt of two SETs and has indicated it wants to wait until the next 376 SET is available. 378 2.4.4. Poll with Acknowledgement and Errors 380 In the case where errors were detected in previously delivered SETs, 381 the SET Recipient MAY use the "setErrs" member to communicate the 382 errors in the following poll request. 384 The following is a non-normative example of a response acknowledging 385 one successfully received SET and one SET with an error from the two 386 SETs received in Figure 6: 388 POST /Events HTTP/1.1 389 Host: notify.exampleidp.com 390 Content-Language: en-US 391 Content-Type: application/json 393 { 394 "ack": ["3d0c3cf797584bd193bd0fb1bd4e7d30"], 395 "setErrs": { 396 "4d3559ec67504aaba65d40b0363faad8": { 397 "err": "jwtAud", 398 "description": "The audience value was invalid." 399 } 400 }, 401 "returnImmediately": true 402 } 404 Figure 5: Example Poll Acknowledgement with Error 406 2.5. Poll Response 408 In response to a poll request, the service provider MAY respond 409 immediately if SETs are available to be delivered. If no SETs are 410 available at the time of the request, the SET Transmitter SHALL delay 411 responding until a SET is available or the timeout interval has 412 elapsed unless the poll request parameter "returnImmediately" is 413 "true". 415 As described in Section 2.3, a JSON document is returned containing a 416 number of members including "sets", which SHALL contain zero or more 417 SETs. 419 The following is a non-normative example response to the request 420 shown in Section 2.4. This example shows two SETs being returned: 422 HTTP/1.1 200 OK 423 Content-Type: application/json 425 { 426 "sets": { 427 "4d3559ec67504aaba65d40b0363faad8": 428 "eyJhbGciOiJub25lIn0. 429 eyJqdGkiOiI0ZDM1NTllYzY3NTA0YWFiYTY1ZDQwYjAzNjNmYWFkOCIsImlhdCI6MTQ 430 1ODQ5NjQwNCwiaXNzIjoiaHR0cHM6Ly9zY2ltLmV4YW1wbGUuY29tIiwiYXVkIjpbIm 431 h0dHBzOi8vc2NpbS5leGFtcGxlLmNvbS9GZWVkcy85OGQ1MjQ2MWZhNWJiYzg3OTU5M 432 2I3NzU0IiwiaHR0cHM6Ly9zY2ltLmV4YW1wbGUuY29tL0ZlZWRzLzVkNzYwNDUxNmIx 433 ZDA4NjQxZDc2NzZlZTciXSwiZXZlbnRzIjp7InVybjppZXRmOnBhcmFtczpzY2ltOmV 434 2ZW50OmNyZWF0ZSI6eyJyZWYiOiJodHRwczovL3NjaW0uZXhhbXBsZS5jb20vVXNlcn 435 MvNDRmNjE0MmRmOTZiZDZhYjYxZTc1MjFkOSIsImF0dHJpYnV0ZXMiOlsiaWQiLCJuY 436 W1lIiwidXNlck5hbWUiLCJwYXNzd29yZCIsImVtYWlscyJdfX19.", 437 "3d0c3cf797584bd193bd0fb1bd4e7d30": 438 "eyJhbGciOiJub25lIn0. 439 eyJqdGkiOiIzZDBjM2NmNzk3NTg0YmQxOTNiZDBmYjFiZDRlN2QzMCIsImlhdCI6MTQ 440 1ODQ5NjAyNSwiaXNzIjoiaHR0cHM6Ly9zY2ltLmV4YW1wbGUuY29tIiwiYXVkIjpbIm 441 h0dHBzOi8vamh1Yi5leGFtcGxlLmNvbS9GZWVkcy85OGQ1MjQ2MWZhNWJiYzg3OTU5M 442 2I3NzU0IiwiaHR0cHM6Ly9qaHViLmV4YW1wbGUuY29tL0ZlZWRzLzVkNzYwNDUxNmIx 443 ZDA4NjQxZDc2NzZlZTciXSwic3ViIjoiaHR0cHM6Ly9zY2ltLmV4YW1wbGUuY29tL1V 444 zZXJzLzQ0ZjYxNDJkZjk2YmQ2YWI2MWU3NTIxZDkiLCJldmVudHMiOnsidXJuOmlldG 445 Y6cGFyYW1zOnNjaW06ZXZlbnQ6cGFzc3dvcmRSZXNldCI6eyJpZCI6IjQ0ZjYxNDJkZ 446 jk2YmQ2YWI2MWU3NTIxZDkifSwiaHR0cHM6Ly9leGFtcGxlLmNvbS9zY2ltL2V2ZW50 447 L3Bhc3N3b3JkUmVzZXRFeHQiOnsicmVzZXRBdHRlbXB0cyI6NX19fQ." 448 } 449 } 451 Figure 6: Example Poll Response 453 In the above example, two SETs whose "jti" values are 454 "4d3559ec67504aaba65d40b0363faad8" and 455 "3d0c3cf797584bd193bd0fb1bd4e7d30" are delivered. 457 The following is a non-normative example response to the request 458 shown in Section 2.4, which indicates that no new SETs or 459 unacknowledged SETs are available: 461 HTTP/1.1 200 OK 462 Content-Type: application/json 464 { 465 "sets": {} 466 } 468 Figure 7: Example No SETs Poll Response 470 Upon receiving the JSON document (e.g., as shown in Figure 6), the 471 SET Recipient parses and verifies the received SETs and notifies the 472 SET Transmitter via the next poll request to the SET Transmitter, as 473 described in Section 2.4.3 or Section 2.4.4. 475 2.6. Error Response Handling 477 If a SET is invalid, error codes from the IANA "Security Event Token 478 Delivery Error Codes" registry established by 479 [I-D.ietf-secevent-http-push] are used in error responses. As 480 described in Section 2.3 of [I-D.ietf-secevent-http-push], an error 481 response is a JSON object providing details about the error that 482 includes the following name/value pairs: 484 err 485 A value from the IANA "Security Event Token Delivery Error Codes" 486 registry that identifies the error. 488 description 489 A human-readable string that provides additional diagnostic 490 information. 492 When included as part of a batch of SETs, the above JSON is included 493 as part of the "setErrs" member, as defined in Section 2.3 and 494 Section 2.4.4. 496 When the SET Recipient includes one or more error responses in a 497 request to the SET Transmitter, it must also include in the request a 498 "Content-Language" header whose value indicates the language of the 499 error descriptions included in the request. The method of language 500 selection in the case when the SET Recipient can provide error 501 messages in multiple languages is out of scope for this 502 specification. 504 3. Authentication and Authorization 506 The SET delivery method described in this specification is based upon 507 HTTP and depends on the use of TLS and/or standard HTTP 508 authentication and authorization schemes, as per [RFC7235]. 510 As per Section 4.1 of [RFC7235], a SET delivery endpoint SHALL 511 indicate supported HTTP authentication schemes via the "WWW- 512 Authenticate" header. 514 Authorization for the ability to pick-up or deliver SETs can be 515 determined by using the identity of the SET issuer, or via an 516 authentication method above. This specification considers 517 authentication as a feature to prevent denial-of-service attacks. 518 Because SETs are not commands, SET Recipients are free to ignore SETs 519 that are not of interest after acknowledging their receipt. 521 3.1. Use of Tokens as Authorizations 523 When using bearer tokens or proof-of-possession tokens that represent 524 an authorization grant such as issued by OAuth (see [RFC6749]), 525 implementers SHOULD consider the type of authorization granted, any 526 authorized scopes (see Section 3.3 of [RFC6749]), and the security 527 subject(s) that SHOULD be mapped from the authorization when 528 considering local access control rules. Section 6 of the OAuth 529 Assertion Framework specification [RFC7521] documents common 530 scenarios for authorization including: 532 o Clients using an assertion to authenticate and/or act on behalf of 533 itself; 535 o Clients acting on behalf of a user; and, 537 o A Client acting on behalf of an anonymous user. 539 When using OAuth access tokens, implementers MUST take into account 540 the threats and countermeasures documented in the security 541 considerations for the use of client authorizations (see Section 8 of 542 [RFC7521]). When using other token formats or frameworks, 543 implementers MUST take into account similar threats and 544 countermeasures, especially those documented by the relevant 545 specifications. 547 4. Security Considerations 548 4.1. Authentication Using Signed SETs 550 In scenarios where HTTP authorization or TLS mutual authentication 551 are not used or are considered weak, JWS signed SETs SHOULD be used 552 (see [RFC7515] and Section 5 of [RFC8417]). This enables the SET 553 Recipient to validate that the SET issuer is authorized to deliver 554 the SET. 556 4.2. HTTP Considerations 558 SET delivery depends on the use of Hypertext Transfer Protocol and is 559 thus subject to the security considerations of HTTP Section 9 of 560 [RFC7230] and its related specifications. 562 As stated in Section 2.7.1 of [RFC7230], an HTTP requestor MUST NOT 563 generate the "userinfo" (i.e., username and password) component (and 564 its "@" delimiter) when an "http" URI reference is generated with a 565 message, as they are now disallowed in HTTP. 567 4.3. Confidentiality of SETs 569 SETs may contain sensitive information that is considered Personally 570 Identifiable Information (PII). In such cases, SET Transmitters and 571 SET Recipients MUST protect the confidentiality of the SET contents 572 by encrypting the SET as described in JWE [RFC7516], using a 573 transport-layer security mechanism such as TLS, or both. If an Event 574 delivery endpoint supports TLS, it MUST support at least TLS version 575 1.2 [RFC5246] and SHOULD support the newest version of TLS that meets 576 its security requirements. When using TLS, the client MUST perform a 577 TLS/SSL server certificate check, per [RFC6125]. Implementation 578 security considerations for TLS can be found in "Recommendations for 579 Secure Use of TLS and DTLS" [RFC7525]. 581 4.4. Access Token Considerations 583 When using access tokens, such as those issued by OAuth 2.0 584 [RFC6749], implementers MUST take into account threats and 585 countermeasures documented in Section 8 of [RFC7521]. 587 4.4.1. Bearer Token Considerations 589 Due to the possibility of interception, Bearer tokens MUST be 590 exchanged using TLS. 592 Bearer tokens SHOULD have a limited lifetime that can be determined 593 directly or indirectly (e.g., by checking with a validation service) 594 by the service provider. By expiring tokens, clients are forced to 595 obtain a new token (which usually involves re-authentication) for 596 continued authorized access. For example, in OAuth 2.0, a client MAY 597 use an OAuth refresh token to obtain a new bearer token after 598 authenticating to an authorization server, per Section 6 of 599 [RFC6749]. 601 Implementations supporting OAuth bearer tokens need to factor in 602 security considerations of this authorization method [RFC7521]. 603 Since security is only as good as the weakest link, implementers also 604 need to consider authentication choices coupled with OAuth bearer 605 tokens. The security considerations of the default authentication 606 method for OAuth bearer tokens, HTTP Basic, are well documented in 607 [RFC7617], therefore implementers are encouraged to prefer stronger 608 authentication methods. Designating the specific methods of 609 authentication and authorization are out of scope for the delivery of 610 SETs, however this information is provided as a resource to 611 implementers. 613 5. Privacy Considerations 615 If a SET needs to be retained for audit purposes, a JWS signature MAY 616 be used to provide verification of its authenticity. 618 SET Transmitters SHOULD attempt to deliver SETs that are targeted to 619 the specific business and protocol needs of subscribers. 621 When sharing personally identifiable information or information that 622 is otherwise considered confidential to affected users, SET 623 Transmitters and Recipients MUST have the appropriate legal 624 agreements and user consent or terms of service in place. 626 The propagation of subject identifiers can be perceived as personally 627 identifiable information. Where possible, SET Transmitters and 628 Recipients SHOULD devise approaches that prevent propagation, for 629 example, the passing of a hash value that requires the subscriber to 630 already know the subject. 632 6. IANA Considerations 634 This specification requires no IANA actions. 636 7. References 638 7.1. Normative References 640 [I-D.ietf-secevent-http-push] 641 Backman, A., Jones, M., Scurtescu, M., Ansari, M., and A. 642 Nadalin, "Push-Based Security Event Token (SET) Delivery 643 Using HTTP", draft-ietf-secevent-http-push-06 (work in 644 progress), May 2019. 646 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 647 Requirement Levels", BCP 14, RFC 2119, 648 DOI 10.17487/RFC2119, March 1997, 649 . 651 [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform 652 Resource Identifier (URI): Generic Syntax", STD 66, 653 RFC 3986, DOI 10.17487/RFC3986, January 2005, 654 . 656 [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security 657 (TLS) Protocol Version 1.2", RFC 5246, 658 DOI 10.17487/RFC5246, August 2008, 659 . 661 [RFC6125] Saint-Andre, P. and J. Hodges, "Representation and 662 Verification of Domain-Based Application Service Identity 663 within Internet Public Key Infrastructure Using X.509 664 (PKIX) Certificates in the Context of Transport Layer 665 Security (TLS)", RFC 6125, DOI 10.17487/RFC6125, March 666 2011, . 668 [RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer 669 Protocol (HTTP/1.1): Semantics and Content", RFC 7231, 670 DOI 10.17487/RFC7231, June 2014, 671 . 673 [RFC7515] Jones, M., Bradley, J., and N. Sakimura, "JSON Web 674 Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May 675 2015, . 677 [RFC7516] Jones, M. and J. Hildebrand, "JSON Web Encryption (JWE)", 678 RFC 7516, DOI 10.17487/RFC7516, May 2015, 679 . 681 [RFC7519] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token 682 (JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015, 683 . 685 [RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre, 686 "Recommendations for Secure Use of Transport Layer 687 Security (TLS) and Datagram Transport Layer Security 688 (DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May 689 2015, . 691 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 692 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 693 May 2017, . 695 [RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data 696 Interchange Format", STD 90, RFC 8259, 697 DOI 10.17487/RFC8259, December 2017, 698 . 700 [RFC8417] Hunt, P., Ed., Jones, M., Denniss, W., and M. Ansari, 701 "Security Event Token (SET)", RFC 8417, 702 DOI 10.17487/RFC8417, July 2018, 703 . 705 7.2. Informative References 707 [RFC3339] Klyne, G. and C. Newman, "Date and Time on the Internet: 708 Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002, 709 . 711 [RFC6202] Loreto, S., Saint-Andre, P., Salsano, S., and G. Wilkins, 712 "Known Issues and Best Practices for the Use of Long 713 Polling and Streaming in Bidirectional HTTP", RFC 6202, 714 DOI 10.17487/RFC6202, April 2011, 715 . 717 [RFC6749] Hardt, D., Ed., "The OAuth 2.0 Authorization Framework", 718 RFC 6749, DOI 10.17487/RFC6749, October 2012, 719 . 721 [RFC6750] Jones, M. and D. Hardt, "The OAuth 2.0 Authorization 722 Framework: Bearer Token Usage", RFC 6750, 723 DOI 10.17487/RFC6750, October 2012, 724 . 726 [RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer 727 Protocol (HTTP/1.1): Message Syntax and Routing", 728 RFC 7230, DOI 10.17487/RFC7230, June 2014, 729 . 731 [RFC7235] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer 732 Protocol (HTTP/1.1): Authentication", RFC 7235, 733 DOI 10.17487/RFC7235, June 2014, 734 . 736 [RFC7521] Campbell, B., Mortimore, C., Jones, M., and Y. Goland, 737 "Assertion Framework for OAuth 2.0 Client Authentication 738 and Authorization Grants", RFC 7521, DOI 10.17487/RFC7521, 739 May 2015, . 741 [RFC7617] Reschke, J., "The 'Basic' HTTP Authentication Scheme", 742 RFC 7617, DOI 10.17487/RFC7617, September 2015, 743 . 745 Appendix A. Acknowledgments 747 The editors would like to thank the members of the SCIM working 748 group, which began discussions of provisioning events starting with 749 draft-hunt-scim-notify-00 in 2015. 751 The editors would like to thank Phil Hunt and the other the authors 752 of draft-ietf-secevent-delivery-02, on which this specification is 753 based. 755 The editors would like to thank the participants in the SecEvents 756 working group for their contributions to this specification. 758 Appendix B. Change Log 760 [[ to be removed by the RFC Editor before publication as an RFC ]] 762 Draft 00 - AB - Based on draft-ietf-secevent-delivery-02 with the 763 following additions: 765 o Renamed to "Poll-Based SET Token Delivery Using HTTP" 767 o Removed references to the HTTP Push delivery method. 769 Draft 01 - mbj: 771 o Addressed problems identified in my 18-Jul-18 review message 772 titled "Issues for both the Push and Poll Specs". 774 o Changes to align terminology with RFC 8417, for instance, by using 775 the already defined term SET Recipient rather than SET Receiver. 777 o Applied editorial and minor normative corrections. 779 o Updated Marius' contact information. 781 o Begun eliminating redundancies between this specification and 782 "Push-Based Security Event Token (SET) Delivery Using HTTP" 783 [I-D.ietf-secevent-http-push], referencing, rather that 784 duplicating common normative text. 786 Draft 02 - mbj: 788 o Removed vestigial language remaining from when the push and poll 789 delivery methods were defined in a common specification. 791 o Replaced remaining uses of the terms Event Transmitter and Event 792 Recipient with the correct terms SET Transmitter and SET 793 Recipient. 795 o Removed uses of the unnecessary term "Event Stream". 797 o Removed dependencies between the semantics of "maxEvents" and 798 "returnImmediately". 800 o Said that PII in SETs is to be encrypted with TLS, JWE, or both. 802 o Corrected grammar and spelling errors. 804 Draft 03 - mbj: 806 o Corrected uses of "attribute" to "member" when describing JSON 807 objects. 809 o Further alignment with the push draft. 811 Draft 04 - AB + mbj 813 o Referenced SET Transmitter definition in http-push. 815 o Removed incorrect normative text regarding SET construction. 817 o Consolidated general out-of-scope items under Introduction. 819 o Removed unnecessary HTTP headers in examples and added Content- 820 Type. 822 o Added Content-Language requirement for error descriptions, 823 aligning with http-push. 825 o Stated that bearer tokens SHOULD have a limited lifetime. 827 o Minor editorial fixes. 829 Authors' Addresses 831 Annabelle Backman (editor) 832 Amazon 834 Email: richanna@amazon.com 836 Michael B. Jones (editor) 837 Microsoft 839 Email: mbj@microsoft.com 840 URI: http://self-issued.info/ 842 Marius Scurtescu 843 Coinbase 845 Email: marius.scurtescu@coinbase.com 847 Morteza Ansari 848 Cisco 850 Email: morteza.ansari@cisco.com 852 Anthony Nadalin 853 Microsoft 855 Email: tonynad@microsoft.com