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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group P. Hunt, Ed. 3 Internet-Draft Oracle 4 Intended status: Standards Track A. Nadalin 5 Expires: September 23, 2018 Microsoft 6 March 22, 2018 8 Symmetric SET Transfer Protocol 9 draft-hunt-secevent-sstp-00 11 Abstract 13 This specification defines how security event tokens (SETs) may be 14 exchanged between a client and service provider using HTTP POST over 15 TLS using a symmetric format. The specification supports three modes 16 of operation: "push", "pull", and "push-pull" bi-directional SET 17 exchange. The specification also defines a simple acknowledge 18 mechanism allowing parties to confirm delivery. 20 Status of This Memo 22 This Internet-Draft is submitted in full conformance with the 23 provisions of BCP 78 and BCP 79. 25 Internet-Drafts are working documents of the Internet Engineering 26 Task Force (IETF). Note that other groups may also distribute 27 working documents as Internet-Drafts. The list of current Internet- 28 Drafts is at https://datatracker.ietf.org/drafts/current/. 30 Internet-Drafts are draft documents valid for a maximum of six months 31 and may be updated, replaced, or obsoleted by other documents at any 32 time. It is inappropriate to use Internet-Drafts as reference 33 material or to cite them other than as "work in progress." 35 This Internet-Draft will expire on September 23, 2018. 37 Copyright Notice 39 Copyright (c) 2018 IETF Trust and the persons identified as the 40 document authors. All rights reserved. 42 This document is subject to BCP 78 and the IETF Trust's Legal 43 Provisions Relating to IETF Documents 44 (https://trustee.ietf.org/license-info) in effect on the date of 45 publication of this document. Please review these documents 46 carefully, as they describe your rights and restrictions with respect 47 to this document. Code Components extracted from this document must 48 include Simplified BSD License text as described in Section 4.e of 49 the Trust Legal Provisions and are provided without warranty as 50 described in the Simplified BSD License. 52 Table of Contents 54 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 55 1.1. Notational Conventions . . . . . . . . . . . . . . . . . 4 56 1.2. Definitions . . . . . . . . . . . . . . . . . . . . . . . 4 57 2. Simple SET Transfer Protocol . . . . . . . . . . . . . . . . 5 58 2.1. SSTP Message Format (Content-Type: application/sstp+json) 5 59 2.2. Examples . . . . . . . . . . . . . . . . . . . . . . . . 7 60 2.2.1. Example Push Transfer . . . . . . . . . . . . . . . . 8 61 2.2.2. Example Pull Transfer . . . . . . . . . . . . . . . . 9 62 2.2.3. Example Push-Pull Bi-directional Transfer . . . . . . 13 63 2.3. Error Response Handling . . . . . . . . . . . . . . . . . 15 64 3. Authentication and Authorization . . . . . . . . . . . . . . 16 65 3.1. Use of Tokens as Authorizations . . . . . . . . . . . . . 17 66 4. Security Considerations . . . . . . . . . . . . . . . . . . . 18 67 4.1. Authentication Using Signed SETs . . . . . . . . . . . . 18 68 4.2. HTTP Considerations . . . . . . . . . . . . . . . . . . . 18 69 4.3. TLS Support Considerations . . . . . . . . . . . . . . . 18 70 4.4. Authorization Token Considerations . . . . . . . . . . . 19 71 4.4.1. Bearer Token Considerations . . . . . . . . . . . . . 19 72 5. Privacy Considerations . . . . . . . . . . . . . . . . . . . 19 73 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20 74 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 20 75 7.1. Normative References . . . . . . . . . . . . . . . . . . 20 76 7.2. Informative References . . . . . . . . . . . . . . . . . 21 77 Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . 22 78 Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 23 79 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23 81 1. Introduction 83 [EDITORS NOTE: This specification is based upon draft-ietf-secevent- 84 delivery and attempts to provide a unified single MTI protocol 85 solution satisfying all use cases for SECEVENTS.] 87 This specification defines how SETs (see [I-D.ietf-secevent-token]) 88 can be exchanged using HTTP [RFC7231] over TLS using a symmetric 89 request/response format. The specification supports three modes of 90 operation: "push", "pull", and "push-pull" bi-directional SET 91 exchange. The specification also defines a simple acknowledge 92 mechanism allowing parties to confirm delivery or attempt re- 93 delivery. 95 This specification makes several simplifying assumptions: 97 o SSTP is a symmetric protocol meaning it uses the same HTTP 98 content-type and JSON structure to send requests and process 99 responses 101 o Recovery is provided for unacknowledged SETs for short term or 102 missed deliveries. Issuers are able to re-transmit SETs in 103 situations where a SET has been unacknowledged (e.g. over more 104 than one request/response cycles). 106 o The protocol can be used for unidirectional, or bi-directional 107 communication avoiding the need to implement multiple delivery 108 methods. 110 o The use of HTTP Long Polling MAY be used in cases where pull or 111 bi-directional communication is needed in real time. 113 o Only one party in an exchange needs to have an addressable fixed 114 URI endpoint and can act as an SSTP protocol service provider to a 115 mobile or otherwise unrechable client. 117 o SET message exchanges are secured through the use of TLS and some 118 form of HTTP authorization (e.g. RFC6750, RFC7519), and MAY in 119 turn be signed and encrypted. 121 This specification supports the following use-cases: 123 Broadcaster 124 Where a large entity (e.g. an Identity Provider) needs to issue 125 SETs to a large number of relying parties. 127 Protected Client 128 Where a client party is behind a firewall or otherwise network 129 restricted location and cannot act as a SSTP service provider. 130 Examples include Enterprise on-premise security systems, IoT 131 devices which may be shielded in restricted network environments. 133 Mobile 134 Where a client is mobile and thus would be unable to maintain a 135 permanent HTTP endpoint. 137 This specification does not define how endpoints are configured, nor 138 does it define the specifics of which SET event types are exchanged 139 over any particular delivery relationship. 141 1.1. Notational Conventions 143 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 144 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 145 "OPTIONAL" in this document are to be interpreted as described in BCP 146 14 [RFC2119] [RFC8174] when, and only when, they appear in all 147 capitals, as shown here. 149 For purposes of readability examples are not URL encoded. 150 Implementers MUST percent encode URLs as described in Section 2.1 of 151 [RFC3986] . 153 Throughout this documents all figures MAY contain spaces and extra 154 line-wrapping for readability and space limitations. Similarly, some 155 URI's contained within examples, have been shortened for space and 156 readability reasons. All examples are non-normative. 158 1.2. Definitions 160 This specification assumes terminology defined in the Security Event 161 Token specification[I-D.ietf-secevent-token] . 163 This specification defines the following terms: 165 Client An entity which acts as an HTTP client as defined by 166 [RFC7231] which is communicating with an SSTP server. 168 Server An entity which has a permanent endpoint reachable by a 169 client which acts as an HTTP server as defined by [RFC7231] and 170 supports this specification. 172 Event 173 An Event is defined to be an event as represented by a security 174 event token (SET). See [I-D.ietf-secevent-token]. 176 NumericDate 177 A JSON numeric value representing the number of seconds from 178 1970-01-01T00:00:00Z UTC until the specified UTC date/time, 179 ignoring leap seconds. This is equivalent to the IEEE Std 1003.1, 180 2013 Edition [POSIX.1] definition "Seconds Since the Epoch", in 181 which each day is accounted for by exactly 86400 seconds, other 182 than that non-integer values can be represented. See [RFC3339] 183 for details regarding date/times in general and UTC in particular. 185 2. Simple SET Transfer Protocol 187 SSTP is a symmetric protocol. As such an SSTP client uses HTTP POST 188 (Section 4.3.3 [RFC7231]) with a body with "Content-Type" of 189 "application/sstp+json" to deliver 0 or more SETs and/or to 190 acknowledge previously received SETs from an SSTP server. In 191 response, the SSTP server returns an HTTP body with the same 192 document-type which may also return 0 or more SETs, acknowledgments, 193 and errors. 195 Requests MAY be spontaneous (in the case of push mode), scheduled 196 over a a periodic interval (in the case of pull), or requests to pull 197 MAY await new SETS using HTTP long polling (see Section 2 [RFC6202]). 198 An SSTP server choosing NOT to support HTTP long polling MAY do so by 199 returning HTTP Status of 403 "Forbidden" (see Section 6.5.3 200 [RFC7231]) if a particular client is not authorized, or HTTP status 201 501 "Not implemented" (see Section 6.6.2 [RFC7231]) if the server 202 does not support long polling. 204 SSTP provides an acknowledgement capability for the purpose of 205 informing communications partners about which SETs have been 206 successfully delivered. Upon receipt of a SET and before 207 acknowledgement, receivers SHOULD ensure received SETs are valid and 208 have been retained in a manner appropriate to the receiver's 209 retention needs. The level and method of retention of SETs by 210 receivers is out-of-scope of this specification. 212 If after a period of time, negotiated between the client and server, 213 unacknowledged SETs MAY be re-transmitted. The receiver SHOULD 214 accept repeat SETs and acknowledge the SETs regardless of whether the 215 receiver believes it has already acknowledged the SETs previously. A 216 SET issuer MAY limit the number of attempts to deliver a SET. 218 A receiving party (client or server) of SETs SHOULD parse and 219 validate each SET to meet its own requirements and SHOULD acknowledge 220 receipt in a timely (e.g. minutes) fashion so that the issuer may 221 mark the SETs as received. Receivers SHOULD acknowledge receipt 222 before taking any local actions based on the SETs to avoid 223 unnecessary delay in acknowledgement to avoid unnecessary re- 224 transmission. 226 2.1. SSTP Message Format (Content-Type: application/sstp+json) 228 The body (or message) of an SSTP request or response is a "Content- 229 Type" of "application/sstp+json" which is a JSON document consisting 230 of the following optional JSON attributes: 232 Request Handling: 234 returnEvents 235 A JSON boolean parameter which indicates whether the receiver 236 SHOULD return SETs in its upcoming response. When part of an HTTP 237 Request, it indicates the SSTP server SHOULD return with SETs in 238 its response (and optionally wait). When asserted as "false" by 239 an SSTP server in its response, it indicates that the SSTP server 240 is not requesting SETs in the next client request. If omitted, 241 this attribute SHALL have a default value of "true". 243 returnImmediately 244 An OPTIONAL JSON boolean value which when "true" has the effect of 245 declining HTTP long polling. A value of "false" indicates the 246 request is to be treated as an HTTP Long Poll (see Section 2 247 [RFC6202]). When asserted in an HTTP response, the value 248 indicates the SSTP has more information and the client SHOULD NOT 249 wait before initiating its next request. When omitted, the 250 default value of "false" SHALL be assumed. 252 Delivery: 254 sets 255 A JSON object that contains one or more nested JSON attributes. 256 Each nested attribute corresponds to the "jti" of a SET to be 257 delivered and whose value is a JSON String containing the value of 258 the encoded corresponding SET. If there are no SETs to be 259 transmitted, the attribute MAY be omitted. 261 Acknowledgment: 263 ack 264 An array of Strings that each correspond to the "jti" of a 265 successfully received SET by the client. If there are no 266 outstanding SETs to acknowledge, the attribute MAY be omitted. 267 When acknowledging a SET, the issuer is released from any 268 obligation to retain the SET (e.g. for a future re-try). 270 setErrs 271 A JSON Object that contains one or more nested JSON attributes 272 that correspond to the "jti" of each invalid SET received. The 273 value of each is a JSON object whose contents is an "err" 274 attribute and "description" attribute whose value correspond to 275 the errors described in Section 2.3. If there are no errors to 276 acknowledge, the attribute MAY be omitted. 278 The following is an example SSTP message that could be exchanged 279 either in a HTPP POST request or response between a client and an 280 SSTP server. 282 { 283 "returnImmediately":true, 284 "returnEvents":true, 285 "sets":{ 286 "4d3559ec67504aaba65d40b0363faad8": 287 "eyJhbGciOiJub25lIn0. 288 eyJqdGkiOiI0ZDM1NTllYzY3NTA0YWFiYTY1ZDQwYjAzNjNmYWFkOCIsImlhdCI6MTQ 289 1ODQ5NjQwNCwiaXNzIjoiaHR0cHM6Ly9zY2ltLmV4YW1wbGUuY29tIiwiYXVkIjpbIm 290 h0dHBzOi8vc2NpbS5leGFtcGxlLmNvbS9GZWVkcy85OGQ1MjQ2MWZhNWJiYzg3OTU5M 291 2I3NzU0IiwiaHR0cHM6Ly9zY2ltLmV4YW1wbGUuY29tL0ZlZWRzLzVkNzYwNDUxNmIx 292 ZDA4NjQxZDc2NzZlZTciXSwiZXZlbnRzIjp7InVybjppZXRmOnBhcmFtczpzY2ltOmV 293 2ZW50OmNyZWF0ZSI6eyJyZWYiOiJodHRwczovL3NjaW0uZXhhbXBsZS5jb20vVXNlcn 294 MvNDRmNjE0MmRmOTZiZDZhYjYxZTc1MjFkOSIsImF0dHJpYnV0ZXMiOlsiaWQiLCJuY 295 W1lIiwidXNlck5hbWUiLCJwYXNzd29yZCIsImVtYWlscyJdfX19.", 296 "3d0c3cf797584bd193bd0fb1bd4e7d30": 297 "eyJhbGciOiJub25lIn0. 298 eyJqdGkiOiIzZDBjM2NmNzk3NTg0YmQxOTNiZDBmYjFiZDRlN2QzMCIsImlhdCI6MTQ 299 1ODQ5NjAyNSwiaXNzIjoiaHR0cHM6Ly9zY2ltLmV4YW1wbGUuY29tIiwiYXVkIjpbIm 300 h0dHBzOi8vamh1Yi5leGFtcGxlLmNvbS9GZWVkcy85OGQ1MjQ2MWZhNWJiYzg3OTU5M 301 2I3NzU0IiwiaHR0cHM6Ly9qaHViLmV4YW1wbGUuY29tL0ZlZWRzLzVkNzYwNDUxNmIx 302 ZDA4NjQxZDc2NzZlZTciXSwic3ViIjoiaHR0cHM6Ly9zY2ltLmV4YW1wbGUuY29tL1V 303 zZXJzLzQ0ZjYxNDJkZjk2YmQ2YWI2MWU3NTIxZDkiLCJldmVudHMiOnsidXJuOmlldG 304 Y6cGFyYW1zOnNjaW06ZXZlbnQ6cGFzc3dvcmRSZXNldCI6eyJpZCI6IjQ0ZjYxNDJkZ 305 jk2YmQ2YWI2MWU3NTIxZDkifSwiaHR0cHM6Ly9leGFtcGxlLmNvbS9zY2ltL2V2ZW50 306 L3Bhc3N3b3JkUmVzZXRFeHQiOnsicmVzZXRBdHRlbXB0cyI6NX19fQ." 307 } 308 } 310 Figure 1: Example Request or Response Document 312 2.2. Examples 314 Three examples are provided where: 316 o A client pushes SETs to a server using the "sets" JSON attribute 317 in its request and receives "ack" values in response from the SSTP 318 server. 320 o A polling client that requests SETs from a a server and uses the 321 "ack" parameter in its request to acknowledge SETs from a previous 322 HTTP request, and receives new SETs in the response. 324 o A client and SSTP server bi-directionally exchange SETs using both 325 the "sets" and "ack" JSON attributes in both the request and 326 response messages. 328 2.2.1. Example Push Transfer 330 In this example, a client posts SETs to an SSTP server which in turn 331 acknowledges the transferred SETs in its response. 333 In the figure, two SETs are transferred to the SSTP server. The 334 parameter "returnEvents" indicates the client is not interested in 335 receiving SETs. 337 POST /Events HTTP/1.1 339 Host: notify.exampleidp.com 340 Authorization: Bearer h480djs93hd8 341 Content-Type: application/sstp+json 342 Accept: application/sstp+json 343 { 344 "returnImmediately":true, 345 "returnEvents":false, 346 "sets":{ 347 "4d3559ec67504aaba65d40b0363faad8": 348 "eyJhbGciOiJub25lIn0. 349 eyJqdGkiOiI0ZDM1NTllYzY3NTA0YWFiYTY1ZDQwYjAzNjNmYWFkOCIsImlhdCI6MTQ 350 1ODQ5NjQwNCwiaXNzIjoiaHR0cHM6Ly9zY2ltLmV4YW1wbGUuY29tIiwiYXVkIjpbIm 351 h0dHBzOi8vc2NpbS5leGFtcGxlLmNvbS9GZWVkcy85OGQ1MjQ2MWZhNWJiYzg3OTU5M 352 2I3NzU0IiwiaHR0cHM6Ly9zY2ltLmV4YW1wbGUuY29tL0ZlZWRzLzVkNzYwNDUxNmIx 353 ZDA4NjQxZDc2NzZlZTciXSwiZXZlbnRzIjp7InVybjppZXRmOnBhcmFtczpzY2ltOmV 354 2ZW50OmNyZWF0ZSI6eyJyZWYiOiJodHRwczovL3NjaW0uZXhhbXBsZS5jb20vVXNlcn 355 MvNDRmNjE0MmRmOTZiZDZhYjYxZTc1MjFkOSIsImF0dHJpYnV0ZXMiOlsiaWQiLCJuY 356 W1lIiwidXNlck5hbWUiLCJwYXNzd29yZCIsImVtYWlscyJdfX19.", 357 "3d0c3cf797584bd193bd0fb1bd4e7d30": 358 "eyJhbGciOiJub25lIn0. 359 eyJqdGkiOiIzZDBjM2NmNzk3NTg0YmQxOTNiZDBmYjFiZDRlN2QzMCIsImlhdCI6MTQ 360 1ODQ5NjAyNSwiaXNzIjoiaHR0cHM6Ly9zY2ltLmV4YW1wbGUuY29tIiwiYXVkIjpbIm 361 h0dHBzOi8vamh1Yi5leGFtcGxlLmNvbS9GZWVkcy85OGQ1MjQ2MWZhNWJiYzg3OTU5M 362 2I3NzU0IiwiaHR0cHM6Ly9qaHViLmV4YW1wbGUuY29tL0ZlZWRzLzVkNzYwNDUxNmIx 363 ZDA4NjQxZDc2NzZlZTciXSwic3ViIjoiaHR0cHM6Ly9zY2ltLmV4YW1wbGUuY29tL1V 364 zZXJzLzQ0ZjYxNDJkZjk2YmQ2YWI2MWU3NTIxZDkiLCJldmVudHMiOnsidXJuOmlldG 365 Y6cGFyYW1zOnNjaW06ZXZlbnQ6cGFzc3dvcmRSZXNldCI6eyJpZCI6IjQ0ZjYxNDJkZ 366 jk2YmQ2YWI2MWU3NTIxZDkifSwiaHR0cHM6Ly9leGFtcGxlLmNvbS9zY2ltL2V2ZW50 367 L3Bhc3N3b3JkUmVzZXRFeHQiOnsicmVzZXRBdHRlbXB0cyI6NX19fQ." 368 } 369 } 371 Figure 2: Example Push Request 373 The figure below shows the response returned from the SSTP server in 374 response to the request in Figure 2 376 HTTP/1.1 200 OK 377 Content-Type: application/sstp+json 378 Location: https://notify.exampleidp.com/Events 380 { 381 "ack":[ 382 "4d3559ec67504aaba65d40b0363faad8", 383 "3d0c3cf797584bd193bd0fb1bd4e7d30" 384 ] 385 } 387 Figure 3: Example Push Response 389 2.2.2. Example Pull Transfer 391 The figure below is an example pull request to the SSTP server whose 392 location is: "https://nofity.exampleidp.com/Events". In this 393 example, the client is requesting an immediate response whether or 394 not new SETs are available. 396 POST /Events HTTP/1.1 398 Host: notify.exampleidp.com 399 Authorization: Bearer h480djs93hd8 400 Content-Type: application/sstp+json 401 Accept: application/sstp+json 403 { 404 "returnImmediately":true 405 } 407 Figure 4: Example Initial Pull Request 409 The following is an example default pull request to the SSTP server 410 whose location is: "https://nofity.exampleidp.com/Events". The 411 default mode to return events and to wait if necessary is assumed. 413 POST /Events HTTP/1.1 414 Host: notify.exampleidp.com 415 Authorization: Bearer h480djs93hd8 416 Accept: application/sstp+json 418 {} 420 Figure 5: Example Default Pull Request 422 In response to the above two requests, the SSTP server responds 423 immediately if "respondImmediately" is true or SETs are available. 424 If no SETs are available at the time of the request and 425 "respondImmediately" is false, the SSTP server delays response until 426 a SET is available. 428 As described in Section 2.1 a JSON document is returned containing 429 the JSON attribute "sets". 431 The following is an example response to the requests shown Figure 4 432 and Figure 5. This example shows two SETs are returned. 434 HTTP/1.1 200 OK 435 Content-Type: application/sstp+json 436 Location: https://notify.exampleidp/Events 438 { 439 "sets":{ 440 "4d3559ec67504aaba65d40b0363faad8": 441 "eyJhbGciOiJub25lIn0. 442 eyJqdGkiOiI0ZDM1NTllYzY3NTA0YWFiYTY1ZDQwYjAzNjNmYWFkOCIsImlhdCI6MTQ 443 1ODQ5NjQwNCwiaXNzIjoiaHR0cHM6Ly9zY2ltLmV4YW1wbGUuY29tIiwiYXVkIjpbIm 444 h0dHBzOi8vc2NpbS5leGFtcGxlLmNvbS9GZWVkcy85OGQ1MjQ2MWZhNWJiYzg3OTU5M 445 2I3NzU0IiwiaHR0cHM6Ly9zY2ltLmV4YW1wbGUuY29tL0ZlZWRzLzVkNzYwNDUxNmIx 446 ZDA4NjQxZDc2NzZlZTciXSwiZXZlbnRzIjp7InVybjppZXRmOnBhcmFtczpzY2ltOmV 447 2ZW50OmNyZWF0ZSI6eyJyZWYiOiJodHRwczovL3NjaW0uZXhhbXBsZS5jb20vVXNlcn 448 MvNDRmNjE0MmRmOTZiZDZhYjYxZTc1MjFkOSIsImF0dHJpYnV0ZXMiOlsiaWQiLCJuY 449 W1lIiwidXNlck5hbWUiLCJwYXNzd29yZCIsImVtYWlscyJdfX19.", 450 "3d0c3cf797584bd193bd0fb1bd4e7d30": 451 "eyJhbGciOiJub25lIn0. 452 eyJqdGkiOiIzZDBjM2NmNzk3NTg0YmQxOTNiZDBmYjFiZDRlN2QzMCIsImlhdCI6MTQ 453 1ODQ5NjAyNSwiaXNzIjoiaHR0cHM6Ly9zY2ltLmV4YW1wbGUuY29tIiwiYXVkIjpbIm 454 h0dHBzOi8vamh1Yi5leGFtcGxlLmNvbS9GZWVkcy85OGQ1MjQ2MWZhNWJiYzg3OTU5M 455 2I3NzU0IiwiaHR0cHM6Ly9qaHViLmV4YW1wbGUuY29tL0ZlZWRzLzVkNzYwNDUxNmIx 456 ZDA4NjQxZDc2NzZlZTciXSwic3ViIjoiaHR0cHM6Ly9zY2ltLmV4YW1wbGUuY29tL1V 457 zZXJzLzQ0ZjYxNDJkZjk2YmQ2YWI2MWU3NTIxZDkiLCJldmVudHMiOnsidXJuOmlldG 458 Y6cGFyYW1zOnNjaW06ZXZlbnQ6cGFzc3dvcmRSZXNldCI6eyJpZCI6IjQ0ZjYxNDJkZ 459 jk2YmQ2YWI2MWU3NTIxZDkifSwiaHR0cHM6Ly9leGFtcGxlLmNvbS9zY2ltL2V2ZW50 460 L3Bhc3N3b3JkUmVzZXRFeHQiOnsicmVzZXRBdHRlbXB0cyI6NX19fQ." 461 } 462 } 464 Figure 6: Example Pull Response 466 In the above example, two SETs whose "jti" are 467 "4d3559ec67504aaba65d40b0363faad8" and 468 "3d0c3cf797584bd193bd0fb1bd4e7d30" are delivered. 470 The following is an example response to the request shown Figure 4 471 where "returnImmediately" was set showing no new SETs are available. 473 HTTP/1.1 200 OK 474 Content-Type: application/sstp+json 475 Location: https://notify.exampleidp/Events 477 { 478 "sets":{ } 479 } 481 Figure 7: Example No SETs Pull Response 483 2.2.2.1. Acknowledge Only Request 485 This variation is typically used when a client needs to acknowledge 486 received SETs on a separate thread from one receiving SETs. 488 An SSTP client acknowledges previously received SETs but indicates it 489 does not want to receive SETs in the current request/response by 490 setting the "returnEvents" attribute to "false". 492 The following example is an acknowledgement of SETs previously 493 received (e.g. from the response shown in Figure 6). 495 POST /Events HTTP/1.1 496 Host: notify.exampleidp.com 497 Authorization: Bearer h480djs93hd8 498 Content-Type: application/sstp+json 499 Authorization: Bearer h480djs93hd8 501 { 502 "ack":[ 503 "4d3559ec67504aaba65d40b0363faad8", 504 "3d0c3cf797584bd193bd0fb1bd4e7d30" 505 ], 506 "returnEvents":false 507 } 509 Figure 8: Example Acknowledge Only Request 511 2.2.2.2. Poll with Acknowledgement 513 This variation allows a client to simultaneously acknowledge 514 previously received SETs and wait for the next group of SETs in a 515 single HTTP request. 517 The following SSTP request contains an acknowledgement of SETs 518 received from Figure 6. 520 POST /Events HTTP/1.1 522 Host: notify.exampleidp.com 523 Authorization: Bearer h480djs93hd8 524 Content-Type: application/sstp+json 525 Accept: application/sstp+json 526 Authorization: Bearer h480djs93hd8 528 { 529 "ack":[ 530 "4d3559ec67504aaba65d40b0363faad8", 531 "3d0c3cf797584bd193bd0fb1bd4e7d30" 532 ], 533 "returnImmediately":false 534 } 536 Figure 9: Example Pull With Acknowledgement and No Errors 538 2.2.2.3. Pull with Acknowledgement and Errors 540 In the case where errors are detected in previously received SETs, 541 the client (or server) uses the "setErrs" attribute to indicate 542 errors in its request. 544 The following is an example of an SSTP response acknowledges 1 error 545 and 1 receipt of two SETs received in Figure 6. 547 POST /Events HTTP/1.1 549 Host: notify.exampleidp.com 550 Authorization: Bearer h480djs93hd8 551 Content-Type: application/sstp+json 552 Accept: application/sstp+json 553 Authorization: Bearer h480djs93hd8 555 { 556 "ack":["3d0c3cf797584bd193bd0fb1bd4e7d30"], 557 "setErrs":{ 558 "4d3559ec67504aaba65d40b0363faad8":{ 559 "err":"jwtAud", 560 "description":"The audience value was incorrect." 561 } 562 } 563 } 565 Figure 10: Example Pull Acknowledgement With Error 567 2.2.3. Example Push-Pull Bi-directional Transfer 569 In push-pull mode, JSON attributes "sets", "ack" and "setErrs" are 570 used in both HTTP request and response messages between client and 571 SSTP server. 573 In the following example, two SETs are transferred to the SSTP server 574 and events are requested in return. 576 POST /Events HTTP/1.1 577 Host: notify.exampleidp.com 578 Authorization: Bearer h480djs93hd8 579 Content-Type: application/sstp+json 580 Accept: application/sstp+json 581 { 582 "returnEvents":true, 583 "ack":["b453bf9972b84e0492d5c7f55f68fb6a"], 584 "sets":{ 585 "4d3559ec67504aaba65d40b0363faad8": 586 "eyJhbGciOiJub25lIn0. 587 eyJqdGkiOiI0ZDM1NTllYzY3NTA0YWFiYTY1ZDQwYjAzNjNmYWFkOCIsImlhdCI6MTQ 588 1ODQ5NjQwNCwiaXNzIjoiaHR0cHM6Ly9zY2ltLmV4YW1wbGUuY29tIiwiYXVkIjpbIm 589 h0dHBzOi8vc2NpbS5leGFtcGxlLmNvbS9GZWVkcy85OGQ1MjQ2MWZhNWJiYzg3OTU5M 590 2I3NzU0IiwiaHR0cHM6Ly9zY2ltLmV4YW1wbGUuY29tL0ZlZWRzLzVkNzYwNDUxNmIx 591 ZDA4NjQxZDc2NzZlZTciXSwiZXZlbnRzIjp7InVybjppZXRmOnBhcmFtczpzY2ltOmV 592 2ZW50OmNyZWF0ZSI6eyJyZWYiOiJodHRwczovL3NjaW0uZXhhbXBsZS5jb20vVXNlcn 593 MvNDRmNjE0MmRmOTZiZDZhYjYxZTc1MjFkOSIsImF0dHJpYnV0ZXMiOlsiaWQiLCJuY 594 W1lIiwidXNlck5hbWUiLCJwYXNzd29yZCIsImVtYWlscyJdfX19.", 595 "3d0c3cf797584bd193bd0fb1bd4e7d30": 596 "eyJhbGciOiJub25lIn0. 597 eyJqdGkiOiIzZDBjM2NmNzk3NTg0YmQxOTNiZDBmYjFiZDRlN2QzMCIsImlhdCI6MTQ 598 1ODQ5NjAyNSwiaXNzIjoiaHR0cHM6Ly9zY2ltLmV4YW1wbGUuY29tIiwiYXVkIjpbIm 599 h0dHBzOi8vamh1Yi5leGFtcGxlLmNvbS9GZWVkcy85OGQ1MjQ2MWZhNWJiYzg3OTU5M 600 2I3NzU0IiwiaHR0cHM6Ly9qaHViLmV4YW1wbGUuY29tL0ZlZWRzLzVkNzYwNDUxNmIx 601 ZDA4NjQxZDc2NzZlZTciXSwic3ViIjoiaHR0cHM6Ly9zY2ltLmV4YW1wbGUuY29tL1V 602 zZXJzLzQ0ZjYxNDJkZjk2YmQ2YWI2MWU3NTIxZDkiLCJldmVudHMiOnsidXJuOmlldG 603 Y6cGFyYW1zOnNjaW06ZXZlbnQ6cGFzc3dvcmRSZXNldCI6eyJpZCI6IjQ0ZjYxNDJkZ 604 jk2YmQ2YWI2MWU3NTIxZDkifSwiaHR0cHM6Ly9leGFtcGxlLmNvbS9zY2ltL2V2ZW50 605 L3Bhc3N3b3JkUmVzZXRFeHQiOnsicmVzZXRBdHRlbXB0cyI6NX19fQ." 606 } 607 } 609 Figure 11: Example Push-Pull Request 611 The following is an example response to the request shown Figure 11. 613 HTTP/1.1 200 OK 614 Content-Type: application/sstp+json 615 Location: https://notify.exampleidp/Events 617 { 618 "ack":[ 619 "4d3559ec67504aaba65d40b0363faad8", 620 "3d0c3cf797584bd193bd0fb1bd4e7d30" 621 ], 622 "sets":{ 623 "6f332aefc730400a9f645d36a12ba4ab": 624 "eyJhbGciOiJub25lIn0. 625 eyJqdGkiOiI0ZDM1NTllYzY3NTA0YWFiYTY1ZDQwYjAzNjNmYWFkOCIsImlhdCI6MTQ 626 1ODQ5NjQwNCwiaXNzIjoiaHR0cHM6Ly9zY2ltLmV4YW1wbGUuY29tIiwiYXVkIjpbIm 627 h0dHBzOi8vc2NpbS5leGFtcGxlLmNvbS9GZWVkcy85OGQ1MjQ2MWZhNWJiYzg3OTU5M 628 2I3NzU0IiwiaHR0cHM6Ly9zY2ltLmV4YW1wbGUuY29tL0ZlZWRzLzVkNzYwNDUxNmIx 629 ZDA4NjQxZDc2NzZlZTciXSwiZXZlbnRzIjp7InVybjppZXRmOnBhcmFtczpzY2ltOmV 630 2ZW50OmNyZWF0ZSI6eyJyZWYiOiJodHRwczovL3NjaW0uZXhhbXBsZS5jb20vVXNlcn 631 MvNDRmNjE0MmRmOTZiZDZhYjYxZTc1MjFkOSIsImF0dHJpYnV0ZXMiOlsiaWQiLCJuY 632 W1lIiwidXNlck5hbWUiLCJwYXNzd29yZCIsImVtYWlscyJdfX19." 633 } 634 } 636 Figure 12: Example Push-Pull Response 638 Following the response from the SSTP server, the client would 639 subsequently repeats the request-response cycle by acknowledging the 640 SET identified by a "jti" value of 641 "6f332aefc730400a9f645d36a12ba4ab". 643 2.3. Error Response Handling 645 If a SET is invalid, the following error codes are defined: 647 +-------------+-----------------------------------------------------+ 648 | Err Value | Description | 649 +-------------+-----------------------------------------------------+ 650 | json | Invalid JSON object. | 651 | jwtParse | Invalid or unparsable JWT or JSON structure. | 652 | jwtHdr | In invalid JWT header was detected. | 653 | jwtCrypto | Unable to parse due to unsupported algorithm. | 654 | jws | Signature was not validated. | 655 | jwe | Unable to decrypt JWE encoded data. | 656 | jwtAud | Invalid audience value. | 657 | jwtIss | Issuer not recognized. | 658 | setType | An unexpected Event type was received. | 659 | setParse | Invalid structure was encountered such as an | 660 | | inability to parse or an incomplete set of event | 661 | | claims. | 662 | setData | SET event claims incomplete or invalid. | 663 | directional | The SSTP does not support transfer of SETs in the | 664 | | requested direction. | 665 +-------------+-----------------------------------------------------+ 667 Table 1: SET Errors 669 An error response has a "Content-Type" of "application/sstp+json" 670 which is a JSON document that provides details about the error. The 671 JSON document includes the JSON attributes: 673 err 674 A value which is a keyword that describes the error (see Table 1). 676 description 677 A human-readable text that provides additional diagnostic 678 information. 680 When included as part of an HTTP Status 400 response, the above JSON 681 is the HTTP response body in the JSON attribute "setErrs" (see 682 Section 2.1). 684 3. Authentication and Authorization 686 The SET delivery methods described in this specification are based 687 upon HTTP and depend on the use of TLS and/or standard HTTP 688 authentication and authorization schemes as per [RFC7235]. For 689 example, the following methodologies could be used among others: 691 TLS Client Authentication 692 SSTP server MAY negotiate TLS mutual client authentication. See 693 Section 7.3 [RFC5246]. 695 Bearer Tokens 696 Bearer tokens [RFC6750] MAY be used when combined with TLS and a 697 token framework such as OAuth 2.0 [RFC6749]. For security 698 considerations regarding the use of bearer tokens in SET delivery 699 see Section 4.4.1. 701 Basic Authentication 702 Usage of basic authentication should be avoided due to its use of 703 a single factor that is based upon a relatively static, symmetric 704 secret. Implementers SHOULD combine the use of basic 705 authentication with other factors. The security considerations of 706 HTTP BASIC, are well documented in [RFC7617] and SHOULD be 707 considered along with using signed SETs (see SET Payload 708 Authentication below). 710 SET Payload Authentication 711 In scenarios where SETs are signed and the delivery method is HTTP 712 POST, SSTP clients MAY elect to use Basic Authentication or not to 713 use HTTP or TLS based authentication at all. See Section 4.1 for 714 considerations. 716 As per Section 4.1 of [RFC7235], a SET delivery endpoint SHALL 717 indicate supported HTTP authentication schemes via the "WWW- 718 Authenticate" header. 720 Because SET Delivery describes a simple function, authorization for 721 the ability to pick-up or deliver SETs can be derived by considering 722 the identity of the SET issuer, or via an authentication method 723 above. This specification considers authentication as a feature to 724 prevent denial-of-service attacks. Because SETs are not commands 725 (see ), event receivers are free to ignore SETs that are not of 726 interest. 728 For illustrative purposes only, SET delivery examples show an OAuth2 729 bearer token value [RFC6750] in the authorization header. This is 730 not intended to imply that bearer tokens are preferred. However, the 731 use of bearer tokens in the specification does reflect common 732 practice. 734 3.1. Use of Tokens as Authorizations 736 When using bearer tokens or proof-of-possession tokens that represent 737 an authorization grant such as issued by OAuth (see [RFC6749]), 738 implementers SHOULD consider the type of authorization granted, any 739 authorized scopes (see Section 3.3 of [RFC6749]), and the security 740 subject(s) that SHOULD be mapped from the authorization when 741 considering local access control rules. Section 6 of the OAuth 742 Assertions draft [RFC7521], documents common scenarios for 743 authorization including: 745 o Clients using an assertion to authenticate and/or act on behalf of 746 itself; 748 o Clients acting on behalf of a user; and, 750 o A Client acting on behalf of an anonymous user (e.g., see next 751 section). 753 When using OAuth authorization tokens, implementers MUST take into 754 account the threats and countermeasures documented in the security 755 considerations for the use of client authorizations (see Section 8 of 756 [RFC7521]). When using other token formats or frameworks, 757 implementers MUST take into account similar threats and 758 countermeasures, especially those documented by the relevant 759 specifications. 761 4. Security Considerations 763 4.1. Authentication Using Signed SETs 765 In scenarios where HTTP authorization or TLS mutual authentication 766 are not used or are considered weak, JWS signed SETs SHOULD be used 767 (see [RFC7515] and Security Considerations 768 [I-D.ietf-secevent-token]). This enables event receivers to validate 769 that the SET issuer is authorized to deliver SETs. 771 4.2. HTTP Considerations 773 SET delivery depends on the use of Hypertext Transfer Protocol and 774 thus subject to the security considerations of HTTP Section 9 775 [RFC7230] and its related specifications. 777 As stated in Section 2.7.1 [RFC7230], an HTTP requestor MUST NOT 778 generate the "userinfo" (i.e., username and password) component (and 779 its "@" delimiter) when an "http" URI reference is generated with a 780 message as they are now disallowed in HTTP. 782 4.3. TLS Support Considerations 784 SETs contain sensitive information that is considered PII (e.g. 785 subject claims). Therefore, event issuers and receivers MUST require 786 the use of a transport-layer security mechanism. Event delivery 787 endpoints MUST support TLS 1.2 [RFC5246] and MAY support additional 788 transport-layer mechanisms meeting its security requirements. When 789 using TLS, the client MUST perform a TLS/SSL server certificate 790 check, per [RFC6125]. Implementation security considerations for TLS 791 can be found in "Recommendations for Secure Use of TLS and DTLS" 792 [RFC7525]. 794 4.4. Authorization Token Considerations 796 When using authorization tokens such as those issued by OAuth 2.0 797 [RFC6749], implementers MUST take into account threats and 798 countermeasures documented in Section 8 of [RFC7521]. 800 4.4.1. Bearer Token Considerations 802 Due to the possibility of interception, Bearer tokens MUST be 803 exchanged using TLS. 805 Bearer tokens MUST have a limited lifetime that can be determined 806 directly or indirectly (e.g., by checking with a validation service) 807 by the service provider. By expiring tokens, clients are forced to 808 obtain a new token (which usually involves re-authentication) for 809 continued authorized access. For example, in OAuth2, a client MAY 810 use OAuth token refresh to obtain a new bearer token after 811 authenticating to an authorization server. See Section 6 of 812 [RFC6749]. 814 Implementations supporting OAuth bearer tokens need to factor in 815 security considerations of this authorization method [RFC7521]. 816 Since security is only as good as the weakest link, implementers also 817 need to consider authentication choices coupled with OAuth bearer 818 tokens. The security considerations of the default authentication 819 method for OAuth bearer tokens, HTTP BASIC, are well documented in 820 [RFC7617], therefore implementers are encouraged to prefer stronger 821 authentication methods. Designating the specific methods of 822 authentication and authorization are out-of-scope for the delivery of 823 SET tokens, however this information is provided as a resource to 824 implementers. 826 5. Privacy Considerations 828 If a SET needs to be retained for audit purposes, JWS MAY be used to 829 provide verification of its authenticity. 831 Event transmitters SHOULD attempt to filter SETs issued so that the 832 content is targeted to the specific business and protocol needs of 833 receivers. 835 When sharing personally identifiable information or information that 836 is otherwise considered confidential to affected users, event 837 transmitters and receivers MUST have the appropriate legal agreements 838 and user consent or terms of service in place. 840 The propagation of subject identifiers can be perceived as personally 841 identifiable information. Where possible, event transmitters and 842 receivers SHOULD devise approaches that prevent propagation -- for 843 example, the passing of a hash value that requires the subscriber to 844 already know the subject. 846 6. IANA Considerations 848 There are no IANA considerations. 850 7. References 852 7.1. Normative References 854 [I-D.ietf-secevent-token] 855 Hunt, P., Jones, M., Denniss, W., and M. Ansari, "Security 856 Event Token (SET)", draft-ietf-secevent-token-07 (work in 857 progress), March 2018. 859 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 860 Requirement Levels", BCP 14, RFC 2119, 861 DOI 10.17487/RFC2119, March 1997, 862 . 864 [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform 865 Resource Identifier (URI): Generic Syntax", STD 66, 866 RFC 3986, DOI 10.17487/RFC3986, January 2005, 867 . 869 [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security 870 (TLS) Protocol Version 1.2", RFC 5246, 871 DOI 10.17487/RFC5246, August 2008, 872 . 874 [RFC5988] Nottingham, M., "Web Linking", RFC 5988, 875 DOI 10.17487/RFC5988, October 2010, 876 . 878 [RFC6125] Saint-Andre, P. and J. Hodges, "Representation and 879 Verification of Domain-Based Application Service Identity 880 within Internet Public Key Infrastructure Using X.509 881 (PKIX) Certificates in the Context of Transport Layer 882 Security (TLS)", RFC 6125, DOI 10.17487/RFC6125, March 883 2011, . 885 [RFC7159] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data 886 Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March 887 2014, . 889 [RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer 890 Protocol (HTTP/1.1): Semantics and Content", RFC 7231, 891 DOI 10.17487/RFC7231, June 2014, 892 . 894 [RFC7519] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token 895 (JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015, 896 . 898 [RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre, 899 "Recommendations for Secure Use of Transport Layer 900 Security (TLS) and Datagram Transport Layer Security 901 (DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May 902 2015, . 904 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 905 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 906 May 2017, . 908 7.2. Informative References 910 [openid-connect-core] 911 NRI, "OpenID Connect Core 1.0", Nov 2014. 913 [POSIX.1] Institute of Electrical and Electronics Engineers, "The 914 Open Group Base Specifications Issue 7", IEEE Std 1003.1, 915 2013 Edition, 2013. 917 [RFC3339] Klyne, G. and C. Newman, "Date and Time on the Internet: 918 Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002, 919 . 921 [RFC6202] Loreto, S., Saint-Andre, P., Salsano, S., and G. Wilkins, 922 "Known Issues and Best Practices for the Use of Long 923 Polling and Streaming in Bidirectional HTTP", RFC 6202, 924 DOI 10.17487/RFC6202, April 2011, 925 . 927 [RFC6749] Hardt, D., Ed., "The OAuth 2.0 Authorization Framework", 928 RFC 6749, DOI 10.17487/RFC6749, October 2012, 929 . 931 [RFC6750] Jones, M. and D. Hardt, "The OAuth 2.0 Authorization 932 Framework: Bearer Token Usage", RFC 6750, 933 DOI 10.17487/RFC6750, October 2012, 934 . 936 [RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer 937 Protocol (HTTP/1.1): Message Syntax and Routing", 938 RFC 7230, DOI 10.17487/RFC7230, June 2014, 939 . 941 [RFC7235] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer 942 Protocol (HTTP/1.1): Authentication", RFC 7235, 943 DOI 10.17487/RFC7235, June 2014, 944 . 946 [RFC7515] Jones, M., Bradley, J., and N. Sakimura, "JSON Web 947 Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May 948 2015, . 950 [RFC7516] Jones, M. and J. Hildebrand, "JSON Web Encryption (JWE)", 951 RFC 7516, DOI 10.17487/RFC7516, May 2015, 952 . 954 [RFC7521] Campbell, B., Mortimore, C., Jones, M., and Y. Goland, 955 "Assertion Framework for OAuth 2.0 Client Authentication 956 and Authorization Grants", RFC 7521, DOI 10.17487/RFC7521, 957 May 2015, . 959 [RFC7617] Reschke, J., "The 'Basic' HTTP Authentication Scheme", 960 RFC 7617, DOI 10.17487/RFC7617, September 2015, 961 . 963 [saml-core-2.0] 964 Internet2, "Assertions and Protocols for the OASIS 965 Security Assertion Markup Language (SAML) V2.0", March 966 2005. 968 Appendix A. Acknowledgments 970 The editor would like to thank the participants in the the SECEVENTS 971 working group for their support of this specification. 973 This specification is based on and ideally replaces draft-ietf- 974 secevent-delivery, and we thank its contributors Annabelle Backman, 975 Marius Scurtescu, and Morteza Ansari. 977 Appendix B. Change Log 979 Draft 00 - PH - Original 981 Authors' Addresses 983 Phil Hunt (editor) 984 Oracle Corporation 986 Email: phil.hunt@yahoo.com 988 Anthony Nadalin 989 Microsoft 991 Email: tonynad@microsoft.com