Security Events Working Group A. Backman, Ed. Internet-Draft Amazon Intended status: Standards Track M. Jones, Ed. Expires: August 10, 2020 Microsoft M. Scurtescu Coinbase M. Ansari Cisco A. Nadalin Microsoft February 7, 2020 Poll-Based Security Event Token (SET) Delivery Using HTTP draft-ietf-secevent-http-poll-08 Abstract This specification defines how a series of Security Event Tokens (SETs) may be delivered to an intended recipient using HTTP POST over TLS initiated as a poll by the recipient. The specification also defines how delivery can be assured, subject to the SET Recipient's need for assurance. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on August 10, 2020. Copyright Notice Copyright (c) 2020 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents Backman, et al. Expires August 10, 2020 [Page 1] Internet-Draft draft-ietf-secevent-http-poll February 2020 (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction and Overview . . . . . . . . . . . . . . . . . . 2 1.1. Notational Conventions . . . . . . . . . . . . . . . . . 3 1.2. Definitions . . . . . . . . . . . . . . . . . . . . . . . 3 2. SET Delivery . . . . . . . . . . . . . . . . . . . . . . . . 3 2.1. Polling Delivery using HTTP . . . . . . . . . . . . . . . 4 2.2. Polling HTTP Request . . . . . . . . . . . . . . . . . . 4 2.3. Polling HTTP Response . . . . . . . . . . . . . . . . . . 5 2.4. Poll Request . . . . . . . . . . . . . . . . . . . . . . 6 2.4.1. Poll Only Request . . . . . . . . . . . . . . . . . . 7 2.4.2. Acknowledge Only Request . . . . . . . . . . . . . . 7 2.4.3. Poll with Acknowledgement . . . . . . . . . . . . . . 8 2.4.4. Poll with Acknowledgement and Errors . . . . . . . . 9 2.5. Poll Response . . . . . . . . . . . . . . . . . . . . . . 9 2.5.1. Poll Error Response . . . . . . . . . . . . . . . . . 11 2.6. Error Response Handling . . . . . . . . . . . . . . . . . 11 3. Authentication and Authorization . . . . . . . . . . . . . . 12 4. Security Considerations . . . . . . . . . . . . . . . . . . . 12 4.1. Authentication Using Signed SETs . . . . . . . . . . . . 13 4.2. HTTP Considerations . . . . . . . . . . . . . . . . . . . 13 4.3. Confidentiality of SETs . . . . . . . . . . . . . . . . . 13 4.4. Access Token Considerations . . . . . . . . . . . . . . . 13 4.4.1. Bearer Token Considerations . . . . . . . . . . . . . 13 5. Privacy Considerations . . . . . . . . . . . . . . . . . . . 14 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 14 7.1. Normative References . . . . . . . . . . . . . . . . . . 14 7.2. Informative References . . . . . . . . . . . . . . . . . 16 Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . 17 Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 17 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19 1. Introduction and Overview This specification defines how a stream of Security Event Tokens (SETs) [RFC8417] can be transmitted to an intended SET Recipient using HTTP [RFC7231] over TLS. The specification defines a method to poll for SETs using HTTP POST. This is an alternative SET delivery method to the one defined in [I-D.ietf-secevent-http-push]. Backman, et al. Expires August 10, 2020 [Page 2] Internet-Draft draft-ietf-secevent-http-poll February 2020 A mechanism for exchanging configuration metadata such as endpoint URLs and cryptographic keys between the transmitter and recipient is out of scope for this specification. How SETs are defined and the process by which security events are identified for SET Recipients are specified in [RFC8417]. 1.1. Notational Conventions The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. Throughout this document, all figures may contain spaces and extra line wrapping for readability and due to space limitations. 1.2. Definitions This specification utilizes terminology defined in [RFC8417] and [I-D.ietf-secevent-http-push]. 2. SET Delivery When a SET is available for a SET Recipient, the SET Transmitter queues the SET in a buffer so that a SET Recipient can poll for SETs using HTTP/1.1 POST. In Poll-Based SET Delivery Using HTTP, zero or more SETs are delivered in a JSON [RFC8259] document to a SET Recipient in response to an HTTP POST request to the SET Transmitter. Then in a following request, the SET Recipient acknowledges received SETs and can poll for more. All requests and responses are JSON documents and use a "Content-Type" of "application/json", as described in Section 2.1. After successful (acknowledged) SET delivery, SET Transmitters are not required to retain or record SETs for retransmission. Once a SET is acknowledged, the SET Recipient SHALL be responsible for retention, if needed. Upon receiving a SET, the SET Recipient reads the SET and validates it in the manner described in Section 2 of [I-D.ietf-secevent-http-push]. The SET Recipient MUST acknowledge receipt to the SET Transmitter, and SHOULD do in a timely fashion, as described in Section 2.4. The SET Recipient SHALL NOT use the event acknowledgement mechanism to report event errors other than those relating to the parsing and validation of the SET. Backman, et al. Expires August 10, 2020 [Page 3] Internet-Draft draft-ietf-secevent-http-poll February 2020 2.1. Polling Delivery using HTTP This method allows a SET Recipient to use HTTP POST (Section 4.3.3 of [RFC7231]) to acknowledge SETs and to check for and receive zero or more SETs. Requests MAY be made at a periodic interval (short polling) or requests MAY wait, pending availability of new SETs using long polling, per Section 2 of [RFC6202]. Note that short polling will result in retrieving zero or more SETs whereas long polling will typically result in retrieving one or more SETs unless a timeout occurs. The delivery of SETs in this method is facilitated by HTTP POST requests initiated by the SET Recipient in which: o The SET Recipient makes a request for available SETs using an HTTP POST to a pre-arranged endpoint provided by the SET Transmitter or, o after validating previously received SETs, the SET Recipient initiates another poll request using HTTP POST that includes acknowledgement of previous SETs and requests the next batch of SETs. The purpose of the acknowledgement is to inform the SET Transmitter that delivery has succeeded and redelivery is no longer required. Before acknowledgement, SET Recipients SHOULD ensure that received SETs have been validated and retained in a manner appropriate to the recipient's requirements. The level and method of retention of SETs by SET Recipients is out of scope of this specification. 2.2. Polling HTTP Request When initiating a poll request, the SET Recipient constructs a JSON document that consists of polling request parameters and SET acknowledgement parameters in the form of JSON objects. When making a request, the HTTP header "Content-Type" is set to "application/json". The following JSON object members are used in a polling request: Request Processing Parameters maxEvents An OPTIONAL JSON integer value indicating the maximum number of unacknowledged SETs that SHOULD be returned. If more than the maximum number of SETs are available, the oldest SETs available SHOULD be returned first. A value of "0" MAY be used by SET Backman, et al. Expires August 10, 2020 [Page 4] Internet-Draft draft-ietf-secevent-http-poll February 2020 Recipients that would like to perform an acknowledge only request. This enables the Recipient to use separate HTTP requests for acknowledgement and reception of SETs. If this parameter is omitted, no limit is placed on the number of SETs to be returned. returnImmediately An OPTIONAL JSON boolean value that indicates the SET Transmitter SHOULD return an immediate response even if no results are available (short polling). The default value is "false", which indicates the request is to be treated as an HTTP Long Poll, per Section 2 of [RFC6202]. The timeout for the request is part of the configuration between the participants, which is out of scope of this specification. SET Acknowledgment Parameters ack A JSON array of strings whose values are the "jti" values of successfully received SETs that are being acknowledged. If there are no outstanding SETs to acknowledge, this member is omitted. Once a SET has been acknowledged, the SET Transmitter is released from any obligation to retain the SET. setErrs A JSON object with one or more members whose keys are the "jti" values of invalid SETs received. The values of these objects are themselves JSON objects that describe the errors detected using the "err" and "description" values specified in Section 2.6. If there are no outstanding SETs with errors to report, this member is omitted. 2.3. Polling HTTP Response In response to a poll request, the SET Transmitter checks for available SETs and responds with a JSON document containing the following JSON object members: sets A JSON object containing zero or more SETs being returned. Each member name is the "jti" of a SET to be delivered and its value is a JSON string representing the corresponding SET. If there are no outstanding SETs to be transmitted, the JSON object SHALL be empty. moreAvailable A JSON boolean value that indicates if more unacknowledged SETs are available to be returned. This member MAY be omitted, with Backman, et al. Expires August 10, 2020 [Page 5] Internet-Draft draft-ietf-secevent-http-poll February 2020 the meaning being the same as including it with the boolean value "false". When making a response, the HTTP header "Content-Type" is set to "application/json". 2.4. Poll Request The SET Recipient performs an HTTP POST (see Section 4.3.4 of [RFC7231]) to a pre-arranged polling endpoint URI to check for SETs that are available. Because the SET Recipient has no prior SETs to acknowledge, the "ack" and "setErrs" request parameters are omitted. After a period of time configured between the SET Transmitter and Recipient, a SET Transmitter MAY redeliver SETs it has previously delivered. The SET Recipient SHOULD accept repeat SETs and acknowledge the SETs regardless of whether the Recipient believes it has already acknowledged the SETs previously. A SET Transmitter MAY limit the number of times it attempts to deliver a SET. If the SET Recipient has received SETs from the SET Transmitter, the SET Recipient SHOULD parse and validate received SETs to meet its own requirements and SHOULD acknowledge receipt in a timely fashion (e.g., seconds or minutes) so that the SET Transmitter can mark the SETs as received. SET Recipients SHOULD acknowledge receipt before taking any local actions based on the SETs to avoid unnecessary delay in acknowledgement, where possible. Poll requests have three variations: Poll Only In which a SET Recipient asks for the next set of events where no previous SET deliveries are acknowledged (such as in the initial poll request). Acknowledge Only In which a SET Recipient sets the "maxEvents" value to "0" along with "ack" and "setErrs" members indicating the SET Recipient is acknowledging previously received SETs and does not want to receive any new SETs in response to the request. Combined Acknowledge and Poll In which a SET Recipient is both acknowledging previously received SETs using the "ack" and "setErrs" members and will wait for the next group of SETs in the SET Transmitters response. Backman, et al. Expires August 10, 2020 [Page 6] Internet-Draft draft-ietf-secevent-http-poll February 2020 2.4.1. Poll Only Request In the case where no SETs were received in a previous poll (see Figure 7), the SET Recipient simply polls without acknowledgement parameters ("ack" and "setErrs"). The following is an example request made by a SET Recipient that has no outstanding SETs to acknowledge and is polling for available SETs at the endpoint "https://notify.idp.example.com/Events": POST /Events HTTP/1.1 Host: notify.idp.example.com Content-Type: application/json { "returnImmediately": true } Figure 1: Example Initial Poll Request A SET Recipient can poll using default parameter values by passing an empty JSON object. The following is a non-normative example default poll request to the endpoint "https://notify.idp.example.com/Events": POST /Events HTTP/1.1 Host: notify.idp.example.com Content-Type: application/json {} Figure 2: Example Default Poll Request 2.4.2. Acknowledge Only Request In this variation, the SET Recipient acknowledges previously received SETs and indicates it does not want to receive SETs in response by setting the "maxEvents" value to "0". This variation might be used, for instance, when a SET Recipient needs to acknowledge received SETs independently (e.g., on separate threads) from the process of receiving SETs. Backman, et al. Expires August 10, 2020 [Page 7] Internet-Draft draft-ietf-secevent-http-poll February 2020 The following is a non-normative example poll request with acknowledgement of SETs received (for example as shown in Figure 6): POST /Events HTTP/1.1 Host: notify.idp.example.com Content-Type: application/json { "ack": [ "4d3559ec67504aaba65d40b0363faad8", "3d0c3cf797584bd193bd0fb1bd4e7d30" ], "maxEvents": 0, "returnImmediately": true } Figure 3: Example Acknowledge Only Request 2.4.3. Poll with Acknowledgement This variation allows a recipient thread to simultaneously acknowledge previously received SETs and wait for the next group of SETs in a single request. The following is a non-normative example poll with acknowledgement of the SETs received in Figure 6: POST /Events HTTP/1.1 Host: notify.idp.example.com Content-Type: application/json { "ack": [ "4d3559ec67504aaba65d40b0363faad8", "3d0c3cf797584bd193bd0fb1bd4e7d30" ], "returnImmediately": false } Figure 4: Example Poll with Acknowledgement and No Errors In the above acknowledgement, the SET Recipient has acknowledged receipt of two SETs and has indicated it wants to wait until the next SET is available. Backman, et al. Expires August 10, 2020 [Page 8] Internet-Draft draft-ietf-secevent-http-poll February 2020 2.4.4. Poll with Acknowledgement and Errors In the case where errors were detected in previously delivered SETs, the SET Recipient MAY use the "setErrs" member to communicate the errors in the following poll request. The following is a non-normative example of a response acknowledging one successfully received SET and one SET with an error from the two SETs received in Figure 6: POST /Events HTTP/1.1 Host: notify.idp.example.com Content-Language: en-US Content-Type: application/json { "ack": ["3d0c3cf797584bd193bd0fb1bd4e7d30"], "setErrs": { "4d3559ec67504aaba65d40b0363faad8": { "err": "authentication_failed", "description": "The SET could not be authenticated" } }, "returnImmediately": true } Figure 5: Example Poll Acknowledgement with Error 2.5. Poll Response In response to a valid poll request, the service provider MAY respond immediately if SETs are available to be delivered. If no SETs are available at the time of the request, the SET Transmitter SHALL delay responding until a SET is available or the timeout interval has elapsed unless the poll request parameter "returnImmediately" is present with the value "true". As described in Section 2.3, a JSON document is returned containing members including "sets", which SHALL contain zero or more SETs. Backman, et al. Expires August 10, 2020 [Page 9] Internet-Draft draft-ietf-secevent-http-poll February 2020 The following is a non-normative example response to the request shown in Section 2.4. This example shows two SETs being returned: HTTP/1.1 200 OK Content-Type: application/json { "sets": { "4d3559ec67504aaba65d40b0363faad8": "eyJhbGciOiJub25lIn0. eyJqdGkiOiI0ZDM1NTllYzY3NTA0YWFiYTY1ZDQwYjAzNjNmYWFkOCIsImlhdCI6MTQ 1ODQ5NjQwNCwiaXNzIjoiaHR0cHM6Ly9zY2ltLmV4YW1wbGUuY29tIiwiYXVkIjpbIm h0dHBzOi8vc2NpbS5leGFtcGxlLmNvbS9GZWVkcy85OGQ1MjQ2MWZhNWJiYzg3OTU5M 2I3NzU0IiwiaHR0cHM6Ly9zY2ltLmV4YW1wbGUuY29tL0ZlZWRzLzVkNzYwNDUxNmIx ZDA4NjQxZDc2NzZlZTciXSwiZXZlbnRzIjp7InVybjppZXRmOnBhcmFtczpzY2ltOmV 2ZW50OmNyZWF0ZSI6eyJyZWYiOiJodHRwczovL3NjaW0uZXhhbXBsZS5jb20vVXNlcn MvNDRmNjE0MmRmOTZiZDZhYjYxZTc1MjFkOSIsImF0dHJpYnV0ZXMiOlsiaWQiLCJuY W1lIiwidXNlck5hbWUiLCJwYXNzd29yZCIsImVtYWlscyJdfX19.", "3d0c3cf797584bd193bd0fb1bd4e7d30": "eyJhbGciOiJub25lIn0. eyJqdGkiOiIzZDBjM2NmNzk3NTg0YmQxOTNiZDBmYjFiZDRlN2QzMCIsImlhdCI6MTQ 1ODQ5NjAyNSwiaXNzIjoiaHR0cHM6Ly9zY2ltLmV4YW1wbGUuY29tIiwiYXVkIjpbIm h0dHBzOi8vamh1Yi5leGFtcGxlLmNvbS9GZWVkcy85OGQ1MjQ2MWZhNWJiYzg3OTU5M 2I3NzU0IiwiaHR0cHM6Ly9qaHViLmV4YW1wbGUuY29tL0ZlZWRzLzVkNzYwNDUxNmIx ZDA4NjQxZDc2NzZlZTciXSwic3ViIjoiaHR0cHM6Ly9zY2ltLmV4YW1wbGUuY29tL1V zZXJzLzQ0ZjYxNDJkZjk2YmQ2YWI2MWU3NTIxZDkiLCJldmVudHMiOnsidXJuOmlldG Y6cGFyYW1zOnNjaW06ZXZlbnQ6cGFzc3dvcmRSZXNldCI6eyJpZCI6IjQ0ZjYxNDJkZ jk2YmQ2YWI2MWU3NTIxZDkifSwiaHR0cHM6Ly9leGFtcGxlLmNvbS9zY2ltL2V2ZW50 L3Bhc3N3b3JkUmVzZXRFeHQiOnsicmVzZXRBdHRlbXB0cyI6NX19fQ." } } Figure 6: Example Poll Response In the above example, two SETs whose "jti" values are "4d3559ec67504aaba65d40b0363faad8" and "3d0c3cf797584bd193bd0fb1bd4e7d30" are delivered. Backman, et al. Expires August 10, 2020 [Page 10] Internet-Draft draft-ietf-secevent-http-poll February 2020 The following is a non-normative example response to the request shown in Section 2.4.1, which indicates that no new SETs or unacknowledged SETs are available: HTTP/1.1 200 OK Content-Type: application/json { "sets": {} } Figure 7: Example No SETs Poll Response Upon receiving the JSON document (e.g., as shown in Figure 6), the SET Recipient parses and verifies the received SETs and notifies the SET Transmitter of successfully received SETs and SETs with errors via the next poll request to the SET Transmitter, as described in Section 2.4.3 or Section 2.4.4. 2.5.1. Poll Error Response In the event of a general HTTP error condition in the context of processing a poll request, the service provider SHOULD respond with an appropriate HTTP Response Status Code as defined in Section 6 of [RFC7231]. Service providers MAY respond to any invalid poll request with an HTTP Response Status Code of 400 (Bad Request) even when a more specific code might apply, for example if the service provider deemed that a more specific code presented an information disclosure risk. When no more specific code might apply, the service provider SHALL respond to an invalid poll request with an HTTP Status Code of 400. The response body for responses to invalid poll requests is left undefined, and its contents SHOULD be ignored. The following is a non-normative example of a response to an invalid poll request: HTTP/1.1 400 Bad Request Example Poll Error Response 2.6. Error Response Handling If a SET is invalid, error codes from the IANA "Security Event Token Delivery Error Codes" registry established by [I-D.ietf-secevent-http-push] are used in error responses. As Backman, et al. Expires August 10, 2020 [Page 11] Internet-Draft draft-ietf-secevent-http-poll February 2020 described in Section 2.3 of [I-D.ietf-secevent-http-push], an error response is a JSON object providing details about the error that includes the following name/value pairs: err A value from the IANA "Security Event Token Delivery Error Codes" registry that identifies the error. description A human-readable string that provides additional diagnostic information. When included as part of a batch of SETs, the above JSON is included as part of the "setErrs" member, as defined in Section 2.2 and Section 2.4.4. When the SET Recipient includes one or more error responses in a request to the SET Transmitter, it must also include in the request a "Content-Language" header whose value indicates the language of the error descriptions included in the request. The method of language selection in the case when the SET Recipient can provide error messages in multiple languages is out of scope for this specification. 3. Authentication and Authorization The SET delivery method described in this specification is based upon HTTP and HTTP over TLS [RFC2818] and/or standard HTTP authentication and authorization schemes, as per [RFC7235]. The TLS server certificate MUST be validated, per [RFC6125]. As per Section 4.1 of [RFC7235], a SET delivery endpoint SHALL indicate supported HTTP authentication schemes via the "WWW-Authenticate" header when using HTTP authentication. Authorization for the eligibility to provide actionable SETs can be determined by using the identity of the SET Issuer, validating the polling endpoint URL, perhaps using TLS, or via other employed authentication methods. Among other benefits, authentication can help prevent denial-of-service attacks. Because SETs are not commands, SET Recipients are free to ignore SETs that are not of interest after acknowledging their receipt. 4. Security Considerations Backman, et al. Expires August 10, 2020 [Page 12] Internet-Draft draft-ietf-secevent-http-poll February 2020 4.1. Authentication Using Signed SETs In scenarios where HTTP authorization or TLS mutual authentication are not used or are considered weak, JWS signed SETs SHOULD be used (see [RFC7515] and Section 5 of [RFC8417]). This enables the SET Recipient to validate that the SET Issuer is authorized to provide actionable SETs. 4.2. HTTP Considerations SET delivery depends on the use of Hypertext Transfer Protocol and is thus subject to the security considerations of HTTP Section 9 of [RFC7230] and its related specifications. As stated in Section 2.7.1 of [RFC7230], an HTTP requestor MUST NOT generate the "userinfo" (i.e., username and password) component (and its "@" delimiter) when an "http" URI reference is generated with a message, as they are now disallowed in HTTP. 4.3. Confidentiality of SETs SETs may contain sensitive information that is considered Personally Identifiable Information (PII). In such cases, SET Transmitters and SET Recipients MUST protect the confidentiality of the SET contents by encrypting the SET as described in JWE [RFC7516], using a transport-layer security mechanism such as TLS, or both. If an Event delivery endpoint supports TLS, it MUST support at least TLS version 1.2 [RFC5246] and SHOULD support the newest version of TLS that meets its security requirements, which as of the time of this publication is TLS 1.3 [RFC8446]. When using TLS, the client MUST perform a TLS/ SSL server certificate check using DNS-ID [RFC6125]. Implementation security considerations for TLS can be found in "Recommendations for Secure Use of TLS and DTLS" [RFC7525]. 4.4. Access Token Considerations If HTTP Authentication is performed using OAuth access tokens [RFC6749], implementers MUST take into account the threats and countermeasures documented in Section 8 of [RFC7521]. 4.4.1. Bearer Token Considerations Due to the possibility of interception, Bearer tokens [RFC6750] MUST be exchanged using TLS. Bearer tokens SHOULD have a limited lifetime that can be determined directly or indirectly (e.g., by checking with a validation service) by the service provider. By expiring tokens, clients are forced to Backman, et al. Expires August 10, 2020 [Page 13] Internet-Draft draft-ietf-secevent-http-poll February 2020 obtain a new token (which usually involves re-authentication) for continued authorized access. For example, in OAuth 2.0, a client MAY use an OAuth refresh token to obtain a new bearer token after authenticating to an authorization server, per Section 6 of [RFC6749]. Implementations supporting OAuth bearer tokens need to factor in security considerations of this authorization method [RFC7521]. Since security is only as good as the weakest link, implementers also need to consider authentication choices coupled with OAuth bearer tokens. The security considerations of the default authentication method for OAuth bearer tokens, HTTP Basic, are well documented in [RFC7617], therefore implementers are encouraged to prefer stronger authentication methods. 5. Privacy Considerations SET Transmitters SHOULD attempt to deliver SETs that are targeted to the specific business and protocol needs of subscribers. When sharing personally identifiable information or information that is otherwise considered confidential to affected users, SET Transmitters and Recipients MUST have the appropriate legal agreements and user consent or terms of service in place. Furthermore, data that needs confidentiality protection MUST be encrypted, either via TLS or using JSON Web Encryption (JWE) [RFC7516], or both. In some cases, subject identifiers themselves may be considered sensitive information, such that their inclusion within a SET may be considered a violation of privacy. SET Transmitters should consider the ramifications of sharing a particular subject identifier with a SET Recipient (e.g., whether doing so could enable correlation and/or de-anonymization of data) and choose appropriate subject identifiers for their use cases. 6. IANA Considerations This specification requires no IANA actions. 7. References 7.1. Normative References Backman, et al. Expires August 10, 2020 [Page 14] Internet-Draft draft-ietf-secevent-http-poll February 2020 [I-D.ietf-secevent-http-push] Backman, A., Jones, M., Scurtescu, M., Ansari, M., and A. Nadalin, "Push-Based Security Event Token (SET) Delivery Using HTTP", draft-ietf-secevent-http-push-08 (work in progress), February 2020. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, DOI 10.17487/RFC2818, May 2000, . [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security (TLS) Protocol Version 1.2", RFC 5246, DOI 10.17487/RFC5246, August 2008, . [RFC6125] Saint-Andre, P. and J. Hodges, "Representation and Verification of Domain-Based Application Service Identity within Internet Public Key Infrastructure Using X.509 (PKIX) Certificates in the Context of Transport Layer Security (TLS)", RFC 6125, DOI 10.17487/RFC6125, March 2011, . [RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content", RFC 7231, DOI 10.17487/RFC7231, June 2014, . [RFC7515] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May 2015, . [RFC7516] Jones, M. and J. Hildebrand, "JSON Web Encryption (JWE)", RFC 7516, DOI 10.17487/RFC7516, May 2015, . [RFC7521] Campbell, B., Mortimore, C., Jones, M., and Y. Goland, "Assertion Framework for OAuth 2.0 Client Authentication and Authorization Grants", RFC 7521, DOI 10.17487/RFC7521, May 2015, . Backman, et al. Expires August 10, 2020 [Page 15] Internet-Draft draft-ietf-secevent-http-poll February 2020 [RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre, "Recommendations for Secure Use of Transport Layer Security (TLS) and Datagram Transport Layer Security (DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May 2015, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data Interchange Format", STD 90, RFC 8259, DOI 10.17487/RFC8259, December 2017, . [RFC8417] Hunt, P., Ed., Jones, M., Denniss, W., and M. Ansari, "Security Event Token (SET)", RFC 8417, DOI 10.17487/RFC8417, July 2018, . [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, . 7.2. Informative References [RFC6202] Loreto, S., Saint-Andre, P., Salsano, S., and G. Wilkins, "Known Issues and Best Practices for the Use of Long Polling and Streaming in Bidirectional HTTP", RFC 6202, DOI 10.17487/RFC6202, April 2011, . [RFC6749] Hardt, D., Ed., "The OAuth 2.0 Authorization Framework", RFC 6749, DOI 10.17487/RFC6749, October 2012, . [RFC6750] Jones, M. and D. Hardt, "The OAuth 2.0 Authorization Framework: Bearer Token Usage", RFC 6750, DOI 10.17487/RFC6750, October 2012, . [RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing", RFC 7230, DOI 10.17487/RFC7230, June 2014, . Backman, et al. Expires August 10, 2020 [Page 16] Internet-Draft draft-ietf-secevent-http-poll February 2020 [RFC7235] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer Protocol (HTTP/1.1): Authentication", RFC 7235, DOI 10.17487/RFC7235, June 2014, . [RFC7617] Reschke, J., "The 'Basic' HTTP Authentication Scheme", RFC 7617, DOI 10.17487/RFC7617, September 2015, . Appendix A. Acknowledgments The editors would like to thank the members of the SCIM working group, which began discussions of provisioning events starting with draft-hunt-scim-notify-00 in 2015. The editors would like to thank Phil Hunt and the other the authors of draft-ietf-secevent-delivery-02, on which this specification is based. The editors would like to thank the participants in the SecEvents working group for their contributions to this specification. Appendix B. Change Log [[ to be removed by the RFC Editor before publication as an RFC ]] Draft 00 - AB - Based on draft-ietf-secevent-delivery-02 with the following additions: o Renamed to "Poll-Based SET Token Delivery Using HTTP" o Removed references to the HTTP Push delivery method. Draft 01 - mbj: o Addressed problems identified in my 18-Jul-18 review message titled "Issues for both the Push and Poll Specs". o Changes to align terminology with RFC 8417, for instance, by using the already defined term SET Recipient rather than SET Receiver. o Applied editorial and minor normative corrections. o Updated Marius' contact information. o Begun eliminating redundancies between this specification and "Push-Based Security Event Token (SET) Delivery Using HTTP" Backman, et al. Expires August 10, 2020 [Page 17] Internet-Draft draft-ietf-secevent-http-poll February 2020 [I-D.ietf-secevent-http-push], referencing, rather that duplicating common normative text. Draft 02 - mbj: o Removed vestigial language remaining from when the push and poll delivery methods were defined in a common specification. o Replaced remaining uses of the terms Event Transmitter and Event Recipient with the correct terms SET Transmitter and SET Recipient. o Removed uses of the unnecessary term "Event Stream". o Removed dependencies between the semantics of "maxEvents" and "returnImmediately". o Said that PII in SETs is to be encrypted with TLS, JWE, or both. o Corrected grammar and spelling errors. Draft 03 - mbj: o Corrected uses of "attribute" to "member" when describing JSON objects. o Further alignment with the push draft. Draft 04 - AB + mbj o Referenced SET Transmitter definition in http-push. o Removed incorrect normative text regarding SET construction. o Consolidated general out-of-scope items under Introduction. o Removed unnecessary HTTP headers in examples and added Content- Type. o Added Content-Language requirement for error descriptions, aligning with http-push. o Stated that bearer tokens SHOULD have a limited lifetime. o Minor editorial fixes. Draft 05 - AB + mbj Backman, et al. Expires August 10, 2020 [Page 18] Internet-Draft draft-ietf-secevent-http-poll February 2020 o Added normative text defining how to respond to invalid poll requests. o Addressed shepherd comments by Yaron Sheffer. Draft 06 - mbj o Addressed nits identified by the idnits tool. Draft 07 - mbj o Addressed area director review comments by Benjamin Kaduk. Draft 08 - mbj + AB o Corrected editorial nits. Authors' Addresses Annabelle Backman (editor) Amazon Email: richanna@amazon.com Michael B. Jones (editor) Microsoft Email: mbj@microsoft.com URI: http://self-issued.info/ Marius Scurtescu Coinbase Email: marius.scurtescu@coinbase.com Morteza Ansari Cisco Email: morteza.ansari@cisco.com Anthony Nadalin Microsoft Email: tonynad@microsoft.com Backman, et al. Expires August 10, 2020 [Page 19]