| Network Working Group | P. Hunt, Ed. |
| Internet-Draft | Oracle |
| Intended status: Standards Track | A. Nadalin |
| Expires: September 23, 2018 | Microsoft |
| March 22, 2018 |
Symmetric SET Transfer Protocol
draft-hunt-secevent-sstp-00
This specification defines how security event tokens (SETs) may be exchanged between a client and service provider using HTTP POST over TLS using a symmetric format. The specification supports three modes of operation: "push", "pull", and "push-pull" bi-directional SET exchange. The specification also defines a simple acknowledge mechanism allowing parties to confirm delivery.
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This Internet-Draft will expire on September 23, 2018.
Copyright (c) 2018 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 (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.
[EDITORS NOTE: This specification is based upon draft-ietf-secevent-delivery and attempts to provide a unified single MTI protocol solution satisfying all use cases for SECEVENTS.]
This specification defines how SETs (see [I-D.ietf-secevent-token]) can be exchanged using HTTP [RFC7231] over TLS using a symmetric request/response format. The specification supports three modes of operation: "push", "pull", and "push-pull" bi-directional SET exchange. The specification also defines a simple acknowledge mechanism allowing parties to confirm delivery or attempt re-delivery.
This specification makes several simplifying assumptions:
This specification supports the following use-cases:
This specification does not define how endpoints are configured, nor does it define the specifics of which SET event types are exchanged over any particular delivery relationship.
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.
For purposes of readability examples are not URL encoded. Implementers MUST percent encode URLs as described in Section 2.1 of .
Throughout this documents all figures MAY contain spaces and extra line-wrapping for readability and space limitations. Similarly, some URI's contained within examples, have been shortened for space and readability reasons. All examples are non-normative.
This specification assumes terminology defined in the Security Event Token specification[I-D.ietf-secevent-token] .
This specification defines the following terms:
SSTP is a symmetric protocol. As such an SSTP client uses HTTP POST (Section 4.3.3) with a body with Content-Type of application/sstp+json to deliver 0 or more SETs and/or to acknowledge previously received SETs from an SSTP server. In response, the SSTP server returns an HTTP body with the same document-type which may also return 0 or more SETs, acknowledgments, and errors.
Requests MAY be spontaneous (in the case of push mode), scheduled over a a periodic interval (in the case of pull), or requests to pull MAY await new SETS using HTTP long polling (see Section 2). An SSTP server choosing NOT to support HTTP long polling MAY do so by returning HTTP Status of 403 "Forbidden" (see Section 6.5.3) if a particular client is not authorized, or HTTP status 501 "Not implemented" (see Section 6.6.2) if the server does not support long polling.
SSTP provides an acknowledgement capability for the purpose of informing communications partners about which SETs have been successfully delivered. Upon receipt of a SET and before acknowledgement, receivers SHOULD ensure received SETs are valid and have been retained in a manner appropriate to the receiver's retention needs. The level and method of retention of SETs by receivers is out-of-scope of this specification.
If after a period of time, negotiated between the client and server, unacknowledged SETs MAY be re-transmitted. The receiver SHOULD accept repeat SETs and acknowledge the SETs regardless of whether the receiver believes it has already acknowledged the SETs previously. A SET issuer MAY limit the number of attempts to deliver a SET.
A receiving party (client or server) of SETs SHOULD parse and validate each SET to meet its own requirements and SHOULD acknowledge receipt in a timely (e.g. minutes) fashion so that the issuer may mark the SETs as received. Receivers SHOULD acknowledge receipt before taking any local actions based on the SETs to avoid unnecessary delay in acknowledgement to avoid unnecessary re-transmission.
The body (or message) of an SSTP request or response is a Content-Type of application/sstp+json which is a JSON document consisting of the following optional JSON attributes:
The following is an example SSTP message that could be exchanged either in a HTPP POST request or response between a client and an SSTP server.
{
"returnImmediately":true,
"returnEvents":true,
"sets":{
"4d3559ec67504aaba65d40b0363faad8":
"eyJhbGciOiJub25lIn0.
eyJqdGkiOiI0ZDM1NTllYzY3NTA0YWFiYTY1ZDQwYjAzNjNmYWFkOCIsImlhdCI6MTQ
1ODQ5NjQwNCwiaXNzIjoiaHR0cHM6Ly9zY2ltLmV4YW1wbGUuY29tIiwiYXVkIjpbIm
h0dHBzOi8vc2NpbS5leGFtcGxlLmNvbS9GZWVkcy85OGQ1MjQ2MWZhNWJiYzg3OTU5M
2I3NzU0IiwiaHR0cHM6Ly9zY2ltLmV4YW1wbGUuY29tL0ZlZWRzLzVkNzYwNDUxNmIx
ZDA4NjQxZDc2NzZlZTciXSwiZXZlbnRzIjp7InVybjppZXRmOnBhcmFtczpzY2ltOmV
2ZW50OmNyZWF0ZSI6eyJyZWYiOiJodHRwczovL3NjaW0uZXhhbXBsZS5jb20vVXNlcn
MvNDRmNjE0MmRmOTZiZDZhYjYxZTc1MjFkOSIsImF0dHJpYnV0ZXMiOlsiaWQiLCJuY
W1lIiwidXNlck5hbWUiLCJwYXNzd29yZCIsImVtYWlscyJdfX19.",
"3d0c3cf797584bd193bd0fb1bd4e7d30":
"eyJhbGciOiJub25lIn0.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."
}
}
Figure 1: Example Request or Response Document
Three examples are provided where:
In this example, a client posts SETs to an SSTP server which in turn acknowledges the transferred SETs in its response.
In the figure, two SETs are transferred to the SSTP server. The parameter returnEvents indicates the client is not interested in receiving SETs.
POST /Events HTTP/1.1
Host: notify.exampleidp.com
Authorization: Bearer h480djs93hd8
Content-Type: application/sstp+json
Accept: application/sstp+json
{
"returnImmediately":true,
"returnEvents":false,
"sets":{
"4d3559ec67504aaba65d40b0363faad8":
"eyJhbGciOiJub25lIn0.
eyJqdGkiOiI0ZDM1NTllYzY3NTA0YWFiYTY1ZDQwYjAzNjNmYWFkOCIsImlhdCI6MTQ
1ODQ5NjQwNCwiaXNzIjoiaHR0cHM6Ly9zY2ltLmV4YW1wbGUuY29tIiwiYXVkIjpbIm
h0dHBzOi8vc2NpbS5leGFtcGxlLmNvbS9GZWVkcy85OGQ1MjQ2MWZhNWJiYzg3OTU5M
2I3NzU0IiwiaHR0cHM6Ly9zY2ltLmV4YW1wbGUuY29tL0ZlZWRzLzVkNzYwNDUxNmIx
ZDA4NjQxZDc2NzZlZTciXSwiZXZlbnRzIjp7InVybjppZXRmOnBhcmFtczpzY2ltOmV
2ZW50OmNyZWF0ZSI6eyJyZWYiOiJodHRwczovL3NjaW0uZXhhbXBsZS5jb20vVXNlcn
MvNDRmNjE0MmRmOTZiZDZhYjYxZTc1MjFkOSIsImF0dHJpYnV0ZXMiOlsiaWQiLCJuY
W1lIiwidXNlck5hbWUiLCJwYXNzd29yZCIsImVtYWlscyJdfX19.",
"3d0c3cf797584bd193bd0fb1bd4e7d30":
"eyJhbGciOiJub25lIn0.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."
}
}
Figure 2: Example Push Request
The figure below shows the response returned from the SSTP server in response to the request in Figure 2
HTTP/1.1 200 OK
Content-Type: application/sstp+json
Location: https://notify.exampleidp.com/Events
{
"ack":[
"4d3559ec67504aaba65d40b0363faad8",
"3d0c3cf797584bd193bd0fb1bd4e7d30"
]
}
Figure 3: Example Push Response
The figure below is an example pull request to the SSTP server whose location is: https://nofity.exampleidp.com/Events. In this example, the client is requesting an immediate response whether or not new SETs are available.
POST /Events HTTP/1.1
Host: notify.exampleidp.com
Authorization: Bearer h480djs93hd8
Content-Type: application/sstp+json
Accept: application/sstp+json
{
"returnImmediately":true
}
Figure 4: Example Initial Pull Request
The following is an example default pull request to the SSTP server whose location is: https://nofity.exampleidp.com/Events. The default mode to return events and to wait if necessary is assumed.
POST /Events HTTP/1.1
Host: notify.exampleidp.com
Authorization: Bearer h480djs93hd8
Accept: application/sstp+json
{}
Figure 5: Example Default Pull Request
In response to the above two requests, the SSTP server responds immediately if respondImmediately is true or SETs are available. If no SETs are available at the time of the request and respondImmediately is false, the SSTP server delays response until a SET is available.
As described in Section 2.1 a JSON document is returned containing the JSON attribute sets.
The following is an example response to the requests shown Figure 4 and Figure 5. This example shows two SETs are returned.
HTTP/1.1 200 OK
Content-Type: application/sstp+json
Location: https://notify.exampleidp/Events
{
"sets":{
"4d3559ec67504aaba65d40b0363faad8":
"eyJhbGciOiJub25lIn0.
eyJqdGkiOiI0ZDM1NTllYzY3NTA0YWFiYTY1ZDQwYjAzNjNmYWFkOCIsImlhdCI6MTQ
1ODQ5NjQwNCwiaXNzIjoiaHR0cHM6Ly9zY2ltLmV4YW1wbGUuY29tIiwiYXVkIjpbIm
h0dHBzOi8vc2NpbS5leGFtcGxlLmNvbS9GZWVkcy85OGQ1MjQ2MWZhNWJiYzg3OTU5M
2I3NzU0IiwiaHR0cHM6Ly9zY2ltLmV4YW1wbGUuY29tL0ZlZWRzLzVkNzYwNDUxNmIx
ZDA4NjQxZDc2NzZlZTciXSwiZXZlbnRzIjp7InVybjppZXRmOnBhcmFtczpzY2ltOmV
2ZW50OmNyZWF0ZSI6eyJyZWYiOiJodHRwczovL3NjaW0uZXhhbXBsZS5jb20vVXNlcn
MvNDRmNjE0MmRmOTZiZDZhYjYxZTc1MjFkOSIsImF0dHJpYnV0ZXMiOlsiaWQiLCJuY
W1lIiwidXNlck5hbWUiLCJwYXNzd29yZCIsImVtYWlscyJdfX19.",
"3d0c3cf797584bd193bd0fb1bd4e7d30":
"eyJhbGciOiJub25lIn0.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."
}
}
Figure 6: Example Pull Response
In the above example, two SETs whose jti are 4d3559ec67504aaba65d40b0363faad8 and 3d0c3cf797584bd193bd0fb1bd4e7d30 are delivered.
The following is an example response to the request shown Figure 4 where returnImmediately was set showing no new SETs are available.
HTTP/1.1 200 OK
Content-Type: application/sstp+json
Location: https://notify.exampleidp/Events
{
"sets":{ }
}
Figure 7: Example No SETs Pull Response
This variation is typically used when a client needs to acknowledge received SETs on a separate thread from one receiving SETs.
An SSTP client acknowledges previously received SETs but indicates it does not want to receive SETs in the current request/response by setting the returnEvents attribute to false.
The following example is an acknowledgement of SETs previously received (e.g. from the response shown in Figure 6).
POST /Events HTTP/1.1
Host: notify.exampleidp.com
Authorization: Bearer h480djs93hd8
Content-Type: application/sstp+json
Authorization: Bearer h480djs93hd8
{
"ack":[
"4d3559ec67504aaba65d40b0363faad8",
"3d0c3cf797584bd193bd0fb1bd4e7d30"
],
"returnEvents":false
}
Figure 8: Example Acknowledge Only Request
This variation allows a client to simultaneously acknowledge previously received SETs and wait for the next group of SETs in a single HTTP request.
The following SSTP request contains an acknowledgement of SETs received from Figure 6.
POST /Events HTTP/1.1
Host: notify.exampleidp.com
Authorization: Bearer h480djs93hd8
Content-Type: application/sstp+json
Accept: application/sstp+json
Authorization: Bearer h480djs93hd8
{
"ack":[
"4d3559ec67504aaba65d40b0363faad8",
"3d0c3cf797584bd193bd0fb1bd4e7d30"
],
"returnImmediately":false
}
Figure 9: Example Pull With Acknowledgement and No Errors
In the case where errors are detected in previously received SETs, the client (or server) uses the setErrs attribute to indicate errors in its request.
The following is an example of an SSTP response acknowledges 1 error and 1 receipt of two SETs received in Figure 6.
POST /Events HTTP/1.1
Host: notify.exampleidp.com
Authorization: Bearer h480djs93hd8
Content-Type: application/sstp+json
Accept: application/sstp+json
Authorization: Bearer h480djs93hd8
{
"ack":["3d0c3cf797584bd193bd0fb1bd4e7d30"],
"setErrs":{
"4d3559ec67504aaba65d40b0363faad8":{
"err":"jwtAud",
"description":"The audience value was incorrect."
}
}
}
Figure 10: Example Pull Acknowledgement With Error
In push-pull mode, JSON attributes sets, ack and setErrs are used in both HTTP request and response messages between client and SSTP server.
In the following example, two SETs are transferred to the SSTP server and events are requested in return.
POST /Events HTTP/1.1
Host: notify.exampleidp.com
Authorization: Bearer h480djs93hd8
Content-Type: application/sstp+json
Accept: application/sstp+json
{
"returnEvents":true,
"ack":["b453bf9972b84e0492d5c7f55f68fb6a"],
"sets":{
"4d3559ec67504aaba65d40b0363faad8":
"eyJhbGciOiJub25lIn0.
eyJqdGkiOiI0ZDM1NTllYzY3NTA0YWFiYTY1ZDQwYjAzNjNmYWFkOCIsImlhdCI6MTQ
1ODQ5NjQwNCwiaXNzIjoiaHR0cHM6Ly9zY2ltLmV4YW1wbGUuY29tIiwiYXVkIjpbIm
h0dHBzOi8vc2NpbS5leGFtcGxlLmNvbS9GZWVkcy85OGQ1MjQ2MWZhNWJiYzg3OTU5M
2I3NzU0IiwiaHR0cHM6Ly9zY2ltLmV4YW1wbGUuY29tL0ZlZWRzLzVkNzYwNDUxNmIx
ZDA4NjQxZDc2NzZlZTciXSwiZXZlbnRzIjp7InVybjppZXRmOnBhcmFtczpzY2ltOmV
2ZW50OmNyZWF0ZSI6eyJyZWYiOiJodHRwczovL3NjaW0uZXhhbXBsZS5jb20vVXNlcn
MvNDRmNjE0MmRmOTZiZDZhYjYxZTc1MjFkOSIsImF0dHJpYnV0ZXMiOlsiaWQiLCJuY
W1lIiwidXNlck5hbWUiLCJwYXNzd29yZCIsImVtYWlscyJdfX19.",
"3d0c3cf797584bd193bd0fb1bd4e7d30":
"eyJhbGciOiJub25lIn0.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."
}
}
Figure 11: Example Push-Pull Request
The following is an example response to the request shown Figure 11.
HTTP/1.1 200 OK
Content-Type: application/sstp+json
Location: https://notify.exampleidp/Events
{
"ack":[
"4d3559ec67504aaba65d40b0363faad8",
"3d0c3cf797584bd193bd0fb1bd4e7d30"
],
"sets":{
"6f332aefc730400a9f645d36a12ba4ab":
"eyJhbGciOiJub25lIn0.
eyJqdGkiOiI0ZDM1NTllYzY3NTA0YWFiYTY1ZDQwYjAzNjNmYWFkOCIsImlhdCI6MTQ
1ODQ5NjQwNCwiaXNzIjoiaHR0cHM6Ly9zY2ltLmV4YW1wbGUuY29tIiwiYXVkIjpbIm
h0dHBzOi8vc2NpbS5leGFtcGxlLmNvbS9GZWVkcy85OGQ1MjQ2MWZhNWJiYzg3OTU5M
2I3NzU0IiwiaHR0cHM6Ly9zY2ltLmV4YW1wbGUuY29tL0ZlZWRzLzVkNzYwNDUxNmIx
ZDA4NjQxZDc2NzZlZTciXSwiZXZlbnRzIjp7InVybjppZXRmOnBhcmFtczpzY2ltOmV
2ZW50OmNyZWF0ZSI6eyJyZWYiOiJodHRwczovL3NjaW0uZXhhbXBsZS5jb20vVXNlcn
MvNDRmNjE0MmRmOTZiZDZhYjYxZTc1MjFkOSIsImF0dHJpYnV0ZXMiOlsiaWQiLCJuY
W1lIiwidXNlck5hbWUiLCJwYXNzd29yZCIsImVtYWlscyJdfX19."
}
}
Figure 12: Example Push-Pull Response
Following the response from the SSTP server, the client would subsequently repeats the request-response cycle by acknowledging the SET identified by a jti value of 6f332aefc730400a9f645d36a12ba4ab.
If a SET is invalid, the following error codes are defined:
| Err Value | Description |
|---|---|
| json | Invalid JSON object. |
| jwtParse | Invalid or unparsable JWT or JSON structure. |
| jwtHdr | In invalid JWT header was detected. |
| jwtCrypto | Unable to parse due to unsupported algorithm. |
| jws | Signature was not validated. |
| jwe | Unable to decrypt JWE encoded data. |
| jwtAud | Invalid audience value. |
| jwtIss | Issuer not recognized. |
| setType | An unexpected Event type was received. |
| setParse | Invalid structure was encountered such as an inability to parse or an incomplete set of event claims. |
| setData | SET event claims incomplete or invalid. |
| directional | The SSTP does not support transfer of SETs in the requested direction. |
An error response has a Content-Type of application/sstp+json which is a JSON document that provides details about the error. The JSON document includes the JSON attributes: setErrs (see Section 2.1).
When included as part of an HTTP Status 400 response, the above JSON is the HTTP response body in the JSON attribute
The SET delivery methods described in this specification are based upon HTTP and depend on the use of TLS and/or standard HTTP authentication and authorization schemes as per [RFC7235]. For example, the following methodologies could be used among others:
As per Section 4.1 of, a SET delivery endpoint SHALL indicate supported HTTP authentication schemes via the WWW-Authenticate header.
Because SET Delivery describes a simple function, authorization for the ability to pick-up or deliver SETs can be derived by considering the identity of the SET issuer, or via an authentication method above. This specification considers authentication as a feature to prevent denial-of-service attacks. Because SETs are not commands (see ), event receivers are free to ignore SETs that are not of interest.
For illustrative purposes only, SET delivery examples show an OAuth2 bearer token value [RFC6750] in the authorization header. This is not intended to imply that bearer tokens are preferred. However, the use of bearer tokens in the specification does reflect common practice.
When using bearer tokens or proof-of-possession tokens that represent an authorization grant such as issued by OAuth (see [RFC6749]), implementers SHOULD consider the type of authorization granted, any authorized scopes (see Section 3.3 of [RFC6749]), and the security subject(s) that SHOULD be mapped from the authorization when considering local access control rules. Section 6 of the OAuth Assertions draft [RFC7521], documents common scenarios for authorization including:[RFC7521]). When using other token formats or frameworks, implementers MUST take into account similar threats and countermeasures, especially those documented by the relevant specifications.
When using OAuth authorization tokens, implementers MUST take into account the threats and countermeasures documented in the security considerations for the use of client authorizations (see Section 8 of
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 Security Considerations). This enables event receivers to validate that the SET issuer is authorized to deliver SETs.
SET delivery depends on the use of Hypertext Transfer Protocol and thus subject to the security considerations of HTTP Section 9 and its related specifications.
As stated in Section 2.7.1, 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.
SETs contain sensitive information that is considered PII (e.g. subject claims). Therefore, event issuers and receivers MUST require the use of a transport-layer security mechanism. Event delivery endpoints MUST support TLS 1.2 [RFC5246] and MAY support additional transport-layer mechanisms meeting its security requirements. When using TLS, the client MUST perform a TLS/SSL server certificate check, per [RFC6125]. Implementation security considerations for TLS can be found in "Recommendations for Secure Use of TLS and DTLS" [RFC7525].
When using authorization tokens such as those issued by OAuth 2.0 [RFC6749], implementers MUST take into account threats and countermeasures documented in Section 8 of [RFC7521].
Due to the possibility of interception, Bearer tokens MUST be exchanged using TLS.
Bearer tokens MUST 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 obtain a new token (which usually involves re-authentication) for continued authorized access. For example, in OAuth2, a client MAY use OAuth token refresh to obtain a new bearer token after authenticating to an authorization server. See 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. Designating the specific methods of authentication and authorization are out-of-scope for the delivery of SET tokens, however this information is provided as a resource to implementers.
If a SET needs to be retained for audit purposes, JWS MAY be used to provide verification of its authenticity.
Event transmitters SHOULD attempt to filter SETs issued so that the content is targeted to the specific business and protocol needs of receivers.
When sharing personally identifiable information or information that is otherwise considered confidential to affected users, event transmitters and receivers MUST have the appropriate legal agreements and user consent or terms of service in place.
The propagation of subject identifiers can be perceived as personally identifiable information. Where possible, event transmitters and receivers SHOULD devise approaches that prevent propagation -- for example, the passing of a hash value that requires the subscriber to already know the subject.
There are no IANA considerations.
The editor would like to thank the participants in the the SECEVENTS working group for their support of this specification.
This specification is based on and ideally replaces draft-ietf-secevent-delivery, and we thank its contributors Annabelle Backman, Marius Scurtescu, and Morteza Ansari.
Draft 00 - PH - Original