Internet DRAFT - draft-hunt-secevent-sstp
draft-hunt-secevent-sstp
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
Abstract
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.
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
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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 September 23, 2018.
Copyright Notice
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
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to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Notational Conventions . . . . . . . . . . . . . . . . . 4
1.2. Definitions . . . . . . . . . . . . . . . . . . . . . . . 4
2. Simple SET Transfer Protocol . . . . . . . . . . . . . . . . 5
2.1. SSTP Message Format (Content-Type: application/sstp+json) 5
2.2. Examples . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2.1. Example Push Transfer . . . . . . . . . . . . . . . . 8
2.2.2. Example Pull Transfer . . . . . . . . . . . . . . . . 9
2.2.3. Example Push-Pull Bi-directional Transfer . . . . . . 13
2.3. Error Response Handling . . . . . . . . . . . . . . . . . 15
3. Authentication and Authorization . . . . . . . . . . . . . . 16
3.1. Use of Tokens as Authorizations . . . . . . . . . . . . . 17
4. Security Considerations . . . . . . . . . . . . . . . . . . . 18
4.1. Authentication Using Signed SETs . . . . . . . . . . . . 18
4.2. HTTP Considerations . . . . . . . . . . . . . . . . . . . 18
4.3. TLS Support Considerations . . . . . . . . . . . . . . . 18
4.4. Authorization Token Considerations . . . . . . . . . . . 19
4.4.1. Bearer Token Considerations . . . . . . . . . . . . . 19
5. Privacy Considerations . . . . . . . . . . . . . . . . . . . 19
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 20
7.1. Normative References . . . . . . . . . . . . . . . . . . 20
7.2. Informative References . . . . . . . . . . . . . . . . . 21
Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . 22
Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 23
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23
1. Introduction
[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:
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o SSTP is a symmetric protocol meaning it uses the same HTTP
content-type and JSON structure to send requests and process
responses
o Recovery is provided for unacknowledged SETs for short term or
missed deliveries. Issuers are able to re-transmit SETs in
situations where a SET has been unacknowledged (e.g. over more
than one request/response cycles).
o The protocol can be used for unidirectional, or bi-directional
communication avoiding the need to implement multiple delivery
methods.
o The use of HTTP Long Polling MAY be used in cases where pull or
bi-directional communication is needed in real time.
o Only one party in an exchange needs to have an addressable fixed
URI endpoint and can act as an SSTP protocol service provider to a
mobile or otherwise unrechable client.
o SET message exchanges are secured through the use of TLS and some
form of HTTP authorization (e.g. RFC6750, RFC7519), and MAY in
turn be signed and encrypted.
This specification supports the following use-cases:
Broadcaster
Where a large entity (e.g. an Identity Provider) needs to issue
SETs to a large number of relying parties.
Protected Client
Where a client party is behind a firewall or otherwise network
restricted location and cannot act as a SSTP service provider.
Examples include Enterprise on-premise security systems, IoT
devices which may be shielded in restricted network environments.
Mobile
Where a client is mobile and thus would be unable to maintain a
permanent HTTP endpoint.
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.
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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.
For purposes of readability examples are not URL encoded.
Implementers MUST percent encode URLs as described in Section 2.1 of
[RFC3986] .
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.
1.2. Definitions
This specification assumes terminology defined in the Security Event
Token specification[I-D.ietf-secevent-token] .
This specification defines the following terms:
Client An entity which acts as an HTTP client as defined by
[RFC7231] which is communicating with an SSTP server.
Server An entity which has a permanent endpoint reachable by a
client which acts as an HTTP server as defined by [RFC7231] and
supports this specification.
Event
An Event is defined to be an event as represented by a security
event token (SET). See [I-D.ietf-secevent-token].
NumericDate
A JSON numeric value representing the number of seconds from
1970-01-01T00:00:00Z UTC until the specified UTC date/time,
ignoring leap seconds. This is equivalent to the IEEE Std 1003.1,
2013 Edition [POSIX.1] definition "Seconds Since the Epoch", in
which each day is accounted for by exactly 86400 seconds, other
than that non-integer values can be represented. See [RFC3339]
for details regarding date/times in general and UTC in particular.
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2. Simple SET Transfer Protocol
SSTP is a symmetric protocol. As such an SSTP client uses HTTP POST
(Section 4.3.3 [RFC7231]) 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 [RFC6202]).
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
[RFC7231]) if a particular client is not authorized, or HTTP status
501 "Not implemented" (see Section 6.6.2 [RFC7231]) 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.
2.1. SSTP Message Format (Content-Type: application/sstp+json)
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:
Request Handling:
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returnEvents
A JSON boolean parameter which indicates whether the receiver
SHOULD return SETs in its upcoming response. When part of an HTTP
Request, it indicates the SSTP server SHOULD return with SETs in
its response (and optionally wait). When asserted as "false" by
an SSTP server in its response, it indicates that the SSTP server
is not requesting SETs in the next client request. If omitted,
this attribute SHALL have a default value of "true".
returnImmediately
An OPTIONAL JSON boolean value which when "true" has the effect of
declining HTTP long polling. A value of "false" indicates the
request is to be treated as an HTTP Long Poll (see Section 2
[RFC6202]). When asserted in an HTTP response, the value
indicates the SSTP has more information and the client SHOULD NOT
wait before initiating its next request. When omitted, the
default value of "false" SHALL be assumed.
Delivery:
sets
A JSON object that contains one or more nested JSON attributes.
Each nested attribute corresponds to the "jti" of a SET to be
delivered and whose value is a JSON String containing the value of
the encoded corresponding SET. If there are no SETs to be
transmitted, the attribute MAY be omitted.
Acknowledgment:
ack
An array of Strings that each correspond to the "jti" of a
successfully received SET by the client. If there are no
outstanding SETs to acknowledge, the attribute MAY be omitted.
When acknowledging a SET, the issuer is released from any
obligation to retain the SET (e.g. for a future re-try).
setErrs
A JSON Object that contains one or more nested JSON attributes
that correspond to the "jti" of each invalid SET received. The
value of each is a JSON object whose contents is an "err"
attribute and "description" attribute whose value correspond to
the errors described in Section 2.3. If there are no errors to
acknowledge, the attribute MAY be omitted.
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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
2.2. Examples
Three examples are provided where:
o A client pushes SETs to a server using the "sets" JSON attribute
in its request and receives "ack" values in response from the SSTP
server.
o A polling client that requests SETs from a a server and uses the
"ack" parameter in its request to acknowledge SETs from a previous
HTTP request, and receives new SETs in the response.
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o A client and SSTP server bi-directionally exchange SETs using both
the "sets" and "ack" JSON attributes in both the request and
response messages.
2.2.1. Example Push Transfer
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.
eyJqdGkiOiIzZDBjM2NmNzk3NTg0YmQxOTNiZDBmYjFiZDRlN2QzMCIsImlhdCI6MTQ
1ODQ5NjAyNSwiaXNzIjoiaHR0cHM6Ly9zY2ltLmV4YW1wbGUuY29tIiwiYXVkIjpbIm
h0dHBzOi8vamh1Yi5leGFtcGxlLmNvbS9GZWVkcy85OGQ1MjQ2MWZhNWJiYzg3OTU5M
2I3NzU0IiwiaHR0cHM6Ly9qaHViLmV4YW1wbGUuY29tL0ZlZWRzLzVkNzYwNDUxNmIx
ZDA4NjQxZDc2NzZlZTciXSwic3ViIjoiaHR0cHM6Ly9zY2ltLmV4YW1wbGUuY29tL1V
zZXJzLzQ0ZjYxNDJkZjk2YmQ2YWI2MWU3NTIxZDkiLCJldmVudHMiOnsidXJuOmlldG
Y6cGFyYW1zOnNjaW06ZXZlbnQ6cGFzc3dvcmRSZXNldCI6eyJpZCI6IjQ0ZjYxNDJkZ
jk2YmQ2YWI2MWU3NTIxZDkifSwiaHR0cHM6Ly9leGFtcGxlLmNvbS9zY2ltL2V2ZW50
L3Bhc3N3b3JkUmVzZXRFeHQiOnsicmVzZXRBdHRlbXB0cyI6NX19fQ."
}
}
Figure 2: Example Push Request
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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
2.2.2. Example Pull Transfer
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
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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.
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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
2.2.2.1. Acknowledge Only Request
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
2.2.2.2. Poll with Acknowledgement
This variation allows a client to simultaneously acknowledge
previously received SETs and wait for the next group of SETs in a
single HTTP request.
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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
2.2.2.3. Pull with Acknowledgement and 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.
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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
2.2.3. Example Push-Pull Bi-directional Transfer
In push-pull mode, JSON attributes "sets", "ack" and "setErrs" are
used in both HTTP request and response messages between client and
SSTP server.
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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
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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".
2.3. Error Response Handling
If a SET is invalid, the following error codes are defined:
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+-------------+-----------------------------------------------------+
| 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. |
+-------------+-----------------------------------------------------+
Table 1: SET Errors
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:
err
A value which is a keyword that describes the error (see Table 1).
description
A human-readable text that provides additional diagnostic
information.
When included as part of an HTTP Status 400 response, the above JSON
is the HTTP response body in the JSON attribute "setErrs" (see
Section 2.1).
3. Authentication and Authorization
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:
TLS Client Authentication
SSTP server MAY negotiate TLS mutual client authentication. See
Section 7.3 [RFC5246].
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Bearer Tokens
Bearer tokens [RFC6750] MAY be used when combined with TLS and a
token framework such as OAuth 2.0 [RFC6749]. For security
considerations regarding the use of bearer tokens in SET delivery
see Section 4.4.1.
Basic Authentication
Usage of basic authentication should be avoided due to its use of
a single factor that is based upon a relatively static, symmetric
secret. Implementers SHOULD combine the use of basic
authentication with other factors. The security considerations of
HTTP BASIC, are well documented in [RFC7617] and SHOULD be
considered along with using signed SETs (see SET Payload
Authentication below).
SET Payload Authentication
In scenarios where SETs are signed and the delivery method is HTTP
POST, SSTP clients MAY elect to use Basic Authentication or not to
use HTTP or TLS based authentication at all. See Section 4.1 for
considerations.
As per Section 4.1 of [RFC7235], 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.
3.1. Use of Tokens as Authorizations
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
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Assertions draft [RFC7521], documents common scenarios for
authorization including:
o Clients using an assertion to authenticate and/or act on behalf of
itself;
o Clients acting on behalf of a user; and,
o A Client acting on behalf of an anonymous user (e.g., see next
section).
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
[RFC7521]). When using other token formats or frameworks,
implementers MUST take into account similar threats and
countermeasures, especially those documented by the relevant
specifications.
4. Security Considerations
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 Security Considerations
[I-D.ietf-secevent-token]). This enables event receivers to validate
that the SET issuer is authorized to deliver SETs.
4.2. HTTP Considerations
SET delivery depends on the use of Hypertext Transfer Protocol and
thus subject to the security considerations of HTTP Section 9
[RFC7230] and its related specifications.
As stated in Section 2.7.1 [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. TLS Support Considerations
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
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check, per [RFC6125]. Implementation security considerations for TLS
can be found in "Recommendations for Secure Use of TLS and DTLS"
[RFC7525].
4.4. Authorization Token Considerations
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].
4.4.1. Bearer Token Considerations
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.
5. Privacy Considerations
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
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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.
6. IANA Considerations
There are no IANA considerations.
7. References
7.1. Normative References
[I-D.ietf-secevent-token]
Hunt, P., Jones, M., Denniss, W., and M. Ansari, "Security
Event Token (SET)", draft-ietf-secevent-token-07 (work in
progress), March 2018.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005,
<https://www.rfc-editor.org/info/rfc3986>.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246,
DOI 10.17487/RFC5246, August 2008,
<https://www.rfc-editor.org/info/rfc5246>.
[RFC5988] Nottingham, M., "Web Linking", RFC 5988,
DOI 10.17487/RFC5988, October 2010,
<https://www.rfc-editor.org/info/rfc5988>.
[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, <https://www.rfc-editor.org/info/rfc6125>.
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[RFC7159] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March
2014, <https://www.rfc-editor.org/info/rfc7159>.
[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,
<https://www.rfc-editor.org/info/rfc7231>.
[RFC7519] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token
(JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015,
<https://www.rfc-editor.org/info/rfc7519>.
[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, <https://www.rfc-editor.org/info/rfc7525>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
7.2. Informative References
[openid-connect-core]
NRI, "OpenID Connect Core 1.0", Nov 2014.
[POSIX.1] Institute of Electrical and Electronics Engineers, "The
Open Group Base Specifications Issue 7", IEEE Std 1003.1,
2013 Edition, 2013.
[RFC3339] Klyne, G. and C. Newman, "Date and Time on the Internet:
Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002,
<https://www.rfc-editor.org/info/rfc3339>.
[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,
<https://www.rfc-editor.org/info/rfc6202>.
[RFC6749] Hardt, D., Ed., "The OAuth 2.0 Authorization Framework",
RFC 6749, DOI 10.17487/RFC6749, October 2012,
<https://www.rfc-editor.org/info/rfc6749>.
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[RFC6750] Jones, M. and D. Hardt, "The OAuth 2.0 Authorization
Framework: Bearer Token Usage", RFC 6750,
DOI 10.17487/RFC6750, October 2012,
<https://www.rfc-editor.org/info/rfc6750>.
[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,
<https://www.rfc-editor.org/info/rfc7230>.
[RFC7235] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Authentication", RFC 7235,
DOI 10.17487/RFC7235, June 2014,
<https://www.rfc-editor.org/info/rfc7235>.
[RFC7515] Jones, M., Bradley, J., and N. Sakimura, "JSON Web
Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May
2015, <https://www.rfc-editor.org/info/rfc7515>.
[RFC7516] Jones, M. and J. Hildebrand, "JSON Web Encryption (JWE)",
RFC 7516, DOI 10.17487/RFC7516, May 2015,
<https://www.rfc-editor.org/info/rfc7516>.
[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, <https://www.rfc-editor.org/info/rfc7521>.
[RFC7617] Reschke, J., "The 'Basic' HTTP Authentication Scheme",
RFC 7617, DOI 10.17487/RFC7617, September 2015,
<https://www.rfc-editor.org/info/rfc7617>.
[saml-core-2.0]
Internet2, "Assertions and Protocols for the OASIS
Security Assertion Markup Language (SAML) V2.0", March
2005.
Appendix A. Acknowledgments
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.
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Appendix B. Change Log
Draft 00 - PH - Original
Authors' Addresses
Phil Hunt (editor)
Oracle Corporation
Email: phil.hunt@yahoo.com
Anthony Nadalin
Microsoft
Email: tonynad@microsoft.com
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