Internet DRAFT - draft-scurtescu-secevent-event-stream-mgmt-api
draft-scurtescu-secevent-event-stream-mgmt-api
secevent M. Scurtescu
Internet-Draft Google
Intended status: Informational A. Backman
Expires: February 11, 2018 Amazon
August 10, 2017
Management API for SET Event Streams
draft-scurtescu-secevent-event-stream-mgmt-api-00
Abstract
Security Event Token (SET) delivery requires event receivers to
indicate to event transmitters the subjects about which they wish to
receive events, and how they wish to receive them. This
specification defines an HTTP API for a basic control plane that
event transmitters can implement and event receivers may use to
manage the flow of events from one to the other.
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 http://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 February 11, 2018.
Copyright Notice
Copyright (c) 2017 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
(http://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
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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
2. Notational Conventions . . . . . . . . . . . . . . . . . . . 3
3. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Event Stream Management . . . . . . . . . . . . . . . . . . . 3
4.1. Stream Configuration . . . . . . . . . . . . . . . . . . 4
4.1.1. Checking a Stream's Status . . . . . . . . . . . . . 5
4.1.2. Reading a Stream's Configuration . . . . . . . . . . 6
4.1.3. Updating a Stream's Configuration . . . . . . . . . . 7
4.2. Subjects . . . . . . . . . . . . . . . . . . . . . . . . 9
4.2.1. Adding a Subject to a Stream . . . . . . . . . . . . 10
4.2.2. Removing a Subject . . . . . . . . . . . . . . . . . 11
4.3. Verification . . . . . . . . . . . . . . . . . . . . . . 13
4.3.1. Verification Event . . . . . . . . . . . . . . . . . 13
4.3.2. Triggering a Verification Event. . . . . . . . . . . 13
5. Security Considerations . . . . . . . . . . . . . . . . . . . 15
5.1. Subject Probing . . . . . . . . . . . . . . . . . . . . . 15
5.2. Information Harvesting . . . . . . . . . . . . . . . . . 16
5.3. Malicious Subject Removal . . . . . . . . . . . . . . . . 16
6. Normative References . . . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17
1. Introduction
This specification defines an HTTP API to be implemented by Event
Transmitters and that can be used by Event Receivers to query the
Event Stream status, to add and remove subjects and to trigger
verification.
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+------------+ +------------+
| | Stream Config | |
| Event <----------------+ Event |
| Stream | | Receiver |
| Management | Stream Status | |
| API <----------------+ |
| | | |
| | Add Subject | |
| <----------------+ |
| | | |
| | Remove Subject | |
| <----------------+ |
| | | |
| | Verification | |
| <----------------+ |
| | | |
+------------+ +------------+
Figure 1: Event Stream Management API
How events are delivered and the structure of events are not in scope
for this specification.
2. Notational Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
3. Definitions
In addition to terms defined in [SET], this specification uses the
following terms:
Subject Identifier Object
A JSON object containing a set of one or more claims about a
subject that when taken together uniquely identify that subject.
This set of claims SHOULD be declared as an acceptable way to
identify subjects of SETs by one or more specifications that
profile [SET].
4. Event Stream Management
Event Receivers manage how they receive events, and the subjects
about which they want to receive events over an Event Stream by
making HTTP requests to endpoints in the Event Stream Management API.
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The Event Stream Management API is implemented by the Event
Transmitter and consists of the following endpoints:
Configuration Endpoint
An endpoint used to read the Event Stream's current configuration.
Status Endpoint
An endpoint used to read the Event Stream's current status.
Add Subject Endpoint
An endpoint used to add subjects to an Event Stream.
Remove Subject Endpoint
An endpoint used to remove subjects from an Event Stream.
Verification Endpoint
An endpoint used to request the Event Transmitter transmit a
Verification Event over the Event Stream.
An Event Transmitter MAY use the same URLs as endpoints for multiple
streams, provided that the Event Transmitter has some mechanism
through which they can identify the applicable Event Stream for any
given request, e.g. from authentication credentials. The definition
of such mechanisms is outside the scope of this specification.
4.1. Stream Configuration
An Event Stream's configuration is represented as a JSON object with
the following properties:
aud
A string containing an audience claim as defined in JSON Web Token
(JWT) [RFC7519] that identifies the Event Receiver for the Event
Stream. This property cannot be updated.
events
OPTIONAL. An array of URIs identifying the set of events which
MAY be delivered over the Event Stream. If omitted, Event
Transmitters SHOULD make this set available to the Event Receiver
via some other means (e.g. publishing it in online
documentation).
delivery
A JSON object containing a set of name/value pairs specifying
configuration parameters for the SET delivery method. The actual
delivery method is identified by the special key "delivery_method"
with the value being a URI as defined in [DELIVERY].
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min_verification_interval
An integer indicating the minimum amount of time in seconds that
must pass in between verification requests. If an Event Receiver
submits verification requests more frequently than this, the Event
Transmitter MAY respond with a 429 status code. An Event
Transmitter SHOULD NOT respond with a 429 status code if an Event
Receiver is not exceeding this frequency.
status
A string indicating the current status of the event stream. It
MUST have one of the following values:
enabled
The transmitter will transmit events over the stream, according
to the stream's configured delivery method.
paused
The transmitter will not transmit events over the stream. The
transmitter will hold any events it would have transmitted
while paused, and will transmit them when the stream's status
becomes "enabled".
disabled
The transmitter will not transmit events over the stream, and
will not hold any events for later transmission.
4.1.1. Checking a Stream's Status
An Event Receiver checks the current status of an event stream by
making an HTTP GET request to the stream's Status Endpoint. On
receiving a valid request the Event Transmitter responds with a 200
OK response containing a [JSON] object with a single attribute
"status", whose string value is the value of the stream's status.
The following is a non-normative example request to check an event
stream's status:
GET /set/stream/status HTTP/1.1
Host: transmitter.example.com
Authorization: Bearer eyJ0b2tlbiI6ImV4YW1wbGUifQo=
Figure 2: Example: Check Stream Status Request
The following is a non-normative example response:
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HTTP/1.1 200 OK
Content-Type: application/json; charset=UTF-8
Cache-Control: no-store
Pragma: no-cache
{
"status": "enabled"
}
Figure 3: Example: Check Stream Status Response
4.1.2. Reading a Stream's Configuration
An Event Receiver gets the current configuration of a stream by
making an HTTP GET request to the Configuration Endpoint. On
receiving a valid request the Event Transmitter responds with a 200
OK response containing a [JSON] representation of the stream's
configuration in the body.
The following is a non-normative example request to read an Event
Stream's configuration:
GET /set/stream HTTP/1.1
Host: transmitter.example.com
Authorization: Bearer eyJ0b2tlbiI6ImV4YW1wbGUifQo=
Figure 4: Example: Read Stream Configuration Request
The following is a non-normative example response:
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HTTP/1.1 200 OK
Content-Type: application/json; charset=UTF-8
Cache-Control: no-store
Pragma: no-cache
{
"aud": "http://www.example.com",
"delivery": {
"delivery_method": "urn:example:secevent:delivery:http_post",
"url": "https://receiver.example.com/events"
},
"status": "enabled",
"events": [
"urn:example:secevent:events:type_1",
"urn:example:secevent:events:type_2",
"urn:example:secevent:events:type_3"
],
"min_verification_interval": 60,
}
Figure 5: Example: Read Stream Configuration Response
Errors are signaled with HTTP staus codes as follows:
+------+------------------------------------------------------------+
| Code | Description |
+------+------------------------------------------------------------+
| 401 | if authorization failed or it is missing |
| | |
| 403 | if the Event Receiver is not allowed to read the stream |
| | configuration |
| | |
| 404 | if there is no Event Stream configured for this Event |
| | Receiver |
+------+------------------------------------------------------------+
Table 1: Read Stream Configuration Errors
4.1.3. Updating a Stream's Configuration
An Event Receiver updates the current configuration of a stream by
making an HTTP POST request to the Configuration Endpoint. The POST
body contains a {{!JSON} representation of the updated configuration.
On receiving a valid request the Event Transmitter responds with a
200 OK response containing a [JSON] representation of the updated
stream configuration in the body.
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The full set of editable properties must be present in the POST body,
not only the ones that are specifically intended to be changed.
Missing properties SHOULD be interpreted as requested to be deleted.
Event Receivers should read the configuration first, modify the
[JSON] representation, then make an update request.
Properties that cannot be updated MAY be present, but they MUST match
the expected value.
The following is a non-normative example request to read an Event
Stream's configuration:
POST /set/stream HTTP/1.1
Host: transmitter.example.com
Authorization: Bearer eyJ0b2tlbiI6ImV4YW1wbGUifQo=
{
"aud": "http://www.example.com",
"delivery": {
"delivery_method": "urn:example:secevent:delivery:http_post",
"url": "https://receiver.example.com/events"
},
"status": "paused",
"events": [
"urn:example:secevent:events:type_1",
"urn:example:secevent:events:type_2",
"urn:example:secevent:events:type_3"
]
}
Figure 6: Example: Update Stream Configuration Request
The following is a non-normative example response:
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HTTP/1.1 200 OK
Content-Type: application/json; charset=UTF-8
Cache-Control: no-store
Pragma: no-cache
{
"aud": "http://www.example.com",
"delivery": {
"delivery_method": "urn:example:secevent:delivery:http_post",
"url": "https://receiver.example.com/events"
},
"status": "paused",
"events": [
"urn:example:secevent:events:type_1",
"urn:example:secevent:events:type_2",
"urn:example:secevent:events:type_3"
]
}
Figure 7: Example: Update Stream Configuration Response
Errors are signaled with HTTP staus codes as follows:
+------+------------------------------------------------------------+
| Code | Description |
+------+------------------------------------------------------------+
| 400 | if the request body cannot be parsed or if the request is |
| | otherwise invalid |
| | |
| 401 | if authorization failed or it is missing |
| | |
| 403 | if the Event Receiver is not allowed to update the stream |
| | configuration |
+------+------------------------------------------------------------+
Table 2: Update Stream Configuration Errors
4.2. Subjects
An Event Receiver can indicate to an Event Transmitter whether or not
the receiver wants to receive events about a particular subject by
"adding" or "removing" that subject to the Event Stream,
respectively.
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4.2.1. Adding a Subject to a Stream
To add a subject to an Event Stream, the Event Receiver makes an HTTP
POST request to the Add Subject Endpoint, containing in the body a
Subject Identifier Object identifying the subject to be added. On a
successful response, the Event Transmitter responds with an empty 200
OK response.
The Event Transmitter MAY choose to silently ignore the request, for
example if the subject has previously indicated to the transmitter
that they do not want events to be transmitted to the Event Receiver.
In this case, the transmitter MAY return an empty 200 OK response or
an appropriate error code (See Security Considerations (Section 5)).
Errors are signaled with HTTP staus codes as follows:
+------+------------------------------------------------------------+
| Code | Description |
+------+------------------------------------------------------------+
| 400 | if the request body cannot be parsed or if the request is |
| | otherwise invalid |
| | |
| 401 | if authorization failed or it is missing |
| | |
| 403 | if the Event Receiver is not allowed to add this |
| | particular subject |
| | |
| 404 | if the subject is not recognized by the Event Transmitter, |
| | the Event Transmitter may chose to stay silent in this |
| | case and respond with 200 |
| | |
| 429 | if the Event Receiver is sending too many requests in a |
| | gvien amount of time |
+------+------------------------------------------------------------+
Table 3: Add Subject Errors
The following is a non-normative example request to add a subject to
a stream, where the subject is identified by an OpenID Connect email
claim:
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POST /set/subjects:add HTTP/1.1
Host: transmitter.example.com
Authorization: Bearer eyJ0b2tlbiI6ImV4YW1wbGUifQo=
{
"email": "example.user@example.com"
}
Figure 8: Example: Add Subject Request
The following is a non-normative example response to a successful
request:
HTTP/1.1 200 OK
Server: transmitter.example.com
Cache-Control: no-store
Pragma: no-cache
Figure 9: Example: Add Subject Response
4.2.2. Removing a Subject
To remove a subject from an Event Stream, the Event Receiver makes an
HTTP POST request to the Remove Subject Endpoint, containing in the
body a Subject Identifier Object identifying the subject to be
removed. On a successful response, the Event Transmitter responds
with a 204 No Content response.
Errors are signaled with HTTP staus codes as follows:
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+------+------------------------------------------------------------+
| Code | Description |
+------+------------------------------------------------------------+
| 400 | if the request body cannot be parsed or if the request is |
| | otherwise invalid |
| | |
| 401 | if authorization failed or it is missing |
| | |
| 403 | if the Event Receiver is not allowed to remove this |
| | particular subject |
| | |
| 404 | if the subject is not recognized by the Event Transmitter, |
| | the Event Transmitter may chose to stay silent in this |
| | case and respond with 204 |
| | |
| 429 | if the Event Receiver is sending too many requests in a |
| | gvien amount of time |
+------+------------------------------------------------------------+
Table 4: Remove Subject Errors
The following is a non-normative example request where the subject is
identified by a phone_number claim:
POST /set/subjects:remove HTTP/1.1
Host: transmitter.example.com
Authorization: Bearer eyJ0b2tlbiI6ImV4YW1wbGUifQo=
{
"phone_number": "+1 206 555 0123"
}
Figure 10: Example: Remove Subject Request
The following is a non-normative example response to a successful
request:
HTTP/1.1 204 No Content
Server: transmitter.example.com
Cache-Control: no-store
Pragma: no-cache
Figure 11: Example: Remove Subject Response
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4.3. Verification
In some cases, the frequency of event transmission on an Event Stream
will be very low, making it difficult for an Event Receiver to tell
the difference between expected behavior and event transmission
failure due to a misconfigured stream. Event Receivers can request
that a verification event be transmitted over the Event Stream,
allowing the receiver to confirm that the stream is configured
correctly upon successful receipt of the event. The acknowledgment
of a Verification Event also confirms to the Event Transmitter that
end-to-end delivery is working, including signature verification and
encryption.
An Event Transmitter MAY send a Verification Event at any time, even
if one was not requested by the Event Receiver.
4.3.1. Verification Event
The Verification Event is a standard SET with the following
attributes:
event type
The Event Type URI is: "urn:ietf:params:secevent:event-
type:core:verification".
state
OPTIONAL An opaque value provided by the Event Receiver when the
event is triggered. This is a nested attribute in the event
payload.
Upon receiving a Verification Event, the Event Receiver SHALL parse
the SET and validate its claims. In particular, the Event Receiver
SHALL confirm that the value for "state" is as expected. If the
value of "state" does not match, an error response of "setData"
SHOULD be returned (see Section 2.4 of [DELIVERY]).
In many cases, Event Transmitters MAY disable or suspend an Event
Stream that fails to successfully verify based on the acknowledgement
or lack of acknowledgement by the Event Receiver.
4.3.2. Triggering a Verification Event.
To request that a verification event be sent over an Event Stream,
the Event Receiver makes an HTTP POST request to the Verification
Endpoint, with a JSON object containing the parameters of the
verification request, if any. On a successful request, the event
transmitter responds with an empty 204 No Content response.
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Verification requests have the following properties:
state
OPTIONAL. An arbitrary string that the Event Transmitter MUST
echo back to the Event Receiver in the verification event's
payload. Event Receivers MAY use the value of this parameter to
correlate a verification event with a verification request. If
the verification event is initiated by the transmitter then this
parameter MUST not be set.
A successful response from a POST to the Verification Endpoint does
not indicate that the verification event was transmitted
successfully, only that the Event Transmitter has transmitted the
event or will do so at some point in the future. Event Transmitters
MAY transmit the event via an asynchronous process, and SHOULD
publish an SLA for verification event transmission times. Event
Receivers MUST NOT depend on the verification event being transmitted
synchronously or in any particular order relative to the current
queue of events.
Errors are signaled with HTTP staus codes as follows:
+------+------------------------------------------------------------+
| Code | Description |
+------+------------------------------------------------------------+
| 400 | if the request body cannot be parsed or if the request is |
| | otherwise invalid |
| | |
| 401 | if authorization failed or it is missing |
| | |
| 429 | if the Event Receiver is sending too many requests in a |
| | gvien amount of time |
+------+------------------------------------------------------------+
Table 5: Verification Errors
The following is a non-normative example request to trigger a
verification event:
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POST /set/verify HTTP/1.1
Host: transmitter.example.com
Authorization: Bearer eyJ0b2tlbiI6ImV4YW1wbGUifQo=
Content-Type: application/json; charset=UTF-8
{
"state": "VGhpcyBpcyBhbiBleGFtcGxlIHN0YXRlIHZhbHVlLgo="
}
Figure 12: Example: Trigger Verification Request
The following is a non-normative example response to a successful
request:
HTTP/1.1 204 No Content
Server: transmitter.example.com
Cache-Control: no-store
Pragma: no-cache
Figure 13: Example: Trigger Verification Response
And the following is a non-normative example of a verification event
sent to the Event Receiver as a result of the above request:
{
"jti": "123456",
"iss": "https://transmitter.example.com",
"aud": "receiver.example.com",
"iat": "1493856000",
"events": [
"urn:ietf:params:secevent:event-type:core:verification" : {
"state": "VGhpcyBpcyBhbiBleGFtcGxlIHN0YXRlIHZhbHVlLgo=",
},
],
}
Figure 14: Example: Verification SET
5. Security Considerations
5.1. Subject Probing
It may be possible for an Event Transmitter to leak information about
subjects through their responses to add subject requests. A 404
response may indicate to the Event Receiver that the subject does not
exist, which may inadvertantly reveal information about the subject
(e.g. that a particular individual does or does not use the Event
Transmitter's service).
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Event Transmitters SHOULD carefully evaluate the conditions under
which they will return error responses to add subject requests.
Event Transmitters MAY return a 204 response even if they will not
actually send any events related to the subject, and Event Receivers
MUST NOT assume that a 204 response means that they will receive
events related to the subject.
5.2. Information Harvesting
SETs may contain personally identifiable information (PII) or other
non-public information about the event transmitter, the subject (of
an event in the SET), or the relationship between the two. It is
important for Event Transmitters to understand what information they
are revealing to Event Receivers when transmitting events to them,
lest the event stream become a vector for unauthorized access to
private information.
Event Transmitters SHOULD interpret add subject requests as
statements of interest in a subject by an Event Receiver, and ARE NOT
obligated to transmit events related to every subject an Event
Receiver adds to the stream. Event Transmitters MAY choose to
transmit some, all, or no events related to any given subject and
SHOULD validate that they are permitted to share the information
contained within an event with the Event Receiver before transmitting
the event. The mechanisms by which such validation is performed are
outside the scope of this specification.
5.3. Malicious Subject Removal
A malicious party may find it advantageous to remove a particular
subject from a stream, in order to reduce the Event Receiver's
ability to detect malicious activity related to the subject,
inconvenience the subject, or for other reasons. Consequently it may
be in the best interests of the subject for the Event Transmitter to
continue to send events related to the subject for some time after
the subject has been removed from a stream.
Event Transmitters MAY continue sending events related to a subject
for some amount of time after that subject has been removed from the
stream. Event Receivers MUST tolerate receiving events for subjects
that have been removed from the stream, and MUST NOT report these
events as errors to the Event Transmitter.
6. Normative References
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[DELIVERY]
"SET Token Delivery Using HTTP", n.d., <https://github
.com/independentid/Identity-Events/blob/master/draft-hunt-
secevent-delivery.txt>.
[JSON] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March
2014, <http://www.rfc-editor.org/info/rfc7159>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/
RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC7519] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token
(JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015,
<http://www.rfc-editor.org/info/rfc7519>.
[SET] "Security Event Token (SET)", n.d., <https://tools.ietf
.org/html/draft-ietf-secevent-token-01>.
Authors' Addresses
Marius Scurtescu
Google
Email: mscurtescu@google.com
Annabelle Backman
Amazon
Email: richanna@amazon.com
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