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Versions: (draft-hunt-idevent-token) 00

Security Events Working Group                               P. Hunt, Ed.
Internet-Draft                                                    Oracle
Intended status: Standards Track                              W. Denniss
Expires: July 27, 2017                                            Google
                                                               M. Ansari
                                                                   Cisco
                                                                M. Jones
                                                               Microsoft
                                                        January 23, 2017


                       Security Event Token (SET)
                      draft-ietf-secevent-token-00

Abstract

   This specification defines the Security Event Token, which may be
   distributed via a protocol such as HTTP.  The Security Event Token
   (SET) specification profiles the JSON Web Token (JWT) and may be
   optionally signed and/or encrypted.  A SET describes a statement of
   fact that may be shared by an event publisher with event subscribers.

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 July 27, 2017.

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



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   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  . . . . . . . . . . . . . . . . .   4
     1.2.  Definitions . . . . . . . . . . . . . . . . . . . . . . .   4
   2.  The Security Event Token (SET)  . . . . . . . . . . . . . . .   5
     2.1.  Core SET Claims . . . . . . . . . . . . . . . . . . . . .   8
     2.2.  Security Event Token Construction . . . . . . . . . . . .  10
   3.  Security Considerations . . . . . . . . . . . . . . . . . . .  12
     3.1.  Confidentiality and Integrity . . . . . . . . . . . . . .  12
     3.2.  Delivery  . . . . . . . . . . . . . . . . . . . . . . . .  13
     3.3.  Sequencing  . . . . . . . . . . . . . . . . . . . . . . .  13
     3.4.  Timing Issues . . . . . . . . . . . . . . . . . . . . . .  13
     3.5.  Distinguishing SETs from Access Tokens  . . . . . . . . .  14
   4.  Privacy Considerations  . . . . . . . . . . . . . . . . . . .  14
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  15
     5.1.  JSON Web Token Claims Registration  . . . . . . . . . . .  15
       5.1.1.  Registry Contents . . . . . . . . . . . . . . . . . .  15
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  15
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .  15
     6.2.  Informative References  . . . . . . . . . . . . . . . . .  16
   Appendix A.  Acknowledgments  . . . . . . . . . . . . . . . . . .  17
   Appendix B.  Change Log . . . . . . . . . . . . . . . . . . . . .  17
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  18

1.  Introduction and Overview

   This specification defines an extensible Security Event Token (SET)
   format which may be exchanged using protocols such as HTTP.  The
   specification builds on the JSON Web Token (JWT) format [RFC7519] in
   order to provide a self-contained token that can be optionally signed
   using JSON Web Signature (JWS) [RFC7515] and/or encrypted using JSON
   Web Encryption (JWE) [RFC7516].

   For the purpose of this specification, an event is a statement of
   fact by a publisher (also known as the event issuer) that the state
   of a security subject (e.g., a web resource, token, IP address) it
   controls or is aware of, has changed in some way (explicitly or
   implicitly).  A security subject may be permanent (e.g., a user
   account) or temporary (e.g., an HTTP session) in nature.  A state
   change may include direct changes of entity state, implicit changes
   to state or other higher-level security statements such as:



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   o  The creation, modification, removal of a resource.

   o  The resetting or suspension of an account.

   o  The revocation of a security token prior to its expiry.

   o  The logout of a user session.  Or,

   o  A cumulative conclusion such as to indicate that a user has taken
      over an email identifier that may have been used in the past by
      another user.

   Based on some externally agreed criteria for an event feed, the
   publisher distributes events to the appropriate subscribers of a
   feed.  While an event may be delivered via synchronous means (e.g.,
   HTTP POST), the distribution of the event often happens
   asynchronously to the change of state which generated the security
   event.  As an example, an OAuth2 Authorization Server [RFC6749],
   having received a token revocation request [RFC7009], may issue a
   token revocation event to downstream web resource providers.  Having
   been informed of a token revocation, the OAuth2 web resource service
   provider may add the token identifier to its local revocation list
   assuming the token has not already expired.

   A subscriber having received an event, validates and interprets the
   event and takes its own independent action, if any.  For example,
   having been informed of a personal identifier now being associated
   with a different security subject (i.e., is being used by someone
   else), the subscriber may choose to ensure that the new user is not
   granted access to resources associated with the previous user.  Or it
   may not have any relationship with the subject, and no action is
   taken.

   While subscribers will often take actions upon receiving one or more
   events, events MUST NOT be assumed to be commands or requests.  To do
   so requires complex bi-directional signals and error recovery
   mechanisms that fall outside the scope of this specification.  The
   intent of this specification is to define a way of exchanging
   statements of fact that subscribers may interpret for their own
   purposes.  Since events are typically historical statements by a
   publisher and are not commands, idempotency or lack thereof, does not
   apply.

   Unless otherwise specified, this specification uses example events
   intended to serve as non-normative examples showing how an event may
   be constructed.  It is expected that other "profiling" specifications
   will use this specification to define normative events within some
   specified context or protocol.



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   This specification is scoped to security and identity related events.
   While security event tokens may be used for other purposes, the
   specification only considers security and privacy concerns relevant
   to identity and personal information.

1.1.  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].  These
   keywords are capitalized when used to unambiguously specify
   requirements of the protocol or application features and behavior
   that affect the inter-operability and security of implementations.
   When these words are not capitalized, they are meant in their
   natural-language sense.

   For purposes of readability, examples are not URL encoded.
   Implementers MUST percent encode URLs as described in Section 2.1 of
   [RFC3986].

   Throughout this document, all figures MAY contain spaces and extra
   line-wrapping for readability and space limitations.  Similarly, some
   URIs contained within examples have been shortened for space and
   readability reasons.

1.2.  Definitions

   The following definitions are used with SETs:

   Feed Publisher
      The Feed Publisher creates SETs to be distributed to registered
      subscribers.  In JWT terminology, the Feed Publisher is also known
      as the issuer ("iss").

   Security Event Token (SET)
      An SET is a JWT that is to be distributed to one or more
      registered subscribers.  A SET MAY be signed or encrypted using
      JWS and/or JWE for authentication and confidentiality reasons.

   Feed
      A Feed is a logical grouping of SETs or a context under which SETs
      may be issued.  A Subscriber registers with the Feed Publisher to
      subscribe to SETs associated with a Feed.  How a Feed is defined
      or the method for subscription is out-of-scope of this
      specification.

   Subscriber




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      A Subscriber registers to receive SETs from a Feed Publisher using
      a protocol such as HTTP.  The method of registration and delivery
      is out-of-scope of this specification.

   Security Subject
      A Security Subject is the entity to which a SET refers.  A
      Security Subject may be a principle (e.g., Section 4.1.2
      [RFC7519]), a web resource, or other thing such as an IP address
      that a SET might reference.

2.  The Security Event Token (SET)

   A SET conveys a statement (in the form of a JWT [RFC7519]) about a
   single security event in relation to a Security Subject that may be
   of interest to a Subscriber or set of Subscribers receiving SETs from
   a Feed Publisher.

   The schema and structure of a SET follows the JWT [RFC7519]
   specification.  A SET has the following structure:

   o  An outer JSON structure that acts as the SET envelope.  The
      envelope contains a set of name/value pairs called the JWT Claims
      Set, typically common to every SET or common to a number of
      different Security Events within a single profiling specification
      or a related series of specifications.  Claims in the envelope
      SHOULD be registered in the JWT Token Claims Registry Section 10.1
      [RFC7519] or be Public Claims or Private Claims as also defined in
      [RFC7519].

   o  Envelope claims that are profiled and defined in this
      specification are used to validate a SET and declare the event
      data included in the SET.  The claim "events" identifies the
      security event types being expressed related to the Security
      Subject and MAY also include event-specific data.

   o  Each JSON member of the "events" object is a name/value pair.  The
      JSON attribute name is a URI String value that expresses an event
      type.  The corresponding value is a JSON object known as the event
      "payload".  The payload JSON object contains claims typically
      unique to the event's URI type value and are not registered as JWT
      claims.  These claims are defined by their associated event
      specification.  An event with no payload claims SHALL be
      represented as the empty JSON object ("{}").  In many cases, one
      event URI expresses the primary event URI, while other events
      might be considered extensions that MAY be used to do things such
      as:





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      *  A categorization event type to provide classification
         information (e.g., threat type or level).

      *  An enhancement of an existing specifications the arise over
         time.

      *  An extensions needed to link a potential series of events.

      *  Localized specific purpose extensions needed between a
         particular publisher and subscriber.

   The following is a non-normative example showing the JWT Claims Set
   for a hypothetical SCIM password reset SET.  This example shows an
   extension ("https://example.com/scim/event/passwordResetExt") that is
   used to convey additional information -- in this case, the current
   count of reset attempts:

   {
     "jti": "3d0c3cf797584bd193bd0fb1bd4e7d30",
     "iat": 1458496025,
     "iss": "https://scim.example.com",
     "aud": [
       "https://jhub.example.com/Feeds/98d52461fa5bbc879593b7754",
       "https://jhub.example.com/Feeds/5d7604516b1d08641d7676ee7"
     ],
     "sub": "https://scim.example.com/Users/44f6142df96bd6ab61e7521d9",
     "events": {
       "urn:ietf:params:scim:event:passwordReset":
         { "id":"44f6142df96bd6ab61e7521d9"},
       "https://example.com/scim/event/passwordResetExt":
         { "resetAttempts":5}
     }
   }

                Figure 1: Example SCIM Password Reset Event

   The event in the figure above expresses hypothetical password reset
   event for SCIM [RFC7644].  The JWT consists of:

   o  An "events" claim specifying the hypothetical SCIM URN
      ("urn:ietf:params:scim:event:passwordReset") for a password reset,
      and a custom extension, "https://example.com/scim/event/
      passwordResetExt", that is used to provide additional event
      information such as the current count of resets.

   o  An "iss" claim, denoting the event publisher.

   o  The "sub" claim specifies the SCIM resource URI that was affected.



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   o  The "aud" claim specifies the intended audiences for the event.
      In practical terms, an audience MAY be the URI for an event feed
      that a client has subscribed to.

   In this example, the SCIM event indicates that a password has been
   updated and the current password reset count is 5.  Notice that the
   value for "resetAttempts" is actually part of its own JSON object
   associated with its own event URI attribute.

   Here is another example JWT Claims Set for a security event token,
   this one for a Logout Token:

   {
      "iss": "https://server.example.com",
      "sub": "248289761001",
      "aud": "s6BhdRkqt3",
      "iat": 1471566154,
      "jti": "bWJq",
      "sid": "08a5019c-17e1-4977-8f42-65a12843ea02",
      "events": {
        "http://schemas.openid.net/event/backchannel-logout": {}
      }
   }

            Figure 2: Example OpenID Back-Channel Logout Event

   Note that the above SET has an empty JSON object and uses the JWT
   registered claims "sub" and "sid" to identify the subject that was
   logged-out.






















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   In the following example JWT Claims Set, a fictional medical service
   collects consent for medical actions and notifies other parties.  The
   individual for whom consent is identified was originally
   authenticated via OpenID Connect.  In this case, the issuer of the
   security event is an application rather than the OpenID provider:

   {
     "jti": "fb4e75b5411e4e19b6c0fe87950f7749",

     "sub": "248289761001",
     "iat": 1458496025,
     "iss": "https://my.examplemed.com",
     "aud": [
       "https://rp.example.com"
     ],
     "events": {
       "https://openid.net/heart/specs/consent.html":{
         "iss":"https://connect.example.com",
         "consentUri":[
           "https://terms.examplemed.com/labdisclosure.html#Agree"
         ]
       }
     }
   }

                      Figure 3: Example Consent Event

   In the above example, the attribute "iss" contained within the
   payload for the event "https://openid.net/heart/specs/consent.html",
   refers to the issuer of the Security Subject ("sub") rather than the
   event issuer "https://my.examplemed.com".  They are distinct from the
   top level value of "iss" which always refers to the issuer of the
   event - a medical consent service that is a relying party to the
   OpenID Provider.

2.1.  Core SET Claims

   The following are claims that are based on [RFC7519] claim
   definitions and are profiled for use in an event token:

   jti
      As defined by Section 4.1.7 [RFC7519] contains a unique identifier
      for an event.  The identifier SHOULD be unique within a particular
      event feed and MAY be used by clients to track whether a
      particular event has already been received.  This claim is
      REQUIRED.

   iss



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      A single valued String containing the URI of the service provider
      publishing the SET (the issuer).  This claim is REQUIRED.  Note
      that when a SET is expressing an event about a Security Subject
      for which the SET issuer is not the issuer of the Security
      Subject, the conflict SHALL be resolved by including the Security
      Subject "iss" value within the event "payload" (see "events"
      claim).

   aud
      As defined in Section 4.1.3 [RFC7519], an array containing the
      StringOrURI values representing the audience of the event.  Values
      are typically URLs of the feeds the event is associated with.
      This claim is RECOMMENDED.

   iat
      As defined by Section 4.1.6 [RFC7519], a value containing a
      NumericDate, which represents when the event was issued.  Unless
      otherwise specified, the value SHOULD be interpreted by the
      subscriber as equivalent to the actual time of the event.  This
      claim is REQUIRED.

   nbf
      Defined by Section 4.1.5 [RFC7519], a number whose value is a
      NumericDate.  In the context of the SET token it SHALL be
      interpreted to mean a date in which the event is believed to have
      occurred (in the past) or will occur in the future.  Note: there
      MAY be some cases where "nbf" is still smaller than "iat" such as
      when it took an extended time for a SET to be issued (for example
      after some analysis).  This claim is OPTIONAL.

   sub  As defined by Section 4.1.2 [RFC7519], a String or URI value
      representing the principal or the subject of the SET.  This is
      usually the entity whose "state" was changed.  For example, an IP
      Address was added to a black list.  A URI representing a user
      resource that was modified.  A token identifier for a revoked
      token.  If used, the profile specification SHOULD define the
      content and format semantics for the value.  This claim is
      OPTIONAL, as the principal for any given profile may already be
      identified without the inclusion of a subject claim.

   exp  As defined by [RFC7519], this claim is time on which the JWT
      MUST NOT be accepted for processing.  In the context of a SET
      however, this notion does not apply since a SET reflects something
      that has already been processed and is historical in nature.
      While some specifications MAY have a need for this claim, its use
      in general cases is NOT RECOMMENDED.

   The following are new claims defined by this specification:



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   events
      The semantics of this claim is to define a set of event statements
      that each MAY add additional claims to fully describe a single
      logical event that has occurred (e.g. a state change to a
      subject).  Multiple event statements of the same type SHALL NOT be
      accepted.  The "events" claim SHOULD NOT be used to express
      multiple logical events.

      The value of "events" is a JSON object whose members are a set of
      JSON name/value pairs whose names are URIs representing the event
      statements being expressed.  Event URI values SHOULD be stable
      values (e.g. a permanent URL for an event specification).  For
      each name present, the corresponding value SHALL be a JSON object.
      The JSON object MAY be an empty object ("{}"), or it MAY be a JSON
      object containing data as described by the profiling event
      specification.

   txn
      An OPTIONAL String value that represents a unique transaction
      identifier.  In cases where multiple SETs are issued based on
      different event URIs, the transaction identifier MAY be used to
      correlate SETs to the same originating event or stateful change.

2.2.  Security Event Token Construction

   A SET is a JWT [RFC7519] that is constructed by building a JSON
   structure that constitutes an event object and which is then used as
   the body of a JWT.

   While this specification uses JWT to convey a SET, implementers SHALL
   NOT use SETs to convey authentication or authorization assertions.




















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   The following is an example JWT Claims Set for a security event token
   (which has been formatted for readability):

   {
     "jti": "4d3559ec67504aaba65d40b0363faad8",
     "iat": 1458496404,
     "iss": "https://scim.example.com",
     "aud": [
      "https://scim.example.com/Feeds/98d52461fa5bbc879593b7754",
      "https://scim.example.com/Feeds/5d7604516b1d08641d7676ee7"
     ],

     "events": {
       "urn:ietf:params:scim:event:create": {
         "ref":
           "https://scim.example.com/Users/44f6142df96bd6ab61e7521d9",
         "attributes":["id", "name", "userName", "password", "emails"]
       }
     }
   }

                      Figure 4: Example Event Claims

   When transmitted, the above JSON body must be converted into a JWT as
   per [RFC7519].

   The following is an example of a SCIM Event expressed as an unsecured
   JWT.  The JWT header of:

   {"alg":"none"}

   Base64url encoding of the octets of the UTF-8 representation of the
   header yields:

   eyJhbGciOiJub25lIn0

   The example JSON Event Data is encoded as follows:

   e3sgIAogICJqdGkiOiAiNGQzNTU5ZWM2NzUwNGFhYmE2NWQ0MGIwMzYzZmFhZDgiLAog
   ICJpYXQiOiAxNDU4NDk2NDA0LAogICJpc3MiOiAiaHR0cHM6Ly9zY2ltLmV4YW1wbGUu
   Y29tIiwgIAogICJhdWQiOiBbCiAgICJodHRwczovL3NjaW0uZXhhbXBsZS5jb20vRmVl
   ZHMvOThkNTI0NjFmYTViYmM4Nzk1OTNiNzc1NCIsCiAgICJodHRwczovL3NjaW0uZXhh
   bXBsZS5jb20vRmVlZHMvNWQ3NjA0NTE2YjFkMDg2NDFkNzY3NmVlNyIKICBdLCAgCiAg
   CiAgImV2ZW50cyI6IHsKICAgICJ1cm46aWV0ZjpwYXJhbXM6c2NpbTpldmVudDpjcmVh
   dGUiOiB7CiAgICAgICJyZWYiOgogICAgICAgICJodHRwczovL3NjaW0uZXhhbXBsZS5j
   b20vVXNlcnMvNDRmNjE0MmRmOTZiZDZhYjYxZTc1MjFkOSIsCiAgICAgICJhdHRyaWJ1
   dGVzIjpbImlkIiwgIm5hbWUiLCAidXNlck5hbWUiLCAicGFzc3dvcmQiLCAiZW1haWxz
   Il0KICAgIH0KICB9Cn0



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   The encoded JWS signature is the empty string.  Concatenating the
   parts yields:

   eyJhbGciOiJub25lIn0
   .
   e3sgIAogICJqdGkiOiAiNGQzNTU5ZWM2NzUwNGFhYmE2NWQ0MGIwMzYzZmFhZDgiLAog
   ICJpYXQiOiAxNDU4NDk2NDA0LAogICJpc3MiOiAiaHR0cHM6Ly9zY2ltLmV4YW1wbGUu
   Y29tIiwgIAogICJhdWQiOiBbCiAgICJodHRwczovL3NjaW0uZXhhbXBsZS5jb20vRmVl
   ZHMvOThkNTI0NjFmYTViYmM4Nzk1OTNiNzc1NCIsCiAgICJodHRwczovL3NjaW0uZXhh
   bXBsZS5jb20vRmVlZHMvNWQ3NjA0NTE2YjFkMDg2NDFkNzY3NmVlNyIKICBdLCAgCiAg
   CiAgImV2ZW50cyI6IHsKICAgICJ1cm46aWV0ZjpwYXJhbXM6c2NpbTpldmVudDpjcmVh
   dGUiOiB7CiAgICAgICJyZWYiOgogICAgICAgICJodHRwczovL3NjaW0uZXhhbXBsZS5j
   b20vVXNlcnMvNDRmNjE0MmRmOTZiZDZhYjYxZTc1MjFkOSIsCiAgICAgICJhdHRyaWJ1
   dGVzIjpbImlkIiwgIm5hbWUiLCAidXNlck5hbWUiLCAicGFzc3dvcmQiLCAiZW1haWxz
   Il0KICAgIH0KICB9Cn0
   .

             Figure 5: Example Unsecured Security Event Token

   For the purpose of a simpler example in Figure 5 an unencrypted token
   was shown.  When SETs are not signed or encrypted, the subscriber
   MUST depend upon TLS and HTTP to authenticate the sender and the
   security of the channel to authenticate the SET and its sender.

   When validation (i.e. auditing), or additional transmission security
   is required, JWS Signing and JWS Encryption MAY be used.  To create
   and or validate a signed or encrypted SET, follow the instructions in
   section 7 of [RFC7519].

3.  Security Considerations

3.1.  Confidentiality and Integrity

   SETs may often contain sensitive information.  Therefore, methods for
   distribution of events SHOULD require the use of a transport-layer
   security mechanism when distributing events.  Parties 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].

   Security Events distributed through third-parties or that carry
   personally identifiable information, SHOULD be encrypted using JWE
   [RFC7516] or secured for confidentiality by other means.

   Security Events distributed without authentication over the channel,
   such as via TLS ([RFC5246] and [RFC6125]), and/or OAuth2 [RFC6749],



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   or Basic Authentication [RFC7617], MUST be signed using JWS [RFC7515]
   so that individual events MAY be authenticated and validated by the
   subscriber.

3.2.  Delivery

   This specification does not define a delivery mechanism by itself.
   In addition to confidentiality and integrity (discussed above),
   implementers and profile specifications MUST consider the
   consequences of delivery mechanisms that are not secure and/or not
   assured.  For example, while a SET may be end-to-end secured using
   JWE encrypted SETs, without TLS there is no assurance that the
   correct endpoint received the SET and that it could be successfully
   processed.

3.3.  Sequencing

   As defined in this specification, there is no defined way to order
   multiple SETs in a sequence.  Depending on the type and nature of SET
   event, order may or may not matter.  For example, in provisioning,
   event order is critical -- an object could not be modified before it
   was created.  In other SET types, such as a token revocation, the
   order of SETs for revoked tokens does not matter.  If however, the
   event was described as a log-in or logged-out status for a user
   subject, then order becomes important.

   Extension specifications and implementers SHOULD take caution when
   using timestamps such as "iat" to define order.  Distributed systems
   will have some amount of clock-skew and thus time by itself will not
   guarantee order.

   Specifications profiling SET SHOULD define a mechanism for detecting
   order or sequence of events.  For example, the "txn" claim could
   contain an ordered value (e.g., a counter) that the publisher
   defines.

3.4.  Timing Issues

   When SETs are delivered asynchronously and/or out-of-band with
   respect to the original action that incurred the security event, it
   is important to consider that a SET might be delivered to a
   Subscriber in advance or well behind the process that caused the
   event.  For example, a user having been required to logout and then
   log back in again, may cause a logout SET to be issued that may
   arrive at the same time as the user-agent accesses a web site having
   just logged-in.  If timing is not handled properly, the effect would
   be to erroneously treat the new user session as logged out.
   Profiling specifications SHOULD be careful to anticipate timing and



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   subject selection information.  For example, it might be more
   appropriate to cancel a "session" rather than a "user".
   Alternatively, the specification could use timestamps that allows new
   sessions to be started immediately after a stated logout event time.

3.5.  Distinguishing SETs from Access Tokens

   Because [RFC7519] states that "all claims that are not understood by
   implementations MUST be ignored.", there is a consideration that a
   SET token might be confused as an access or authorization token in
   the case where a SET is mistakenly or intentionally intercepted and
   presented as an access token.  To avoid this, it is recommended that
   implementers consider one or more of the following:

   o  Avoid use of the JWT claim "exp" within the envelope.

   o  Where possible, use a separate "aud" claim value to distinguish
      between the SET subscriber and the audience of an access token.
      For example, a Logout while intended for the same relying party
      could use a different audience to distinguish between normal
      access and logout notification.

   o  Modify access validation systems to check for the presence of the
      "events" claim as a means to detect security event tokens.  This
      is particularly useful if the same endpoint may receive both types
      of tokens.

   o  Consider avoiding use of the "sub" claim at the top level.

4.  Privacy Considerations

   If a SET needs to be retained for audit purposes, JWS MAY be used to
   provide verification of its authenticity.

   Event Publishers SHOULD attempt to specialize feeds so that the
   content is 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, the
   publishers and subscribers MUST have the appropriate legal agreements
   and user consent in place.

   The propagation of subject identifiers can be perceived as personally
   identifiable information.  Where possible, publishers and subscribers
   should devise approaches that prevent propagation -- for example, the
   passing of a hash value that requires the subscriber to already know
   the subject.



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5.  IANA Considerations

5.1.  JSON Web Token Claims Registration

   This specification registers the "events" and "txn" claims in the
   IANA "JSON Web Token Claims" registry [IANA.JWT.Claims] established
   by [RFC7519].

5.1.1.  Registry Contents

   o  Claim Name: "events"
   o  Claim Description: Security Event Object
   o  Change Controller: IESG
   o  Specification Document(s): Section 2 of [[ this specification ]]

   o  Claim Name: "txn"
   o  Claim Description: Transaction Identifier
   o  Change Controller: IESG
   o  Specification Document(s): Section 2 of [[ this specification ]]

6.  References

6.1.  Normative References

   [IANA.JWT.Claims]
              IANA, "JSON Web Token Claims",
              <http://www.iana.org/assignments/jwt>.

   [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>.

   [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,
              <http://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,
              <http://www.rfc-editor.org/info/rfc5246>.









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   [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, <http://www.rfc-editor.org/info/rfc6125>.

   [RFC6749]  Hardt, D., Ed., "The OAuth 2.0 Authorization Framework",
              RFC 6749, DOI 10.17487/RFC6749, October 2012,
              <http://www.rfc-editor.org/info/rfc6749>.

   [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>.

   [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, <http://www.rfc-editor.org/info/rfc7525>.

   [RFC7617]  Reschke, J., "The 'Basic' HTTP Authentication Scheme",
              RFC 7617, DOI 10.17487/RFC7617, September 2015,
              <http://www.rfc-editor.org/info/rfc7617>.

6.2.  Informative References

   [RFC7009]  Lodderstedt, T., Ed., Dronia, S., and M. Scurtescu, "OAuth
              2.0 Token Revocation", RFC 7009, DOI 10.17487/RFC7009,
              August 2013, <http://www.rfc-editor.org/info/rfc7009>.

   [RFC7515]  Jones, M., Bradley, J., and N. Sakimura, "JSON Web
              Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May
              2015, <http://www.rfc-editor.org/info/rfc7515>.

   [RFC7516]  Jones, M. and J. Hildebrand, "JSON Web Encryption (JWE)",
              RFC 7516, DOI 10.17487/RFC7516, May 2015,
              <http://www.rfc-editor.org/info/rfc7516>.

   [RFC7517]  Jones, M., "JSON Web Key (JWK)", RFC 7517,
              DOI 10.17487/RFC7517, May 2015,
              <http://www.rfc-editor.org/info/rfc7517>.

   [RFC7644]  Hunt, P., Ed., Grizzle, K., Ansari, M., Wahlstroem, E.,
              and C. Mortimore, "System for Cross-domain Identity
              Management: Protocol", RFC 7644, DOI 10.17487/RFC7644,
              September 2015, <http://www.rfc-editor.org/info/rfc7644>.




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Appendix A.  Acknowledgments

   The editors would like to thank the participants in the IETF id-event
   mailing list and related working groups for their support of this
   specification.

Appendix B.  Change Log

   Draft 01 - PH - Renamed eventUris to events

   Draft 00 - PH - First Draft

   Draft 01 - PH - Fixed some alignment issues with JWT.  Remove event
   type attribute.

   Draft 02 - PH - Renamed to Security Events, removed questions,
   clarified examples and intro text, and added security and privacy
   section.

   Draft 03 - PH

      General edit corrections from Sarah Squire
      Changed "event" term to "SET"
      Corrected author organization for William Denniss to Google
      Changed definition of SET to be 2 parts, an envelope and 1 or more
      payloads.
      Clarified that the intent is to express a single event with
      optional extensions only.

   - mbj - Registered "events" claim, and proof-reading corrections.

   Draft 04 - PH -

   o  Re-added the "sub" claim with clarifications that any SET type may
      use it.
   o  Added additional clarification on the use of envelope vs. payload
      attributes
   o  Added security consideration for event timing.
   o  Switched use of "attribute" to "claim" for consistency.
   o  Revised examples to put "sub" claim back in the top level.
   o  Added clarification that SETs typically do not use "exp".
   o  Added security consideration for distinguishing Access Tokens and
      SETs.

   Draft 05 - PH - Fixed find/replace error that resulted in claim being
   spelled claimc

   Draft 06 - PH -



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   o  Corrected typos
   o  New txn claim
   o  New security considerations Sequencing and Timing Issues

   Draft 07 -

   o  PH - Moved payload objects to be values of event URI attributes,
      per discussion.
   o  mbj - Applied terminology consistency and grammar cleanups.

   Draft 08 - PH -

   o  Added clarification to status of examples
   o  Changed from primary vs. extension to state that multiple events
      may be expressed, some of which may or may not be considered
      extensions of others (which is for the subscriber or profiling
      specifications to determine).
   o  Other editorial changes suggested by Yaron

Authors' Addresses

   Phil Hunt (editor)
   Oracle Corporation

   Email: phil.hunt@yahoo.com


   William Denniss
   Google

   Email: wdenniss@google.com


   Morteza Ansari
   Cisco

   Email: morteza.ansari@cisco.com


   Michael B. Jones
   Microsoft

   Email: mbj@microsoft.com
   URI:   http://self-issued.info/







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