Security Event Token (SET)
draft-hunt-idevent-token-04

Network Working Group                                       P. Hunt, Ed.
Internet-Draft                                                    Oracle
Intended status: Standards Track                              W. Denniss
Expires: March 5, 2017                                            Google
                                                               M. Ansari
                                                                   Cisco
                                                                M. Jones
                                                               Microsoft
                                                       September 1, 2016

                       Security Event Token (SET)
                      draft-hunt-idevent-token-04

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 March 5, 2017.

Copyright Notice

   Copyright (c) 2016 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.  Timing Issues . . . . . . . . . . . . . . . . . . . . . .  13
     3.3.  Distinguishing SETs from Access Tokens  . . . . . . . . .  13
   4.  Privacy Considerations  . . . . . . . . . . . . . . . . . . .  14
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  14
     5.1.  JSON Web Token Claims Registration  . . . . . . . . . . .  14
       5.1.1.  Registry Contents . . . . . . . . . . . . . . . . . .  14
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  14
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .  14
     6.2.  Informative References  . . . . . . . . . . . . . . . . .  15
   Appendix A.  Acknowledgments  . . . . . . . . . . . . . . . . . .  16
   Appendix B.  Change Log . . . . . . . . . . . . . . . . . . . . .  16
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  17

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., a login 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:

   o  The creation, modification, removal of a resource.

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   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 agreed upon criteria for an event Feed, the publisher
   distributes events to the appropriate subscribers.  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 as non-normative examples showing how an event may be used.
   It is expected that other specifications will use this specification
   to define normative events.

   This specification is scoped to security and identity related events.
   While event tokens may be used for other purposes, the specification

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   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
      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.

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   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 JSON attributes, called JWT claims,
      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 the SET and determine the event
      data included.  The claim "events" describes the type of SET event
      and indicates the data that MAY be present in the SET.  While a
      SET contains a single event, it MAY have multiple extensions
      providing additional data about the same event.  The primary event
      is the first value in the "events" array, while event extensions
      are the 2nd, 3rd, etc.

   o  For each value of "events", a JSON attribute, whose value is a
      JSON object, MAY be added known as an event "payload".  The
      payload object contains claimcs typically unique to the events URI
      value and are not registered as JWT claims.  These claimcs are
      defined within their associated event specification.  Event
      extensions can be used for many purposes.  Some examples include
      but are not limited to:

      *  A categorization extension applied to multiple event types in
         order to provide classification information (e.g. threat type
         or level).

      *  Enhancement of an existing specifications the arise over time.

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

      *  Localized contextual extensions needed between a publisher and
         subscriber.

   The following is a non-normative example showing a hypothetical SCIM
   password reset SET.  The example also shows an example where the
   issuer has provided an extension ("https://example.com/scim/event/
   passwordResetExt") that is used to convey additional information such
   as the current count of reset attempts:

   {
     "jti": "3d0c3cf797584bd193bd0fb1bd4e7d30",
     "events":[
       "urn:ietf:params:scim:event:passwordReset",
       "https://example.com/scim/event/passwordResetExt"
     ],
     "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",
     "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" claimc, denotes the event publisher.

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

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   o  The "aud" claimc specifies the intended audience for the event.
      In practical terms, this MAY be the URI for the event Feed that a
      client has subscribed to.

   Additional extensions to an event may be added by adding more values
   to the "events" claimc.  For each event URI value specified, there
   MAY be a corresponding claimc that has a JSON object that contains
   the claimcs associated with that event (e.g.,
   "https://example.com/scim/event/passwordResetExt").  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
   "https://example.com/scim/event/passwordResetExt".

   Here is another example event token, this one for a Logout Token:

   {
     "iss": "https://server.example.com",
     "aud": "https://rp.example.com",
     "jti": "3d0c3cf797584bd193bd0fb1bd4e7d30",
     "iat": 1458668180,
     "exp": 1458668580,
     "sub": "248289761001",
     "events": [
       "https://specs.openid.net/logout"
     ],
     "https://specs.openid.net/logout": {
       "iss": "https://token.example.com",
       "sid": "08a5019c-17e1-4977-8f42-65a12843ea02"
     }
   }

                   Figure 2: Example OpenID Logout Event

   In the above example, the event has its own issuer,
   "https://server.example.com" while the event is about the logging out
   of a user session identified in the event extension by "jti" that was
   issued by "https://token.example.com".

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   In the following example, 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
   SET event is an application rather than the OpenID provider:

   {
     "jti": "fb4e75b5411e4e19b6c0fe87950f7749",
     "events":[
       "https://openid.net/heart/consent.html"
     ],
     "sub": "248289761001",
     "iat": 1458496025,
     "iss": "https://my.examplemed.com",
     "aud":[
       "https://rp.example.com"
     ],
     "https://openid.net/heart/consent":{
       "consentUri":[
         "https://terms.examplemed.com/labdisclosure.html#Agree"
       ]
     }
   }

                      Figure 3: Example Consent Event

   In the above example "iss" and "sub" contained within the claimc
   "https://openid.net/heart/consent", refer to the subject and issuer
   of the original OpendID Provider.  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 claimcs 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 claimc is
      REQUIRED.

   iss
      A single valued String containing the URI of the service provider
      publishing the SET (the issuer).  This claimc is REQUIRED.

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   aud
      A multi-valued String containing the URIs representing the
      audience of the event.  Values are typically URLs of the Feeds the
      event is associated with.  When an event has multiple audiences
      that go to the same subscriber, the publisher is not obligated to
      deliver repeated events to the same subscriber.  This claimc 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
      claimc is REQUIRED.

   nbf
      As defined by Section 4.1.5 [RFC7519], a value containing a
      NumericDate, which represents a future date when the event will
      occur.  This claimc 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 is a new claim defined by this specification:

   events
      A multi-valued String that contains one or more URIs representing
      the type of event being expressed and the claims that MAY be
      available within the JWT.  The first value SHALL indicate the type
      of SET event and following values represent extensions to that
      event.  For each value present, there MAY be an associated JSON
      sub-objects present in the SET.  Each JSON sub-object is denoted
      by an claim whose name matches a value in "events".  This claim is
      REQUIRED to have at least one value.

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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.

   The following is an example 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"
    ],
    "urn:ietf:params:scim:event:create":{
      "ref": "https://scim.example.com/Users/44f6142df96bd6ab61e7521d9",
      "attributes":["id", "name", "userName", "password", "emails"],
      "values":{
        "emails":[
         {"type":"work", "value":"jdoe@example.com"}
        ],
        "password":"not4u2no",
        "userName":"jdoe",
        "id":"44f6142df96bd6ab61e7521d9",
        "name":{
          "givenName":"John",
          "familyName":"Doe"
        }
      }
    }
  }

                     Figure 4: Example Event JSON Data

   When transmitted, the above JSON body must be converted into a JWT as
   per [RFC7519].  In this example, because the event contains attribute
   values, the token MUST be encrypted per JWE (see [RFC7516]) before
   transmission.

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   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:

   eyAgCiAgImp0aSI6ICI0ZDM1NTllYzY3NTA0YWFiYTY1ZDQwYjAzNjNmYWFkOCIsCiAg
   ImlhdCI6IDE0NTg0OTY0MDQsCiAgImlzcyI6ICJodHRwczovL3NjaW0uZXhhbXBsZS5j
   b20iLCAgCiAgImF1ZCI6WwogICAiaHR0cHM6Ly9zY2ltLmV4YW1wbGUuY29tL0ZlZWRz
   Lzk4ZDUyNDYxZmE1YmJjODc5NTkzYjc3NTQiLAogICAiaHR0cHM6Ly9zY2ltLmV4YW1w
   bGUuY29tL0ZlZWRzLzVkNzYwNDUxNmIxZDA4NjQxZDc2NzZlZTciCiAgXSwgIAogIAog
   ICJldmVudHMiOlsKICAgICJ1cm46aWV0ZjpwYXJhbXM6c2NpbTpldmVudDpjcmVhdGUi
   CiAgXSwKICAidXJuOmlldGY6cGFyYW1zOnNjaW06ZXZlbnQ6Y3JlYXRlIjp7CiAgICAi
   cmVmIjogImh0dHBzOi8vc2NpbS5leGFtcGxlLmNvbS9Vc2Vycy80NGY2MTQyZGY5NmJk
   NmFiNjFlNzUyMWQ5IiwKICAgICJhdHRyaWJ1dGVzIjpbImlkIiwibmFtZSIsInVzZXJO
   YW1lIiwicGFzc3dvcmQiLCJlbWFpbHMiXSwKICAgICJ2YWx1ZXMiOnsKICAgICAgImVt
   YWlscyI6WwogICAgICAgeyJ0eXBlIjoid29yayIsInZhbHVlIjoiamRvZUBleGFtcGxl
   LmNvbSJ9CiAgICAgIF0sCiAgICAgICJwYXNzd29yZCI6Im5vdDR1Mm5vIiwKICAgICAg
   InVzZXJOYW1lIjoiamRvZSIsCiAgICAgICJpZCI6IjQ0ZjYxNDJkZjk2YmQ2YWI2MWU3
   NTIxZDkiLAogICAgICAibmFtZSI6ewogICAgICAgICJnaXZlbk5hbWUiOiJKb2huIiwK
   ICAgICAgICAiZmFtaWx5TmFtZSI6IkRvZSIKICAgICAgfQogICAgfSAgCiAgfQp9

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

   eyJhbGciOiJub25lIn0
   .
   eyAgCiAgImp0aSI6ICI0ZDM1NTllYzY3NTA0YWFiYTY1ZDQwYjAzNjNmYWFkOCIsCiAg
   ImlhdCI6IDE0NTg0OTY0MDQsCiAgImlzcyI6ICJodHRwczovL3NjaW0uZXhhbXBsZS5j
   b20iLCAgCiAgImF1ZCI6WwogICAiaHR0cHM6Ly9zY2ltLmV4YW1wbGUuY29tL0ZlZWRz
   Lzk4ZDUyNDYxZmE1YmJjODc5NTkzYjc3NTQiLAogICAiaHR0cHM6Ly9zY2ltLmV4YW1w
   bGUuY29tL0ZlZWRzLzVkNzYwNDUxNmIxZDA4NjQxZDc2NzZlZTciCiAgXSwgIAogIAog
   ICJldmVudHMiOlsKICAgICJ1cm46aWV0ZjpwYXJhbXM6c2NpbTpldmVudDpjcmVhdGUi
   CiAgXSwKICAidXJuOmlldGY6cGFyYW1zOnNjaW06ZXZlbnQ6Y3JlYXRlIjp7CiAgICAi
   cmVmIjogImh0dHBzOi8vc2NpbS5leGFtcGxlLmNvbS9Vc2Vycy80NGY2MTQyZGY5NmJk
   NmFiNjFlNzUyMWQ5IiwKICAgICJhdHRyaWJ1dGVzIjpbImlkIiwibmFtZSIsInVzZXJO
   YW1lIiwicGFzc3dvcmQiLCJlbWFpbHMiXSwKICAgICJ2YWx1ZXMiOnsKICAgICAgImVt
   YWlscyI6WwogICAgICAgeyJ0eXBlIjoid29yayIsInZhbHVlIjoiamRvZUBleGFtcGxl
   LmNvbSJ9CiAgICAgIF0sCiAgICAgICJwYXNzd29yZCI6Im5vdDR1Mm5vIiwKICAgICAg
   InVzZXJOYW1lIjoiamRvZSIsCiAgICAgICJpZCI6IjQ0ZjYxNDJkZjk2YmQ2YWI2MWU3
   NTIxZDkiLAogICAgICAibmFtZSI6ewogICAgICAgICJnaXZlbk5hbWUiOiJKb2huIiwK
   ICAgICAgICAiZmFtaWx5TmFtZSI6IkRvZSIKICAgICAgfQogICAgfSAgCiAgfQp9
   .

                  Figure 5: Example Unsecured Event Token

   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],
   or Basic Authentication [RFC7617], MUST be signed using JWS [RFC7515]

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   so that individual events MAY be authenticated and validated by the
   subscriber.

3.2.  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
   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.

3.3.  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 itended 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 SET 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.

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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.

5.  IANA Considerations

5.1.  JSON Web Token Claims Registration

   This specification registers the "events" claim 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 Events
   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>.

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   [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>.

   [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>.

   [RFC7159]  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>.

   [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

   [idevent-scim]
              Oracle Corporation, "SCIM Event Extensions (work in
              progress)", <draft-hunt-idevent-scim-00.txt>.

   [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>.

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   [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>.

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 Dennis 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 proofreading corrections.

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   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. paylaod
      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.

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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