Security Events Working Group                               P. Hunt, Ed.
Internet-Draft                                                    Oracle
Intended status: Standards Track                                M. Jones
Expires: July 24, 2018                                         Microsoft
                                                              W. Denniss
                                                               M. Ansari
                                                        January 20, 2018

                       Security Event Token (SET)


   This specification defines the Security Event Token (SET) data
   structure.  A SET describes a statement of fact from the perspective
   of an issuer, which is intended to be shared with one or more
   recipients.  A SET is a JSON Web Token (JWT), which can be optionally
   signed and/or encrypted.  SETs can be distributed via protocols such
   as HTTP.

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

   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 24, 2018.

Copyright Notice

   Copyright (c) 2018 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   ( in effect on the date of

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   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

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.  Illustrative Examples . . . . . . . . . . . . . . . . . .   6
       2.1.1.  SCIM Example  . . . . . . . . . . . . . . . . . . . .   6
       2.1.2.  Logout Example  . . . . . . . . . . . . . . . . . . .   7
       2.1.3.  Consent Example . . . . . . . . . . . . . . . . . . .   7
       2.1.4.  RISC Example  . . . . . . . . . . . . . . . . . . . .   8
     2.2.  Core SET Claims . . . . . . . . . . . . . . . . . . . . .   9
     2.3.  Explicit Typing of SETs . . . . . . . . . . . . . . . . .  11
     2.4.  Security Event Token Construction . . . . . . . . . . . .  11
   3.  Requirements for SET Profiles . . . . . . . . . . . . . . . .  13
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .  14
     4.1.  Confidentiality and Integrity . . . . . . . . . . . . . .  14
     4.2.  Delivery  . . . . . . . . . . . . . . . . . . . . . . . .  14
     4.3.  Sequencing  . . . . . . . . . . . . . . . . . . . . . . .  15
     4.4.  Timing Issues . . . . . . . . . . . . . . . . . . . . . .  15
     4.5.  Distinguishing SETs from ID Tokens  . . . . . . . . . . .  15
     4.6.  Distinguishing SETs from Access Tokens  . . . . . . . . .  16
     4.7.  Distinguishing SETs from other kinds of JWTs  . . . . . .  17
   5.  Privacy Considerations  . . . . . . . . . . . . . . . . . . .  17
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  18
     6.1.  JSON Web Token Claims Registration  . . . . . . . . . . .  18
       6.1.1.  Registry Contents . . . . . . . . . . . . . . . . . .  18
     6.2.  Media Type Registration . . . . . . . . . . . . . . . . .  18
       6.2.1.  Registry Contents . . . . . . . . . . . . . . . . . .  18
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  19
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .  19
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  20
   Appendix A.  Acknowledgments  . . . . . . . . . . . . . . . . . .  22
   Appendix B.  Change Log . . . . . . . . . . . . . . . . . . . . .  22
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  25

1.  Introduction and Overview

   This specification defines an extensible Security Event Token (SET)
   data structure, which can be exchanged using protocols such as HTTP.
   The specification builds on the JSON Web Token (JWT) format [RFC7519]

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   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].

   This specification profiles the use of JWT for the purpose of issuing
   Security Event Tokens (SETs).  This specification defines a base
   format used by profiling specifications to define actual events and
   their meanings.  This specification uses non-normative example events
   to demonstrate how events can be constructed.

   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.

   Security Events are not commands issued between parties.  A security
   event is a statement of fact from the perspective of an issuer about
   the state of a security subject (e.g., a web resource, token, IP
   address, the issuer itself) that the issuer controls or is aware of,
   that 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 could describe a direct
   change of entity state, an implicit change of state, or other higher-
   level security statements such as:

   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  An indication that a user has been given control of an email
      identifier that was previously controlled by another user.

   While subject state changes are often triggered by a user agent or
   security subsystem, the issuance and transmission of an event may
   occur asynchronously and in a back channel to the action that caused
   the change that generated the security event.  Subsequently, an Event
   Recipient, having received a SET, validates and interprets the
   received SET and takes its own independent actions, if any.  For
   example, having been informed of a personal identifier being
   associated with a different security subject (e.g., an email address
   is being used by someone else), the Event Recipient may choose to
   ensure that the new user is not granted access to resources
   associated with the previous user.  Or, the Event Recipient may not
   have any relationship with the subject, and no action is taken.

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   While Event Recipients will often take actions upon receiving SETs,
   security events cannot be assumed to be commands or requests.  The
   intent of this specification is to define a syntax for statements of
   fact that Event Recipients may interpret for their own purposes.  As
   such, SETs have no capability for error signaling to ensure the
   validation of a received SET.

1.1.  Notational Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "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

   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:

   Security Event Token (SET)
      A SET is a JWT [RFC7519] conforming to this specification that is
      distributed to one or more Event Recipients.

   Event Issuer
      A service provider that creates SETs to be sent to other providers
      known as Event Recipients.

   Event Recipient
      An Event Recipient is an entity that receives SETs through some
      distribution method.  An Event Recipient is the same entity
      referred as a "recipient" or "receiver" in [RFC7519] and related

      A SET describes an event or state change that has occurred about a
      Subject.  A Subject might, for instance, be a principal (e.g.,

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      Section 4.1.2 of [RFC7519]), a web resource, an entity such as an
      IP address, or the issuer of the SET.

   Profiling Specification
      A specification that profiles the SET data structure to define one
      or more specific event types and their associated claims and
      processing rules.

2.  The Security Event Token (SET)

   A SET is a JWT [RFC7519] data structure that represents one or more
   related aspects of a security event about a Subject.  The JWT Claims
   Set in a SET has the following structure:

   o  The top-level claims in the JWT Claims Set are called the SET
      "envelope".  Some of these claims are present in every SET; others
      will be specific to particular SET profiles or profile families.
      Claims in the envelope SHOULD be registered in the "JSON Web Token
      Claims" registry [IANA.JWT.Claims] or be Public Claims or Private
      Claims, as defined in [RFC7519].

   o  Envelope claims that are profiled and defined in this
      specification are used to validate the SET and provide information
      about the event data included in the SET.  The claim "events"
      contains the event identifiers and event-specific data expressed
      about the Security Subject.  The envelope MAY include event-
      specific or profile-specific data.

   o  Each member of the "events" JSON object is a name/value pair.  The
      JSON member name is a URI string value is an event identifier, and
      the corresponding value is a JSON object known as the event
      "payload".  The payload JSON object contains claims that pertain
      to that event identifier and need not be registered as JWT claims.
      These claims are defined by the Profiling Specification that
      defines the event.  An event with no payload claims SHALL be
      represented as the empty JSON object ("{}").

   o  When multiple event identifiers are contained in a SET, they
      represent multiple aspects of the same state transition that
      occurred to the Security Subject.  They are not intended to be
      used to aggregate distinct events about the same subject.  Beyond
      this, the interpretation of SETs containing multiple event
      identifiers is out of scope for this specification; Profiling
      Specifications MAY define their own rules regarding their use of
      SETs containing multiple event identifiers, as described in
      Section 3.  Possible uses of multiple values include, but are not
      limited to:

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      *  Values to provide classification information (e.g., threat type
         or level).

      *  Additions to existing event representations.

      *  Values used to link potential series of events.

      *  Specific-purpose event URIs used between particular Event
         Issuers and Event Recipients.

2.1.  Illustrative Examples

2.1.1.  SCIM Example

   The following is a non-normative example showing the JWT Claims Set
   for a hypothetical SCIM [RFC7644] password reset SET.  This example
   uses a second "events" value ("
   passwordResetExt") to convey additional information about the state
   change -- in this case, the current count of reset attempts:

     "jti": "3d0c3cf797584bd193bd0fb1bd4e7d30",
     "iat": 1458496025,
     "iss": "",
     "aud": [
     "sub": "",
     "events": {
         { "id": "44f6142df96bd6ab61e7521d9"},
         { "resetAttempts": 5}

                Figure 1: Example SCIM Password Reset Event

   The JWT Claims Set consists of:

   o  The "events" claim specifying the hypothetical SCIM URN
      ("urn:ietf:params:scim:event:passwordReset") for a password reset,
      and a second value, "
      passwordResetExt", that is used to provide additional event
      information such as the current count of resets.

   o  The "iss" claim, denoting the Event Issuer.

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   o  The "sub" claim, specifying the SCIM resource URI that was

   o  The "aud" claim, specifying the intended audiences for the event.
      (The syntax of the "aud" claim is defined in Section 4.1.3 of

   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 in the event payload of an event used to
   convey this information.

2.1.2.  Logout Example

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

      "iss": "",
      "sub": "248289761001",
      "aud": "s6BhdRkqt3",
      "iat": 1471566154,
      "jti": "bWJq",
      "sid": "08a5019c-17e1-4977-8f42-65a12843ea02",
      "events": {
        "": {}

            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.

2.1.3.  Consent Example

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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",
     "iat": 1458496025,
     "iss": "",
     "aud": [
     "events": {
       "": {
         "iss": "",
         "sub": "248289761001",
         "consentUri": [

                      Figure 3: Example Consent Event

   In the above example, the attribute "iss" contained within the
   payload for the event ""
   refers to the issuer of the Security Subject ("sub") rather than the
   event issuer "".  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.

2.1.4.  RISC Example

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   The following example JWT Claims Set is for an account disabled
   event.  This example was taken from a working draft of the RISC
   events specification, where RISC is the OpenID RISC (Risk and
   Incident Sharing and Coordination) working group [RISC].  The example
   is subject to change.

     "iss": "",
     "sub": "7375626A656374",
     "jti": "756E69717565206964656E746966696572",
     "iat": 1508184845,
     "aud": "636C69656E745F6964",
     "events": {
       account-disabled": {
         "reason": "hijacking",
         "cause-time": 1508012752,

                       Figure 4: Example RISC Event

   Notice that parameters to the event are included in the event
   payload, in this case, the "reason" and "cause-time" values.  The
   account that is the subject of the event is identified using the
   "iss" and "sub" values, in the same manner as OpenID Connect
   [OpenID.Core] ID Tokens.

2.2.  Core SET Claims

   The following claims from [RFC7519] are profiled for use in SETs:

      As defined by Section 4.1.7 of [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

      A string identifying the service provider publishing the SET (the
      issuer).  In some cases, the SET issuer is not the issuer of the
      Security Subject.  Therefore, implementers cannot assume that the
      issuers are the same unless the Profiling Specification specifies
      that they are for SETs conforming to that profile.  This claim is

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      The syntax of the claim is as defined in Section 4.1.3 of
      [RFC7519].  This claim contains one or more audience identifiers
      for the SET.  This claim is RECOMMENDED.

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

      As defined by Section 4.1.2 of [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 Profiling 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.  Note that
      some SET profiles MAY choose to convey event subject information
      in the event payload (either using the "sub" member name or
      another name), particularly if the subject information is relative
      to issuer information that is also conveyed in the event payload,
      which may be the case for some identity SET profiles.

      As defined by Section 4.1.4 of [RFC7519], this claim is time after
      which the JWT MUST NOT be accepted for processing.  In the context
      of a SET however, this notion does not apply, since a SET
      represents something that has already occurred and is historical
      in nature.  While some profiles MAY choose to use this claim, its
      use is NOT RECOMMENDED.

   The following new claims are defined by this specification:

      This claim contains a set of event statements that each provide
      information describing a single logical event that has occurred
      about a Security Subject (e.g., a state change to the subject).
      Multiple event identifiers with the same value MUST NOT be used.
      The "events" claim SHOULD NOT be used to express multiple
      independent logical events.

      The value of the "events" claim is a JSON object whose members are
      name/value pairs whose names are URIs identifying the event
      statements being expressed.  Event identifiers SHOULD be stable

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      values (e.g., a permanent URL for an event specification).  For
      each name present, the corresponding value MUST be a JSON object.
      The JSON object MAY be an empty object ("{}"), or it MAY be a JSON
      object containing data described by the Profiling Specification.

      An OPTIONAL string value that represents a unique transaction
      identifier.  In cases in which multiple related JWTs are issued,
      the transaction identifier claim can be used to correlate these
      related JWTs.

      A value that represents the date and time at which the event
      occurred.  This value is a NumericDate (see Section 2 of
      [RFC7519]).  This claim is RECOMMENDED.  Note that some profiles
      may choose to omit "toe" and convey event time information with
      the "iat" claim or another claim.

2.3.  Explicit Typing of SETs

   This specification registers the "application/secevent+jwt" media
   type, which can be used to indicate that the content is a SET.  SETs
   MAY include this media type in the "typ" header parameter of the JWT
   representing the SET to explicitly declare that the JWT is a SET.
   This MUST be included if the SET could be used in an application
   context in which it could be confused with other kinds of JWTs.

   Per the definition of "typ" in Section 4.1.9 of [RFC7515], it is
   RECOMMENDED that the "application/" prefix be omitted.  Therefore,
   the "typ" value used SHOULD be "secevent+jwt".

2.4.  Security Event Token Construction

   This section describes how to construct a SET.

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   The following is an example JWT Claims Set for a hypothetical SCIM
   SET (which has been formatted for readability):

     "jti": "4d3559ec67504aaba65d40b0363faad8",
     "iat": 1458496404,
     "iss": "",
     "aud": [

     "events": {
       "urn:ietf:params:scim:event:create": {
         "attributes": ["id", "name", "userName", "password", "emails"]

                      Figure 5: Example Event Claims

   The JSON Claims Set is encoded per [RFC7519].

   In this example, the SCIM SET claims are encoded in an unsecured JWT.
   The JOSE Header for this example is:


   Base64url encoding of the octets of the UTF-8 representation of the
   JOSE Header yields:


   The above example JWT Claims Set is encoded as follows:


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


             Figure 6: Example Unsecured Security Event Token

   For the purpose of having a simpler example in Figure 6, an unsecured
   token is shown.  When SETs are not signed or encrypted, the Event
   Recipient MUST employ other mechanisms such as TLS to provide
   integrity, confidentiality, and issuer validation, as needed by the

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

3.  Requirements for SET Profiles

   Profiling Specifications for SETs define the syntax and semantics of
   SETs conforming to that SET profile and rules for validating those
   SETs.  The syntax defined by profiling specifications includes what
   claims and event payload values are used by SETs utilizing the

   Defining the semantics of the SET contents for SETs utilizing the
   profile is equally important.  Possibly most important is defining
   the procedures used to validate the SET issuer and to obtain the keys
   controlled by the issuer that were used for cryptographic operations
   used in the JWT representing the SET.  For instance, some profiles
   may define an algorithm for retrieving the SET issuer's keys that
   uses the "iss" claim value as its input.  Likewise, if the profile
   allows (or requires) that the JWT be unsecured, the means by which
   the integrity of the JWT is ensured MUST be specified.

   Profiling Specifications MUST define how the event Subject is
   identified in the SET, as well as how to differentiate between the
   event Subject's Issuer and the SET Issuer, if applicable.  It is NOT
   RECOMMENDED for Profiling Specifications to use the "sub" claim in

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   cases in which the Subject is not globally unique and has a different
   Issuer from the SET itself.

   Among the syntax and semantics of SETs that Profiling Specifications
   define is whether and how multiple "events" values are used for SETs
   conforming to those profiles.  Many valid choices are possible.  For
   instance, some profiles might allow multiple event identifiers to be
   present and specify that any that are not understood by recipients be
   ignored, thus enabling extensibility.  Other profiles might allow
   multiple event identifiers to be present but require that all be
   understood if the SET is to be accepted.  Some profiles might require
   that only a single value be present.  All such choices are within the
   scope of Profiling Specifications to define.

   Profiling Specifications MUST clearly specify the steps that a
   recipient of a SET utilizing that profile MUST perform to validate
   that the SET is both syntactically and semantically valid.

4.  Security Considerations

4.1.  Confidentiality and Integrity

   SETs may 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.

   Unless integrity of the JWT is ensured by other means, it MUST be
   signed using JWS [RFC7515] so that the SET can be authenticated and
   validated by the Event Recipient.

4.2.  Delivery

   This specification does not define a delivery mechanism for SETs.  In
   addition to confidentiality and integrity (discussed above),
   implementers and Profiling 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

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   correct endpoint received the SET and that it could be successfully

4.3.  Sequencing

   This specification defines no means of ordering multiple SETs in a
   sequence.  Depending on the type and nature of the events represented
   by SETs, order may or may not matter.  For example, in provisioning,
   event order is critical -- an object cannot be modified before it is
   created.  In other SET types, such as a token revocation, the order
   of SETs for revoked tokens does not matter.  If however, the event
   conveys a logged in or logged out status for a user subject, then
   order becomes important.

   Profiling Specifications and implementers SHOULD take caution when
   using timestamps such as "iat" to define order.  Distributed systems
   will have some amount of clock skew.  Thus, time by itself will not
   guarantee order.

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

4.4.  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 an Event
   Recipient in advance of or behind the process that caused the event.
   For example, a user having been required to log out 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 allow new sessions to be
   started immediately after a stated logout event time.

4.5.  Distinguishing SETs from ID Tokens

   Because [RFC7519] states that "all claims that are not understood by
   implementations MUST be ignored", there is a consideration that a SET
   might be confused with ID Token [OpenID.Core] if a SET is mistakenly
   or intentionally used in a context requiring an ID Token.  If a SET
   could otherwise be interpreted as a valid ID Token (because it

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   includes the required claims for an ID Token and valid issuer and
   audience claim values for an ID Token) then that SET profile MUST
   require that the "exp" claim not be present in the SET.  Because
   "exp" is a required claim in ID Tokens, valid ID Token
   implementations will reject such a SET if presented as if it were an
   ID Token.

   Excluding "exp" from SETs that could otherwise be confused with ID
   Tokens is actually defense in depth.  In any OpenID Connect contexts
   in which an attacker could attempt to substitute a SET for an ID
   Token, the SET would actually already be rejected as an ID Token
   because it would not contain the correct "nonce" claim value for the
   ID Token to be accepted in contexts for which substitution is

   Note that the use of explicit typing, as described in Section 2.3,
   will not achieve disambiguation between ID Tokens and SETs, as the ID
   Token validation rules do not use the "typ" header parameter value.

4.6.  Distinguishing SETs from Access Tokens

   OAuth 2.0 [RFC6749] defines access tokens as being opaque.
   Nonetheless, some implementations implement access tokens as JWTs.
   Because the structure of these JWTs is implementation-specific,
   ensuring that a SET cannot be confused with such an access token is
   therefore likewise, in general, implementation specific.
   Nonetheless, it is recommended that SET profiles employ the following
   strategies to prevent possible substitutions of SETs for access
   tokens in contexts in which that might be possible:

   o  Prohibit use of the "exp" claim, as is done to prevent ID Token

   o  Where possible, use a separate "aud" claim value to distinguish
      between the Event Recipient and the protected resource that is the
      audience of an access token.

   o  Modify access token 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  Employ explicit typing, as described in Section 2.3, and modify
      access token validation systems to use the "typ" header parameter

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4.7.  Distinguishing SETs from other kinds of JWTs

   JWTs are now being used in application areas beyond the identity
   applications in which they first appeared.  For instance, the Session
   Initiation Protocol (SIP) Via Header Field [RFC8055] and Personal
   Assertion Token (PASSporT) [I-D.ietf-stir-passport] specifications
   both define JWT profiles that use mostly or completely different sets
   of claims than are used by ID Tokens.  If it would otherwise be
   possible for an attacker to substitute a SET for one of these (or
   other) kinds of JWTs, then the SET profile must be defined in such a
   way that any substituted SET will result in its rejection when
   validated as the intended kind of JWT.

   The most direct way to prevent confusion is to employ explicit
   typing, as described in Section 2.3, and modify applicable token
   validation systems to use the "typ" header parameter value.  This
   approach can be employed for new systems but may not be applicable to
   existing systems.

   Another way to ensure that a SET is not confused with another kind of
   JWT is to have the JWT validation logic reject JWTs containing an
   "events" claim unless the JWT is intended to be a SET.  This approach
   can be employed for new systems but may not be applicable to existing

   For many use cases, the simplest way to prevent substitution is
   requiring that the SET not include claims that are required for the
   kind of JWT that might be the target of an attack.  For example, for
   [RFC8055], the "sip_callid" claim could be omitted and for
   [I-D.ietf-stir-passport], the "orig" claim could be omitted.

   In many contexts, simple measures such as these will accomplish the
   task, should confusion otherwise even be possible.  Note that this
   topic is being explored in a more general fashion in JSON Web Token
   Best Current Practices [I-D.ietf-oauth-jwt-bcp].  The proposed best
   practices in that draft may also be applicable for particular SET
   profiles and use cases.

5.  Privacy Considerations

   If a SET needs to be retained for audit purposes, the signature can
   be used to provide verification of its authenticity.

   Event Issuers SHOULD attempt to specialize SETs so that their content
   is targeted to the specific business and protocol needs of the
   intended Event Recipients.

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   When sharing personally identifiable information or information that
   is otherwise considered confidential to affected users, Event Issuers
   and Recipients MUST have the appropriate legal agreements and user
   consent and/or terms of service in place.

   The propagation of subject identifiers can be perceived as personally
   identifiable information.  Where possible, Event Issuers and
   Recipients SHOULD devise approaches that prevent propagation -- for
   example, the passing of a hash value that requires the Event
   Recipient to know the subject.

6.  IANA Considerations

6.1.  JSON Web Token Claims Registration

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

6.1.1.  Registry Contents

   o  Claim Name: "events"
   o  Claim Description: Security Event URI
   o  Change Controller: IESG
   o  Specification Document(s): Section 2.2 of [[ this specification ]]

   o  Claim Name: "toe"
   o  Claim Description: Time of Event
   o  Change Controller: IESG
   o  Specification Document(s): Section 2.2 of [[ this specification ]]

   o  Claim Name: "txn"
   o  Claim Description: Transaction Identifier
   o  Change Controller: IESG
   o  Specification Document(s): Section 2.2 of [[ this specification ]]

6.2.  Media Type Registration

6.2.1.  Registry Contents

   This section registers the "application/secevent+jwt" media type
   [RFC2046] in the "Media Types" registry [IANA.MediaTypes] in the
   manner described in [RFC6838], which can be used to indicate that the
   content is a SET.

   o  Type name: application
   o  Subtype name: secevent+jwt
   o  Required parameters: n/a

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   o  Optional parameters: n/a
   o  Encoding considerations: 8bit; A SET is a JWT; JWT values are
      encoded as a series of base64url-encoded values (some of which may
      be the empty string) separated by period ('.') characters.
   o  Security considerations: See the Security Considerations section
      of [[ this specification ]]
   o  Interoperability considerations: n/a
   o  Published specification: Section 2.3 of [[ this specification ]]
   o  Applications that use this media type: TBD
   o  Fragment identifier considerations: n/a
   o  Additional information:

         Magic number(s): n/a
         File extension(s): n/a
         Macintosh file type code(s): n/a

   o  Person & email address to contact for further information:
      Michael B. Jones,
   o  Intended usage: COMMON
   o  Restrictions on usage: none
   o  Author: Michael B. Jones,
   o  Change controller: IESG
   o  Provisional registration?  No

7.  References

7.1.  Normative References

              IANA, "JSON Web Token Claims",

              IANA, "Media Types",

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,

   [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,

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   [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security
              (TLS) Protocol Version 1.2", RFC 5246,
              DOI 10.17487/RFC5246, August 2008,

   [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, <>.

   [RFC6749]  Hardt, D., Ed., "The OAuth 2.0 Authorization Framework",
              RFC 6749, DOI 10.17487/RFC6749, October 2012,

   [RFC7519]  Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token
              (JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015,

   [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, <>.

   [RFC7617]  Reschke, J., "The 'Basic' HTTP Authentication Scheme",
              RFC 7617, DOI 10.17487/RFC7617, September 2015,

7.2.  Informative References

              Sheffer, Y., Hardt, D., and M. Jones, "JSON Web Token Best
              Current Practices", draft-ietf-oauth-jwt-bcp-00 (work in
              progress), July 2017.

              Wendt, C. and J. Peterson, "Personal Assertion Token
              (PASSporT)", draft-ietf-stir-passport-11 (work in
              progress), February 2017.

              Sakimura, N., Bradley, J., Jones, M., de Medeiros, B., and
              C. Mortimore, "OpenID Connect Core 1.0", November 2014,

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   [RFC2046]  Freed, N. and N. Borenstein, "Multipurpose Internet Mail
              Extensions (MIME) Part Two: Media Types", RFC 2046,
              DOI 10.17487/RFC2046, November 1996,

   [RFC6838]  Freed, N., Klensin, J., and T. Hansen, "Media Type
              Specifications and Registration Procedures", BCP 13,
              RFC 6838, DOI 10.17487/RFC6838, January 2013,

   [RFC7009]  Lodderstedt, T., Ed., Dronia, S., and M. Scurtescu, "OAuth
              2.0 Token Revocation", RFC 7009, DOI 10.17487/RFC7009,
              August 2013, <>.

   [RFC7515]  Jones, M., Bradley, J., and N. Sakimura, "JSON Web
              Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May
              2015, <>.

   [RFC7516]  Jones, M. and J. Hildebrand, "JSON Web Encryption (JWE)",
              RFC 7516, DOI 10.17487/RFC7516, May 2015,

   [RFC7517]  Jones, M., "JSON Web Key (JWK)", RFC 7517,
              DOI 10.17487/RFC7517, May 2015,

   [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, <>.

   [RFC8055]  Holmberg, C. and Y. Jiang, "Session Initiation Protocol
              (SIP) Via Header Field Parameter to Indicate Received
              Realm", RFC 8055, DOI 10.17487/RFC8055, January 2017,

   [RISC]     OpenID Foundation, "OpenID Risk and Incident Sharing and
              Coordination (RISC) Working Group",

              Internet2, "Assertions and Protocols for the OASIS
              Security Assertion Markup Language (SAML) V2.0", March

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Appendix A.  Acknowledgments

   The editors would like to thank the members of the IETF SCIM working
   group, which began discussions of provisioning events starting with
   draft-hunt-scim-notify-00 in 2015.

   The editors would like to thank the participants in the IETF id-event
   mailing list, the Security Events working group, and related working
   groups for their contributions to this specification.

Appendix B.  Change Log

   [[ to be removed by the RFC Editor before publication as an RFC ]]

   From the original draft-hunt-idevent-token:

   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

   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

      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.

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   o  Added additional clarification on the use of envelope vs. payload

   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

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

   Draft 06 - PH -

   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
   From draft-ietf-secevent-token:

   Draft 00 - PH - First WG Draft based on draft-hunt-idevent-token

   Draft 01 - PH - Changes as follows:

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   o  Changed terminology away from pub-sub to transmitter/receiver
      based on WG feedback

   o  Cleaned up/removed some text about extensions (now only used as

   o  Clarify purpose of spec vs. future profiling specs that define
      actual events

   Draft 02 - Changes are as follows:

   o  mbj - Added the Requirements for SET Profiles section.

   o  mbj - Expanded the Security Considerations section to describe how
      to prevent confusion of SETs with ID Tokens, access tokens, and
      other kinds of JWTs.

   o  mbj - Registered the "application/secevent+jwt" media type and
      defined how to use it for explicit typing of SETs.

   o  mbj - Clarified the misleading statement that used to say that a
      SET conveys a single security event.

   o  mbj - Added a note explicitly acknowledging that some SET profiles
      may choose to convey event subject information in the event

   o  PH - Corrected encoded claim example on page 10.

   o  mbj - Applied grammar corrections.

   Draft 03 - Changes As Follows:

   o  pjh - Corrected old "subscriber" to "Event Receiver".  Added
      clarification in definition that Event Receiver is the same as JWT

   o  pjh - Added definition for "toe" (and IANA registration).

   o  pjh - Removed "nbf" claim.

   o  pjh - Figure 3, moved "sub" to the events payload next to "iss".

   o  pjh - Clarified the use of "nonce" in contexts where substitution
      is possible.

   o  mbj - Addressed WGLC comments by Nat Sakimura.

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   o  mbj - Addressed WGLC comments by Annabelle Backman.

   o  mbj - Addressed WGLC comments by Marius Scurtescu.

   Draft 04 - mbj - Changes were as follows:

   o  Clarified that all "events" values must represent aspects of the
      same state change that occurred to the subject -- not an
      aggregation of unrelated events about the subject.

   o  Removed ambiguities about the roles of multiple "events" values
      and the responsibilities of profiling specifications for defining
      how and when they are used.

   o  Corrected places where the term JWT was used when what was
      actually being discussed was the JWT Claims Set.

   o  Addressed terminology inconsistencies.  In particular,
      standardized on using the term "issuer" to align with JWT
      terminology and the "iss" claim.  Previously the term
      "transmitter" was sometimes used and "issuer" was sometimes used.
      Likewise, standardized on using the term "recipient" instead of
      "receiver" for the same reasons.

   o  Added a RISC event example, courtesy of Marius Scurtescu.

   o  Applied wording clarifications suggested by Annabelle Backman and
      Yaron Sheffer.

   o  Applied numerous grammar, syntax, and formatting corrections.

Authors' Addresses

   Phil Hunt (editor)
   Oracle Corporation


   Michael B. Jones


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   William Denniss


   Morteza Ansari


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