Security Events Working Group                               P. Hunt, Ed.
Internet-Draft                                                    Oracle
Intended status: Standards Track                                M. Jones
Expires: September 5, October 6, 2018                                       Microsoft
                                                              W. Denniss
                                                               M. Ansari
                                                           April 4, 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 about the state of a security subject, which is intended
   to be shared with one or more recipients.  This statement of fact
   represents an event that occurred to the security subject.  In some
   use cases, the security subject may be a digitial identity, but SETs
   are also applicable  This
   specification is intended to non-identity use cases. enable representing security- and
   identity-related events.  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.

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   This Internet-Draft will expire on September 5, October 6, 2018.

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Table of Contents

   1.  Introduction and Overview . . . . . . . . . . . . . . . . . .   3
     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  . . . . . . . . . . . . . . . . . . .   8
       2.1.3.  Consent Example . . . . . . . . . . . . . . . . . . .   8
       2.1.4.  RISC Example  . . . . . . . . . . . . . . . . . . . .   9
     2.2.  Core SET Claims . . . . . . . . . . . . . . . . . . . . .  10
     2.3.  Explicit Typing of SETs . . . . . . . . . . . . . . . . .  12
     2.4.  Security Event Token Construction . . . . . . . . . . . .  12
   3.  Requirements for SET Profiles . . . . . . . . . . . . . . . .  14
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .  15
     4.1.  Confidentiality and Integrity . . . . . . . . . . . . . .  15
     4.2.  Delivery  . . . . . . . . . . . . . . . . . . . . . . . .  15
     4.3.  Sequencing  . . . . . . . . . . . . . . . . . . . . . . .  16
     4.4.  Timing Issues . . . . . . . . . . . . . . . . . . . . . .  16
     4.5.  Distinguishing SETs from ID Tokens  . . . . . . . . . . .  16  17
     4.6.  Distinguishing SETs from Access Tokens  . . . . . . . . .  17
     4.7.  Distinguishing SETs from other kinds of JWTs  . . . . . .  18
   5.  Privacy Considerations  . . . . . . . . . . . . . . . . . . .  18
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  19
     6.1.  JSON Web Token Claims Registration  . . . . . . . . . . .  19
       6.1.1.  Registry Contents . . . . . . . . . . . . . . . . . .  19
     6.2.  Media Type Registration . . . . . . . . . . . . . . . . .  20
       6.2.1.  Registry Contents . . . . . . . . . . . . . . . . . .  20
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  20
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .  20
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  21  22
   Appendix A.  Acknowledgments  . . . . . . . . . . . . . . . . . .  23
   Appendix B.  Change Log . . . . . . . . . . . . . . . . . . . . .  23
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  27

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]
   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 security- and identity related 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, a SET
   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 SET recipient may choose to
   ensure that the new user is not granted access to resources
   associated with the previous user.  Or, the SET recipient may not
   have any relationship with the subject, and no action is taken.

   While SET 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 SET recipients may interpret for their own purposes.

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 BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

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

   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 SET recipients.

   SET Issuer
      A service provider that creates SETs to be sent to other service
      providers known as SET recipients.

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

      A SET describes an event or state change that has occurred to a
      subject.  A subject might, for instance, be a principal (e.g.,
      Section 4.1.2 of [RFC7519]), a web resource, an entity such as an
      IP address, or the issuer of the SET.

   Event Identifier
      A member name for an element of the JSON object that is the value
      of the "events" claim in a SET.  This member name MUST be a URI.

   Event Payload
      A member value for an element of the JSON object that is the value
      of the "events" claim in a SET.  This member value MUST be JSON

   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 that occurred to 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.  The "events" claim value MUST
      be a JSON object that contains at least one member.

   o  Each member of the "events" JSON object is a name/value pair.  The
      JSON member name is a URI string value, which is the 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:

      *  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 SET issuers
         and SET recipients.

2.1.  Illustrative Examples

   This section illustrates several possible uses of SETs through non-
   normative examples.

2.1.1.  SCIM Example
   The following is a non-normative example showing shows 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:

     "iss": "",
     "iat": 1458496025,
     "jti": "3d0c3cf797584bd193bd0fb1bd4e7d30",
     "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 SET issuer.

   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
   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:

     "iss": "",
     "iat": 1458496025,
     "jti": "fb4e75b5411e4e19b6c0fe87950f7749",
     "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
   SET 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
   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": "",
     "jti": "756E69717565206964656E746966696572",
     "iat": 1508184845,
     "aud": "636C69656E745F6964",
     "events": {
       account-disabled": {
         "subject": {
           "subject_type": "iss-sub",
           "iss": "",
           "sub": "7375626A656374"
         "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
   subject of the event is identified using the "subject" payload value,
   which itself is a JSON object.

2.2.  Core SET Claims

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

   "iss" (Issuer) Claim
      As defined by Section 4.1.1 of [RFC7519], this claim contains 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

   "iat" (Issued At) Claim
      As defined by Section 4.1.6 of [RFC7519], this claim contains a
      value representing when the SET was issued.  This claim is

   "jti" (JWT ID) Claim
      As defined by Section 4.1.7 of [RFC7519], this claim contains a
      unique identifier for the SET.  The identifier SHOULD be unique
      within a particular event feed and MAY be used by clients to track
      whether a particular SET has already been received.  This claim is

   "aud" (Audience) Claim
      As defined by Section 4.1.3 of [RFC7519], this claim contains one
      or more audience identifiers for the SET.  This claim is

   "sub" (Subject) Claim
      As defined by Section 4.1.2 of [RFC7519], this claim contains a
      StringOrURI value representing the principal that is 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.

   "exp" (Expiration Time) Claim
      As defined by Section 4.1.4 of [RFC7519], this claim is the time
      after which the JWT MUST NOT be accepted for processing.  In the
      context of a SET however, this notion does not typically apply,
      since a SET represents something that has already occurred and is
      historical in nature.  Therefore, its use is NOT RECOMMENDED.
      (Also, see Section 4.5 for additional reasons not to use the "exp"
      claim in some SET use cases.)

   The following new claims are defined by this specification:

   "events" (Security Events) Claim
      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
      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.

   "txn" (Transaction Identifier) Claim
      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.  Note that this claim can be used in JWTs that are
      SETs and also in JWTs using non-SET profiles.

   "toe" (Time of Event) Claim
      A value that represents the date and time at which the event
      occurred.  This value is a NumericDate (see Section 2 of
      [RFC7519]).  By omitting this claim, the issuer indicates that
      they are not sharing an event time with the recipient.  (Note that
      in some use cases, the represented time might be approximate.)
      This claim is OPTIONAL.

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.

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

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

   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, other
   mechanisms such as TLS MUST be employed to provide integrity,
   confidentiality, and issuer authenticity, 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 of this specification define actual SETs to
   be used in particular use cases.  These profiling specifications
   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 profile.

   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
   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 a profiling specification
   may define is whether the value of the "events" claim may contain
   multiple members, and what processing instructions are employed in
   the single- and multiple-valued cases for SETs conforming to that
   profile.  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] or a higher version 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"

   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 SET 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
   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 a SET
   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 maliciously used in a context requiring an ID Token.  If a SET
   could otherwise be interpreted as a valid ID Token (because it
   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 SET 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

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.

   SET issuers SHOULD attempt to specialize SETs so that their content
   is targeted to the specific business and protocol needs of the
   intended SET recipients.

   When sharing personally identifiable information or information that
   is otherwise considered confidential to affected users, SET 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, SET issuers and recipients
   SHOULD devise approaches that prevent propagation -- for example, the
   passing of a hash value that requires the SET recipient to know the

   In some cases, it may be possible for a SET recipient to correlate
   different events and thereby gain information about a subject that
   the SET issuer did not intend to share.  For example, a SET recipient
   might be able to use "iat" values or highly precise "toe" values to
   determine that two otherwise un-relatable events actually relate to
   the same real-world event.  The union of information from both events
   could allow a SET recipient to de-anonymize data or recognize that
   unrelated identifiers relate to the same individual.  SET issuers
   SHOULD take steps to minimize the chance of event correlation, when
   such correlation would constitute a privacy violation.  For instance,
   they could use approximate values for the "toe" claim or arbitrarily
   delay SET issuance, where such delay can be tolerated.

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 Events
   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
   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,

   [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, <>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <>.

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,

   [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",

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.  The specification incorporates
   suggestions made by many people, including Annabelle Backman, John
   Bradley, Dick Hardt, Russ Housley, Benjamin Kaduk, Mark Lizar, Andrew
   Nash, Justin Richer, Nat Sakimura, Marius Scurtescu, and Yaron

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.

   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:

   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 are 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.

   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.

   Draft 05 - mbj - Changes were as follows:

   o  Simplified the definitions of the "iat" and "toe" claims in ways
      suggested by Annabelle Backman.

   o  Added privacy considerations text suggested by Annabelle Backman.

   o  Updated the RISC event example, courtesy of Marius Scurtescu.

   o  Reordered the claim definitions to place the required claims

   o  Changed to using the RFC 8174 boilerplate instead of the RFC 2119

   Draft 06 - mbj - Changes were as follows:

   o  Changed "when the event was issued" to "when the SET was issued"
      in the "iat" description, as suggested by Annabelle Backman.

   o  Applied editorial improvements that improve the consistency of the
      specification that were suggested by Annabelle Backman, Marius
      Scurtescu, and Yaron Sheffer.

   Draft 07 - PH - Text refinement to Section 3 proposed by Annabelle
   Backman post WGLC

   Draft 08 - mbj - Changes were as follows:

   o  Incorporated wording improvements resulting from Russ Housley's
      SecDir comments.

   o  Acknowledged individuals who made significant contributions.

Authors' Addresses

   Phil Hunt (editor)
   Oracle Corporation


   Michael B. Jones


   William Denniss

   Morteza Ansari