Security Event Token (SET)
draft-hunt-idevent-token-08

Abstract

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

Status of This Memo

This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.

Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at http://datatracker.ietf.org/drafts/current/.

Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress."

This Internet-Draft will expire on July 13, 2017.

Copyright Notice

Copyright (c) 2017 IETF Trust and the persons identified as the document authors. All rights reserved.

This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents 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
• 1.1. Notational Conventions
• 1.2. Definitions
• 2. The Security Event Token (SET)
• 2.1. Core SET Claims
• 2.2. Security Event Token Construction
• 3. Security Considerations
• 3.1. Confidentiality and Integrity
• 3.2. Delivery
• 3.3. Sequencing
• 3.4. Timing Issues
• 3.5. Distinguishing SETs from Access Tokens
• 4. Privacy Considerations
• 5. IANA Considerations
• 5.1. JSON Web Token Claims Registration
• 5.1.1. Registry Contents
• 6. References
• 6.1. Normative References
• 6.2. Informative References
• Appendix A. Acknowledgments
• Appendix B. Change Log
• Authors' Addresses

1. Introduction and Overview

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

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

• The creation, modification, removal of a resource.
• The resetting or suspension of an account.
• The revocation of a security token prior to its expiry.
• The logout of a user session. Or,
• A cumulative conclusion such as to indicate that a user has taken over an email identifier that may have been used in the past by another user.

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

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

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

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

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

1.1. Notational Conventions

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. These keywords are capitalized when used to unambiguously specify requirements of the protocol or application features and behavior that affect the inter-operability and security of implementations. When these words are not capitalized, they are meant in their natural-language sense.

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

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

1.2. Definitions

The following definitions are used with SETs:

Feed Publisher

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

Security Event Token (SET)

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

Feed

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

Subscriber

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

Security Subject

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

2. The Security Event Token (SET)

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

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

• An outer JSON structure that acts as the SET envelope. The envelope contains a set of name/value pairs called the JWT Claims Set, typically common to every SET or common to a number of different Security Events within a single profiling specification or a related series of specifications. Claims in the envelope SHOULD be registered in the JWT Token Claims Registry Section 10.1 [RFC7519] or be Public Claims or Private Claims as also defined in [RFC7519].
• Envelope claims that are profiled and defined in this specification are used to validate a SET and declare the event data included in the SET. The claim events identifies the security event types being expressed related to the Security Subject and MAY also include event-specific data.
• Each JSON member of the events object is a name/value pair. The JSON attribute name is a URI String value that expresses an event type. The corresponding value is a JSON object known as the event "payload". The payload JSON object contains claims typically unique to the event's URI type value and are not registered as JWT claims. These claims are defined by their associated event specification. An event with no payload claims SHALL be represented as the empty JSON object ({}). In many cases, one event URI expresses the primary event URI, while other events might be considered extensions that MAY be used to do things such as:
  • A categorization event type to provide classification information (e.g., threat type or level).
  • An enhancement of an existing specifications the arise over time.
  • An extensions needed to link a potential series of events.
  • Localized specific purpose extensions needed between a particular publisher and subscriber.

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

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

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

{  
  "jti": "4d3559ec67504aaba65d40b0363faad8",
  "iat": 1458496404,
  "iss": "https://scim.example.com",  
  "aud": [
   "https://scim.example.com/Feeds/98d52461fa5bbc879593b7754",
   "https://scim.example.com/Feeds/5d7604516b1d08641d7676ee7"
  ],  
  
  "events": {
    "urn:ietf:params:scim:event:create": {
      "ref":
        "https://scim.example.com/Users/44f6142df96bd6ab61e7521d9",
      "attributes":["id", "name", "userName", "password", "emails"]
    }
  }
}

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