| Security Events Working Group | A. Backman, Ed. |
| Internet-Draft | Amazon |
| Intended status: Standards Track | M. Scurtescu |
| Expires: April 25, 2019 | |
| October 22, 2018 |
Subject Identifiers for Security Event Tokens
draft-ietf-secevent-subject-identifiers-01
Security events communicated within Security Event Tokens may support a variety of identifiers to identify the subject and/or other principals related to the event. This specification formalizes the notion of subject identifiers as named sets of well-defined claims describing the subject, a mechanism for representing subject identifiers within a [JSON] object such as a JSON Web Token or Security Event Token, and a registry for defining and allocating names for these claim sets.
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As described in section 1.2 of [SET], the subject of a security event may take a variety of forms, including but not limited to a JWT principal, an IP address, a URL, etc. Furthermore, even in the case where the subject of an event is more narrowly scoped, there may be multiple ways by which a given subject may be identified. For example, an account may be identified by an opaque identifier, an email address, a phone number, a JWT iss claim and sub claim, etc., depending on the nature and needs of the transmitter and receiver. Even within the context of a given transmitter and receiver relationship, it may be appropriate to identify different accounts in different ways, for example if some accounts only have email addresses associated with them while others only have phone numbers. Therefore it can be necessary to indicate within a SET the mechanism by which the subject of the security event is being identified.
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].
A Subject Identifier Type is a light-weight schema that describes a set of claims that identifies a subject. Every Subject Identifier Type MUST have a unique name registered in the IANA “Security Event Subject Identifier Types” registry established by Section 4.1. A Subject Identifier Type MAY describe more claims than are strictly necessary to uniquely identify a subject, and MAY describe conditions under which those claims are required, optional, or prohibited.
A Subject Identifier is a [JSON] object containing a subject_type claim whose value is the unique name of a Subject Identifier Type, and a set of additional “payload claims” which are to be interpreted according to the rules defined by that Subject Identifier Type. Payload claim values MUST match the format specified for the claim by the Subject Identifier Type. A Subject Identifier MUST NOT contain any payload claims prohibited or not described by its Subject Identifier Type, and MUST contain all payload claims required by its Subject Identifier Type.
The following Subject Identifier Types are registered in the IANA “Security Event Subject Identifier Types” registry established by Section 4.1.
The Email Subject Identifier Type describes a subject that is a user account associated with an email address. Subject Identifiers of this type MUST contain an email claim whose value is a string containing the email address of the subject, formatted as an addr-spec as defined in Section 3.4.1 of [RFC5322]. The email claim is REQUIRED and MUST NOT be null or empty. The Email Subject Identifier Type is identified by the name email.
Below is a non-normative example Subject Identifier for the Email Subject Identifier Type:
{
"subject_type": "email",
"email": "user@example.com",
}
Figure 1: Example: Subject Identifier for the Email Subject Identifier Type.
The Phone Number Subject Identifier Type describes a subject that is a user account associated with a telephone number. Subject Identifiers of this type MUST contain a phone claim whose value is a string containing the full telephone number of the subject, including international dialing prefix, formatted according to E.164. The phone claim is REQUIRED and MUST NOT be null or empty. The Phone Number Subject Identifier Type is identified by the name phone.
Below is a non-normative example Subject Identifier for the Email Subject Identifier Type:
{
"subject_type": "phone",
"phone": "+1 (206) 555-0100",
}
Figure 2: Example: Subject Identifier for the Phone Number Subject Identifier Type.
The Issuer and Subject Subject Identifier Type describes a subject that is an account identified by a pair of iss and sub claims, as defined by [JWT]. These claims MUST follow the formats of the iss claim and sub claim defined by [JWT], respectively. Both the iss claim and the sub claim are REQUIRED and MUST NOT be null or empty. The Issuer and Subject Subject Identifier Type is identified by the name iss-sub.
Below is a non-normative example Subject Identifier for the Issuer and Subject Subject Identifier Type:
{
"subject_type": "iss-sub",
"iss": "http://issuer.example.com/",
"sub": "145234573",
}
Figure 3: Example: Subject Identifier for the Issuer and Subject Subject Identifier Type.
The ID Token Claims Subject Identifier Type describes a subject that was the subject of a previously issued ID Token. It is intended for use when a variety of identifiers have been shared with the party that will be interpreting the Subject Identifier, and it is unknown which of those identifiers they require. This type is identified by the name id-token-claims.
Subject Identifiers of this type MUST contain at least one of the following claims:
At least one of email, phone_number, or sub MUST be present.
Below is a non-normative example Subject Identifier for the ID Token Claims Subject Identifier Type:
{
"subject_type": "id-token-claims",
"iss": "http://issuer.example.com/",
"sub": "145234573",
"email": "user@example.com",
}
Figure 4: Example: Subject Identifier for the ID Token Claims Subject Identifier Type.
This document defines Subject Identifier Types, for which IANA is asked to create and maintain a new registry titled “Security Event Subject Identifier Types”. Initial values for the Security Event Subject Identifier Types registry are given in Section 3. Future assignments are to be made through the Expert Review registration policy [BCP26] and shall follow the template presented in Section 4.1.1.
The Expert Reviewer is expected to review the documentation referenced in a registration request to verify its completeness. The Expert Reviewer must base their decision to accept or reject the request on a fair and impartial assessment of the request. If the Expert Reviewer has a conflict of interest, such as being an author of a defining document referenced by the request, they must recuse themselves from the approval process for that request. In the case where a request is rejected, the Expert Reviewer should provide the requesting party with a written statement expressing the reason for rejection, and be prepared to cite any sources of information that went into that decision.
Subject Identifier Types need not be generally applicable and may be highly specific to a particular domain; it is expected that types may be registered for niche or industry-specific use cases. The Expert Reviewer should focus on whether the type is thoroughly documented, and whether its registration will promote or harm interoperability. In most cases, the Expert Reviewer should not approve a request if the registration would contribute to confusion, or amount to a synonym for an existing type.
There are no privacy considerations.
There are no security considerations.
This document is based on work developed within the OpenID RISC Working Group. The authors would like to thank the members of this group for their hard work and contributions.
(This section to be removed by the RFC Editor before publication as an RFC.)
Draft 00 - AB - First draft
Draft 01 - AB: * Added reference to RFC 5322 for format of email claim. * Renamed iss_sub type to iss-sub. * Renamed id_token_claims type to id-token-claims. * Added text specifying the nature of the subjects described by each type.