Internet DRAFT - draft-ietf-secevent-subject-identifiers
draft-ietf-secevent-subject-identifiers
Security Events Working Group A. Backman, Ed.
Internet-Draft Amazon
Intended status: Standards Track M. Scurtescu
Expires: 26 December 2023 Coinbase
P. Jain
Fastly
24 June 2023
Subject Identifiers for Security Event Tokens
draft-ietf-secevent-subject-identifiers-18
Abstract
Security events communicated within Security Event Tokens may support
a variety of identifiers to identify subjects related to the event.
This specification formalizes the notion of subject identifiers as
structured information that describe a subject, and named formats
that define the syntax and semantics for encoding subject identifiers
as JSON objects. It also defines a registry for defining and
allocating names for such formats, as well as the "sub_id" JSON Web
Token (JWT) claim.
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 26 December 2023.
Copyright Notice
Copyright (c) 2023 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 (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Notational Conventions . . . . . . . . . . . . . . . . . . . 5
2.1. Definitions . . . . . . . . . . . . . . . . . . . . . . . 5
3. Subject Identifiers . . . . . . . . . . . . . . . . . . . . . 5
3.1. Identifier Formats versus Principal Types . . . . . . . . 6
3.2. Identifier Format Definitions . . . . . . . . . . . . . . 6
3.2.1. Account Identifier Format . . . . . . . . . . . . . . 7
3.2.2. Email Identifier Format . . . . . . . . . . . . . . . 7
3.2.3. Issuer and Subject Identifier Format . . . . . . . . 8
3.2.4. Opaque Identifier Format . . . . . . . . . . . . . . 9
3.2.5. Phone Number Identifier Format . . . . . . . . . . . 9
3.2.6. Decentralized Identifier (DID) Format . . . . . . . . 10
3.2.7. Uniform Resource Identifier (URI) Format . . . . . . 10
3.2.8. Aliases Identifier Format . . . . . . . . . . . . . . 11
4. Subject Identifiers in JWTs . . . . . . . . . . . . . . . . . 12
4.1. sub_id Claim . . . . . . . . . . . . . . . . . . . . . . 12
4.2. sub_id and iss_sub Subject Identifiers . . . . . . . . . 14
5. Considerations for Specifications that Define Identifier
Formats . . . . . . . . . . . . . . . . . . . . . . . . . 15
6. Privacy Considerations . . . . . . . . . . . . . . . . . . . 15
6.1. Identifier Correlation . . . . . . . . . . . . . . . . . 15
7. Security Considerations . . . . . . . . . . . . . . . . . . . 16
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16
8.1. Security Event Identifier Formats Registry . . . . . . . 16
8.1.1. Registry Location . . . . . . . . . . . . . . . . . . 16
8.1.2. Registration Template . . . . . . . . . . . . . . . . 16
8.1.3. Initial Registry Contents . . . . . . . . . . . . . . 17
8.1.4. Guidance for Expert Reviewers . . . . . . . . . . . . 19
8.2. JSON Web Token Claims Registration . . . . . . . . . . . 19
8.2.1. Registry Contents . . . . . . . . . . . . . . . . . . 19
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 19
9.1. Normative References . . . . . . . . . . . . . . . . . . 19
9.2. Informative References . . . . . . . . . . . . . . . . . 21
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 21
Change Log . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 25
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1. Introduction
As described in Section 1.2 of SET [RFC8417], subjects related to
security events may take a variety of forms, including but not
limited to a JWT [RFC7519] principal, an IP address, a URL, etc.
Different types of subjects may need to be identified in different
ways (e.g., a user might be identified by an email address or a phone
number or an account number). Furthermore, even in the case where
the type of the subject is known, 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 a subject is being identified.
To address this problem, this specification defines Subject
Identifiers - JSON [RFC8259] objects containing information
identifying a subject - and Identifier Formats - named sets of rules
describing how to encode different kinds of subject identifying
information (e.g., an email address, or an issuer and subject pair)
as a Subject Identifier.
Below is a non-normative example of a Subject Identifier that
identifies a subject by email address, using the Email Identifier
Format.
{
"format": "email",
"email": "user@example.com"
}
Figure 1: Example: Subject Identifier using the Email Identifier
Format
Subject Identifiers are intended to be a general-purpose mechanism
for identifying subjects within JSON objects and their usage need not
be limited to SETs. Below is a non-normative example of a JWT that
uses a Subject Identifier in the "sub_id" claim (defined in this
specification) to identify the JWT Subject.
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{
"iss": "issuer.example.com",
"sub_id": {
"format": "phone_number",
"phone_number": "+12065550100"
}
}
Figure 2: Example: JWT using a Subject Identifier with the
"sub_id" claim
Usage of Subject Identifiers also need not be limited to identifying
JWT Subjects. They are intended as a general-purpose means of
expressing identifying information in an unambiguous manner. Below
is a non-normative example of a SET containing a hypothetical
security event describing the interception of a message, using
Subject Identifiers to identify the sender, intended recipient, and
interceptor.
{
"iss": "issuer.example.com",
"iat": 1508184845,
"aud": "aud.example.com",
"events": {
"https://secevent.example.com/events/message-interception": {
"from": {
"format": "email",
"email": "alice@example.com"
},
"to": {
"format": "email",
"email": "bob@example.com"
},
"interceptor": {
"format": "email",
"email": "eve@example.com"
}
}
}
}
Figure 3: Example: SET with an event payload containing multiple
Subject Identifiers
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2. 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 BCP 14
[RFC2119][RFC8417].
2.1. Definitions
This specification utilizes terminology defined in [RFC8259] and
[RFC8417].
Within this specification, the terms "Subject" and "subject" refer
generically to anything being identified via one or more pieces of
information. The term "JWT Subject" refers specifically to the
subject of a JWT (i.e., the subject that the JWT asserts claims
about).
3. Subject Identifiers
A Subject Identifier is a JSON [RFC8259] object whose contents may be
used to identify a subject within some context. An Identifier Format
is a named definition of a set of information that may be used to
identify a subject, and the rules for encoding that information as a
Subject Identifier; they define the syntax and semantics of Subject
Identifiers. A Subject Identifier MUST conform to a specific
Identifier Format, and MUST contain a "format" member whose value is
the name of that Identifier Format.
Every Identifier Format MUST have a unique name registered in the
IANA "Security Event Identifier Formats" registry established by
Section 8.1, or a Collision-Resistant Name as defined in [RFC7519].
Identifier Formats that are expected to be used broadly by a variety
of parties SHOULD be registered in the "Security Event Identifier
Formats" registry.
An Identifier Format MAY describe more members than are strictly
necessary to identify a subject, and MAY describe conditions under
which those members are required, optional, or prohibited. The
"format" member is reserved for use as described in this
specification; Identifier Formats MUST NOT declare any rules
regarding the "format" member.
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Every member within a Subject Identifier MUST match the rules
specified for that member by this specification or by Subject
Identifier's Identifier Format. A Subject Identifier MUST NOT
contain any members prohibited or not described by its Identifier
Format, and MUST contain all members required by its Identifier
Format.
3.1. Identifier Formats versus Principal Types
Identifier Formats define how to encode identifying information for a
subject. Unlike Principal Types, they do not define the type or
nature of the subject itself. For example, while the "email"
Identifier Format declares that the value of the "email" member is an
email address, a subject in a Security Event that is identified by an
"email" Subject Identifier could be an end user who controls that
email address, the mailbox itself, or anything else that the
transmitter and receiver both understand to be associated with that
email address. Consequently Subject Identifiers remove ambiguity
around how a subject is being identified, and how to parse an
identifying structure, but do not remove ambiguity around how to
resolve that identifier to a subject. For example, consider a
directory management API that allows callers to identify users and
groups through both opaque unique identifiers and email addresses.
Such an API could use Subject Identifiers to disambiguate between
which of these two types of identifiers is in use. However, the API
would have to determine whether the subject is a user or group via
some other means, such as by querying a database, interpreting other
parameters in the request, or inferring the type from the API
contract.
3.2. Identifier Format Definitions
The following Identifier Formats are registered in the IANA "Security
Event Identifier Formats" registry established by Section 8.1.
Since the subject identifier format conveys semantic information,
applications SHOULD choose the most specific possible format for the
identifier in question. For example, an email address can be
conveyed using a mailto: URI and the uri identifier format, but since
the value is known to be an email address, the application should
prefer to use the "email" identifier format instead.
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3.2.1. Account Identifier Format
The Account Identifier Format identifies a subject using an account
at a service provider, identified with an "acct" URI as defined in
[RFC7565]. An account is an arrangement or agreement through which a
user gets access to a service and gets a unique identity with the
service provider. Subject Identifiers in this format MUST contain a
"uri" member whose value is the "acct" URI for the subject. The
"uri" member is REQUIRED and MUST NOT be null or empty. The Account
Identifier Format is identified by a value of "account" in the
"format" member.
Below is a non-normative example Subject Identifier for the Account
Identifier Format:
{
"format": "account",
"uri": "acct:example.user@service.example.com"
}
Figure 4: Example: Subject Identifier for the Account Identifier
Format
3.2.2. Email Identifier Format
The Email Identifier Format identifies a subject using an email
address. Subject Identifiers in this format MUST contain an "email"
member 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" member is REQUIRED and MUST NOT be null or
empty. The value of the "email" member MUST identify a mailbox to
which email may be delivered, in accordance with [RFC5321]. The
Email Identifier Format is identified by the name "email".
Below is a non-normative example Subject Identifier in the Email
Identifier Format:
{
"format": "email",
"email": "user@example.com"
}
Figure 5: Example: Subject Identifier in the Email Identifier Format
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3.2.2.1. Email Canonicalization
Many email providers will treat multiple email addresses as
equivalent. While the domain portion of an [RFC5322] email address
is consistently treated as case-insensitive per [RFC1034], most
providers treat the local part of the email address as case-
insensitive as well, and consider "user@example.com",
"User@example.com", and "USER@example.com" as the same email address.
Some providers also treat dots (".") as optional; for example,
"user.name@example.com", "username@example.com",
"u.s.e.r.name@example.com", and "u.s.e.r.n.a.m.e@example.com" might
all be treated as equivalent. This has led users to view these
strings as equivalent, driving service providers to implement
proprietary email canonicalization algorithms to ensure that email
addresses entered by users resolve to the same canonical string.
Email canonicalization is not standardized, and there is no way for
the event recipient to determine the mail provider’s canonicalization
method. Therefore, the recipient SHOULD apply its own
canonicalization algorithm to incoming events that reproduces the
translation done by the local email system.
3.2.3. Issuer and Subject Identifier Format
The Issuer and Subject Identifier Format identifies a subject using a
pair of "iss" and "sub" members, analogous to how subjects are
identified using the "iss" and "sub" claims in OpenID Connect
[OpenID.Core] ID Tokens. These members MUST follow the formats of
the "iss" member and "sub" member defined by [RFC7519], respectively.
Both the "iss" member and the "sub" member are REQUIRED and MUST NOT
be null or empty. The Issuer and Subject Identifier Format is
identified by the name "iss_sub".
Below is a non-normative example Subject Identifier in the Issuer and
Subject Identifier Format:
{
"format": "iss_sub",
"iss": "https://issuer.example.com/",
"sub": "145234573"
}
Figure 6: Example: Subject Identifier in the Issuer and Subject
Identifier Format
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3.2.4. Opaque Identifier Format
The Opaque Identifier Format describes a subject that is identified
with a string with no semantics asserted beyond its usage as an
identifier for the subject, such as a UUID or hash used as a
surrogate identifier for a record in a database. Subject Identifiers
in this format MUST contain an "id" member whose value is a JSON
string containing the opaque string identifier for the subject. The
"id" member is REQUIRED and MUST NOT be null or empty. The Opaque
Identifier Format is identified by the name "opaque".
Below is a non-normative example Subject Identifier in the Opaque
Identifier Format:
{
"format": "opaque",
"id": "11112222333344445555"
}
Figure 7: Example: Subject Identifier in the Opaque Identifier Format
3.2.5. Phone Number Identifier Format
The Phone Number Identifier Format identifies a subject using a
telephone number. Subject Identifiers in this format MUST contain a
"phone_number" member whose value is a string containing the full
telephone number of the subject, including international dialing
prefix, formatted according to E.164 [E164]. The "phone_number"
member is REQUIRED and MUST NOT be null or empty. The Phone Number
Identifier Format is identified by the name "phone_number".
Below is a non-normative example Subject Identifier in the Email
Identifier Format:
{
"format": "phone_number",
"phone_number": "+12065550100"
}
Figure 8: Example: Subject Identifier in the Phone Number
Identifier Format
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3.2.6. Decentralized Identifier (DID) Format
The Decentralized Identifier Format identifies a subject using a
Decentralized Identifier (DID) URL as defined in [DID]. Subject
Identifiers in this format MUST contain a "URL" member whose value is
a DID URL for the DID Subject being identified. The value of the
"url" member MUST be a valid DID URL and MAY be a bare DID. The
"url" member is REQUIRED and MUST NOT be null or empty. The
Decentralized Identifier Format is identified by the name "did".
Below are non-normative example Subject Identifiers for the
Decentralized Identifier Format:
{
"format": "did",
"url": "did:example:123456"
}
Figure 9: Example: Subject Identifier for the Decentralized
Identifier Format, identifying a subject with a bare DID
{
"format": "did",
"url": "did:example:123456/did/url/path?versionId=1"
}
Figure 10: Example: Subject Identifier for the Decentralized
Identifier Format, identifying a subject with a DID URL with non-
empty path and query components
3.2.7. Uniform Resource Identifier (URI) Format
The Uniform Resource Identifier (URI) Format identifies a subject
using a URI as defined in [RFC3986]. This identifier format makes no
assumptions or guarantees with regard to the content, scheme, or
reachability of the URI within the field. Subject Identifiers in
this format MUST contain a "uri" member whose value is a URI for the
subject being identified. The "uri" member is REQUIRED and MUST NOT
be null or empty. The URI format is identified by the name "uri".
Below are non-normative example Subject Identifiers for the URI
format:
{
"format": "uri",
"uri": "https://user.example.com/"
}
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Figure 11: Example: Subject Identifier for the URI Format,
identifying a subject with a website URI
{
"format": "uri",
"uri": "urn:uuid:4e851e98-83c4-4743-a5da-150ecb53042f"
}
Figure 12: Example: Subject Identifier for the URI Format,
identifying a subject with a random URN
3.2.8. Aliases Identifier Format
The Aliases Identifier Format describes a subject that is identified
with a list of different Subject Identifiers. 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 will recognize or support. Subject
Identifiers in this format MUST contain an "identifiers" member whose
value is a JSON array containing one or more Subject Identifiers.
Each Subject Identifier in the array MUST identify the same entity.
The "identifiers" member is REQUIRED and MUST NOT be null or empty.
It MAY contain multiple instances of the same Identifier Format
(e.g., multiple Email Subject Identifiers), but SHOULD NOT contain
exact duplicates. This format is identified by the name "aliases".
"aliases" Subject Identifiers MUST NOT be nested; i.e., the
"identifiers" member of an "aliases" Subject Identifier MUST NOT
contain a Subject Identifier in the "aliases" format.
Below is a non-normative example Subject Identifier in the Aliases
Identifier Format:
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{
"format": "aliases",
"identifiers": [
{
"format": "email",
"email": "user@example.com"
},
{
"format": "phone_number",
"phone_number": "+12065550100"
},
{
"format": "email",
"email": "user+qualifier@example.com"
}
]
}
Figure 13: Example: Subject Identifier in the Aliases Identifier
Format
4. Subject Identifiers in JWTs
4.1. sub_id Claim
The "sub" JWT Claim is defined in Section 4.1.2 of [RFC7519] as
containing a string value, and therefore cannot contain a Subject
Identifier (which is a JSON object) as its value. This document
defines the "sub_id" JWT Claim, in accordance with Section 4.2 of
[RFC7519], as a common claim that identifies the JWT Subject using a
Subject Identifier. When present, the value of this claim MUST be a
Subject Identifier that identifies the subject of the JWT. The
"sub_id" claim MAY be included in a JWT, whether or not the "sub"
claim is present. When both the "sub" and "sub_id" claims are
present in a JWT, they MUST identify the same subject, as a JWT has
one and only one JWT Subject.
When processing a JWT with both "sub" and "sub_id" claims,
implementations MUST NOT rely on both claims to determine the JWT
Subject. An implementation MAY attempt to determine the JWT Subject
from one claim and fall back to using the other if it determines it
does not understand the format of the first claim. For example, an
implementation may attempt to use "sub_id", and fall back to using
"sub" upon finding that "sub_id" contains a Subject Identifier whose
format is not recognized by the implementation.
Below are non-normative examples of JWTs containing the "sub_id"
claim:
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{
"iss": "issuer.example.com",
"sub_id": {
"format": "email",
"email": "user@example.com"
}
}
Figure 14: Example: JWT containing a "sub_id" claim and no "sub"
claim
{
"iss": "issuer.example.com",
"sub": "user@example.com",
"sub_id": {
"format": "email",
"email": "user@example.com"
}
}
Figure 15: Example: JWT where both the "sub" and "sub_id" claims
identify the JWT Subject using the same identifier
{
"iss": "issuer.example.com",
"sub": "liz@example.com",
"sub_id": {
"format": "email",
"email": "elizabeth@example.com"
}
}
Figure 16: Example: JWT where both the "sub" and "sub_id" claims
identify the JWT Subject using different values of the same
identifier type
{
"iss": "issuer.example.com",
"sub": "user@example.com",
"sub_id": {
"format": "account",
"uri": "acct:example.user@service.example.com"
}
}
Figure 17: Example: JWT where the "sub" and "sub_id" claims
identify the JWT Subject via different types of identifiers
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4.2. sub_id and iss_sub Subject Identifiers
The "sub_id" claim MAY contain an "iss_sub" Subject Identifier. In
this case, the JWT's "iss" claim and the Subject Identifier's "iss"
member MAY be different. For example, in OpenID Connect
[OpenID.Core] client may construct such a JWT when sending JWTs back
to its OpenID Connect Identity Provider, in order to identify the JWT
Subject using an identifier known to be understood by both parties.
Similarly, the JWT's "sub" claim and the Subject Identifier's "sub"
member MAY be different. For example, this may be used by an OpenID
Connect client to communicate the JWT Subject's local identifier at
the client back to its Identity Provider.
Below are non-normative examples of a JWT where the "iss" claim and
"iss" member within the "sub_id" claim are the same, and a JWT where
they are different.
{
"iss": "issuer.example.com",
"sub_id": {
"format": "iss_sub",
"iss": "issuer.example.com",
"sub": "example_user"
}
}
Figure 18: Example: JWT with an "iss_sub" Subject Identifier
where JWT issuer and JWT Subject issuer are the same
{
"iss": "client.example.com",
"sub_id": {
"format": "iss_sub",
"iss": "issuer.example.com",
"sub": "example_user"
}
}
Figure 19: Example: JWT with an "iss_sub" Subject Identifier
where the JWT issuer and JWT Subject issuer are different
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{
"iss": "client.example.com",
"sub": "client_user",
"sub_id": {
"format": "iss_sub",
"iss": "issuer.example.com",
"sub": "example_user"
}
}
Figure 20: Example: JWT with an "iss_sub" Subject Identifier
where the JWT "iss" and "sub" claims differ from the JWT
Subject's "iss" and "sub" members
5. Considerations for Specifications that Define Identifier Formats
Identifier Format definitions MUST NOT make assertions or
declarations regarding the subject being identified by the Subject
Identifier (e.g., an Identifier Format cannot be defined as
specifically identifying human end users), as such statements are
outside the scope of Identifier Formats and Subject Identifiers, and
expanding that scope for some Identifier Formats but not others would
harm interoperability, as applications that depend on this expanded
scope to disambiguate the subject type would be unable to use
Identifier Formats that do not provide such rules.
6. Privacy Considerations
6.1. Identifier Correlation
The act of presenting two or more identifiers for a single subject
together (e.g., within an "aliases" Subject Identifier, or via the
"sub" and "sub_id" JWT claims) may communicate more information about
the subject than was intended. For example, the entity to which the
identifiers are presented now knows that both identifiers relate to
the same subject, and may be able to correlate additional data based
on that. When transmitting Subject Identifiers, the transmitter
SHOULD take care that they are only transmitting multiple identifiers
together when it is known that the recipient already knows that the
identifiers are related (e.g., because they were previously sent to
the recipient as claims in an OpenID Connect ID Token), or when
correlation is essential to the use case. Implementers must consider
such risks, and specifications that use subject identifiers must
provide appropriate privacy considerations of their own.
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The considerations described in Section 6 of [RFC8417] also apply
when Subject Identifiers are used within SETs. The considerations
described in Section 12 of [RFC7519] also apply when Subject
Identifiers are used within JWTs.
7. Security Considerations
This specification does not define any mechanism for ensuring the
confidentiality or integrity of a Subject Identifier. Where such
properties are required, implementations MUST use mechanisms provided
by the containing format (e.g., integrity protecting SETs or JWTs
using JWS [RFC7515]), or at the transport layer or other layer in the
application stack (e.g., using TLS [RFC8446]).
Further considerations regarding confidentiality and integrity of
SETs can be found in Section 5.1 of [RFC8417].
8. IANA Considerations
8.1. Security Event Identifier Formats Registry
This document defines Identifier Formats, for which IANA is asked to
create and maintain a new registry titled "Security Event Identifier
Formats". Initial values for the Security Event Identifier Formats
registry are given in Section 3. Future assignments are to be made
through the Specification Required registration policy [BCP26] and
shall follow the template presented in Section 8.1.2.
It is suggested that multiple Designated Experts be appointed who are
able to represent the perspectives of different applications using
this specification, in order to enable broadly informed review of
registration decisions.
8.1.1. Registry Location
(This section to be removed by the RFC Editor before publication as
an RFC.)
The authors recommend that the Identifier Formats registry be located
at https://www.iana.org/assignments/secevent/.
8.1.2. Registration Template
Format Name
The name of the Identifier Format, as described in Section 3. The
name MUST be an ASCII string consisting only of lower-case
characters ("a" - "z"), digits ("0" - "9"), underscores ("_"), and
hyphens ("-"), and SHOULD NOT exceed 20 characters in length.
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Format Description
A brief description of the Identifier Format.
Change Controller
For formats defined in documents published by the IETF or its
working groups, list "IETF". For all other formats, list the name
of the party responsible for the registration. Contact
information such as mailing address, email address, or phone
number must also be provided.
Defining Document(s)
A reference to the document or documents that define the
Identifier Format. The reference document(s) MUST specify the
name, format,and meaning of each member that may occur within a
Subject Identifier of the defined format, as well as whether each
member is optional, required or conditional, and the circumstances
under which these optional or conditional fields would be used.
URIs that can be used to retrieve copies of each document SHOULD
be included.
8.1.3. Initial Registry Contents
8.1.3.1. Account Identifier Format
* Format Name: "account"
* Format Description: Subject identifier based on acct URI.
* Change Controller: IETF
* Defining Document(s): Section 3 of this document.
8.1.3.2. Email Identifier Format
* Format Name: email
* Format Description: Subject identifier based on email address.
* Change Controller: IETF
* Defining Document(s): Section 3 of this document.
8.1.3.3. Issuer and Subject Identifier Format
* Format Name: "iss_sub"
* Format Description: Subject identifier based on an issuer and
subject.
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* Change Controller: IETF
* Defining Document(s): Section 3 of this document.
8.1.3.4. Opaque Identifier Format
* Format Name: "opaque"
* Format Description: Subject identifier based on an opaque string.
* Change Controller: IETF
* Defining Document(s): Section 3 of this document.
8.1.3.5. Phone Number Identifier Format
* Format Name: "phone_number"
* Format Description: Subject identifier based on an phone number.
* Change Controller: IETF
* Defining Document(s): Section 3 of this document.
8.1.3.6. Decentralized Identifier Format
* Format Name: "did"
* Format Description: Subject identifier based on a decentralized
identifier (DID).
* Change Controller: IETF
* Defining Document(s): Section 3 of this document.
8.1.3.7. Uniform Resource Identifier Format
* Format Name: "uri"
* Format Description: Subject identifier based on a uniform resource
identifier (URI).
* Change Controller: IETF
* Defining Document(s): Section 3 of this document.
8.1.3.8. Aliases Identifier Format
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* Format Name: "aliases"
* Format Description: Subject identifier that groups together
multiple different subject identifiers for the same subject.
* Change Controller: IETF
* Defining Document(s): Section 3 of this document.
8.1.4. Guidance for Expert Reviewers
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.
Identifier Formats need not be generally applicable and may be highly
specific to a particular domain; it is expected that formats may be
registered for niche or industry-specific use cases. The Expert
Reviewer should focus on whether the format 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 format.
8.2. JSON Web Token Claims Registration
This document defines the sub_id JWT Claim, which IANA is asked to
register in the "JSON Web Token Claims" registry IANA JSON Web Token
Claims Registry [IANA.JWT.Claims] established by [RFC7519].
8.2.1. Registry Contents
* Claim Name: "sub_id"
* Claim Description: Subject Identifier
* Change Controller: IETF
* Specification Document(s): Section 4.1 of this document.
9. References
9.1. Normative References
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[BCP26] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[DID] World Wide Web Consortium (W3C), "Decentralized
Identifiers (DIDs) v1.0", 2021,
<https://www.w3.org/TR/did-core/>.
[E164] International Telecommunication Union, "The international
public telecommunication numbering plan", 2010,
<https://www.itu.int/rec/T-REC-E.164-201011-I/en>.
[IANA.JWT.Claims]
IANA, "JSON Web Token Claims", n.d.,
<https://www.iana.org/assignments/jwt>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[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,
<https://www.rfc-editor.org/info/rfc3986>.
[RFC5321] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321,
DOI 10.17487/RFC5321, October 2008,
<https://www.rfc-editor.org/info/rfc5321>.
[RFC5322] Resnick, P., Ed., "Internet Message Format", RFC 5322,
DOI 10.17487/RFC5322, October 2008,
<https://www.rfc-editor.org/info/rfc5322>.
[RFC7519] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token
(JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015,
<https://www.rfc-editor.org/info/rfc7519>.
[RFC7565] Saint-Andre, P., "The 'acct' URI Scheme", RFC 7565,
DOI 10.17487/RFC7565, May 2015,
<https://www.rfc-editor.org/info/rfc7565>.
[RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
Interchange Format", STD 90, RFC 8259,
DOI 10.17487/RFC8259, December 2017,
<https://www.rfc-editor.org/info/rfc8259>.
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[RFC8417] Hunt, P., Ed., Jones, M., Denniss, W., and M. Ansari,
"Security Event Token (SET)", RFC 8417,
DOI 10.17487/RFC8417, July 2018,
<https://www.rfc-editor.org/info/rfc8417>.
9.2. Informative References
[OpenID.Core]
Sakimura, N., Bradley, J., Jones, M., de Medeiros, B., and
C. Mortimore, "OpenID Connect Core 1.0", November 2014,
<https://openid.net/specs/openid-connect-core-1_0.html>.
[RFC1034] Mockapetris, P., "Domain names - concepts and facilities",
STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987,
<https://www.rfc-editor.org/info/rfc1034>.
[RFC7515] Jones, M., Bradley, J., and N. Sakimura, "JSON Web
Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May
2015, <https://www.rfc-editor.org/info/rfc7515>.
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>.
Acknowledgements
The authors would like to thank the members of the IETF Security
Events working group, as well as those of the OpenID Shared Signals
and Events Working Group, whose work provided the original basis for
this document. We would also like to acknowledge Aaron Parecki,
Denis Pinkas, Justin Richer, Mike Jones and other members of the
working group for reviewing this document.
Change Log
(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.
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* Added text specifying the nature of the subjects described by each
type.
Draft 02 - AB:
* Corrected format of phone numbers in examples.
* Updated author info.
Draft 03 - AB:
* Added account type for acct URIs.
* Replaced id-token-claims type with aliases type.
* Added email canonicalization guidance.
* Updated semantics for email, phone, and iss-sub types.
Draft 04 - AB:
* Added sub_id JWT Claim definition, guidance, examples.
* Added text prohibiting aliases nesting.
* Added privacy considerations for identifier correlation.
Draft 05 - AB:
* Renamed the phone type to phone-number and its phone claim to
phone_number.
Draft 06 - AB:
* Replaced usage of the word "claim" to describe members of a
Subject Identifier with the word "member", in accordance with
terminology in RFC8259.
* Renamed the phone-number type to phone_number and iss-sub to
iss_sub.
* Added normative requirements limiting the use of both sub and
sub_id claims together when processing a JWT.
* Clarified that identifier correlation may be acceptable when it is
a core part of the use case.
* Replaced references to OIDF with IETF in IANA Considerations.
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* Recommended the appointment of multiple Designated Experts, and a
location for the Subject Identifier Types registry.
* Added "_" to list of allowed characters in the Type Name for
Subject Identifier Types.
* Clarified that Subject Identifiers don't provide confidentiality
or integrity protection.
* Added references to SET, JWT privacy and security considerations.
* Added section describing the difference between subject identifier
type and principal type that hopefully clarifies things and
doesn't just muddy the water further.
Draft 07 - AB:
* Emphasized that the spec is about identifiers, not the things they
identify:
- Renamed "Subject Identifier Type" to "Identifier Format".
- Renamed subject_type to format.
- Renamed "Security Event Subject Identifier Type Registry" to
"Security Event Identifier Format Registry".
- Added new section with guidance for specs defining Identifier
Formats, with normative prohibition on formats that describe
the subject itself, rather than the identifier.
* Clarified the meaning of "subject":
- Defined "subject" as applying generically and "JWT Subject" as
applying specifically to the subject of a JWT.
- Replaced most instances of the word "principal" with "subject".
* Added opaque Identifier Format
Draft 08 - JR, AB:
* Added did Identifier Format
* Alphabetized identifier format definitions
* Replaced "type" with "format" in places that had been missed in
the -07 change. (mostly IANA Considerations)
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* Miscellaneous editorial fixes
Draft 09 - AB:
* Miscellaneous editorial fixes
Draft 10 - PJ:
* Added author
* Editorial nits
Draft 11 - PJ:
* Miscellaneous editorial fixes
* Moved aliases to the last in identifier format definitions
* Acknowledged individual reviewers
Draft 12 - PJ:
* Restore the DID format that was removed in -11
* Added a generic "URI" format
* Normative advice on choosing the format
Draft 13 - PJ:
* Editorial nits found during AD review
Draft 14 - PJ:
* Fix IANA issues found during AD review
Draft 15 - PJ:
* Fix issues found during review
Draft 16 - PJ:
* Change controller updated to IETF
Draft 17 -PJ:
* Fixed nits identified during IESG reviews
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Draft 18 -PJ:
* Fixed issues identified during IESG reviews
Authors' Addresses
Annabelle Backman (editor)
Amazon
Email: richanna@amazon.com
Marius Scurtescu
Coinbase
Email: marius.scurtescu@coinbase.com
Prachi Jain
Fastly
Email: prachi.jain1288@gmail.com
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