]> MATTR

tobias.looker@mattr.global

Bundesdruckerei

paul.bastian@posteo.de

SPRIND

chris.bormann@gmx.de

Security Web Authorization Protocol This specification defines a status mechanism called Token Status List (abbreviated TSL), data structures and processing rules for representing the status of tokens secured by JSON Object Signing and Encryption (JOSE) or CBOR Object Signing and Encryption (COSE), such as JWT, SD-JWT VC, CBOR Web Token and ISO mdoc. It also defines an extension point and a registry for future status mechanisms. About This Document The latest revision of this draft can be found at . Status information for this document may be found at . Discussion of this document takes place on the Web Authorization Protocol Working Group mailing list (), which is archived at . Subscribe at . Source for this draft and an issue tracker can be found at .

Introduction Token formats secured by JOSE or COSE , such as JWTs , SD-JWT VCs , CWTs and ISO mdoc , have vast possible applications. Some of these applications can involve issuing a token whereby certain semantics about the token or its validity may change over time. Communicating these changes to relying parties in an interoperable manner, such as whether the token is considered invalidated or suspended by its issuer is important for many of these applications. This document defines a Status List data structure that describes the individual statuses of multiple Referenced Tokens. A Referenced Token may be of any format, but is most commonly a data structure secured by JOSE or COSE. The Referenced Token is referenced by the Status List, which describes the status of the Referenced Token. The statuses of all Referenced Tokens are conveyed via a bit array in the Status List. Each Referenced Token is allocated an index during issuance that represents its position within this bit array. The value of the bit(s) at this index corresponds to the Referenced Token's status. A Status List is provided within a Status List Token protected by cryptographic signature or MAC and this document defines its representations in JWT and CWT format. The following diagram depicts the relationship between the artifacts: An Issuer issues Referenced Tokens to a Holder, the Holder uses and presents those Referenced Tokens to a Relying Party. The Issuer gives updated status information to the Status Issuer, who issues a Status List Token. The Status Issuer can be either the Issuer or an entity that has been authorized by the Issuer to issue Status List Tokens. The Status Issuer provides the Status List Token to the Status Provider, who serves the Status List Token on a public, resolvable endpoint. The Relying Party or the Holder may fetch the Status List Token to retrieve the status of the Referenced Token. The roles of the Issuer (of the Referenced Token), the Status Issuer and the Status Provider may be fulfilled by the same entity. If not further specified, the term Issuer may refer to an entity acting for all three roles. This document describes how an Issuer references a Status List Token and how a Relying Party fetches and validates Status Lists. The following diagram depicts the relationship between the involved roles (Relying Party is equivalent to Verifier of ): Status Lists can be used to express a variety of Status Types. This document defines basic Status Types for the most common use cases as well as an extensibility mechanism for custom Status Types. Furthermore, the document creates an extension point and an IANA registry that enables other specifications to describe additional status mechanisms.

Example Use Cases An example of the usage of a Status List is to manage the statuses of issued access tokens as defined in section 1.4 of . Token Introspection provides a method to determine the status of an issued access token, but it necessitates the party attempting to validate the state of access tokens to directly contact the Issuer of each token for validation. In contrast, the mechanism defined in this specification allows a party to retrieve the statuses for many tokens, reducing interactions with the Issuer substantially. This not only improves scalability but also enhances privacy by preventing the Issuer from gaining knowledge of access tokens being verified (herd anonymity). Another possible use case for the Status List is to express the status of verifiable credentials (Referenced Tokens) issued by an Issuer in the Issuer-Holder-Verifier model .

Rationale Revocation mechanisms are an essential part of most identity ecosystems. In the past, revocation of X.509 TLS certificates has been proven difficult. Traditional certificate revocation lists (CRLs) have limited scalability; Online Certificate Status Protocol (OCSP) has additional privacy risks, since the client is leaking the requested website to a third party. OCSP stapling is addressing some of these problems at the cost of less up-to-date data. Modern approaches use accumulator-based revocation registries and Zero-Knowledge-Proofs to accommodate for this privacy gap, but face scalability issues again. Another alternative is short-lived Referenced Tokens with regular re-issuance, but this puts additional burden on the Issuer's infrastructure. This specification seeks to find a balance between scalability, security and privacy by representing statuses as individual bits, packing the them into an array, and compressing the resulting binary data. Thereby, a Status List may contain statuses of many thousands or millions Referenced Tokens while remaining as small as possible. Placing a large number of Referenced Tokens into the same list also offers Holders and Relying Parties herd privacy from the Status Provider.

Design Considerations The decisions taken in this specification aim to achieve the following design goals:

• the specification shall favor a simple and easy-to-understand concept
• the specification shall be easy, fast and secure to implement in all major programming languages
• the specification shall be optimized to support the most common use cases and avoid unnecessary complexity of corner cases
• the Status List shall scale up to millions of tokens to support large-scale government or enterprise use cases
• the Status List shall enable caching policies and offline support
• the specification shall support JSON and CBOR based tokens
• the specification shall not specify key resolution or trust frameworks
• the specification shall define an extension point that enables other mechanisms to convey information about the status of a Referenced Token

Prior Work Representing statuses with bits in an array is a rather old and well-known concept in computer science and there has been prior work to use this for revocation and status management such as a paper by Smith et al. that proposed a mechanism called Certificate Revocation Vectors based on xz compressed bit vectors for each expiration day and the W3C bit Status List that similarly uses a compressed bit representation.

Status Mechanisms Registry This specification establishes IANA "Status Mechanisms" registries for status mechanisms for JOSE-based tokens and for status mechanisms for COSE-based tokens and registers the members defined by this specification. Other specifications can register other members used for status retrieval. Other status mechanisms may have different tradeoffs regarding security, privacy, scalability and complexity. The privacy and security considerations in this document only represent the properties of the Status List mechanism.

Conventions and Definitions The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 when, and only when, they appear in all capitals, as shown here.

Terminology

Issuer:

An entity that issues the Referenced Token. Also known as a Provider.

Status Issuer:

An entity that issues the Status List Token about the status information of the Referenced Token. This role may be fulfilled by the Issuer.

Status Provider:

An entity that provides the Status List Token on a public endpoint. This role may be fulfilled by the Status Issuer.

Holder:

An entity that receives Referenced Tokens from the Issuer and presents them to Relying Parties.

Relying Party:

An entity that relies on the Referenced Token and fetches the corresponding Status List Token to validate the status of that Referenced Token. Also known as a Verifier.

Status List:

An object in JSON or CBOR representation containing a compressed byte array that represents the statuses of many Referenced Tokens.

Status List Token:

A token in JWT (as defined in ) or CWT (as defined in ) representation that contains a cryptographically secured Status List.

Referenced Token:

A cryptographically secured data structure that contains a "status" claim that references a mechanism to retrieve status information about this Referenced Token. This document defines the Status List mechanism in which case the Referenced Token contains a reference to an entry in a Status List Token. It is RECOMMENDED to use JSON with JOSE as defined in or CBOR with COSE as defined in . Examples for Referenced Tokens are SD-JWT VC and ISO mdoc.

Client:

An application that fetches information, such as a Status List Token, from the Status List Provider on behalf of the Holder or Relying Party.

base64url:

Denotes the URL-safe base64 encoding with all trailing '=' characters omitted as defined in Section 2 of as "Base64url Encoding".

Status List A Status List is a data structure that contains the statuses of many Referenced Tokens represented by one or multiple bits. The first section describes how to construct a compressed byte array that is the base component for the Status List data structure. The second and third sections describe how to encode such a Status List in JSON and CBOR representations.

Compressed Byte Array A compressed byte array containing the status information of the Referenced Token is composed by the following algorithm:

1. The Status Issuer MUST define a number of bits (bits) of either 1,2,4 or 8, that represents the amount of bits used to describe the status of each Referenced Token within this Status List. Therefore up to 2,4,16 or 256 statuses for a Referenced Token are possible, depending on the bit size. This limitation is intended to limit bit manipulation necessary to a single byte for every operation and thus keeping implementations simpler and less error-prone.
2. The Status Issuer creates a byte array of size = amount of Referenced Tokens * bits / 8 or greater. Depending on the bits, each byte in the array corresponds to 8/(bits) statuses (8,4,2 or 1).
3. The Status Issuer sets the status values for all Referenced Tokens within the byte array. Each Referenced Token is assigned a distinct index from 0 to one less than the number of Referenced Tokens assigned to the Status List. Each index identifies a contiguous block of bits in the byte array, with the blocks being packed into bytes from the least significant bit ("0") to the most significant bit ("7"). These bits contain the encoded status value of the Referenced Token (see for more details on the values).
4. The Status Issuer compresses the byte array using DEFLATE with the ZLIB data format. Implementations are RECOMMENDED to use the highest compression level available.

The following example illustrates the byte array of a Status List that represents the statuses of 16 Referenced Tokens with a bits of 1, requiring 2 bytes (16 bits) for the uncompressed byte array: These bits are concatenated: In the following example, the Status List additionally includes the Status Type "SUSPENDED". As the Status Type value for "SUSPENDED" is 0x02 and does not fit into 1 bit, the bits is required to be 2. This example illustrates the byte array of a Status List that represents the statuses of 12 Referenced Tokens with a bits of 2, requiring 3 bytes (24 bits) for the uncompressed byte array: These bits are concatenated:

Status List in JSON Format This section defines the data structure for a JSON-encoded Status List:

• The StatusList structure is a JSON Object contains the following members:
  • bits: REQUIRED. JSON Integer specifying the number of bits per Referenced Token in the compressed byte array (lst). The allowed values for bits are 1,2,4 and 8.
  • lst: REQUIRED. JSON String that contains the status values for all the Referenced Tokens it conveys statuses for. The value MUST be the base64url-encoded compressed byte array as specified in .
  • aggregation_uri: OPTIONAL. JSON String that contains a URI to retrieve the Status List Aggregation for this type of Referenced Token or Issuer. See section for further details.

The following example illustrates the JSON representation of the Status List with bits=1 from the examples above: The following example illustrates the JSON representation of the Status List with bits=2 from the examples above: See section for more test vectors.

Status List in CBOR Format This section defines the data structure for a CBOR-encoded Status List:

• The StatusList structure is a CBOR map (major type 5) and defines the following entries:
  • bits: REQUIRED. CBOR Unsigned integer (major type 0) that contains the number of bits per Referenced Token in the compressed byte array (lst). The allowed values for bits are 1, 2, 4 and 8.
  • lst: REQUIRED. CBOR Byte string (major type 2) that contains the status values for all the Referenced Tokens it conveys statuses for. The value MUST be the compressed byte array as specified in .
  • aggregation_uri: OPTIONAL. CBOR Text string (major type 3) that contains a URI to retrieve the Status List Aggregation for this type of Referenced Token. See section for further detail.

The following is the CDDL definition of the StatusList structure: The following example illustrates the CBOR representation of the Status List in Hex: The following is the CBOR Annotated Hex output of the example above: See section for more test vectors.

Status List Token A Status List Token embeds a Status List into a token that is cryptographically signed and protects the integrity of the Status List. This allows for the Status List Token to be hosted by third parties or be transferred for offline use cases. This section specifies Status List Tokens in JSON Web Token (JWT) and CBOR Web Token (CWT) format.

Status List Token in JWT Format The Status List Token MUST be encoded as a "JSON Web Token (JWT)" according to . The following content applies to the JWT Header:

• typ: REQUIRED. The JWT type MUST be statuslist+jwt.

The following content applies to the JWT Claims Set:

• sub: REQUIRED. As generally defined in . The sub (subject) claim MUST specify the URI of the Status List Token. The value MUST be equal to that of the uri claim contained in the status_list claim of the Referenced Token.
• iat: REQUIRED. As generally defined in . The iat (issued at) claim MUST specify the time at which the Status List Token was issued.
• exp: RECOMMENDED. As generally defined in . The exp (expiration time) claim, if present, MUST specify the time at which the Status List Token is considered expired by the Status Issuer. Consider the guidance provided in .
• ttl: RECOMMENDED. The ttl (time to live) claim, if present, MUST specify the maximum amount of time, in seconds, that the Status List Token can be cached by a consumer before a fresh copy SHOULD be retrieved. The value of the claim MUST be a positive number encoded in JSON as a number. Consider the guidance provided in .
• status_list: REQUIRED. The status_list (status list) claim MUST specify the Status List conforming to the structure defined in .

The following additional rules apply:

1. The JWT MAY contain other claims.
2. The JWT MUST be secured using a cryptographic signature or MAC algorithm. Relying Parties MUST reject JWTs with an invalid signature.
3. Relying Parties MUST reject JWTs that are not valid in all other respects per "JSON Web Token (JWT)" .
4. Application of additional restrictions and policies are at the discretion of the Relying Party.

The following is a non-normative example of a Status List Token in JWT format:

Status List Token in CWT Format The Status List Token MUST be encoded as a "CBOR Web Token (CWT)" according to . The following content applies to the protected header of the CWT:

• 16 (type): REQUIRED. The type of the CWT MUST be application/statuslist+cwt or the registered CoAP Content-Format ID (see ) as defined in .

The following content applies to the CWT Claims Set:

• 2 (subject): REQUIRED. As generally defined in . The subject claim MUST specify the URI of the Status List Token. The value MUST be equal to that of the uri claim contained in the status_list claim of the Referenced Token.
• 6 (issued at): REQUIRED. As generally defined in . The issued at claim MUST specify the time at which the Status List Token was issued.
• 4 (expiration time): RECOMMENDED. As generally defined in . The expiration time claim, if present, MUST specify the time at which the Status List Token is considered expired by its issuer. Consider the guidance provided in .
• 65534 (time to live): RECOMMENDED. Unsigned integer (major type 0). The time to live claim, if present, MUST specify the maximum amount of time, in seconds, that the Status List Token can be cached by a consumer before a fresh copy SHOULD be retrieved. The value of the claim MUST be a positive number. Consider the guidance provided in .
• 65533 (status list): REQUIRED. The status list claim MUST specify the Status List conforming to the structure defined in .

The following additional rules apply:

1. The CWT MAY contain other claims.
2. The CWT MUST be secured using a cryptographic signature or MAC algorithm. Relying Parties MUST reject CWTs with an invalid signature.
3. Relying Parties MUST reject CWTs that are not valid in all other respects per "CBOR Web Token (CWT)" .
4. Application of additional restrictions and policies are at the discretion of the Relying Party.

The following is a non-normative example of a Status List Token in CWT format in Hex: The following is the CBOR Annotated Hex output of the example above:

Referenced Token

Status Claim By including a "status" claim in a Referenced Token, the Issuer is referencing a mechanism to retrieve status information about this Referenced Token. This specification defines one possible member of the "status" object, called "status_list". Other members of the "status" object may be defined by other specifications. This is analogous to "cnf" claim in Section 3.1 of in which different authenticity confirmation methods can be included.

Referenced Token in JOSE The Referenced Token MAY be encoded as a "JSON Web Token (JWT)" according to or other formats based on JOSE. The following content applies to the JWT Claims Set:

• status: REQUIRED. The status (status) claim MUST specify a JSON Object that contains at least one reference to a status mechanism.
  • status_list: REQUIRED when the status mechanism defined in this specification is used. It MUST specify a JSON Object that contains a reference to a Status List Token. It MUST at least contain the following claims:
    • idx: REQUIRED. The idx (index) claim MUST specify a non-negative Integer that represents the index to check for status information in the Status List for the current Referenced Token.
    • uri: REQUIRED. The uri (URI) claim MUST specify a String value that identifies the Status List Token containing the status information for the Referenced Token. The value of uri MUST be a URI conforming to .

Application of additional restrictions and policies are at the discretion of the Relying Party. The following is a non-normative example of a decoded header and payload of a Referenced Token: SD-JWT-based Verifiable Credentials section 3.2.2.2. introduces the usage of the status mechanism defined in this section. Therefore, an SD-JWT VC can be considered a Referenced Token. The following is a non-normative example of a Referenced Token in SD-JWT VC serialized form as received from an Issuer: The resulting payload of the example above:

Referenced Token in COSE The Referenced Token MAY be encoded as a "CBOR Web Token (CWT)" object according to or other formats based on COSE. Referenced Tokens in CBOR should share the same core data structure for a status list reference:

• The Status CBOR structure is a Map that MUST include at least one data item that refers to a status mechanism. Each data item in the Status CBOR structure comprises a key-value pair, where the key must be a CBOR text string (major type 3) specifying the identifier of the status mechanism and the corresponding value defines its contents.
  • status_list (status list): REQUIRED when the status mechanism defined in this specification is used. It has the same definition as the status_list claim in but MUST be encoded as a StatusListInfo CBOR structure with the following fields:
    • idx: REQUIRED. Unsigned integer (major type 0) The idx (index) claim MUST specify a non-negative Integer that represents the index to check for status information in the Status List for the current Referenced Token.
    • uri: REQUIRED. Text string (major type 3). The uri (URI) claim MUST specify a String value that identifies the Status List Token containing the status information for the Referenced Token. The value of uri MUST be a URI conforming to .

CBOR Web Token (CWT) The following content applies to the CWT Claims Set:

• 65535 (status): REQUIRED. The status claim contains the Status CBOR structure as described in .

Application of additional restrictions and policies are at the discretion of the Relying Party. The following is a non-normative example of a Referenced Token in CWT format in Hex: The following is the CBOR Annotated Hex output of the example above: Üãrm\x80" f1e52bbf # "ñå+¿" ]]>

ISO mdoc ISO mdoc may utilize the Status List mechanism by introducing the status parameter in the Mobile Security Object (MSO) as specified in Section 9.1.2 of . The status parameter contains the Status CBOR structure as described in . It is RECOMMENDED to use status for the label of the field that contains the Status CBOR structure. Application of additional restrictions and policies are at the discretion of the Relying Party. The following is a non-normative example of an IssuerAuth as specified in ISO mDL (also referred to as signed MSO) in Hex: The following is the CBOR Diagnostic Notation of the example above: >, { 33: h'308201ef30820195a00302010202140bfec7da97e048e15ac3dacb9ea fe82e64fd07f5300a06082a8648ce3d04030230233114301206035504030c0b 75746f7069612069616361310b3009060355040613025553301e170d3234313 030313030303030305a170d3235313030313030303030305a30213112301006 035504030c0975746f706961206473310b30090603550406130255533059301 306072a8648ce3d020106082a8648ce3d03010703420004ace7ab7340e5d964 8c5a72a9a6f56745c7aad436a03a43efea77b5fa7b88f0197d57d8983e1b37d 3a539f4d588365e38cbbf5b94d68c547b5bc8731dcd2f146ba381a83081a530 1c0603551d1f041530133011a00fa00d820b6578616d706c652e636f6d301e0 603551d120417301581136578616d706c65406578616d706c652e636f6d301d 0603551d0e0416041414e29017a6c35621ffc7a686b7b72db06cd12351301f0 603551d2304183016801454fa2383a04c28e0d930792261c80c4881d2c00b30 0e0603551d0f0101ff04040302078030150603551d250101ff040b300906072 8818c5d050102300a06082a8648ce3d0403020348003045022100b7103fd4b9 0529f50bd6f70c5ae5ce7f4f3d4d15a4e082812f9fa1f5c2e5aa0a0220070b2 822ec7ce6c56804923a85b2cfbffd054cf9a915f070cfef7179a4bc6569' }, << 24( << { "status": { "status_list": { "idx": 412, "uri": "https://example.com/statuslists/1" } }, "docType": "org.iso.18013.5.1.mDL", "version": "1.0", "validityInfo": { "signed": 2024-10-01 13:30:02+00:00, "validFrom": 2024-10-01 13:30:02+00:00, "validUntil": 2025-10-01 13:30:02+00:00 }, "valueDigests": { "org.iso.18013.5.1": { 0: h'a81d65ed5075fbd7ee19fa66e2bb3047ed826e2769873e7ef07c92 3da7a6f243', 1: h'48701a9546492284d266ed81d439230a582d0e1f17a08ab1859a3e fe980690a4', 2: h'd11fe48c8835b30bfb3895c3905436ddfb63f59ab9eee181b11098 53292a8f62', 3: h'a741bf05e20a8bc359e32426106ed0899b2c60262cc3acc637ddc9 941095fb7a', 4: h'ab67cb9a8f20a8572f77f02727367d08dc8e57fb89deb46b9c626e 94457b7d8b', 5: h'bacddb4142b3842bd555206eb5acb27ded063294995c7e7fefbf93 ece522604d', 6: h'bfd02b3aebdc05b53b5539226c38088d6d784b0ea0fab69eb93116 50a48d3253', 7: h'27dab70fe71da63e5e5d199e8ae5b79cbe8904bc30c5b7544fb809 e02ccb3e6a', 8: h'0dbd7ccc9c7727d3d17295f1b6f1914071670ee23d4d33530c31f1 f406b8e3b7', 9: h'a5beb5efadf37f21637209abc519830681cc51f334818a823fec13 b29552f5ba', 10: h'd8047c95f9272d7d07b2c13a9f5ac2ee02380ab272a165e569391 d89a2152c3c', 11: h'04939930ffb4911ef03487a153605a30368b69f2437d6d21b4c90 f92bc144c3e' } }, "deviceKeyInfo": { "deviceKey": { 1: 2, -1: 1, -2: h'96313d6c63e24e3372742bfdb1a33ba2c897dcd68ab8c753e4fbd 48dca6b7f9a', -3: h'1fb3269edd418857de1b39a4e4a44b92fa484caa722c228288f01 d0c03a2c3d6' } }, "digestAlgorithm": "SHA-256" } >> ) >>, h'b7c2d4abe85aa5ba814ef95de0385c71c802be8ac33a4a971a85ed800ba7acb 59cb21035f4a68fc0caa450cbefd3b255aec72f83595f0ae7b7d50fe8a1c4cafe' ] ]]>

Status Types This document defines the statuses of Referenced Tokens as Status Type values. A status describes the state, mode, condition or stage of an entity that is represented by the Referenced Token. A Status List represents exactly one status per Referenced Token. If the Status List contains more than one bit per token (as defined by bits in the Status List), then the whole value of bits MUST describe one value. Status Types MUST have a numeric value between 0 and 255 for their representation in the Status List. The issuer of the Status List MUST choose an adequate bits value (bit size) to be able to describe the required Status Types for its application.

Status Types Values The processing rules for Referenced Tokens (such as JWT or CWT) supersede the Referenced Token's status in a TSL. In particular, a Referenced Token that is evaluated as being expired (e.g. through the exp claim) but in a TSL has a status of 0x00 ("VALID"), is considered expired. This document creates a registry in that includes the most common Status Type values. Applications SHOULD use registered values for statuses if they have the correct semantics. Additional values may defined for particular use cases. Status Types described by this document comprise:

• 0x00 - "VALID" - The status of the Referenced Token is valid, correct or legal.
• 0x01 - "INVALID" - The status of the Referenced Token is revoked, annulled, taken back, recalled or cancelled.
• 0x02 - "SUSPENDED" - The status of the Referenced Token is temporarily invalid, hanging, debarred from privilege. This status is usually temporary.

The Status Type value 0x03 and Status Type values in the range 0x0C until 0x0F are permanently reserved as application specific. The processing of Status Types using these values is application specific. All other Status Type values are reserved for future registration. See for privacy considerations on status types.

Verification and Processing The fetching, processing and verifying of a Status List Token may be done by either the Holder or the Relying Party. The following section is described from the role of the Relying Party, however the same rules apply for the Holder.

Status List Request The Status Provider SHOULD provide Status List Token on an endpoint serving an HTTP GET request to the URI provided in the Referenced Token, unless the Relying Party and the Status Provider have alternative methods of distribution. The HTTP endpoint SHOULD support the use of Cross-Origin Resource Sharing (CORS) and/or other methods as appropriate to enable Browser-based clients to access it, unless ecosystems using this specification choose not to support Browser-based clients. The Relying Party SHOULD send the following Accept HTTP Header to indicate the requested response type unless the Content-Type of Status List Tokens in the respective ecosystem is known or the Relying Party supports both formats:

• "application/statuslist+jwt" for Status List Token in JWT format
• "application/statuslist+cwt" for Status List Token in CWT format

If the Relying Party does not send an Accept Header, the response type is assumed to be known implicitly or out-of-band. The following is a non-normative example of a request for a Status List Token with type application/statuslist+jwt:

Status List Response A successful response that contains a Status List Token MUST use an HTTP status code in the 2xx range. A response MAY also choose to redirect the client to another URI using an HTTP status code in the 3xx range, which clients SHOULD follow. See for security considerations on redirects. In the successful response, the Status Provider MUST use the following content-type:

• "application/statuslist+jwt" for Status List Token in JWT format
• "application/statuslist+cwt" for Status List Token in CWT format

In the case of "application/statuslist+jwt", the response MUST be of type JWT and follow the rules of . In the case of "application/statuslist+cwt", the response MUST be of type CWT and follow the rules of . The body of such an HTTP response contains the raw Status List Token, that means the binary encoding as defined in section 9.2.1 of for a Status List Token in CWT format and the JWS Compact Serialization form for a Status List Token in JWT format. Note that while the examples for Status List Tokens in CWT format in this document are provided in hex encoding, this is done purely for readability; CWT format response bodies are "in binary". The HTTP response SHOULD use gzip Content-Encoding as defined in for Status List Tokens in JWT format. If caching-related HTTP headers are present in the HTTP response, Relying Parties MUST prioritize the exp and ttl claims within the Status List Token over the HTTP headers for determining caching behavior. The following is a non-normative example of a response with a Status List Token with type application/statuslist+jwt:

Validation Rules Upon receiving a Referenced Token, a Relying Party MUST first perform the validation of the Referenced Token - e.g., checking for expected attributes, valid signature and expiration time. The processing rules for Referenced Tokens (such as JWT or CWT) MUST precede any evaluation of a Referenced Token's status. For example, if a token is evaluated as being expired through the "exp" (Expiration Time) but also has a status of 0x00 ("VALID"), the token is considered expired. As this is out of scope for this document, this validation is not described here, but is expected to be done according to the format of the Referenced Token. If this validation is not successful, the Referenced Token MUST be rejected. If the validation was successful, the Relying Party MUST perform the following validation steps to evaluate the status of the reference token:

1. Check for the existence of a status claim, check for the existence of a status_list claim within the status claim and validate that the content of status_list adheres to the rules defined in for JOSE-based Referenced Tokens and for COSE-based Referenced Tokens. Other formats of Referenced Tokens may define other encoding of the URI and index.
2. Resolve the Status List Token from the provided URI
3. Validate the Status List Token:
   1. Validate the Status List Token by following the rules defined in section 7.2 of for JWTs and section 7.2 of for CWTs. This step might require the resolution of a public key as described in .
   2. Check for the existence of the required claims as defined in and depending on the token type
4. All existing claims in the Status List Token MUST be checked according to the rules in and
   1. The subject claim (sub or 2) of the Status List Token MUST be equal to the uri claim in the status_list object of the Referenced Token
   2. If the Relying Party has local policies regarding the freshness of the Status List Token, it SHOULD check the issued at claim (iat or 6)
   3. If the expiration time is defined (exp or 4), it MUST be checked if the Status List Token is expired
   4. If the Relying Party is using a system for caching the Status List Token, it SHOULD check the ttl claim of the Status List Token and retrieve a fresh copy if (time status was resolved + ttl < current time)
5. Decompress the Status List with a decompressor that is compatible with DEFLATE and ZLIB
6. Retrieve the status value of the index specified in the Referenced Token as described in . If the provided index is out of bounds of the Status List, no statement about the status of the Referenced Token can be made and the Referenced Token SHOULD be rejected.
7. Check the status value as described in

If any of these checks fails, no statement about the status of the Referenced Token can be made and the Referenced Token SHOULD be rejected.

Historical resolution By default, the status mechanism defined in this specification only conveys information about the state of Reference Tokens at the time the Status List Token was issued. The validity period for this information, as defined by the issuer, is explicitly stated by the iat (issued at) and exp (expiration time) claims for JWT and their corresponding ones for the CWT representation. If support for historical status information is desired, this can be achieved by extending with a timestamp the request for the Status List Token as defined in . This feature has additional privacy implications as described in . To obtain the Status List Token, the Relying Party MUST send an HTTP GET request to the URI provided in the Referenced Token with the additional query parameter time and its value being a unix timestamp. The response for a valid request SHOULD contain a Status List Token that was valid for that specified time or an error. If the Server does not support the additional query parameter, it SHOULD return a status code of 501 (Not Implemented) or if the requested time is not supported it SHOULD return a status code of 406 (Not Acceptable). A Status List Token might be served via static file hosting (e.g., leveraging a Content Delivery Network) that ignores query parameters, which would result in the client requesting a historical status list but receiving the current status list. Thus, the client MUST reject a response unless the requested timestamp is within the valid time of the returned token signaled via iat (6 for CWT) and exp (4 for CWT). The following is a non-normative example of a GET request using the time query parameter: The following is a non-normative example of a response for the above Request:

Status List Aggregation Status List Aggregation is an optional mechanism offered by the Issuer to publish a list of one or more Status List Tokens URIs, allowing a Relying Party to fetch Status List Tokens provided by this Issuer. This mechanism is intended to support fetching and caching mechanisms and allow offline validation of the status of a Reference Token for a period of time. If a Relying Party encounters an error while validating one of the Status List Tokens returned from the Status List Aggregation endpoint, it SHOULD continue processing the other Status List Tokens. There are two options for a Relying Party to retrieve the Status List Aggregation. An Issuer MAY support any of these mechanisms:

• Issuer metadata: The Issuer of the Referenced Token publishes an URI which links to Status List Aggregation, e.g. in publicly available metadata of an issuance protocol
• Status List Parameter: The Status Issuer includes an additional claim in the Status List Token that contains the Status List Aggregation URI.

Issuer Metadata The Issuer MAY link to the Status List Aggregation URI in metadata that can be provided by different means like .well-known metadata as is used commonly in OAuth and OpenID Connect, or within Issuer certificates or trust lists (such as VICAL as defined in Annex C of ). If the Issuer is an OAuth Authorization Server according to , it is RECOMMENDED to use the status_list_aggregation_endpoint parameter within its metadata defined by . The Issuer MAY limit the Status List Tokens listed by a Status List Aggregation to a particular type of Referenced Token. The concrete implementation details depend on the specific ecosystem and are out of scope of this specification.

Status List Parameter The URI to the Status List Aggregation MAY be provided as the optional parameter aggregation_uri in the Status List itself as explained in and respectively. A Relying Party may use this URI to retrieve an up-to-date list of relevant Status Lists.

Status List Aggregation Data Structure This section defines the structure for a JSON-encoded Status List Aggregation:

• status_lists: REQUIRED. JSON array of strings that contains URIs linking to Status List Tokens.

The Status List Aggregation URI provides a list of Status List Token URIs. This aggregation in JSON and the media type return MUST be application/json. A Relying Party can iterate through this list and fetch all Status List Tokens before encountering the specific URI in a Referenced Token. The following is a non-normative example for media type application/json:

X.509 Certificate Extended Key Usage Extension specifies the Extended Key Usage (EKU) X.509 certificate extension for use on end entity certificates. The extension indicates one or more purposes for which the certified public key is valid. The EKU extension can be used in conjunction with the Key Usage (KU) extension, which indicates the set of basic cryptographic operations for which the certified key may be used. A certificate's issuer explicitly delegates Status List Token signing authority by issuing a X.509 certificate containing the KeyPurposeId defined below in the extended key usage extension. Other specifications MAY choose to re-use this OID for other status mechanisms under the condition that they are registered in the "JWT Status Mechanisms" or "CWT Status Mechanisms" registries. The following OID is defined for usage in the EKU extension

Security Considerations Status List Tokens as defined in only exists in cryptographically secured containers which allows checking the integrity and origin without relying on other factors such as transport security or web PKI.

Correct decoding and parsing of the encoded Status List Implementers should be particularly careful for the correct parsing and decoding of the Status List. Incorrect implementations might check the index on the wrong data or miscalculate the bit and byte index leading to an erroneous status of the Referenced Token. Beware, that bits are indexed (bit order) from least significant bit to most significant bit (also called "right to left") while bytes are indexed (byte order) in their natural incrementing byte order (usually written for display purpose from left to right). Endianness does not apply here because each status value fits within a single byte. Implementations SHOULD verify correctness using the test vectors given by this specification.

Security Guidance for JWT and CWT A Status List Token in the JWT format SHOULD follow the security considerations of and the best current practices of . A Status List Token in the CWT format SHOULD follow the security considerations of .

Key Resolution and Trust Management This specification does not mandate specific methods for key resolution and trust management, however the following recommendations are made for specifications, profiles, or ecosystems that are planning to make use of the Status List mechanism: If the Issuer of the Referenced Token is the same entity as the Status Issuer, then the same key that is embedded into the Referenced Token may be used for the Status List Token. In this case the Status List Token may use:

• the same x5c value or an x5t, x5t#S256 or kid parameter referencing to the same key as used in the Referenced Token for JOSE.
• the same x5chain value or an x5t or kid parameter referencing to the same key as used in the Referenced Token for COSE.

Alternatively, the Status Issuer may use the same web-based key resolution that is used for the Referenced Token. In this case the Status List Token may use:

• an x5u, jwks, jwks_uri or kid parameter referencing to a key using the same web-based resolution as used in the Referenced Token for JOSE.
• an x5u or kid parameter referencing to a key using the same web-based resolution as used in the Referenced Token for COSE.

If the Issuer of the Referenced Token is a different entity than the Status Issuer, then the keys used for the Status List Token may be cryptographically linked, e.g. by a Certificate Authority through an x.509 PKI. The certificate of the Issuer for the Referenced Token and the Status Issuer should be issued by the same Certificate Authority and the Status Issuer's certificate should utilize extended key usage.

Redirection 3xx HTTP clients that follow 3xx (Redirection) class of status codes SHOULD be aware of the possible dangers of redirects, such as infinite redirection loops, since they can be used for denial of service attacks on clients. A client SHOULD detect and intervene in infinite redirections. Clients SHOULD apply the guidance for redirects given in Section 15.4 of .

Expiration and Caching Expiration and caching information is conveyed via the exp and ttl claims as explained in . Clients SHOULD check that both values are within reasonable ranges before requesting new Status List Tokens based on these values to prevent accidentally creating unreasonable amounts of requests for a specific URL. Status Issuers could accidentally or maliciously use this mechanism to effectively DDoS the contained URL of the Status Provider. Reasonable values for both claims highly depend on the use-case requirements and clients SHOULD be configured with lower/upper bounds for these values that fit their respective use-cases.

Status List Token Protection This specification allows both, digital signatures using asymmetric cryptography, and Message Authentication Codes (MAC) to be used to protect Status List Tokens. Implementers SHOULD only use MACs to secure the integrity of Status List Tokens if they fully understand the risks of MACs when compared to digital signatures and especially the requirements of their use-case scenarios. These use-cases typically represent deployments where Status Issuer and Relying Party have a trust relationship and the possibility to securely exchange keys out of band or are the same entity and no other entity needs to verify the Status List Token. We expect most deployments to use digital signatures for the protection of Status List Tokens and implementers SHOULD default to digital signatures if they are unsure.

Privacy Considerations

Observability of Issuers The main privacy consideration for a Status List, especially in the context of the Issuer-Holder-Verifier model , is to prevent the Issuer from tracking the usage of the Referenced Token when the status is being checked. If an Issuer offers status information by referencing a specific token, this would enable the Issuer to create a profile for the issued token by correlating the date and identity of Relying Parties, that are requesting the status. The Status List approaches these privacy implications by integrating the status information of many Referenced Tokens into the same list. Therefore, the Issuer does not learn for which Referenced Token the Relying Party is requesting the Status List. The privacy of the Holder is protected by the anonymity within the set of Referenced Tokens in the Status List, also called herd privacy. This limits the possibilities of tracking by the Issuer. The herd privacy is depending on the number of entities within the Status List called its size. A larger size results in better privacy but also impacts the performance as more data has to be transferred to read the Status List. Additionally, the Issuer may analyse data from the HTTP request to identify the Relying Party, e.g. through the sender's IP address. This behaviour may be mitigated by:

• private relay protocols or other mechanisms hiding the original sender like .
• using trusted Third Party Hosting, see .

Issuer Tracking of Reference Tokens An Issuer could maliciously or accidentally bypass the privacy benefits of the herd privacy by either:

• Generating a unique Status List for every Referenced Token. By these means, the Issuer could maintain a mapping between Referenced Tokens and Status Lists and thus track the usage of Referenced Tokens by utilizing this mapping for the incoming requests.
• Encoding a unique URI in each Reference Token which points to the underlying Status List. This may involve using URI components such as query parameters, unique path segments, or fragments to make the URI unique.

This malicious behavior can be detected by Relying Parties that request large amounts of Referenced Tokens by comparing the number of different Status Lists and their sizes with the volume of Reference Tokens being verified.

Observability of Relying Parties Once the Relying Party receives the Referenced Token, the Relying Party can request the Status List through the provided uri parameter and can validate the Referenced Token's status by looking up the corresponding index. However, the Relying Party may persistently store the uri and index of the Referenced Token to request the Status List again at a later time. By doing so regularly, the Relying Party may create a profile of the Referenced Token's validity status. This behaviour may be intended as a feature, e.g. for an identity proofing (e.g. Know-Your-Customer process in finance industry) that requires regular validity checks, but might also be abused in cases where this is not intended and unknown to the Holder, e.g. profiling the suspension of an employee credential. This behaviour could be mitigated by:

• regular re-issuance of the Referenced Token, see .

Observability of Outsiders Outside actors may analyse the publicly available Status Lists to get information on the internal processes of the Issuer and its related business, e.g. number of customers or clients. This data may allow inferences on the total number of issued Reference Tokens and the revocation rate. Additionally, actors may regularly fetch this data or use the historic data functionality to learn how these numbers change over time. This behaviour could be mitigated by:

• disabling the historical data feature
• disabling the Status List Aggregation
• choosing non-sequential, pseudo-random or random indices
• using decoy entries to obfuscate the real number of Referenced Tokens within a Status List
• choosing to deploy and utilize multiple Status Lists simultaneously

Unlinkability The tuple of uri and index inside the Referenced Token are unique and therefore is traceable data.

Colluding Relying Parties Two or more colluding Relying Parties may link two transactions involving the same Referenced Token by comparing the status claims of received Referenced Tokens and therefore determine that they have interacted with the same Holder. To avoid privacy risks of colluding Relying Parties, it is RECOMMENDED that Issuers provide the ability to issue batches of one-time-use Referenced Tokens, enabling Holders to use in a single interaction with a Relying Party before discarding. See to avoid further correlatable information by the values of uri and index, Status Issuers are RECOMMENDED to:

• choose non-sequential, pseudo-random or random indices
• use decoy entries to obfuscate the real number of Referenced Tokens within a Status List
• choose to deploy and utilize multiple Status Lists simultaneously

Colluding Status Issuer and Relying Party A Status Issuer and a Relying Party Issuer may link two transaction involving the same Referenced Tokens by comparing the status claims of the Referenced Token and therefore determine that they have interacted with the same Holder. It is therefore recommended to use Status Lists for Referenced Token formats that have similar unlinkability properties.

External Status Provider for Privacy If the roles of the Status Issuer and the Status Provider are performed by different entities, this may give additional privacy assurances as the Issuer has no means to identify the Relying Party or its request. Third-Party hosting may also allow for greater scalability, as the Status List Tokens may be served by operators with greater resources, like CDNs, while still ensuring authenticity and integrity of Token Status List, as it is signed by the Status Issuer.

Historical Resolution By default, this specification only supports providing Status List information for the most recent status information and does not allow the lookup of historical information like a validity state at a specific point in time. There exists optional support for a query parameter that allows these kind of historic lookups as described in . There are scenarios where such a functionality is necessary, but this feature should only be implemented when the scenario and the consequences of enabling historical resolution are fully understood. There are strong privacy concerns that have to be carefully taken into consideration when providing a mechanism that allows historic requests for status information - see for more details. Support for this functionality is optional and Implementers are RECOMMENDED to not support historic requests unless there are strong reasons to do so and after carefully considering the privacy implications.

Status Types As previously explained, there is the potential risk of observability by Relying Parties (see ) and Outsiders (see ). That means that any Status Type that transports information beyond the routine statuses VALID and INVALID about a Referenced Token can leak information to other parties. This document defines one additional Status Type with "SUSPENDED" that conveys such additional information, but in practice all statuses other than VALID and INVALID are likely to contain information with privacy implications. Ecosystems that want to use other Status Types than "VALID" and "INVALID" should consider the possible leakage of data and profiling possibilities before doing so and evaluate if revocation and re-issuance might a better fit for their use-case.

Implementation Considerations

Token Lifecycle The lifetime of a Status List Token depends on the lifetime of its Referenced Tokens. Once all Referenced Tokens are expired, the Issuer may stop serving the Status List Token.

Linkability Mitigation Referenced Tokens may be regularly re-issued to mitigate the linkability of presentations to Relying Parties. In this case, every re-issued Referenced Token MUST have a fresh Status List entry in order to prevent the index value from becoming a possible source of correlation. Referenced Tokens may also be issued in batches and be presented by Holders in a one-time-use policy to avoid linkability. In this case, every Referenced Token MUST have a dedicated Status List entry and MAY be spread across multiple Status List Tokens. Batch revocation of a batch of Referenced Tokens might reveal that they are all members of the same batch. Beware, that this mechanism solves linkability issues between Relying Parties, but does not prevent traceability by Issuers.

Default Values and Double Allocation The Status Issuer is RECOMMENDED to initialize the Status List byte array with a default value provided as an initialization parameter by the Issuer of the Referenced Token. The Issuer is RECOMMENDED to use a default value that represents the most common value for its Referenced Tokens to avoid an update during issuance (usually 0x00, VALID). This preserves the benefits from compression and effectively hides the number of managed Referenced Tokens since an unused index value can not be distinguished from a valid Referenced Token. The Status Issuer is RECOMMENDED to prevent double allocation, i.e. re-using the same uri and index for multiple Referenced Tokens (since uri and index form a unique identifier that might be used for tracking, see for more details). The Status Issuer MUST prevent any unintended double allocation.

Status List Size The storage and transmission size of the Status Issuer's Status List Tokens depends on:

• the size of the Status List, i.e. the number of Referenced Tokens
• the revocation rate and distribution of the Status List data (due to compression, revocation rates close to 0% or 100% create lowest sizes while revocation rates closer to 50% and random distribution create highest sizes)
• the lifetime of Referenced Tokens (shorter lifetimes allows for earlier retirement of Status List Tokens)

The Status List Issuer may increase the size of a Status List if it requires indices for additional Referenced Tokens. It is RECOMMENDED that the size of a Status List in bits is divisible in bytes (8 bits) without a remainder, i.e. size-in-bits % 8 = 0. The Status List Issuer may divide its Referenced Tokens up into multiple Status Lists to reduce the transmission size of an individual Status List Token. This may be useful for ecosystems where some entities operate in constrained environments, e.g. for mobile internet or embedded devices. The Status List Issuer may organize the Status List Tokens depending on the Referenced Token's expiry date to align their lifecycles and allow for easier retiring of Status List Tokens, however the Status Issuer must be aware of possible privacy risks due to correlations.

External Status Issuer If the roles of the Issuer of the Referenced Token and the Status Issuer are performed by different entities, this may allow for use case that require revocations of Referenced Tokens to be managed by a different entities, e.g. for regulatory or privacy reasons. In this scenario both parties must align on:

• the key and trust management as described in
• parameters for the Status List
  • number of bits for the Status Type as described in
  • update cycle of the Issuer used for ttl in the Status List Token as described in

External Status Provider for Scalability If the roles of the Status Issuer and the Status Provider are performed by different entities, this may allow for greater scalability, as the Status List Tokens may be served by operators with greater resources, like CDNs. At the same time the authenticity and integrity of Token Status List is still guaranteed, as it is signed by the Status Issuer.

Status List Update Interval and Caching Status Issuers have two options to communicate their update interval policy for the status of their Referenced Tokens:

• the exp claim specifies an absolute timestamp, marking the point in time when the Status List expires and MUST NOT be relied upon any longer
• the ttl claim represents a duration to be interpreted relative to the time the Status List is fetched, indicating when a new version of the Status List may be available

Both ttl and exp are RECOMMENDED to be used by the Status Issuer. When fetching a Status List Token, Relying Parties must carefully evaluate how long a Status List is cached for. Collectively the iat, exp and ttl claims when present in a Status List Token communicate how long a Status List should be cached and should be considered valid for. Relying Parties have different options for caching the Status List:

• After time of fetching, the Relying Party caches the Status List for time duration of ttl before making checks for updates. This method is RECOMMENDED to distribute the load for the Status Provider.
• After initial fetching, the Relying Party checks for updates at time of iat + ttl. This method ensures the most up-to-date information for critical use cases. The Relying Party should account a minimal offset due to the signing and distribution process of the Status Issuer.
• If no ttl is given, then Relying Party SHOULD check for updates latest after the time of exp.

Ultimately, it's the Relying Parties decision how often to check for updates, ecosystems may define their own guidelines and policies for updating the Status List information. Clients should ensure that exp and ttl are within reasonable bounds before creating requests to get a fresh Status List Token (see for more details). The following diagram illustrates the relationship between these claims and how they are designed to influence caching:

Relying Parties avoiding correlatable Information If the Relying Party does not require the Referenced Token or the Status List Token for further processing, it is RECOMMENDED to delete correlatable information, in particular:

• the status claim in the Referenced Token (after the validation)
• the Status List Token itself (after expiration or update)

The Relying Party should instead only keep the needed fields from the Referenced Token.

Status List Formats This specification defines 2 different token formats of the Status List:

• JWT
• CWT

This specification states no requirements to not mix different formats like a CBOR based Referenced Token using a JWT for the Status List, but the expectation is that within an ecosystem, a choice for specific formats is made. Within such an ecosystem, only support for those selected variants is required and implementations should know what to expect via a profile.

IANA Considerations

JSON Web Token Claims Registration This specification requests registration of the following Claims in the IANA "JSON Web Token Claims" registry established by .

Registry Contents

• Claim Name: status
• Claim Description: A JSON object containing a reference to a status mechanism from the JWT Status Mechanisms Registry.
• Change Controller: IETF
• Specification Document(s): of this specification

• Claim Name: status_list
• Claim Description: A JSON object containing up-to-date status information on multiple tokens using the Token Status List mechanism.
• Change Controller: IETF
• Specification Document(s): of this specification

• Claim Name: ttl
• Claim Description: Time to Live
• Change Controller: IETF
• Specification Document(s): of this specification

JWT Status Mechanisms Registry This specification establishes the IANA "JWT Status Mechanisms" registry for JWT "status" member values and adds it to the "JSON Web Token (JWT)" registry group at https://www.iana.org/assignments/jwt. The registry records the status mechanism member and a reference to the specification that defines it. JWT Status Mechanisms are registered by Specification Required after a three-week review period on the jwt-reg-review@ietf.org mailing list, on the advice of one or more Designated Experts. However, to allow for the allocation of names prior to publication, the Designated Expert(s) may approve registration once they are satisfied that such a specification will be published. Registration requests sent to the mailing list for review should use an appropriate subject (e.g., "Request to register JWT Status Mechanism: example"). Within the review period, the Designated Expert(s) will either approve or deny the registration request, communicating this decision to the review list and IANA. Denials should include an explanation and, if applicable, suggestions as to how to make the request successful. IANA must only accept registry updates from the Designated Expert(s) and should direct all requests for registration to the review mailing list.

Registration Template Status Mechanism Value:

• The name requested (e.g., "status_list"). The name is case sensitive. Names may not match other registered names in a case-insensitive manner unless the Designated Experts state that there is a compelling reason to allow an exception.

Status Mechanism Description:

• Brief description of the status mechanism.

Change Controller:

• For IETF Stream RFCs, list the IETF. For others, give the name of the responsible party. Other details (e.g., postal address, email address, home page URI) may also be included.

Specification Document(s):

• Reference to the document or documents that specify the parameter, preferably including URIs that can be used to retrieve copies of the documents. An indication of the relevant sections may also be included but is not required.

Initial Registry Contents

• Status Mechanism Value: status_list
• Status Mechanism Description: A Token Status List containing up-to-date status information on multiple tokens.
• Change Controller: IETF
• Specification Document(s): of this specification

CBOR Web Token Claims Registration This specification requests registration of the following Claims in the IANA "CBOR Web Token (CWT) Claims" registry established by .

Registry Contents

• Claim Name: status
• Claim Description: A CBOR structure containing a reference to a status mechanism from the CWT Status Mechanisms Registry.
• JWT Claim Name: status
• Claim Key: TBD (requested assignment 65535)
• Claim Value Type: map
• Change Controller: IETF
• Reference: of this specification

• Claim Name: status_list
• Claim Description: A CBOR structure containing up-to-date status information on multiple tokens using the Token Status List mechanism.
• JWT Claim Name: status_list
• Claim Key: TBD (requested assignment 65533)
• Claim Value Type: map
• Change Controller: IETF
• Specification Document(s): of this specification

• Claim Name: ttl
• Claim Description: Time to Live
• JWT Claim Name: ttl
• Claim Key: TBD (requested assignment 65534)
• Claim Value Type: unsigned integer
• Change Controller: IETF
• Specification Document(s): of this specification

CWT Status Mechanisms Registry This specification establishes the IANA "CWT Status Mechanisms" registry for CWT "status" member values and adds it to the "CBOR Web Token (CWT) Claims" registry group at https://www.iana.org/assignments/cwt. The registry records the status mechanism member and a reference to the specification that defines it. CWT Status Mechanisms are registered by Specification Required after a three-week review period on the cwt-reg-review@ietf.org mailing list, on the advice of one or more Designated Experts. However, to allow for the allocation of names prior to publication, the Designated Expert(s) may approve registration once they are satisfied that such a specification will be published. Registration requests sent to the mailing list for review should use an appropriate subject (e.g., "Request to register CWT Status Mechanism: example"). Within the review period, the Designated Expert(s) will either approve or deny the registration request, communicating this decision to the review list and IANA. Denials should include an explanation and, if applicable, suggestions as to how to make the request successful. IANA must only accept registry updates from the Designated Expert(s) and should direct all requests for registration to the review mailing list.

Registration Template Status Mechanism Value:

• The name requested (e.g., "status_list"). The name is case sensitive. Names may not match other registered names in a case-insensitive manner unless the Designated Experts state that there is a compelling reason to allow an exception.

Status Mechanism Description:

• Brief description of the status mechanism.

Change Controller:

• For IETF Stream RFCs, list the IETF. For others, give the name of the responsible party. Other details (e.g., postal address, email address, home page URI) may also be included.

Specification Document(s):

• Reference to the document or documents that specify the parameter, preferably including URIs that can be used to retrieve copies of the documents. An indication of the relevant sections may also be included but is not required.

Initial Registry Contents

• Status Mechanism Value: status_list
• Status Mechanism Description: A Token Status List containing up-to-date status information on multiple tokens.
• Change Controller: IETF
• Specification Document(s): of this specification

OAuth Status Types Registry This specification establishes the IANA "OAuth Status Types" registry for Status List values and adds it to the "OAuth Parameters" registry group at https://www.iana.org/assignments/oauth-parameters. The registry records a human readable label, the bit representation and a common description for it. Status Types are registered by Specification Required after a two-week review period on the oauth-ext-review@ietf.org mailing list, on the advice of one or more Designated Experts. However, to allow for the allocation of names prior to publication, the Designated Expert(s) may approve registration once they are satisfied that such a specification will be published. Registration requests sent to the mailing list for review should use an appropriate subject (e.g., "Request to register Status Type name: example"). Within the review period, the Designated Expert(s) will either approve or deny the registration request, communicating this decision to the review list and IANA. Denials should include an explanation and, if applicable, suggestions as to how to make the request successful. IANA must only accept registry updates from the Designated Expert(s) and should direct all requests for registration to the review mailing list.

Registration Template Status Type Name:

• The name is a human-readable case insensitive label for the Status Type that helps to talk about the status of Referenced Token in common language.

Status Type Description:

• Brief description of the Status Type and optional examples.

Status Type value:

• The bit representation of the Status Type in a byte hex representation. Valid Status Type values range from 0x00-0xFF. Values are filled up with zeros if they have less than 8 bits.

Change Controller:

• For IETF Stream RFCs, list the IETF. For others, give the name of the responsible party. Other details (e.g., postal address, email address, home page URI) may also be included.

Specification Document(s):

• Reference to the document or documents that specify the parameter, preferably including URIs that can be used to retrieve copies of the documents. An indication of the relevant sections may also be included but is not required.

Initial Registry Contents

• Status Type Name: VALID
• Status Type Description: The status of the Referenced Token is valid, correct or legal.
• Status Type value: 0x00
• Change Controller: IETF
• Specification Document(s): of this specification

• Status Type Name: INVALID
• Status Type Description: The status of the Referenced Token is revoked, annulled, taken back, recalled or cancelled.
• Status Type value: 0x01
• Change Controller: IETF
• Specification Document(s): of this specification

• Status Type Name: SUSPENDED
• Status Type Description: The status of the Referenced Token is temporarily invalid, hanging or debarred from privilege. This state is usually temporary.
• Status Type value: 0x02
• Change Controller: IETF
• Specification Document(s): of this specification

• Status Type Name: APPLICATION_SPECIFIC
• Status Type Description: The status of the Referenced Token is application specific.
• Status Type value: 0x03
• Change Controller: IETF
• Specification Document(s): of this specification

• Status Type Name: APPLICATION_SPECIFIC
• Status Type Description: The status of the Referenced Token is application specific.
• Status Type value: 0x0C-0xOF
• Change Controller: IETF
• Specification Document(s): of this specification

OAuth Parameters Registration This specification requests registration of the following values in the IANA "OAuth Authorization Server Metadata" registry established by .

• Metadata Name: status_list_aggregation_endpoint
• Metadata Description: URL of the Authorization Server aggregating OAuth Token Status List URLs for token status management.
• Change Controller: IESG
• Reference: of this specification

Media Type Registration This section requests registration of the following media types in the "Media Types" registry in the manner described in . To indicate that the content is an JWT-based Status List:

• Type name: application
• Subtype name: statuslist+jwt
• Required parameters: n/a
• Optional parameters: n/a
• Encoding considerations: See of this specification
• Security considerations: See of this specification
• Interoperability considerations: n/a
• Published specification: this specification
• Applications that use this media type: Applications using this specification for updated status information of tokens
• Fragment identifier considerations: n/a
• Additional information: n/a
• Person & email address to contact for further information: Paul Bastian, paul.bastian@posteo.de
• Intended usage: COMMON
• Restrictions on usage: none
• Author: Paul Bastian, paul.bastian@posteo.de
• Change controller: IETF
• Provisional registration? No

To indicate that the content is an CWT-based Status List:

• Type name: application
• Subtype name: statuslist+cwt
• Required parameters: n/a
• Optional parameters: n/a
• Encoding considerations: See of this specification
• Security considerations: See of this specification
• Interoperability considerations: n/a
• Published specification: this specification
• Applications that use this media type: Applications using this specification for updated status information of tokens
• Fragment identifier considerations: n/a
• Additional information: n/a
• Person & email address to contact for further information: Paul Bastian, paul.bastian@posteo.de
• Intended usage: COMMON
• Restrictions on usage: none
• Author: Paul Bastian, paul.bastian@posteo.de
• Change controller: IETF
• Provisional registration? No

CoAP Content-Format Registrations IANA is requested to register the following Content-Format numbers in the "CoAP Content-Formats" sub-registry, within the "Constrained RESTful Environments (CoRE) Parameters" Registry :

• Content Type: application/statuslist+cwt
• Content Coding: -
• ID: TBD
• Reference: this specification

X.509 Certificate Extended Key Purpose OID Registration IANA is requested to register the following OID "1.3.6.1.5.5.7.3.TBD" in the "SMI Security for PKIX Extended Key Purpose" registry (1.3.6.1.5.5.7.3), this OID is defined in section . IANA is requested to register the following OID "1.3.6.1.5.5.7.0.TBD" in the "SMI Security for PKIX Module Identifier" registry (1.3.6.1.5.5.7.0), this OID is defined in section .

Acknowledgments We would like to thank Andrii Deinega, Brian Campbell, Dan Moore, Denis Pinkas, Filip Skokan, Francesco Marino, Giuseppe De Marco, Hannes Tschofenig, Kristina Yasuda, Markus Kreusch, Martijn Haring, Michael B. Jones, Micha Kraus, Michael Schwartz, Mike Prorock, Mirko Mollik, Oliver Terbu, Orie Steele, Rifaat Shekh-Yusef, Rohan Mahy, Timo Glastra and Torsten Lodderstedt for their valuable contributions, discussions and feedback to this specification.

References Normative References This specification defines a lossless compressed data format. This memo provides information for the Internet community. This memo does not specify an Internet standard of any kind. This specification defines a lossless compressed data format that compresses data using a combination of the LZ77 algorithm and Huffman coding, with efficiency comparable to the best currently available general-purpose compression methods. This memo provides information for the Internet community. This memo does not specify an Internet standard of any kind. This second document defines the general structure of the MIME media typing system and defines an initial set of media types. [STANDARDS-TRACK] A Uniform Resource Identifier (URI) is a compact sequence of characters that identifies an abstract or physical resource. This specification defines the generic URI syntax and a process for resolving URI references that might be in relative form, along with guidelines and security considerations for the use of URIs on the Internet. The URI syntax defines a grammar that is a superset of all valid URIs, allowing an implementation to parse the common components of a URI reference without knowing the scheme-specific requirements of every possible identifier. This specification does not define a generative grammar for URIs; that task is performed by the individual specifications of each URI scheme. [STANDARDS-TRACK] Many protocols make use of points of extensibility that use constants to identify various protocol parameters. To ensure that the values in these fields do not have conflicting uses and to promote interoperability, their allocations are often coordinated by a central record keeper. For IETF protocols, that role is filled by the Internet Assigned Numbers Authority (IANA). To make assignments in a given registry prudently, guidance describing the conditions under which new values should be assigned, as well as when and how modifications to existing values can be made, is needed. This document defines a framework for the documentation of these guidelines by specification authors, in order to assure that the provided guidance for the IANA Considerations is clear and addresses the various issues that are likely in the operation of a registry. This is the third edition of this document; it obsoletes RFC 5226. This document defines procedures for the specification and registration of media types for use in HTTP, MIME, and other Internet protocols. This memo documents an Internet Best Current Practice. JSON Web Signature (JWS) represents content secured with digital signatures or Message Authentication Codes (MACs) using JSON-based data structures. Cryptographic algorithms and identifiers for use with this specification are described in the separate JSON Web Algorithms (JWA) specification and an IANA registry defined by that specification. Related encryption capabilities are described in the separate JSON Web Encryption (JWE) specification. JSON Web Token (JWT) is a compact, URL-safe means of representing claims to be transferred between two parties. The claims in a JWT are encoded as a JSON object that is used as the payload of a JSON Web Signature (JWS) structure or as the plaintext of a JSON Web Encryption (JWE) structure, enabling the claims to be digitally signed or integrity protected with a Message Authentication Code (MAC) and/or encrypted. JavaScript Object Notation (JSON) is a lightweight, text-based, language-independent data interchange format. It was derived from the ECMAScript Programming Language Standard. JSON defines a small set of formatting rules for the portable representation of structured data. This document removes inconsistencies with other specifications of JSON, repairs specification errors, and offers experience-based interoperability guidance. CBOR Web Token (CWT) is a compact means of representing claims to be transferred between two parties. The claims in a CWT are encoded in the Concise Binary Object Representation (CBOR), and CBOR Object Signing and Encryption (COSE) is used for added application-layer security protection. A claim is a piece of information asserted about a subject and is represented as a name/value pair consisting of a claim name and a claim value. CWT is derived from JSON Web Token (JWT) but uses CBOR rather than JSON. JSON Web Tokens, also known as JWTs, are URL-safe JSON-based security tokens that contain a set of claims that can be signed and/or encrypted. JWTs are being widely used and deployed as a simple security token format in numerous protocols and applications, both in the area of digital identity and in other application areas. This Best Current Practices document updates RFC 7519 to provide actionable guidance leading to secure implementation and deployment of JWTs. The Concise Binary Object Representation (CBOR) is a data format whose design goals include the possibility of extremely small code size, fairly small message size, and extensibility without the need for version negotiation. These design goals make it different from earlier binary serializations such as ASN.1 and MessagePack. This document obsoletes RFC 7049, providing editorial improvements, new details, and errata fixes while keeping full compatibility with the interchange format of RFC 7049. It does not create a new version of the format. Concise Binary Object Representation (CBOR) is a data format designed for small code size and small message size. There is a need to be able to define basic security services for this data format. This document defines the CBOR Object Signing and Encryption (COSE) protocol. This specification describes how to create and process signatures, message authentication codes, and encryption using CBOR for serialization. This specification additionally describes how to represent cryptographic keys using CBOR. This document, along with RFC 9053, obsoletes RFC 8152. The Hypertext Transfer Protocol (HTTP) is a stateless application-level protocol for distributed, collaborative, hypertext information systems. This document describes the overall architecture of HTTP, establishes common terminology, and defines aspects of the protocol that are shared by all versions. In this definition are core protocol elements, extensibility mechanisms, and the "http" and "https" Uniform Resource Identifier (URI) schemes. This document updates RFC 3864 and obsoletes RFCs 2818, 7231, 7232, 7233, 7235, 7538, 7615, 7694, and portions of 7230. This memo profiles the X.509 v3 certificate and X.509 v2 certificate revocation list (CRL) for use in the Internet. An overview of this approach and model is provided as an introduction. The X.509 v3 certificate format is described in detail, with additional information regarding the format and semantics of Internet name forms. Standard certificate extensions are described and two Internet-specific extensions are defined. A set of required certificate extensions is specified. The X.509 v2 CRL format is described in detail along with standard and Internet-specific extensions. An algorithm for X.509 certification path validation is described. An ASN.1 module and examples are provided in the appendices. [STANDARDS-TRACK] This specification adds the equivalent of the JSON Object Signing and Encryption (JOSE) "typ" (type) header parameter to CBOR Object Signing and Encryption (COSE). This enables the benefits of explicit typing (as defined in RFC 8725, "JSON Web Token Best Current Practices") to be brought to COSE objects. The syntax of the COSE type header parameter value is the same as the existing COSE content type header parameter. IANA n.d. IANA n.d. IANA n.d. IANA n.d. IANA n.d. IANA n.d. WHATWG n.d. International Telecommunications Union International Telecommunications Union In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. RFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings. Informative References The OAuth 2.0 authorization framework enables a third-party application to obtain limited access to an HTTP service, either on behalf of a resource owner by orchestrating an approval interaction between the resource owner and the HTTP service, or by allowing the third-party application to obtain access on its own behalf. This specification replaces and obsoletes the OAuth 1.0 protocol described in RFC 5849. [STANDARDS-TRACK] This specification defines a method for a protected resource to query an OAuth 2.0 authorization server to determine the active state of an OAuth 2.0 token and to determine meta-information about this token. OAuth 2.0 deployments can use this method to convey information about the authorization context of the token from the authorization server to the protected resource. This specification describes how to declare in a JSON Web Token (JWT) that the presenter of the JWT possesses a particular proof-of- possession key and how the recipient can cryptographically confirm proof of possession of the key by the presenter. Being able to prove possession of a key is also sometimes described as the presenter being a holder-of-key. This specification defines a metadata format that an OAuth 2.0 client can use to obtain the information needed to interact with an OAuth 2.0 authorization server, including its endpoint locations and authorization server capabilities. This document describes Oblivious HTTP, a protocol for forwarding encrypted HTTP messages. Oblivious HTTP allows a client to make multiple requests to an origin server without that server being able to link those requests to the client or to identify the requests as having come from the same client, while placing only limited trust in the nodes used to forward the messages. MATTR Authlete Inc. Ping Identity This specification describes data formats as well as validation and processing rules to express Verifiable Credentials with JSON payloads with and without selective disclosure based on the SD-JWT [I-D.ietf-oauth-selective-disclosure-jwt] format. ISO/IEC JTC 1/SC 17 n.d. Brigham Young University Brigham Young University Brigham Young University n.d. Digital Bazaar Digital Bazaar Transmute

ASN.1 Module The following module adheres to ASN.1 specifications and .

Size comparison The following tables show a size comparison for a Status List (compressed byte array as defined in ) and a compressed Byte Array of UUIDs (as an approximation to the list of IDs of Referenced Tokens in a Certificate Revocation List). Readers must be aware that these are not sizes for complete Status List Tokens in JSON/CBOR nor Certificate Revocation Lists (CRLs), as they don't contain metadata, certificates and signatures. If no further metadata is provided in Status List Tokens or CRLs, then the size of Status Lists or arrays of Certificate ids (represented as UUIDs) will be the main factors deciding on the overall size of a Status List Token or CRL respectively.

Size of Status Lists for varying amount of entries and revocation rates Status List Size examples for varying amount of entries and revocation rates

Size	0.01%	0.1%	1%	2%	5%	10%	25%	50%	75%	100%
100k	81 B	252 B	1.4 KB	2.3 KB	4.5 KB	6.9 KB	10.2 KB	12.2 KB	10.2 KB	35 B
1M	442 B	2.2 KB	13.7 KB	23.0 KB	43.9 KB	67.6 KB	102.2 KB	122.1 KB	102.4 KB	144 B
10M	3.8 KB	21.1 KB	135.4 KB	230.0 KB	437.0 KB	672.9 KB	1023.4 KB	1.2 MB	1023.5 KB	1.2 KB
100M	38.3 KB	213.0 KB	1.3 MB	2.2 MB	4.3 MB	6.6 MB	10.0 MB	11.9 MB	10.0 MB	11.9 KB

Size of compressed array of UUIDv4 (128 bit UUIDs) for varying amount of entries and revocation rates This is a simple approximation of a Certificate Revocation List using an array of UUIDs without any additional metadata (128 bit UUID per revoked entry). Size examples for 128 bit UUIDs for varying amount of entries and revocation rates

Size	0.01%	0.1%	1%	2%	5%	10%	25%	50%	75%	100%
100k	219 B	1.6 KB	15.4 KB	29.7 KB	78.1 KB	154.9 KB	392.9 KB	783.1 KB	1.1 MB	1.5 MB
1M	1.6 KB	16.4 KB	157.7 KB	310.4 KB	781 KB	1.5 MB	3.8 MB	7.6 MB	11.4 MB	15.3 MB
10M	15.3 KB	155.9 KB	1.5 MB	3.1 MB	7.6 MB	15.2 MB	38.2 MB	76.3 MB	114.4 MB	152.6 MB
100M	157.6 KB	1.5 MB	15.3 MB	30.5 MB	76.3 MB	152.6 MB	381.4 MB	762.9 MB	1.1 GB	1.5 GB

Test vectors for Status List encoding All examples here are given in the form of JSON or CBOR payloads. The examples are encoded according to for JSON and for CBOR. The CBOR examples are displayed as hex values. All values that are not mentioned for the examples below can be assumed to be 0 (VALID). All examples are initialized with a size of 2^20 entries.

1 bit Status List The following example uses a 1 bit Status List (2 possible values): JSON encoding: CBOR encoding:

2 bit Status List The following example uses a 2 bit Status List (4 possible values): JSON encoding: CBOR encoding:

4 bit Status List The following example uses a 4 bit Status List (16 possible values): JSON encoding: CBOR encoding:

8 bit Status List The following example uses a 8 bit Status List (256 possible values): JSON encoding: CBOR encoding:

Document History [[ To be removed from the final specification ]] -14

• use binary value encoding for all test vectors (display purposes only)
• removed bytes from graphic that were intepreted as padding bytes
• removed 0x0B from application-specific Status Type
• reemphasized that expired tokens with status "VALID" are still expired
• renamed section "Status List Aggregation in JSON Format" to "Status List Aggregation Data Structure"
• slightly restructure/clarify referenced token cose section
• Add ASN.1 module
• many nits and improvements from genart review
• remove cose_sign1 tag from statuslist in cwt form examples
• slightly restructure/clarify referenced token cose section
• Add ASN.1 module
• removed DL suspension example

-13

• add definition of client to terminology
• Make exp and ttl recommended in claim description (fixes inconsistency, was recommended in other text)
• Add short security consideraiton on redirects and ttl
• fix CORS spec to specific version
• explain KYC
• link implementation guidance to exp and ttl in Status List Token definition
• reference RFC7515 instead of IANA:JOSE
• add a note that cwt is encoded in raw/binary.
• added further privacy consideration around issuer tracking using unique URIs

-12

• Allow for extended key usage OID to be used for other status mechanisms
• add Paul's affiliation
• add feedback from Dan Moore
• change JSON Status List structure to only contain JSON object
• further nitpicks
• clarifying status and status_list IANA descriptions for JWT/CWT
• clarifying description texts for status and status_list in CBOR
• splitting Linkability Mitigation from Token Lifecycle section in Implementation Consideration
• relax the accept header from must to should

-11

• incorporate feedback from shepherd review
• some nitpicks
• even more nitpicks

-10

• improve caching guidelines and move them to implementaiton considerations
• Add CoAP Content-Format ID and IANA registration
• Add size comparison for status list and compressed uuids
• Change Controller IESG for OAuths Parameters Registration

-09

• update acknowledgments
• introduce dedicated section for compressed byte array of the Status List
• fix Status List definitions
• Add CDDL for CBOR StatusList encoding
• add diagram for Status List Aggregation for further explanation
• rename "chunking" of Status List Tokens (for scalability reasons) into "divide .. up"

-08

• Fix cwt typ value to full media type
• Holders may also fetch and verify Status List Tokens
• Update terminology for referenced token and Status List Token

-07

• add considerations about External Status Issuer or Status Provider
• add recommendations for Key Resolution and Trust Management
• add extended key usage extensions for x509
• Relying Parties avoiding correlatable Information
• editorial changes on terminology and Referenced Tokens
• clarify privacy consideration around one time use reference tokens
• explain the Status List Token size dependencies
• explain possibility to chunk Status List Tokens depending on Referenced Token's expiry date
• add short-lived tokens in the Rationale
• rename Status Mechanism Methods registry to Status Mechanisms registry
• changes as requested by IANA review
• emphasize that security and privacy considerations only apply to Status List and no other status mechanisms
• differentiate unlinkability between Issuer-RP and RP-RP
• add more test vectors for the status list encoding
• add prior art
• updated language around application specific status type values and assigned ranges for application specific usage
• add short security considerations section for mac based deployments
• privacy considerations for other status types like suspended
• fix aggregation_uri text in referenced token
• mention key resolution in validation rules

-06

• iana registration text updated with update procedures
• explicitly mention that status list is expected to be contained in cryptographically secured containers
• reworked and simplified introduction and abstract
• specify http status codes and allow redirects
• add status_list_aggregation_endpoint OAuth metadata
• remove unsigned options (json/cbor) of status list
• add section about mixing status list formats and media type
• fixes from IETF review
• update guidance around ttl
• add guidance around aggregation endpoint

-05

• add optional support for historical requests
• update CBOR claim definitions
• improve section on Status Types and introduce IANA registry for it
• add Status Issuer and Status Provider role description to the introduction/terminology
• add information on third party hosting to security consideration
• remove constraint that Status List Token must not use a MAC

-04

• add mDL example as Referenced Token and consolidate CWT and CBOR sections
• add implementation consideration for Default Values, Double Allocation and Status List Size
• add privacy consideration on using private relay protocols
• add privacy consideration on observability of outsiders
• add security considerations on correct parsing and decoding
• remove requirement for matching iss claim in Referenced Token and Status List Token
• add sd-jwt-vc example
• fix CWT status_list map encoding
• editorial fixes
• add CORS considerations to the http endpoint
• fix reference of Status List in CBOR format
• added status_list CWT claim key assigned
• move base64url definition to terminology

-03

• remove unused reference to RFC9111
• add validation rules for status list token
• introduce the status list aggregation mechanism
• relax requirements for status_list claims to contain other parameters
• change cwt referenced token example to hex and annotated hex
• require TLS only for fetching Status List, not for Status List Token
• remove the undefined phrase Status List endpoint
• remove http caching in favor of the new ttl claim
• clarify the sub claim of Status List Token
• relax status_list iss requirements for CWT
• Fixes missing parts & iana ttl registration in CWT examples

-02

• add ttl claim to Status List Token to convey caching
• relax requirements on referenced token
• clarify Deflate / zlib compression
• make a reference to the Issuer-Holder-Verifier model of SD-JWT VC
• add COSE/CWT/CBOR encoding

-01

• Rename title of the draft
• add design consideration to the introduction
• Change status claim to in referenced token to allow re-use for other mechanisms
• Add IANA Registry for status mechanisms
• restructure the sections of this document
• add option to return an unsigned Status List
• Changing compression from gzip to zlib
• Change typo in Status List Token sub claim description
• Add access token as an example use-case

-00

• Initial draft after working group adoption
• update acknowledgments
• renamed Verifier to Relying Party
• added IANA consideration

[ draft-ietf-oauth-status-list ] -01

• Applied editorial improvements suggested by Michael Jones.

-00

• Initial draft