Token Status List
Internet-Draft draft-ietf-oauth-status-list-03
Tobias Looker
MATTR
tobias.looker@mattr.global
Paul Bastian
paul.bastian@posteo.de
Christian Bormann
Robert Bosch GmbH
christiancarl.bormann@bosch.com
08 July 2024
This specification defines status list 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 JSON Web Tokens (JWTs), CBOR Web Tokens (CWTs) and ISO mdoc. The status list token data structures themselves are also represented as JWTs or CWTs.
About This Document
The latest revision of this draft can be found at https://oauth-wg.github.io/draft-ietf-oauth-status-list/draft-ietf-oauth-status-list.html. Status information for this document may be found at https://datatracker.ietf.org/doc/draft-ietf-oauth-status-list/.
Source for this draft and an issue tracker can be found at https://github.com/oauth-wg/draft-ietf-oauth-status-list.
Introduction
Token formats secured by JOSE [IANA.JOSE] or COSE [RFC9052], such as JSON Web Tokens (JWTs) [RFC7519], CBOR Web Tokens (CWTs) [RFC8392] and ISO mdoc [ISO.mdoc], have vast possible applications. Some of these applications can involve issuing a token whereby certain semantics about the token can change over time, which are important to be able to communicate to relying parties in an interoperable manner, such as whether the token is considered invalidated or suspended by its issuer.
This document defines a Status List and its representations in JSON and CBOR formats that describe the individual statuses of multiple Referenced Tokens, which themselves are JWTs or CWTs. 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 correspond to the Referenced Token's status. A Status List may either be provided via HTTPS or be signed and embedded into a Status List Token, whereas this document defines its representations in JWT and CWT. Status Lists may be composed for expressing a range 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. The document also defines how an issuer of a Referenced Token references a Status List (Token).
An example for the usage of a Status List is to manage the status of issued access tokens as defined in section 1.4 of [RFC6749]. Token Introspection [RFC7662] defines another way to determine the status of an issued access token, but it requires the party trying to validate an access tokens status to directly contact the token issuer, whereas the mechanism defined in this specification does not have this limitation.
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 [SD-JWT.VC]. The following diagram depicts the basic conceptual relationship.

+-------------------+                  +------------------------+
|                   | describes status |                        |
|    Status List    +----------------->|    Referenced Token    |
|   (JSON or CBOR)  <------------------+      (JOSE, COSE)      |
|                   |   references     |                        |
+-------+-----------+                  +--------+---------------+
        |
        |embedded in
        v
+-------------------+
|                   |
| Status List Token |
|  (JWT or CWT)     |
|                   |
+-------------------+

Rationale
Revocation mechanisms are an essential part for 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.
This specification seeks to find a balance between scalability, security, and privacy by minimizing the status information to mere bits (often a single bit) 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 large amounts of Referenced Tokens into the same list also enables herd privacy relative to the Issuer.
This specification establishes the IANA "Status Mechanism Methods" registry for status mechanism and registers the members defined by this specification. Other specifications can register other members used for status retrieval.
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 design an extension point to convey information about the status of a token that can be re-used by other mechanisms
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 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.
Terminology
Issuer:
An entity that issues the Referenced Token and provides the status information of the Referenced Token by serving a Status List Token on a public endpoint.
Relying Party:
An entity that relies on the Status List to validate the status of the Referenced Token. Also known as Verifier.
Status List:
An object in JSON or CBOR representation containing a bit array that lists the statuses of many Referenced Tokens.
Status List Token:
A token in JWT or CWT representation that contains a cryptographically secured Status List.
Referenced Token:
A cryptographically secured data structure which contains a reference to a Status List or Status List Token. It is RECOMMENDED to use JSON [RFC8259] or CBOR [RFC8949] for representation of the token and secure it using JSON Object Signing as defined in [RFC7515] or CBOR Object Signing and Encryption as defined in [RFC9052]. The information from the contained Status List may give a Relying Party additional information about up-to-date status of the Referenced Token.
Status List
A Status List is a byte array that contains the statuses of many Referenced Tokens represented by one or multiple bits. A common representation of a Status List is composed by the following algorithm:
1. Each status of a Referenced Token MUST be represented with a bit-size of 1,2,4, or 8. 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 overall Status List is encoded as a byte array. Depending on the bit-size, each byte corresponds to 8/(#bit-size) statuses (8,4,2, or 1). The status of each Referenced Token is identified using the index that maps to one or more specific bits within the byte array. The index starts counting at 0 and ends with "size" - 1 (being the last valid entry). The bits within an array are counted from least significant bit "0" to the most significant bit ("7"). All bits of the byte array at a particular index are set to a status value.
3. The byte array is compressed using DEFLATE [RFC1951] with the ZLIB [RFC1950] data format. Implementations are RECOMMENDED to use the highest compression level available.
The following example illustrates a Status List that represents the statuses of 16 Referenced Tokens, requiring 16 bits (2 bytes) for the uncompressed byte array:

status[0] = 1
status[1] = 0
status[2] = 0
status[3] = 1
status[4] = 1
status[5] = 1
status[6] = 0
status[7] = 1
status[8] = 1
status[9] = 1
status[10] = 0
status[11] = 0
status[12] = 0
status[13] = 1
status[14] = 0
status[15] = 1

These bits are concatenated:

byte             0                  1               2
bit       7 6 5 4 3 2 1 0    7 6 5 4 3 2 1 0    7
         +-+-+-+-+-+-+-+-+  +-+-+-+-+-+-+-+-+  +-+...
values   |1|0|1|1|1|0|0|1|  |1|0|1|0|0|0|1|1|  |0|...
         +-+-+-+-+-+-+-+-+  +-+-+-+-+-+-+-+-+  +-+...
index     7 6 5 4 3 2 1 0   15   ...  10 9 8   23
         \_______________/  \_______________/
                0xB9               0xA3

Status List in JSON Format
This section defines the structure for a JSON-encoded Status List:
- status_list: REQUIRED. JSON Object that contains a Status List. It MUST contain at least the following claims:
  - bits: REQUIRED. JSON Integer specifying the number of bits per Referenced Token in the Status List (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 (as defined in Section 2 of [RFC7515]) Status List as specified in Section 4.
  - aggregation_uri: OPTIONAL. JSON String that contains a URI to retrieve the Status List Aggregation for this type of Referenced Token. See section 9 for further detail.
The following example illustrates the JSON representation of the Status List:

byte_array = [0xb9, 0xa3]
encoded:
{
  "bits": 1,
  "lst": "eNrbuRgAAhcBXQ"
}

Status List in CBOR Format
This section defines the structure for a CBOR-encoded Status List:
- The StatusList structure is a map (Major Type 5) and defines the following entries:
  - bits: REQUIRED. Unsigned int (Major Type 0) that contains the number of bits per Referenced Token in the Status List. The allowed values for bits are 1, 2, 4 and 8.
  - lst: REQUIRED. Byte string (Major Type 2) that contains the Status List as specified in Section 4.1.
  - aggregation_uri: OPTIONAL. Text string (Major Type 3) that contains a URI to retrieve the Status List Aggregation for this type of Referenced Token. See section 9 for further detail.
The following example illustrates the CBOR representation of the Status List in Hex:

byte_array = [0xb9, 0xa3]
encoded:
a2646269747301636c73744a78dadbb918000217015d

The following is the CBOR Annotated Hex output of the example above:

a2                              # map(2)
  64                            #   string(4)
    62697473                    #     "bits"
  01                            #   uint(1)
  63                            #   string(3)
    6c7374                      #     "lst"
  4a                            #   bytes(10)
    78dadbb918000217015d        #     "xÚÛ¹\x18\x00\x02\x17\x01]"

Status List Token
A Status List Token embeds the 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 [RFC7519].
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:
- iss: REQUIRED when also present in the Referenced Token. The iss (issuer) claim MUST specify a unique string identifier for the entity that issued the Status List Token. In the absence of an application profile specifying otherwise, compliant applications MUST compare issuer values using the Simple String Comparison method defined in Section 6.2.1 of [RFC3986]. The value MUST be equal to that of the iss claim contained within the Referenced Token.
- sub: REQUIRED. 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. The iat (issued at) claim MUST specify the time at which the Status List Token was issued.
- exp: OPTIONAL. The exp (expiration time) claim, if present, MUST specify the time at which the Status List Token is considered expired by its issuer.
- ttl: OPTIONAL. 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.
- status_list: REQUIRED. The status_list (status list) claim MUST specify the Status List conforming to the rules outlined in Section 4.1.
The following additional rules apply:
1. The JWT MAY contain other claims.
2. The JWT MUST be digitally signed using an asymmetric cryptographic algorithm. Relying parties MUST reject the JWT if it is using a Message Authentication Code (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)" [RFC7519].
4. Application of additional restrictions and policy are at the discretion of the verifying party.
The following is a non-normative example for a Status List Token in JWT format:

{
  "alg": "ES256",
  "kid": "12",
  "typ": "statuslist+jwt"
}
.
{
  "exp": 2291720170,
  "iat": 1686920170,
  "iss": "https://example.com",
  "status_list": {
    "bits": 1,
    "lst": "eNrbuRgAAhcBXQ"
  },
  "sub": "https://example.com/statuslists/1",
  "ttl": 43200
}

Status List Token in CWT Format
The Status List Token MUST be encoded as a "CBOR Web Token (CWT)" according to [RFC8392].
The following content applies to the CWT protected header:
- 16 (type): REQUIRED. The type of the CWT MUST be statuslist+cwt as defined in [RFC9596].
The following content applies to the CWT Claims Set:
- 1 (issuer): REQUIRED. Same definition as iss claim in Section 5.1.
- 2 (subject): REQUIRED. Same definition as sub claim in Section 5.1.
- 6 (issued at): REQUIRED. Same definition as iat claim in Section 5.1.
- 4 (expiration time): OPTIONAL. Same definition as exp claim in Section 5.1.
- 65534 (time to live): OPTIONAL. Same definition as ttl claim in Section 5.1.
- 65535 (status list): REQUIRED. The status list claim MUST specify the Status List conforming to the rules outlined in Section 4.2.
The following additional rules apply:
1. The CWT MAY contain other claims.
2. The CWT MUST be digitally signed using an asymmetric cryptographic algorithm. Relying parties MUST reject the CWT if it is using a Message Authentication Code (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)" [RFC8392].
4. Application of additional restrictions and policy are at the discretion of the verifying party.
The following is a non-normative example for a Status List Token in CWT format in Hex:

d28453a20126106e7374617475736c6973742b637774a1044231325866a602782168
747470733a2f2f6578616d706c652e636f6d2f7374617475736c697374732f310173
68747470733a2f2f6578616d706c652e636f6d061a648c5bea041a8898dfea19fffe
19a8c019ffff56a2646269747301636c73744a78dadbb918000217015d5840631658
af937b8e8ce7e0081027ed8200ebde64e60cab690da369f0d6a85dd899ec1561bfcd
e0a0e38a7c775e46e8e76af7bf7da6448aa8b6c25dd04ddc1128d4

The following is the CBOR Annotated Hex output of the example above:

d2                              # tag(18)
  84                            #   array(4)
    53                          #     bytes(19)
      a20126106e7374617475736c  #       "¢\x01&\x10nstatusl"
      6973742b637774            #       "ist+cwt"
    a1                          #     map(1)
      04                        #       uint(4)
      42                        #       bytes(2)
        3132                    #         "12"
    58 66                       #     bytes(102)
      a602782168747470733a2f2f  #       "¦\x02x!https://"
      6578616d706c652e636f6d2f  #       "example.com/"
      7374617475736c697374732f  #       "statuslists/"
      31017368747470733a2f2f65  #       "1\x01shttps://e"
      78616d706c652e636f6d061a  #       "xample.com\x06\x1a"
      648c5bea041a8898dfea19ff  #       "d\x8c[ê\x04\x1a\x88\x98ßê\x19ÿ"
      fe19a8c019ffff56a2646269  #       "þ\x19¨À\x19ÿÿV¢dbi"
      747301636c73744a78dadbb9  #       "ts\x01clstJxÚÛ¹"
      18000217015d              #       "\x18\x00\x02\x17\x01]"
    58 40                       #     bytes(64)
      631658af937b8e8ce7e00810  #       "c\x16X¯\x93{\x8e\x8cçà\x08\x10"
      27ed8200ebde64e60cab690d  #       "'í\x82\x00ëÞdæ\x0c«i\x0d"
      a369f0d6a85dd899ec1561bf  #       "£iðÖ¨]Ø\x99ì\x15a¿"
      cde0a0e38a7c775e46e8e76a  #       "Íà\xa0ã\x8a|w^Fèçj"
      f7bf7da6448aa8b6c25dd04d  #       "÷¿}¦D\x8a¨¶Â]ÐM"
      dc1128d4                  #       "Ü\x11(Ô"

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. The claim contains members used to reference to a status list as defined in this specification. Other members of the "status" object may be defined by other specifications. This is analogous to "cnf" claim in Section 3.1 of [RFC7800] in which different authenticity confirmation methods can be included.
Referenced Token in JWT Format
The Referenced Token MUST be encoded as a "JSON Web Token (JWT)" according to [RFC7519].
The following content applies to the JWT Claims Set:
- iss: REQUIRED when also present in the Status List Token. The iss (issuer) claim MUST specify a unique string identifier for the entity that issued the Referenced Token. In the absence of an application profile specifying otherwise, compliant applications MUST compare issuer values using the Simple String Comparison method defined in Section 6.2.1 of [RFC3986]. The value MUST be equal to that of the iss claim contained within the referenced Status List Token.
- 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 list mechanism defined in this specification is used. It contains a reference to a Status List or Status List Token. It MUST at least contain the following claims:
    - idx: REQUIRED. The idx (index) claim MUST specify an Integer that represents the index to check for status information in the Status List for the current Referenced Token. The value of idx MUST be a non-negative number, containing a value of zero or greater.
    - uri: REQUIRED. The uri (URI) claim MUST specify a String value that identifies the Status List or Status List Token containing the status information for the Referenced Token. The value of uri MUST be a URI conforming to [RFC3986].
Application of additional restrictions and policy are at the discretion of the verifying party.
The following is a non-normative example for a decoded header and payload of a Referenced Token:

{
  "alg": "ES256",
  "kid": "11"
}
.
{
  "iss": "https://example.com",
  "status": {
    "status_list": {
      "idx": 0,
      "uri": "https://example.com/statuslists/1"
    }
  }
}

Referenced Token in CWT Format
The Referenced Token MUST be encoded as a "COSE Web Token (CWT)" object according to [RFC8392].
The following content applies to the CWT Claims Set:
- 1 (issuer): REQUIRED when also present in the Referenced Token. Same definition as iss claim in Section 6.2.
- 65535 (status): REQUIRED. The status claim is encoded as a Status CBOR structure and 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. This specification defines the following data items:
  - status_list (status list): REQUIRED when the status list mechanism defined in this specification is used. It has the same definition as the status_list claim in Section 6.2 but MUST be encoded as a StatusListInfo CBOR structure with the following fields:
    - idx: REQUIRED. Same definition as idx claim in Section 6.2.
    - uri: REQUIRED. Same definition as uri claim in Section 6.2.
Application of additional restrictions and policy are at the discretion of the verifying party.
The following is a non-normative example of a Referenced Token in CWT format in Hex:

d28443a10126a1044231325866a502653132333435017368747470733a2f2f657861
6d706c652e636f6d061a648c5bea041a8898dfea19ffffa16b7374617475735f6c69
7374a2636964780063757269782168747470733a2f2f6578616d706c652e636f6d2f
7374617475736c697374732f315840af320cd20f3cb5e2e8823d3982d77e56b6f3f3
57c5ba7e128d22eea523f2bd03c1a9fde1005db07883fdb7aaf25c95e67e4a229f97
efd50fb6544dcb218a66d0

The following is the CBOR Annotated Hex output of the example above:

d2                              # tag(18)
  84                            #   array(4)
    43                          #     bytes(3)
      a10126                    #       "¡\x01&"
    a1                          #     map(1)
      04                        #       uint(4)
      42                        #       bytes(2)
        3132                    #         "12"
    58 66                       #     bytes(102)
      a50265313233343501736874  #       "¥\x02e12345\x01sht"
      7470733a2f2f6578616d706c  #       "tps://exampl"
      652e636f6d061a648c5bea04  #       "e.com\x06\x1ad\x8c[ê\x04"
      1a8898dfea19ffffa16b7374  #       "\x1a\x88\x98ßê\x19ÿÿ¡kst"
      617475735f6c697374a26369  #       "atus_list¢ci"
      647800637572697821687474  #       "dx\x00curix!htt"
      70733a2f2f6578616d706c65  #       "ps://example"
      2e636f6d2f7374617475736c  #       ".com/statusl"
      697374732f31              #       "ists/1"
    58 40                       #     bytes(64)
      af320cd20f3cb5e2e8823d39  #       "¯2\x0cÒ\x0f<µâè\x82=9"
      82d77e56b6f3f357c5ba7e12  #       "\x82×~V¶óóWÅº~\x12"
      8d22eea523f2bd03c1a9fde1  #       "\x8d"î¥#ò½\x03Á©ýá"
      005db07883fdb7aaf25c95e6  #       "\x00]°x\x83ý·ªò\\x95æ"
      7e4a229f97efd50fb6544dcb  #       "~J"\x9f\x97ïÕ\x0f¶TMË"
      218a66d0                  #       "!\x8afÐ"

Referenced Token in other COSE/CBOR Format
The Referenced Token MUST be encoded as a COSE_Sign1 or COSE_Sign CBOR structure as defined in "CBOR Object Signing and Encryption (COSE)" [RFC9052].
It is required to encode the status mechanisms referred to in the Referenced Token using the Status CBOR structure defined in Section 6.3.
It is RECOMMENDED to use status for the label of the field that contains the Status CBOR structure.
Application of additional restrictions and policy are at the discretion of the verifying party.
The following is a non-normative example for a decoded payload of a Referenced Token:
TBD: example
Status Types
This document defines potential statuses of Referenced Tokens as Status Type values. 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. A Status List can not represent multiple statuses per Referenced Token.
The registry in this document describes the basic Status Type values required for the most common use cases. Additional values may defined for particular use cases.
Status Types Values
A status describes the state, mode, condition or stage of an entity that is described by the Status List. Status Types MUST be numeric values between 0 and 255. Status types described by this specification comprise:
- 0x00 - "VALID" - The status of the Token is valid, correct or legal.
- 0x01 - "INVALID" - The status of the Token is revoked, annulled, taken back, recalled or cancelled. This state is irreversible.
- 0x02 - "SUSPENDED" - The status of the Token is temporarily invalid, hanging, debarred from privilege. This state is reversible.
The issuer of the Status List MUST choose an adequate bits (bit size) to be able to describe the required Status Types for the application.
The processing rules for JWT or CWT 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.
Verification and Processing
Status List Request
To obtain the Status List or Status List Token, the Relying Party MUST send an HTTP GET request to the URI provided in the Referenced Token.
If the Status List is provided by an HTTP endpoint (and not as a Status List Token), the provider of the Status List MUST utilize TLS. Which version(s) should be implemented will vary over time. A TLS server certificate check MUST be performed as defined in Section 5 and 6 of [RFC6125].
The Relying Party SHOULD send the following Accept-Header to indicate the requested response type:
- "application/statuslist+json" for Status List in JSON format
- "application/statuslist+jwt" for Status List in JWT format
- "application/statuslist+cbor" for Status List in CBOR format
- "application/statuslist+cwt" for Status List in CWT format
If the Relying Party does not send an Accept Header, the response type is assumed to be known implicit or out-of-band.
Status List Response
In the successful response, the Status List Provider MUST use the following content-type:
- "application/statuslist+json" for Status List in JSON format
- "application/statuslist+jwt" for Status List in JWT format
- "application/statuslist+cbor" for Status List in CBOR format
- "application/statuslist+cwt" for Status List in CWT format
In the case of "application/statuslist+json", the response MUST be of type JSON and follow the rules of Section 4.1. In the case of "application/statuslist+jwt", the response MUST be of type JWT and follow the rules of Section 5.1. In the case of "application/statuslist+cbor", the response MUST be of type CBOR and follow the rules of Section 4.2. In the case of "application/statuslist+cwt", the response MUST be of type CWT and follow the rules of Section 5.2.
The HTTP response SHOULD use gzip Content-Encoding as defined in [RFC9110].
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, expiration time. As this is out of scope of this document, this validation is not be described here, but is expected to be done according to the format of the Referenced Token.
If this validation was 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 Section 6.2 for JWTs and Section 6.3 for CWTs. This step can be overruled if defined within the Referenced Token Format natively
2. Resolve the Status List 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 [RFC7519] for JWTs and section 7.2 of [RFC8392] for CWTs.
  2. Check for the existence of the required claims as defined in Section 5.1 and Section 5.2
4. All existing claims in the Status List Token MUST be checked according to the rules in Section 5.1 and Section 5.2
  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 custom policies regarding the freshness of the Status List Token, it SHOULD check the issued at claim (iat or 6)
  3. If expiration time is defined (exp or 4), it MUST be checked if the Status List Token is expired
  4. If the Referenced Token contains an issuer claim, the Status List Token MUST contain the same issuer claim (iss or 1)
  5. 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 [RFC1951] and ZLIB [RFC1950]
6. Retrieve the status value of the index specified in the Referenced Token as described in Section 4. Fail if the provided index is out of bound of the status list
7. Check the status value as described in Section 7
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.
Status List Aggregation
Status List Aggregation is an optional mechanism to retrieve a list of URIs to all Status List Tokens, allowing a Relying Party to fetch all relevant Status Lists for a specific type of Referenced Token or 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.
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 issuer of the Referenced Token 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, or via a VICAL extension for ISO mDoc / mDL.
The concrete specification on how this is implemented depends on the specific ecosystem and is 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 inSection 4.2 and Section 4.1 respectively. A Relying Party may use this URI to retrieve an up-to-date list of relevant Status Lists.
Status List Aggregation in JSON Format
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 URIs. This aggregation in JSON and the media type return SHOULD 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:

{
   "status_lists" : [
      "https://example.com/statuslists/1",
      "https://example.com/statuslists/2",
      "https://example.com/statuslists/3"
   ]
}

Further Examples
Status List Token with 2-Bit Status Values in JWT format
In this 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 Status List represents the status of 12 Referenced Tokens, requiring 24 bits (3 bytes) of status.

status[0] = 1
status[1] = 2
status[2] = 0
status[3] = 3
status[4] = 0
status[5] = 1
status[6] = 0
status[7] = 1
status[8] = 1
status[9] = 2
status[10] = 3
status[11] = 3

These bits are concatenated:

byte             0                  1                  2
bit       7 6 5 4 3 2 1 0    7 6 5 4 3 2 1 0    7 6 5 4 3 2 1 0
         +-+-+-+-+-+-+-+-+  +-+-+-+-+-+-+-+-+  +-+-+-+-+-+-+-+-+
values   |1|1|0|0|1|0|0|1|  |0|1|0|0|0|1|0|0|  |1|1|1|1|1|0|0|1|
         +-+-+-+-+-+-+-+-+  +-+-+-+-+-+-+-+-+  +-+-+-+-+-+-+-+-+
          \ / \ / \ / \ /    \ / \ / \ / \ /    \ / \ / \ / \ /
status     3   0   2   1      1   0   1   0      3   3   2   1
index      3   2   1   0      7   6   5   4      11  10  9   8
           \___________/      \___________/      \___________/
                0xC9               0x44               0xF9

Resulting in the byte array and compressed/base64url encoded status list:

byte_array = [0xc9, 0x44, 0xf9]
encoded:
{
  "bits": 2,
  "lst": "eNo76fITAAPfAgc"
}

Security Considerations
Correct decoding and parsing of the encoded status list
TODO elaborate on risks of incorrect parsing/decoding leading to erroneous status data
Cached and Stale status lists
When consumers or verifiers of the Status List fetch the data, they need to be aware of its up-to-date status. The 'ttl' (time-to-live) claim in the Status List Token provides one mechanism for setting a maximum cache time for the fetched data. This property permits distribution of a status list to a CDN or other distribution mechanism while giving guidance to consumers of the status list on how often they need to fetch a fresh copy of the status list even if that status list is not expired.
Authorized access to the Status List
TODO elaborate on authorization mechanisms preventing misuse and profiling as described in privacy section
History
TODO elaborate on status list only providing the up-to date/latest status, no historical data, may be provided by the underlying hosting architecture
Privacy Considerations
Limiting issuers observability of token verification
The main privacy consideration for a Status List, especially in the context of the Issuer-Holder-Verifier model [SD-JWT.VC], 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 him 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.
Malicious Issuers
A malicious Issuer could bypass the privacy benefits of the herd privacy by generating a unique Status List for every Referenced Token. By these means, he 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. This malicious behaviour could be detected by Relying Parties that request large amounts of Referenced Tokens by comparing the number of different Status Lists and their sizes.
Unobservability of Relying Parties
Once the Relying Party receives the Referenced Token, this enables him to request the Status List to validate its status through the provided uri parameter and look 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 a KYC process 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 a driving license or checking the employment status of an employee credential.
This behaviour could be mitigated by: - adding authorization rules to the Status List, see Section 11.3. - regular re-issuance of the Referenced Token, see Section 13.1.
Unlinkability
Colluding Issuers and a Relying Parties have the possibility to link two transactions, as the tuple of uri and index inside the Referenced Token are unique and therefore traceable data. By comparing the status claims of received Referenced Tokens, two colluding Relying Parties could determine that they have interacted with the same user or an Issuer could trace the usage of its issued Referenced Token by colluding with various Relying Parties. It is therefore recommended to use Status Lists for Referenced Token formats that have similar unlinkability properties.
To avoid privacy risks for colluding Relying Parties, it is RECOMMENDED that Issuers use batch issuance to issue multiple tokens, see Section 13.1.
To avoid further correlatable information by the values of uri and index, Issuers are RECOMMENDED to:
- choose non-sequential, pseudo-random or random indices
- use decoy or dead entries to obfuscate the real number of Referenced Tokens within a Status List
- choose to deploy and utilize multiple Status Lists simultaneously
Third Party Hosting
TODO elaborate on increased privacy if the status list is hosted by a third party instead of the issuer reducing tracking possibilities TODO evaluate definition of Status List Provider? An entity that hosts the Status List as a resource for potential Relying Parties. The Status List Provider may be the issuer of the Status List but may also be outsourced to a trusted third party.
Implementation Considerations
Token Lifecycle
The lifetime of a Status List (and the 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 (and the Status List Token).
Referenced Tokens may be regularly re-issued to increase security or to mitigate linkability and prevent tracking by Relying Parties. In this case, every Referenced Token MUST have a fresh Status List entry.
Referenced Tokens may also be issued in batches, such that Holders can use individual tokens for every transaction. In this case, every Referenced Token MUST have a dedicated Status List entry. Revoking batch issued Referenced Tokens might reveal this correlation later on.
IANA Considerations
JSON Web Token Claims Registration
This specification requests registration of the following Claims in the IANA "JSON Web Token Claims" registry [IANA.JWT] established by [RFC7519].
Registry Contents
- Claim Name: status
- Claim Description: Reference to a status or validity mechanism containing up-to-date status information on the JWT.
- Change Controller: IETF
- Specification Document(s): Section 6.1 of this specification
- Claim Name: status_list
- Claim Description: A status list containing up-to-date status information on multiple other JWTs encoded as a bitarray.
- Change Controller: IETF
- Specification Document(s): Section 5.1 of this specification
- Claim Name: ttl
- Claim Description: Time to Live
- Change Controller: IETF
- Specification Document(s): Section 5.1 of this specification
JWT Status Mechanism Methods Registry
This specification establishes the IANA "Status Mechanism Methods" registry for JWT "status" member values. The registry records the status mechanism method member and a reference to the specification that defines it.
Registration Template
Status Method 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 Method Description:
- Brief description of the status mechanism method.
Change Controller:
- For Standards Track RFCs, list the "IESG". 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 Method Value: status_list
- Status Method Description: A status list containing up-to-date status information on multiple other JWTs encoded as a bitarray.
- Change Controller: IETF
- Specification Document(s): Section 6.2 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 [IANA.CWT] established by [RFC8392].
Registry Contents
- Claim Name: status
- Claim Key: TBD (requested assignment 65535)
- Claim Description: Reference to a status or validity mechanism containing up-to-date status information on the CWT.
- Change Controller: IETF
- Specification Document(s): Section 6.1 of this specification
- Claim Name: status_list
- Claim Description: A status list containing up-to-date status information on multiple other CWTs encoded as a bitarray.
- Change Controller: IETF
- Specification Document(s): Section 5.2 of this specification
- Claim Name: ttl
- Claim Key: TBD (requested assignment 65534)
- Claim Description: Time to Live
- Change Controller: IETF
- Specification Document(s): Section 5.2 of this specification
CWT Status Mechanism Methods Registry
This specification establishes the IANA "Status Mechanism Methods" registry for CWT "status" member values. The registry records the status mechanism method member and a reference to the specification that defines it.
Registration Template
Status Method 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 Method Description:
- Brief description of the status mechanism method.
Change Controller:
- For Standards Track RFCs, list the "IESG". 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 Method Value: status_list
- Status Method Description: A status list containing up-to-date status information on multiple other CWTs encoded as a bitarray.
- Change Controller: IETF
- Specification Document(s): Section 6.3 of this specification
Media Type Registration
This section requests registration of the following media types [RFC2046] in the "Media Types" registry [IANA.MediaTypes] in the manner described in [RFC6838].
To indicate that the content is an JSON-based Status List:
- Type name: application
- Subtype name: statuslist+json
- Required parameters: n/a
- Optional parameters: n/a
- Encoding considerations: binary; A JSON-based Status List is a JSON Object.
- Security considerations: See (#Security) 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:
  - File extension(s): n/a
  - Macintosh file type code(s): 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 JWT-based Status List:
- Type name: application
- Subtype name: statuslist+jwt
- Required parameters: n/a
- Optional parameters: n/a
- Encoding considerations: binary; A JWT-based Status List is a JWT; JWT values are encoded as a series of base64url-encoded values (some of which may be the empty string) separated by period ('.') characters.
- Security considerations: See (#Security) 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:
  - File extension(s): n/a
  - Macintosh file type code(s): 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 CBOR-based Status List:
- Type name: application
- Subtype name: statuslist+cbor
- Required parameters: n/a
- Optional parameters: n/a
- Encoding considerations: binary; A CBOR-based Status List is a CBOR Object.
- Security considerations: See (#Security) 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:
  - File extension(s): n/a
  - Macintosh file type code(s): 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: binary;
- Security considerations: See (#Security) 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:
  - File extension(s): n/a
  - Macintosh file type code(s): 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
References
Normative References
[RFC1950]

ZLIB Compressed Data Format Specification version 3.3
P. Deutsch
J-L. Gailly
May 1996
RFC 1950
DOI 10.17487/RFC1950
[RFC1951]

DEFLATE Compressed Data Format Specification version 1.3
P. Deutsch
May 1996
RFC 1951
DOI 10.17487/RFC1951
[RFC2046]

Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types
N. Freed
N. Borenstein
November 1996
RFC 2046
DOI 10.17487/RFC2046
[RFC3986]

Uniform Resource Identifier (URI): Generic Syntax
T. Berners-Lee
R. Fielding
L. Masinter
January 2005
STD 66
RFC 3986
DOI 10.17487/RFC3986
[RFC6125]

Representation and Verification of Domain-Based Application Service Identity within Internet Public Key Infrastructure Using X.509 (PKIX) Certificates in the Context of Transport Layer Security (TLS)
P. Saint-Andre
J. Hodges
March 2011
RFC 6125
DOI 10.17487/RFC6125
[RFC6838]

Media Type Specifications and Registration Procedures
N. Freed
J. Klensin
T. Hansen
January 2013
BCP 13
RFC 6838
DOI 10.17487/RFC6838
[RFC7515]

JSON Web Signature (JWS)
M. Jones
J. Bradley
N. Sakimura
May 2015
RFC 7515
DOI 10.17487/RFC7515
[RFC7519]

JSON Web Token (JWT)
M. Jones
J. Bradley
N. Sakimura
May 2015
RFC 7519
DOI 10.17487/RFC7519
[RFC8259]

The JavaScript Object Notation (JSON) Data Interchange Format
T. Bray, Ed.
December 2017
STD 90
RFC 8259
DOI 10.17487/RFC8259
[RFC8392]

CBOR Web Token (CWT)
M. Jones
E. Wahlstroem
S. Erdtman
H. Tschofenig
May 2018
RFC 8392
DOI 10.17487/RFC8392
[RFC8949]

Concise Binary Object Representation (CBOR)
C. Bormann
P. Hoffman
December 2020
STD 94
RFC 8949
DOI 10.17487/RFC8949
[RFC9052]

CBOR Object Signing and Encryption (COSE): Structures and Process
J. Schaad
August 2022
STD 96
RFC 9052
DOI 10.17487/RFC9052
[RFC9110]

HTTP Semantics
R. Fielding, Ed.
M. Nottingham, Ed.
J. Reschke, Ed.
June 2022
STD 97
RFC 9110
DOI 10.17487/RFC9110
[RFC9596]

CBOR Object Signing and Encryption (COSE) "typ" (type) Header Parameter
M.B. Jones
O. Steele
June 2024
RFC 9596
DOI 10.17487/RFC9596
[IANA.MediaTypes]

Media Types
IANA
n.d.
[IANA.JOSE]

JSON Object Signing and Encryption (JOSE)
IANA
n.d.
[IANA.JWT]

JSON Web Token Claims
IANA
n.d.
[IANA.CWT]

CBOR Web Token (CWT) Claims
IANA
n.d.
[RFC2119]

Key words for use in RFCs to Indicate Requirement Levels
S. Bradner
March 1997
BCP 14
RFC 2119
DOI 10.17487/RFC2119
[RFC8174]

Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words
B. Leiba
May 2017
BCP 14
RFC 8174
DOI 10.17487/RFC8174
Informative References
[RFC6749]

The OAuth 2.0 Authorization Framework
D. Hardt, Ed.
October 2012
RFC 6749
DOI 10.17487/RFC6749
[RFC7662]

OAuth 2.0 Token Introspection
J. Richer, Ed.
October 2015
RFC 7662
DOI 10.17487/RFC7662
[RFC7800]

Proof-of-Possession Key Semantics for JSON Web Tokens (JWTs)
M. Jones
J. Bradley
H. Tschofenig
April 2016
RFC 7800
DOI 10.17487/RFC7800
[SD-JWT.VC]

SD-JWT-based Verifiable Credentials (SD-JWT VC)
Oliver Terbu
MATTR
Daniel Fett
Authlete Inc.
Brian Campbell
Ping Identity
8 July 2024
Internet-Draft draft-ietf-oauth-sd-jwt-vc-04
[ISO.mdoc]

ISO/IEC 18013-5:2021 ISO-compliant driving licence
ISO/IEC JTC 1/SC 17
n.d.
Acknowledgments
We would like to thank Brian Campbell, Filip Skokan, Francesco Marino, Guiseppe De Marco, Kristina Yasuda, Michael B. Jones, Mike Prorock, Oliver Terbu, Orie Steele, Timo Glastra and Torsten Lodderstedt
for their valuable contributions, discussions and feedback to this specification.
Document History
-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