openid-4-verifiable-presentations-1_0.md

%%% title = "OpenID for Verifiable Presentations - Editor's draft" abbrev = "openid-4-vp" ipr = "none" workgroup = "OpenID Connect" keyword = ["security", "openid", "ssi"]

[seriesInfo] name = "Internet-Draft" value = "openid-4-verifiable-presentations-1_0-22" status = "standard"

[[author]] initials="O." surname="Terbu" fullname="Oliver Terbu" organization="Mattr" [author.address] email = "[email protected]"

[[author]] initials="T." surname="Lodderstedt" fullname="Torsten Lodderstedt" organization="SPRIND" [author.address] email = "[email protected]"

[[author]] initials="K." surname="Yasuda" fullname="Kristina Yasuda" organization="SPRIND" [author.address] email = "[email protected]"

[[author]] initials="T." surname="Looker" fullname="Tobias Looker" organization="Mattr" [author.address] email = "[email protected]"

%%%

.# Abstract

This specification defines a protocol for requesting and presenting Verifiable Credentials.

{mainmatter}

Introduction

This specification defines a mechanism on top of OAuth 2.0 [@!RFC6749] that enables presentation of Verifiable Credentials as Verifiable Presentations. Verifiable Credentials and Verifiable Presentations can be of any format, including, but not limited to W3C Verifiable Credentials Data Model [@VC_DATA], ISO mdoc [@ISO.18013-5], IETF SD-JWT VC [@!I-D.ietf-oauth-sd-jwt-vc], and AnonCreds [@Hyperledger.Indy].

OAuth 2.0 [@!RFC6749] is used as a base protocol as it provides the required rails to build a simple, secure, and developer-friendly Credential presentation layer on top of it. Moreover, implementers can, in a single interface, support Credential presentation and the issuance of Access Tokens for access to APIs based on Verifiable Credentials in the Wallet. OpenID Connect [@!OpenID.Core] deployments can also extend their implementations using this specification with the ability to transport Verifiable Presentations.

This specification can also be combined with [@!SIOPv2], if implementers require OpenID Connect features, such as the issuance of Self-Issued ID Tokens [@!SIOPv2].

Requirements Notation and Conventions

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 RFC 2119 [@!RFC2119].

Terminology

This specification uses the terms "Access Token", "Authorization Request", "Authorization Response", "Client", "Client Authentication", "Client Identifier", "Grant Type", "Response Type", "Token Request" and "Token Response" defined by OAuth 2.0 [@!RFC6749], the terms "End-User", "Entity", "Request Object", "Request URI" as defined by OpenID Connect Core [@!OpenID.Core], the term "JSON Web Token (JWT)" defined by JSON Web Token (JWT) [@!RFC7519], the term "JOSE Header" defined by JSON Web Signature (JWS) [@!RFC7515], the term "JSON Web Encryption (JWE)" defined by [@!RFC7516], and the term "Response Mode" defined by OAuth 2.0 Multiple Response Type Encoding Practices [@!OAuth.Responses].

Base64url-encoded denotes the URL-safe base64 encoding without padding defined in Section 2 of [@!RFC7515].

This specification also defines the following terms. In the case where a term has a definition that differs, the definition below is authoritative.

Credential: : A set of one or more claims about a subject made by a Credential Issuer. Note that the definition of the term "Credential" in this specification is different from that in [@!OpenID.Core].

Verifiable Credential (VC): : An Issuer-signed Credential whose authenticity can be cryptographically verified. Can be of any format used in the Issuer-Holder-Verifier Model, including, but not limited to those defined in [@VC_DATA] (VCDM), [@ISO.18013-5] (mdoc), [@!I-D.ietf-oauth-sd-jwt-vc] (SD-JWT VC), and [@Hyperledger.Indy] (AnonCreds).

W3C Verifiable Credential: : A Verifiable Credential compliant to the [@VC_DATA] specification.

Presentation: : Data that is presented to a specific Verifier, derived from one or more Verifiable Credentials that can be from the same or different Credential Issuers.

Verifiable Presentation (VP): : A Holder-signed Credential whose authenticity can be cryptographically verified to provide Cryptographic Holder Binding. Can be of any format used in the Issuer-Holder-Verifier Model, including, but not limited to those defined in [@VC_DATA] (VCDM), [@ISO.18013-5] (mdoc), [@!I-D.ietf-oauth-sd-jwt-vc] (SD-JWT VC), and [@Hyperledger.Indy] (AnonCreds).

W3C Verifiable Presentation: : A Verifiable Presentations compliant to the [@VC_DATA] specification.

Credential Issuer: : An entity that issues Verifiable Credentials. Also called Issuer.

Holder: : An entity that receives Verifiable Credentials and has control over them to present them to the Verifiers as Verifiable Presentations.

Verifier: : An entity that requests, receives, and validates Verifiable Presentations. During presentation of Credentials, Verifier acts as an OAuth 2.0 Client towards the Wallet that is acting as an OAuth 2.0 Authorization Server. The Verifier is a specific case of OAuth 2.0 Client, just like Relying Party (RP) in [@OpenID.Core].

Issuer-Holder-Verifier Model: : A model for exchanging claims, where claims are issued in the form of Verifiable Credentials independent of the process of presenting them as Verifiable Presentation to the Verifiers. An issued Verifiable Credential can (but must not necessarily) be used multiple times.

Holder Binding: : Ability of the Holder to prove legitimate possession of a Verifiable Credential.

Cryptographic Holder Binding: : Ability of the Holder to prove legitimate possession of a Verifiable Credential by proving control over the same private key during the issuance and presentation. Mechanism might depend on the Credential Format. For example, in jwt_vc_json Credential Format, a Verifiable Credential with Cryptographic Holder Binding contains a public key or a reference to a public key that matches to the private key controlled by the Holder.

Claims-based Holder Binding: : Ability of the Holder to prove legitimate possession of a Verifiable Credential by proofing certain claims, e.g., name and date of birth, for example by presenting another Verifiable Credential. Claims-based Holder Binding allows long term, cross device use of a Credential as it does not depend on cryptographic key material stored on a certain device. One example of such a Verifiable Credential could be a Diploma.

Biometrics-based Holder Binding: : Ability of the Holder to prove legitimate possession of a Verifiable Credential by demonstrating a certain biometric trait, such as finger print or face. One example of a Verifiable Credential with biometric Holder Binding is a mobile driving license [@ISO.18013-5], which contains a portrait of the Holder.

VP Token: : An artifact containing one or more Verifiable Presentations returned as a response to an Authorization Request. The structure of VP Tokens is defined in (#response-parameters).

Wallet: : An entity used by the Holder to receive, store, present, and manage Verifiable Credentials and key material. There is no single deployment model of a Wallet: Verifiable Credentials and keys can both be stored/managed locally, or by using a remote self-hosted service, or a remote third-party service. In the context of this specification, the Wallet acts as an OAuth 2.0 Authorization Server (see [@!RFC6749]) towards the Credential Verifier which acts as the OAuth 2.0 Client.

Overview

This specification defines a mechanism on top of OAuth 2.0 to request and present Verifiable Credentials as Verifiable Presentations.

As the primary extension, OpenID for Verifiable Presentations introduces the VP Token as a container to enable End-Users to present Verifiable Presentations to Verifiers using the Wallet. A VP Token contains one or more Verifiable Presentations in the same or different Credential formats.

This specification supports any Credential format used in the Issuer-Holder-Verifier Model, including, but not limited to those defined in [@VC_DATA] (VCDM), [@ISO.18013-5] (mdoc), [@!I-D.ietf-oauth-sd-jwt-vc] (SD-JWT VC), and [@Hyperledger.Indy] (AnonCreds). Credentials of multiple formats can be presented in the same transaction. The examples given in the main part of this specification use W3C Verifiable Credentials, while examples in other Credential formats are given in (#alternative_credential_formats).

Implementations can use any pre-existing OAuth 2.0 Grant Type and Response Type in conjunction with this specification to support different deployment architectures.

OpenID for Verifiable Presentations supports scenarios where the Authorization Request is sent both when the Verifier is interacting with the End-User using the device that is the same or different from the device on which requested Credential(s) are stored.

This specification supports the response being sent using a redirect but also using an HTTP POST request. This enables the response to be sent across devices, or when the response size exceeds the redirect URL character size limitation.

Implementations can also be built on top of OpenID Connect Core, which is also based on OAuth 2.0. To benefit from the Self-Issued ID Token feature, this specification can also be combined with the Self-Issued OP v2 specification [@SIOPv2].

Any of the OAuth 2.0 related specifications, such as [@RFC9126] and [@RFC9101], and Best Current Practice (BCP) documents, such as [@RFC8252] and [@I-D.ietf-oauth-security-topics], can be implemented on top of this specification.

Same Device Flow {#same_device}

Below is a diagram of a flow where the End-User presents a Credential to a Verifier interacting with the End-User on the same device that the device the Wallet resides on.

The flow utilizes simple redirects to pass Authorization Request and Response between the Verifier and the Wallet. The Verifiable Presentations are returned to the Verifier in the fragment part of the redirect URI, when Response Mode is fragment.

Note: The diagram does not illustrate all the optional features of this specification.

!---

+--------------+   +--------------+                                    +--------------+
|   End-User   |   |   Verifier   |                                    |    Wallet    |
+--------------+   +--------------+                                    +--------------+  
        |                 |                                                   |
        |    Interacts    |                                                   |
        |---------------->|                                                   |
        |                 |  (1) Authorization Request                        |
        |                 |  (Presentation Definition)                        |
        |                 |-------------------------------------------------->|
        |                 |                                                   |
        |                 |                                                   |
        |   End-User Authentication / Consent                                 |
        |                 |                                                   |
        |                 |  (2)   Authorization Response                     |
        |                 |  (VP Token with Verifiable Presentation(s))       |
        |                 |<--------------------------------------------------|

!--- Figure: Same Device Flow

(1) The Verifier sends an Authorization Request to the Wallet. It contains a Presentation Definition as defined in [@!DIF.PresentationExchange] that describes the requirements of the Credential(s) that the Verifier is requesting to be presented. Such requirements could include what type of Credential(s), in what format(s), which individual Claims within those Credential(s) (Selective Disclosure), etc. The Wallet processes the Authorization Request and determines what Credentials are available matching the Verifier's request. The Wallet also authenticates the End-User and gathers consent to present the requested Credentials.

(2) The Wallet prepares the Verifiable Presentation(s) of the Verifiable Credential(s) that the End-User has consented to. It then sends to the Verifier an Authorization Response where the Verifiable Presentation(s) are contained in the vp_token parameter.

Cross Device Flow {#cross_device}

Below is a diagram of a flow where the End-User presents a Credential to a Verifier interacting with the End-User on a different device as the device the Wallet resides on.

In this flow, the Verifier prepares an Authorization Request and renders it as a QR Code. The End-User then uses the Wallet to scan the QR Code. The Verifiable Presentations are sent to the Verifier in a direct HTTP POST request to a URL controlled by the Verifier. The flow uses the Response Type vp_token in conjunction with the Response Mode direct_post, both defined in this specification. In order to keep the size of the QR Code small and be able to sign and optionally encrypt the Request Object, the actual Authorization Request contains just a Request URI according to [@!RFC9101], which the wallet uses to retrieve the actual Authorization Request data.

Note: The diagram does not illustrate all the optional features of this specification.

Note: The usage of the Request URI as defined in [@!RFC9101] does not depend on any other choices made in the protocol extensibility points, i.e., it can be used in the Same Device Flow, too.

!---

+--------------+   +--------------+                                    +--------------+
|   End-User   |   |   Verifier   |                                    |    Wallet    |
|              |   |  (device A)  |                                    |  (device B)  |
+--------------+   +--------------+                                    +--------------+
        |                 |                                                   |
        |    Interacts    |                                                   |
        |---------------->|                                                   |
        |                 |  (1) Authorization Request                        |
        |                 |      (Request URI)                                |
        |                 |-------------------------------------------------->|
        |                 |                                                   |
        |                 |  (2) Request the Request Object                   |
        |                 |<--------------------------------------------------|
        |                 |                                                   |
        |                 |  (2.5) Respond with the Request Object            |
        |                 |      (Presentation Definition)                    |
        |                 |-------------------------------------------------->|
        |                 |                                                   |
        |   End-User Authentication / Consent                                 |
        |                 |                                                   |
        |                 |  (3)   Authorization Response as HTTP POST        |
        |                 |  (VP Token with Verifiable Presentation(s))       |
        |                 |<--------------------------------------------------|

!--- Figure: Cross Device Flow

(1) The Verifier sends to the Wallet an Authorization Request that contains a Request URI from where to obtain the Request Object containing Authorization Request parameters.

(2) The Wallet sends an HTTP GET request to the Request URI to retrieve the Request Object.

(2.5) The HTTP GET response returns the Request Object containing Authorization Request parameters. It especially contains a Presentation Definition as defined in [@!DIF.PresentationExchange] that describes the requirements of the Credential(s) that the Verifier is requesting to be presented. Such requirements could include what type of Credential(s), in what format(s), which individual Claims within those Credential(s) (Selective Disclosure), etc. The Wallet processes the Request Object and determines what Credentials are available matching the Verifier's request. The Wallet also authenticates the End-User and gathers her consent to present the requested Credentials.

(3) The Wallet prepares the Verifiable Presentation(s) of the Verifiable Credential(s) that the End-User has consented to. It then sends to the Verifier an Authorization Response where the Verifiable Presentation(s) are contained in the vp_token parameter.

Scope

OpenID for Verifiable Presentations extends existing OAuth 2.0 mechanisms as following:

• A new presentation_definition Authorization Request parameter that uses the [@!DIF.PresentationExchange] syntax is defined to request presentation of Verifiable Credentials in arbitrary formats. See (#vp_token_request) for more details.
• A new query language, the Digital Credentials Query Language (DCQL), is defined to enable requesting Verifiable Credentials in an easier and more flexible way. See (#dcql_query) for more details.
• A new dcql_query Authorization Request parameter is defined to request presentation of Verifiable Credentials in the JSON-encoded DCQL format. See (#vp_token_request) for more details.
• A new vp_token response parameter is defined to return Verifiable Presentations to the Verifier in either Authorization or Token Response depending on the Response Type. See (#response) for more details.
• New Response Types vp_token and vp_token id_token are defined to request Verifiable Credentials to be returned in the Authorization Response (standalone or along with a Self-Issued ID Token [@!SIOPv2]). See (#response) for more details.
• A new OAuth 2.0 Response Mode direct_post is defined to support sending the response across devices, or when the size of the response exceeds the redirect URL character size limitation. See (#response_mode_post) for more details.
• The [@!DIF.PresentationExchange] format parameter is used throughout the protocol in order to enable customization according to the specific needs of a particular Credential format. Examples in (#alternative_credential_formats) are given for Credential formats as specified in [@VC_DATA], [@ISO.18013-5], [@!I-D.ietf-oauth-sd-jwt-vc], and [@Hyperledger.Indy].
• The concept of a Client Identifier Scheme to enable deployments of this specification to use different mechanisms to obtain and validate metadata of the Verifier beyond the scope of [@!RFC6749].

Presentation of Verifiable Credentials using OpenID for Verifiable Presentations can be combined with the End-User authentication using [@SIOPv2], and the issuance of OAuth 2.0 Access Tokens.

Authorization Request {#vp_token_request}

The Authorization Request follows the definition given in [@!RFC6749] taking into account the recommendations given in [@!I-D.ietf-oauth-security-topics].

The Verifier MAY send an Authorization Request as a Request Object either by value or by reference, as defined in the JWT-Secured Authorization Request (JAR) [@RFC9101].

This specification defines a new mechanism for the cases when the Wallet wants to provide to the Verifier details about its technical capabilities to allow the Verifier to generate a request that matches the technical capabilities of that Wallet. To enable this, the Authorization Request can contain a request_uri_method parameter with the value post that signals to the Wallet that it can make an HTTP POST request to the Verifier's request_uri endpoint with information about its capabilities as defined in (#request_uri_method_post). The Wallet MAY continue with JAR when it receives request_uri_method parameter with the value post but does not support this feature.

The Verifier articulates requirements of the Credential(s) that are requested using presentation_definition and presentation_definition_uri parameters that contain a Presentation Definition JSON object as defined in Section 5 of [@!DIF.PresentationExchange]. Wallet implementations MUST process Presentation Definition JSON object and select candidate Verifiable Credential(s) using the evaluation process described in Section 8 of [@!DIF.PresentationExchange] unless implementing only a credential profile that provides rules on how to evaluate and process [@!DIF.PresentationExchange].

The Verifier communicates a Client Identifier Scheme that indicate how the Wallet is supposed to interpret the Client Identifier and associated data in the process of Client identification, authentication, and authorization as a prefix in the client_id parameter. This enables deployments of this specification to use different mechanisms to obtain and validate Client metadata beyond the scope of [@!RFC6749]. A certain Client Identifier Scheme MAY require the Verifier to sign the Authorization Request as means of authentication and/or pass additional parameters and require the Wallet to process them.

Depending on the Client Identifier Scheme, the Verifier can communicate a JSON object with its metadata using the client_metadata parameter which contains name/value pairs.

This specification enables the Verifier to send both Presentation Definition JSON object and Client Metadata JSON object by value or by reference.

Additional request parameters, other than those defined in this section, MAY be defined and used, as described in [@!RFC6749]. The Wallet MUST ignore any unrecognized parameters, other than the transaction_data parameter. One exception to this rule is transaction_data parameter, and the wallets that do not support this parameter MUST reject requests that contain it.

New Parameters {#new_parameters}

This specification defines the following new request parameters:

presentation_definition: : A string containing a Presentation Definition JSON object. See (#request_presentation_definition) for more details.

presentation_definition_uri: : A string containing an HTTPS URL pointing to a resource where a Presentation Definition JSON object can be retrieved. See (#request_presentation_definition_uri) for more details.

dcql_query: : A string containing a JSON-encoded DCQL query as defined in (#dcql_query).

Exactly one of the following parameters MUST be present in the Authorization Request: dcql_query, presentation_definition, presentation_definition_uri, or a scope value representing a Presentation Definition.

client_metadata: : OPTIONAL. A JSON object containing the Verifier metadata values. It MUST be UTF-8 encoded. The following metadata parameters MAY be used:

* `jwks`: OPTIONAL. A JWKS as defined in [@!RFC7591]. It MAY contain one or more public keys, such as those used by the Wallet as an input to a key agreement that may be used for encryption of the Authorization Response (see (#jarm)), or where the Wallet will require the public key of the Verifier to generate the Verifiable Presentation. This allows the Verifier to pass ephemeral keys specific to this Authorization Request. Public keys included in this parameter MUST NOT be used to verify the signature of signed Authorization Requests.
* `vp_formats`: REQUIRED when not available to the Wallet via another mechanism. As defined in (#client_metadata_parameters).
* `authorization_signed_response_alg`: OPTIONAL. As defined in [@!JARM].
* `authorization_encrypted_response_alg`: OPTIONAL. As defined in [@!JARM].
* `authorization_encrypted_response_enc`: OPTIONAL. As defined in [@!JARM].

Authoritative data the Wallet is able to obtain about the Client from other sources, for example those from an OpenID Federation Entity Statement, take precedence over the values passed in `client_metadata`.

Other metadata parameters MUST be ignored unless a profile of this specification explicitly defines them as usable in the `client_metadata` parameter.

request_uri_method: : OPTIONAL. A string determining the HTTP method to be used when the request_uri parameter is included in the same request. Two case-sensitive valid values are defined in this specification: get and post. If request_uri_method value is get, the Wallet MUST send the request to retrieve the Request Object using the HTTP GET method, i.e., as defined in [@RFC9101]. If request_uri_method value is post, a supporting Wallet MUST send the request using the HTTP POST method as detailed in (#request_uri_method_post). If the request_uri_method parameter is not present, the Wallet MUST process the request_uri parameter as defined in [@RFC9101]. Wallets not supporting the post method will send a GET request to the Request URI (default behavior as defined in [@RFC9101]). request_uri_method parameter MUST NOT be present if a request_uri parameter is not present.

If the Verifier set the request_uri_method parameter value to post and there is no other means to convey its capabilities to the Wallet, it SHOULD add the client_metadata parameter to the Authorization Request. This enables the Wallet to assess the Verifier's capabilities, allowing it to transmit only the relevant capabilities through the wallet_metadata parameter in the Request URI POST request.

transaction_data: : OPTIONAL. Array of strings, where each string is a base64url encoded JSON object that contains a typed parameter set with details about the transaction that the Verifier is requesting the End-User to authorize. See (#transaction_data) for details. The Wallet MUST return an error if a request contains even one unrecognized transaction data type or transaction data not conforming to the respective type definition. In addition to the parameters determined by the type of transaction data, each transaction_data object consists of the following parameters defined by this specification:

* `type`: REQUIRED. String that identifies the type of transaction data . This value determines parameters that can be included in the `transaction_data` object. The specific values are out of scope of this specification. It is RECOMMENDED to use collision-resistant names for `type` values.
* `credential_ids`: REQUIRED. Array of strings each referencing a Credential requested by the Verifier that can be used to authorize this transaction. In Presentation Exchange, the string matches the `id` field in the Input Descriptor. In Verifiable Presentation Query Language, the string matches the `id` field in the Credential Query. If there is more than one element in the array, the Wallet MUST use only one of the referenced Credentials for transaction authorization.
* `transaction_data_hashes_alg`: OPTIONAL. Array of strings each representing a hash algorithm identifier, one of which MUST be used to calculate hashes in `transaction_data_hashes` response parameter. The value of the identifier MUST be a hash algorithm value from the "Hash Name String" column in the IANA "Named Information Hash Algorithm" registry [@IANA.Hash.Algorithms] or a value defined in another specification and/or profile of this specification. If this parameter is not present, a default value of `sha-256` MUST be used. To promote interoperability, implementations MUST support the sha-256 hash algorithm.

Each document specifying details of a transaction data type defines what Credential(s) can be used to authorize those transactions. Those Credential(s) can be issued specifically for the transaction authorization use case or re-use existing Credential(s) used for user identification. A mechanism for Credential Issuers to express that a particular Credential can be used for authorization of transaction data is out of scope for this specification.

The following is a non-normative example of a transaction data content, after base64url decoding one of the strings in the transaction_data parameter:

{
  "type": "example_type",
  "credential_ids": [ "id card credential" ],
  "transaction_data_hashes_alg": [ "sha-256" ]
  // other transaction data type specific parameters
}

Existing Parameters

The following additional considerations are given for pre-existing Authorization Request parameters:

nonce: : REQUIRED. Defined in [@!OpenID.Core]. It is used to securely bind the Verifiable Presentation(s) provided by the Wallet to the particular transaction. See (#preventing-replay) for details. Values MUST only contain ASCII URL safe characters (uppercase and lowercase letters, decimal digits, hyphen, period, underscore, and tilde).

scope: : OPTIONAL. Defined in [@!RFC6749]. The Wallet MAY allow Verifiers to request presentation of Verifiable Credentials by utilizing a pre-defined scope value. See (#request_scope) for more details.

response_mode: : OPTIONAL. Defined in [@!OAuth.Responses]. This parameter is used (through the new Response Mode direct_post) to ask the Wallet to send the response to the Verifier via an HTTPS connection (see (#response_mode_post) for more details). It is also used to request signing and encrypting (see (#jarm) for more details). If the parameter is not present, the default value is fragment.

client_id: : REQUIRED. Defined in [@!RFC6749]. This specification defines additional requirements to enable the use of Client Identifier Schemes as described in (#client_metadata_management).

Examples

The following is a non-normative example of an Authorization Request:

GET /authorize?
  response_type=vp_token
  &client_id=redirect_uri:https%3A%2F%2Fclient.example.org%2Fcb
  &redirect_uri=https%3A%2F%2Fclient.example.org%2Fcb
  &presentation_definition=...
  &transaction_data=...
  &nonce=n-0S6_WzA2Mj HTTP/1.1

The following is a non-normative example of an Authorization Request with a request_uri_method parameter (including the additional client_metadata):

GET /authorize?
  client_id=x509_san_dns:client.example.org
  &client_metadata=...
  &request_uri=https%3A%2F%2Fclient.example.org%2Frequest%2Fvapof4ql2i7m41m68uep
  &request_uri_method=post HTTP/1.1

presentation_definition Parameter {#request_presentation_definition}

This parameter contains a Presentation Definition JSON object conforming to the syntax defined in Section 5 of [@!DIF.PresentationExchange].

The following is a non-normative example how presentation_definition parameter can simply be used to request the presentation of a Credential of a certain type:

<{{examples/request/vp_token_type_only.json}}

The following non-normative example shows how the Verifier can request selective disclosure or certain claims from a Credential of a particular type.

<{{examples/request/vp_token_type_and_claims.json}}

The following non-normative example shows how the Verifiers can also ask for alternative Verifiable Credentials being presented:

<{{examples/request/vp_token_alternative_credentials.json}}

The Verifiable Credential and Verifiable Presentation formats supported by the Wallet should be published in its metadata using the metadata parameter vp_formats_supported (see (#as_metadata_parameters)).

The formats supported by a Verifier may be set up using the metadata parameter vp_formats (see (#client_metadata_parameters)). The Wallet MUST ignore any format property inside a presentation_definition object if that format was not included in the vp_formats property of the metadata.

Note: When a Verifier is requesting the presentation of a Verifiable Presentation containing a Verifiable Credential, the Verifier MUST indicate in the vp_formats parameter the supported formats of both Verifiable Credential and Verifiable Presentation.

presentation_definition_uri Parameter {#request_presentation_definition_uri}

presentation_definition_uri is used to retrieve the Presentation Definition from the resource at the specified URL, rather than being passed by value. The Wallet MUST send an HTTP GET request without additional parameters. The resource MUST be exposed without further need to authenticate or authorize.

The protocol for the presentation_definition_uri MUST be HTTPS.

The following is a non-normative example of an HTTP GET request sent after the Wallet received presentation_definition_uri parameter with the value https://server.example.com/presentationdefs?ref=idcard_presentation_request:

GET /presentationdefs?ref=idcard_presentation_request HTTP/1.1
Host: server.example.com

The following is a non-normative example of an HTTP GET response sent by the Verifier in response to the above HTTP GET request:

HTTP/1.1 200 OK
...
Content-Type: application/json

{
  "id": "vp token example",
  "input_descriptors": [
    {
      "id": "id card credential",
      "format": {
        "ldp_vc": {
          "proof_type": [
            "Ed25519Signature2018"
          ]
        }
      },
      "constraints": {
        "fields": [
          {
            "path": [
              "$.type"
            ],
            "filter": {
              "type": "string",
              "pattern": "IDCardCredential"
            }
          }
        ]
      }
    }
  ]
}

Using scope Parameter to Request Verifiable Credential(s) {#request_scope}

Wallets MAY support requesting presentation of Verifiable Credentials using OAuth 2.0 scope values.

Such a scope value MUST be an alias for

• a well-defined DCQL query, or
• a well-defined Presentation Definition (for Presentation Exchange) that will be referred to in the presentation_submission response parameter.

The specific scope values, and the mapping between a certain scope value and the respective DCQL query or Presentation Definition is out of scope of this specification.

Possible options include normative text in a separate specification defining scope values along with a description of their semantics or machine-readable definitions in the Wallet's server metadata, mapping a scope value to an equivalent Presentation Definition JSON object.

If Presentation Exchange is used, the definition of the scope value MUST allow the Verifier to determine the identifiers of the Presentation Definition and Input Descriptor(s) in the presentation_submission response parameter (definition_id and descriptor_map.id respectively) as well as the Credential formats and types in the vp_token response parameter defined in (#response-parameters).

It is RECOMMENDED to use collision-resistant scopes values.

The following is a non-normative example of an Authorization Request using the scope value com.example.IDCardCredential_presentation, which is an alias for the first Presentation Definition example given in (#request_presentation_definition):

GET /authorize?
  response_type=vp_token
  &client_id=https%3A%2F%2Fclient.example.org%2Fcb
  &redirect_uri=https%3A%2F%2Fclient.example.org%2Fcb
  &scope=com.example.healthCardCredential_presentation
  &nonce=n-0S6_WzA2Mj HTTP/1.1

Response Type vp_token {#response_type_vp_token}

This specification defines the Response Type vp_token.

vp_token: : When supplied as the response_type parameter in an Authorization Request, a successful response MUST include the vp_token parameter. The Wallet SHOULD NOT return an OAuth 2.0 Authorization Code, Access Token, or Access Token Type in a successful response to the grant request. The default Response Mode for this Response Type is fragment, i.e., the Authorization Response parameters are encoded in the fragment added to the redirect_uri when redirecting back to the Verifier. The Response Type vp_token can be used with other Response Modes as defined in [@!OAuth.Responses]. Both successful and error responses SHOULD be returned using the supplied Response Mode, or if none is supplied, using the default Response Mode.

See (#response) on how the response_type value determines the response used to return a VP Token.

Passing Authorization Request Across Devices

There are use-cases when the Authorization Request is being displayed on a device different from a device on which the requested Credential is stored. In those cases, an Authorization Request can be passed across devices by being rendered as a QR Code.

The usage of the Response Mode direct_post (see (#response_mode_post)) in conjunction with request_uri is RECOMMENDED, since Authorization Request size might be large and might not fit in a QR code.

aud of a Request Object

When the Verifier is sending a Request Object as defined in [@!RFC9101], the aud Claim value depends on whether the recipient of the request can be identified by the Verifier or not:

• the aud Claim MUST equal to the issuer Claim value, when Dynamic Discovery is performed.
• the aud Claim MUST be "https://self-issued.me/v2", when Static Discovery metadata is used.

Note: "https://self-issued.me/v2" is a symbolic string and can be used as an aud Claim value even when this specification is used standalone, without SIOPv2.

Client Identifier Scheme and Verifier Metadata Management {#client_metadata_management}

This specification defines the concept of a Client Identifier Scheme that indicates how the Wallet is supposed to interpret the Client Identifier and associated data in the process of Client identification, authentication, and authorization. The Client Identifier Scheme enables deployments of this specification to use different mechanisms to obtain and validate metadata of the Verifier beyond the scope of [@!RFC6749]. The term Client Identifier Scheme is used since the Verifier is acting as an OAuth 2.0 Client.

The Client Identifier Scheme is a string that MAY be communicated by the Verifier in a prefix within the client_id parameter in the Authorization Request. A fallback to pre-registered Clients as in [@!RFC6749] remains in place as a default mechanism in case no Client Identifier Scheme was provided. A certain Client Identifier Scheme may require the Verifier to sign the Authorization Request as means of authentication and/or pass additional parameters and require the Wallet to process them.

Syntax

In the client_id Authorization Request parameter and other places where the Client Identifier is used, the Client Identifier Schemes are prefixed to the usual Client Identifier, separated by a : (colon) character:

<client_id_scheme>:<orig_client_id>

Here, <client_id_scheme> is the Client Identifier Scheme and <orig_client_id> is an identifier for the Client within the namespace of that scheme. See (#client_identifier_schemes) for Client Identifier Schemes defined by this specification.

Wallets MUST use the presence of a : (colon) character to determine whether a Client Identifier Scheme is used. If a : character is present, the Wallet MUST interpret the Client Identifier according to the Client Identifier Scheme, here defined as the string before the (first) : character. If the Wallet does not support the Client Identifier Scheme, the Wallet MUST refuse the request.

For example, an Authorization Request might contain client_id=verifier_attestation:example-client to indicate that the verifier_attestation Client Identifier Scheme is to be used and that within this scheme, the Verifier can be identified by the string example-client. The presentation would contain the full verifier_attestation:example-client string as the audience (intended receiver) and the same full string would be used as the Client Identifier anywhere in the OAuth flow.

Note that the Verifier needs to determine which Client Identifier Schemes the Wallet supports prior to sending the Authorization Request in order to choose a supported scheme.

Depending on the Client Identifier Scheme, the Verifier can communicate a JSON object with its metadata using the client_metadata parameter which contains name/value pairs.

Fallback

If a : character is not present in the Client Identifier, the Wallet MUST treat the Client Identifier as referencing a pre-registered client. This is equivalent to the [@!RFC6749] default behavior, i.e., the Client Identifier needs to be known to the Wallet in advance of the Authorization Request. The Verifier metadata is obtained using [@!RFC7591] or through out-of-band mechanisms.

For example, if an Authorization Request contains client_id=example-client, the Wallet would interprete the Client Identifier as referring to a pre-registered client.

From this definition, it follows that pre-registered clients MUST NOT contain a : character in their Client Identifier.

Security Considerations

Confusing Verifiers using a Client Identifier Scheme with those using none can lead to attacks. Therefore, Wallets MUST always use the full Client Identifier, including the prefix if provided, within the context of the Wallet or its responses to identify the client. This refers in particular to places where the Client Identifier is used in [@!RFC6749] and in the presentation returned to the Verifier.

Defined Client Identifier Schemes {#client_identifier_schemes}

This specification defines the following Client Identifier Schemes, followed by the examples where applicable:

• redirect_uri: This value indicates that the Client Identifier (without the prefix redirect_uri:) is the Verifier's Redirect URI (or Response URI when Response Mode direct_post is used). The Authorization Request MUST NOT be signed. The Verifier MAY omit the redirect_uri Authorization Request parameter (or response_uri when Response Mode direct_post is used). All Verifier metadata parameters MUST be passed using the client_metadata parameter defined in (#new_parameters). Example Client Identifier: redirect_uri:https%3A%2F%2Fclient.example.org%2Fcb.

The following is a non-normative example of a request with this Client Identifier Scheme:

HTTP/1.1 302 Found
Location: https://client.example.org/universal-link?
  response_type=vp_token
  &client_id=redirect_uri:https%3A%2F%2Fclient.example.org%2Fcb
  &redirect_uri=https%3A%2F%2Fclient.example.org%2Fcb
  &presentation_definition=...
  &nonce=n-0S6_WzA2Mj
  &client_metadata=%7B%22vp_formats%22:%7B%22jwt_vp_json%22:%
  7B%22alg%22:%5B%22EdDSA%22,%22ES256K%22%5D%7D,%22ldp
  _vp%22:%7B%22proof_type%22:%5B%22Ed25519Signature201
  8%22%5D%7D%7D%7D

• https: This value indicates that the Client Identifier is an Entity Identifier defined in OpenID Federation [@!OpenID.Federation]. Since the Entity Identifier is already defined to start with https:, this Client Identifier Scheme MUST NOT be prefixed additionally. Processing rules given in [@!OpenID.Federation] MUST be followed. Automatic Registration as defined in [@!OpenID.Federation] MUST be used. The Authorization Request MAY also contain a trust_chain parameter. The final Verifier metadata is obtained from the Trust Chain after applying the policies, according to [@!OpenID.Federation]. The client_metadata parameter, if present in the Authorization Request, MUST be ignored when this Client Identifier scheme is used. Example Client Identifier: https://federation-verifier.example.com.

• did: This value indicates that the Client Identifier is a DID defined in [@!DID-Core]. Since the DID URI is already defined to start with did:, this Client Identifier Scheme MUST NOT be prefixed additionally. The request MUST be signed with a private key associated with the DID. A public key to verify the signature MUST be obtained from the verificationMethod property of a DID Document. Since DID Document may include multiple public keys, a particular public key used to sign the request in question MUST be identified by the kid in the JOSE Header. To obtain the DID Document, the Wallet MUST use DID Resolution defined by the DID method used by the Verifier. All Verifier metadata other than the public key MUST be obtained from the client_metadata parameter as defined in (#new_parameters). Example Client Identifier: did:example:123#1.

The following is a non-normative example of a header and a body of a signed Request Object when Client Identifier scheme is a did:

Header

<{{examples/request/request_header_client_id_did.json}}

Body

<{{examples/request/request_object_client_id_did.json}}

• verifier_attestation: This Client Identifier Scheme allows the Verifier to authenticate using a JWT that is bound to a certain public key as defined in (#verifier_attestation_jwt). When the Client Identifier Scheme is verifier_attestation, the Client Identifier MUST equal the sub claim value in the Verifier attestation JWT. The request MUST be signed with the private key corresponding to the public key in the cnf claim in the Verifier attestation JWT. This serves as proof of possesion of this key. The Verifier attestation JWT MUST be added to the jwt JOSE Header of the request object (see (#verifier_attestation_jwt)). The Wallet MUST validate the signature on the Verifier attestation JWT. The iss claim value of the Verifier Attestation JWT MUST identify a party the Wallet trusts for issuing Verifier Attestation JWTs. If the Wallet cannot establish trust, it MUST refuse the request. If the issuer of the Verifier Attestation JWT adds a redirect_uris claim to the attestation, the Wallet MUST ensure the redirect_uri request parameter value exactly matches one of the redirect_uris claim entries. All Verifier metadata other than the public key MUST be obtained from the client_metadata parameter. Example Client Identifier: verifier_attestation:verifier.example.

• x509_san_dns: When the Client Identifier Scheme is x509_san_dns, the Client Identifier MUST be a DNS name and match a dNSName Subject Alternative Name (SAN) [@!RFC5280] entry in the leaf certificate passed with the request. The request MUST be signed with the private key corresponding to the public key in the leaf X.509 certificate of the certificate chain added to the request in the x5c JOSE header [@!RFC7515] of the signed request object. The Wallet MUST validate the signature and the trust chain of the X.509 certificate. All Verifier metadata other than the public key MUST be obtained from the client_metadata parameter. If the Wallet can establish trust in the Client Identifier authenticated through the certificate, e.g. because the Client Identifier is contained in a list of trusted Client Identifiers, it may allow the client to freely choose the redirect_uri value. If not, the FQDN of the redirect_uri value MUST match the Client Identifier without the prefix x509_san_dns:. Example Client Identifier: x509_san_dns:client.example.org.

• x509_san_uri: When the Client Identifier Scheme is x509_san_uri, the Client Identifier MUST be a URI and match a uniformResourceIdentifier Subject Alternative Name (SAN) [@!RFC5280] entry in the leaf certificate passed with the request. The request MUST be signed with the private key corresponding to the public key in the leaf X.509 certificate of the certificate chain added to the request in the x5c JOSE header [@!RFC7515] of the signed request object. The Wallet MUST validate the signature and the trust chain of the X.509 certificate. All Verifier metadata other than the public key MUST be obtained from the client_metadata parameter. If the Wallet can establish trust in the Client Identifier authenticated through the certificate, e.g., because the Client Identifier is contained in a list of trusted Client Identifiers, it may allow the client to freely choose the redirect_uri value. If not, the redirect_uri value MUST match the Client Identifier without the prefix x509_san_uri:. Example Client Identifier: x509_san_uri:https://client.example.org/cb.

• web-origin: This Client Identifier Scheme is defined in (#browser_api_request). It MUST NOT be used in the Authorization Request.

To use the Client Identifier Schemes https, did, verifier_attestation, x509_san_dns, and x509_san_uri, Verifiers MUST be confidential clients. This might require changes to the technical design of native apps as such apps are typically public clients.

Other specifications can define further Client Identifier Schemes. It is RECOMMENDED to use collision-resistant names for such values.

Request URI Method post {#request_uri_method_post}

This request is handled by the Request URI endpoint of the Verifier.

The request MUST use the HTTP POST method with the https scheme, and the content type application/x-www-form-urlencoded and the accept header set to application/oauth-authz-req+jwt. The names and values in the body MUST be encoded using UTF-8.

The following parameters are defined to be included in the request to the Request URI Endpoint:

wallet_metadata: : OPTIONAL. A String containing a JSON object containing metadata parameters as defined in (#as_metadata_parameters).

wallet_nonce: : OPTIONAL. A String value used to mitigate replay attacks of the Authorization Request. When received, the Verifier MUST use it as the wallet_nonce value in the signed authorization request object. Value can be a base64url-encoded, fresh, cryptographically random number with sufficient entropy.

If the Wallet requires the Verifier to encrypt the Request Object, it SHOULD use the jwks or jwks_uri parameter within the wallet_metadata parameter to pass the public key for the input to the key agreement. Other mechanisms to pass the encryption key can be used as well. If the Wallet requires an encrypted Authorization Response, it SHOULD specify supported encryption algorithms using the authorization_encryption_alg_values_supported and authorization_encryption_enc_values_supported parameters.

Additionally, if the Client Identifier Scheme permits signed Request Objects, the Wallet SHOULD list supported cryptographic algorithms for securing the Request Object through the request_object_signing_alg_values_supported parameter. Conversely, the Wallet MUST NOT include this parameter if the Client Identifier Scheme precludes signed Request Objects.

Additional parameters MAY be defined and used in the request to the Request URI Endpoint. The Verifier MUST ignore any unrecognized parameters.

The following is a non-normative example of a request:

POST /request HTTP/1.1
Host: client.example.org
Content-Type: application/x-www-form-urlencoded

  wallet_metadata=%7B%22vp_formats_supported%22%3A%7B%22jwt_vc_json%22%3A%7B%22alg_values_supported
  %22%3A%5B%22ES256K%22%2C%22ES384%22%5D%7D%2C%22jwt_vp_json%22%3A%7B%22alg_values_supported%22%3A%
  5B%22ES256K%22%2C%22EdDSA%22%5D%7D%7D%7D&
  wallet_nonce=qPmxiNFCR3QTm19POc8u

Request URI Response

The Request URI response MUST be an HTTP response with the content type "application/oauth-authz-req+jwt" and the body being a signed, optionally encrypted, request object as defined in [@RFC9101]. The request object MUST fulfill the requirements as defined in (#vp_token_request).

The following is a non-normative example of a request object:

{
  "client_id": "x509_san_dns:client.example.org",
  "response_uri": "https://client.example.org/post",
  "response_type": "vp_token",
  "response_mode": "direct_post",
  "presentation_definition": {...},
  "nonce": "n-0S6_WzA2Mj",
  "wallet_nonce": "qPmxiNFCR3QTm19POc8u",
  "state" : "eyJhb...6-sVA"
}

The Wallet MUST process the request as defined in [@RFC9101]. Additionally, if the Wallet passed a wallet_nonce in the POST request, the Wallet MUST validate whether the request object contains the respective nonce value in a wallet_nonce claim. If it does not, the Wallet MUST terminate request processing.

The Wallet MUST extract the set of Authorization Request parameters from the Request Object. The Wallet MUST only use the parameters in this Request Object, even if the same parameter was provided in an Authorization Request query parameter. The Client Identifier value in the client_id Authorization Request parameter and the Request Object client_id claim value MUST be identical, including the Client Identifier Scheme. If any of these conditions are not met, the Wallet MUST terminate request processing.

The Wallet then validates the request as specified in OAuth 2.0 [@RFC6749].

Request URI Error Response

If the Verifier responds with any HTTP error response, the Wallet MUST terminate the process.

Digital Credentials Query Language (DCQL) {#dcql_query}

The Digital Credentials Query Language (DCQL, pronounced [ˈdakl̩]) is a JSON-encoded query language that allows the Verifier to request Verifiable Presentations that match the query. The Verifier MAY encode constraints on the combinations of credentials and claims that are requested. The Wallet evaluates the query against the Verifiable Credentials it holds and returns Verifiable Presentations matching the query.

A valid DCQL query is defined as a JSON-encoded object with the following top-level properties:

credentials: : REQUIRED. A non-empty array of Credential Queries as defined in (#credential_query) that specify the requested Verifiable Credentials.

credential_sets: : OPTIONAL. A non-empty array of credential set queries as defined in (#credential_set_query) that specifies additional constraints on which of the requested Verifiable Credentials to return.

Note: Future extensions may define additional properties both on the top level and in the rest of the DCQL data structure. Implementations MUST ignore any unknown properties.

Credential Query {#credential_query}

A Credential Query is an object representing a request for a presentation of one Credential.

Each entry in credentials MUST be an object with the following properties:

id: : REQUIRED. A string identifying the Credential in the response and, if provided, the constraints in credential_sets. The value MUST be a non-empty string consisting of alphanumeric, underscore (_) or hyphen (-) characters. Within the Authorization Request, the same id MUST NOT be present more than once.

format: : REQUIRED. A string that specifies the format of the requested Verifiable Credential. Valid Credential Format Identifier values are defined in Appendix A of [@!OpenID.VCI].

meta: : OPTIONAL. An object defining additional properties requested by the Verifier that apply to the metadata and validity data of the Credential. The properties of this object are defined per Credential Format in (#format_specific_properties). If omitted, no specific constraints are placed on the metadata or validity of the requested Credential.

claims: : OPTIONAL. A non-empty array of objects as defined in (#claims_query) that specifies claims in the requested Credential.

claim_sets: : OPTIONAL. A non-empty array containing arrays of identifiers for elements in claims that specifies which combinations of claims for the Credential are requested. The rules for selecting claims to send are defined in (#selecting_claims).

Note that multiple Credential Queries in a request MAY request a presentation of the same Credential.

Credential Set Query {#credential_set_query}

A Credential Set Query is an object representing a request for one or more credentials to satisfy a particular use case with the Verifier.

Each entry in credential_sets MUST be an object with the following properties:

options : REQUIRED: A non-empty array, where each value in the array is a list of Credential Query identifiers representing one set of Credentials that satisfies the use case. The value of each element in the options array is an array of identifiers which reference elements in credentials.

required : OPTIONAL. A boolean which indicates whether this set of Credentials is required to satisfy the particular use case at the Verifier. If omitted, the default value is true.

purpose : OPTIONAL. A string, number or object specifying the purpose of the query. This specification does not define a specific structure or specific values for this property. The purpose is intended to be used by the Verifier to communicate the reason for the query to the Wallet. The Wallet MAY use this information to show the user the reason for the request.

Claims Query {#claims_query}

Each entry in claims MUST be an object with the following properties:

id: : REQUIRED if claim_sets is present in the Credential Query; OPTIONAL otherwise. A string identifying the particular claim. The value MUST be a non-empty string consisting of alphanumeric, underscore (_) or hyphen (-) characters. Within the particular claims array, the same id MUST NOT be present more than once.

path: : REQUIRED if the Credential Format uses a JSON-based claims structure; MUST NOT be present otherwise. The value MUST be a non-empty array representing a claims path pointer that specifies the path to a claim within the Verifiable Credential, as defined in (#claims_path_pointer).

namespace: : REQUIRED if the Credential Format is based on the mdoc format defined in ISO 18013-5; MUST NOT be present otherwise. The value MUST be a string that specifies the namespace of the data element within the mdoc, e.g., org.iso.18013.5.1.

claim_name: : REQUIRED if the Credential Format is based on mdoc format defined in ISO 18013-5; MUST NOT be present otherwise. The value MUST be a string that specifies the data element identifier of the data element within the provided namespace in the mdoc, e.g., first_name.

values: : OPTIONAL. An array of strings, integers or boolean values that specifies the expected values of the claim. If the values property is present, the Wallet SHOULD return the claim only if the type and value of the claim both match for at least one of the elements in the array. Details of the processing rules are defined in (#selecting_claims).

Selecting Claims and Credentials {#dcql_query_lang_processing_rules}

The following section describes the logic that applies for selecting claims and for selecting credentials.

Selecting Claims {#selecting_claims}

The following rules apply for selecting claims via claims and claim_sets:

• If claims is absent, the Verifier requests all claims existing in the Credential.
• If claims is present, but claim_sets is absent, the Verifier requests all claims listed in claims.
• If both claims and claim_sets are present, the Verifier requests one combination of the claims listed in claim_sets. The order of the options conveyed in the claim_sets array expresses the Verifier's preference for what is returned; the Wallet MUST return the first option that it can satisfy. If the Wallet cannot satisfy any of the options, it MUST NOT return any claims.

When a Claims Query contains a restriction on the values of a claim, the Wallet SHOULD NOT return the claim if its value does not match at least one of the elements in values i.e., the claim should be treated the same as if it did not exist in the Credential. Implementing this restriction may not be possible in all cases, for example, if the Wallet does not have access to the claim value before presentation or user consent or if another component routing the request to the Wallet does not have access to the claim value. Therefore, Verifiers must treat restrictions expressed using values as a best-effort way to improve user privacy, but MUST NOT rely on it for security checks.

The purpose of the claim_sets syntax is to provide a way for a verifier to describe alternative ways a given credential can satisfy the request. The array ordering expresses the Verifier's preference for how to fulfill the request. The first element in the array is the most preferred and the last element in the array is the least preferred. Verifiers SHOULD use the principle of least information disclosure to influence how they order these options. For example, a proof of age request should prioritize requesting an attribute like age_over_18 over an attribute like birth_date. The claim_sets syntax is not intended to define options the user can choose from, see (#dcql_query_ui) for more information.

If the Wallet cannot deliver all claims requested by the Verifier according to these rules, it MUST NOT return the respective Credential.

Selecting Credentials

The following rules apply for selecting Credentials via credentials and credential_sets:

• If credential_sets is not provided, the Verifier requests presentations for all Credentials in credentials to be returned.
• Otherwise, the Verifier requests presentations of Credentials to be returned satisfying
  • all of the Credential Set Queries in the credential_sets array where the required attribute is true or omitted, and
  • optionally, any of the other Credential Set Queries.

To satisfy a Credential Set Query, the Wallet MUST return presentations of a set of Credentials that match to one of the options inside the Credential Set Query.

Credentials not matching the respective constraints expressed within credentials MUST NOT be returned, i.e., they are treated as if they would not exist in the Wallet.

If the Wallet cannot deliver all non-optional Credentials requested by the Verifier according to these rules, it MUST NOT return any Credential(s).

User Interface Considerations {#dcql_query_ui}

While this specification provides the mechanisms for requesting different sets of claims and Credentials, it does not define details about the user interface of the Wallet, for example, if and how users can select which combination of Credentials to present. However, it is typically expected that the Wallet presents the End-User with a choice of which Credential(s) to present if multiple of the sets of Credentials in options can satisfy the request.

Security Considerations {#dcql_query_security}

While the Verifier can specify various constraints both on the claims level and the Credential level as shown above, it MUST NOT rely on the Wallet to enforce these constraints. The Wallet is not controlled by the Verifier and the Verifier MUST perform its own security checks on the returned Credentials and presentations.

Format-specific Properties {#format_specific_properties}

OpenID for Verifiable Presentations is Credential Format agnostic, i.e., it is designed to allow applications to request and receive Verifiable Presentations and Verifiable Credentials in any Credential Format. This section defines Credential Format Profiles for some of the known Credential Formats. Other specifications or deployments can define their own Credential Format Profiles:

IETF SD-JWT VC {#format_vc_sd_jwt}

vct_values: : OPTIONAL. An array of strings that specifies allowed values for the type of the requested Verifiable Credential. All elements in the array MUST be valid type identifiers as defined in [@!I-D.ietf-oauth-sd-jwt-vc]. The Wallet MAY return credentials that inherit from any of the specified types, following the inheritance logic defined in [@!I-D.ietf-oauth-sd-jwt-vc].

Mobile Documents or mdocs (ISO/IEC 18013 and ISO/IEC 23220 series) {#format_mso_mdoc}

doctype_value: : OPTIONAL. String that specifies an allowed value for the doctype of the requested Verifiable Credential. It MUST be a valid doctype identifier as defined in [@ISO.18013-5].

Claims Path Pointer {#claims_path_pointer}

A claims path pointer is a pointer into the JSON structure of the Verifiable Credential, identifying one or more claims. A claims path pointer MUST be a non-empty array of strings and non-negative integers. A string value indicates that the respective key is to be selected, a null value indicates that all elements of the currently selected array(s) are to be selected; and a non-negative integer indicates that the respective index in an array is to be selected. The path is formed as follows:

Start with an empty array and repeat the following until the full path is formed.

• To address a particular claim within an object, append the key (claim name) to the array.
• To address an element within an array, append the index to the array (as a non-negative, 0-based integer).
• To address all elements within an array, append a null value to the array.

Verifiers MUST NOT point to the same claim more than once in a single query. Wallets SHOULD ignore such duplicate claim queries.

Processing

In detail, the array is processed by the Wallet from left to right as follows:

1. Select the root element of the Credential, i.e., the top-level JSON object.
2. Process the query of the claims path pointer array from left to right:
   1. If the component is a string, select the element in the respective key in the currently selected element(s). If any of the currently selected element(s) is not an object, abort processing and return an error. If the key does not exist in any element currently selected, remove that element from the selection.
   2. If the component is null, select all elements of the currently selected array(s). If any of the currently selected element(s) is not an array, abort processing and return an error.
   3. If the component is a non-negative integer, select the element at the respective index in the currently selected array(s). If any of the currently selected element(s) is not an array, abort processing and return an error. If the index does not exist in a selected array, remove that array from the selection.
3. If the set of elements currently selected is empty, abort processing and return an error.

The result of the processing is the set of elements which is requested for presentation.

Claims Path Pointer Example {#claims_path_pointer_example}

The following shows a non-normative, simplified example of a Credential:

{
  "name": "Arthur Dent",
  "address": {
    "street_address": "42 Market Street",
    "locality": "Milliways",
    "postal_code": "12345"
  },
  "degrees": [
    {
      "type": "Bachelor of Science",
      "university": "University of Betelgeuse"
    },
    {
      "type": "Master of Science",
      "university": "University of Betelgeuse"
    }
  ],
  "nationalities": ["British", "Betelgeusian"]
}

The following shows examples of claims path pointers and the respective selected claims:

• ["name"]: The claim name with the value Arthur Dent is selected.
• ["address"]: The claim address with its sub-claims as the value is selected.
• ["address", "street_address"]: The claim street_address with the value 42 Market Street is selected.
• ["degrees", null, "type"]: All type claims in the degrees array are selected.
• ["nationalities", 1]: The second nationality is selected.

DCQL Examples {#dcql_query_example}

The following is a non-normative example of a DCQL query that requests a Verifiable Credential of the format vc+sd-jwt with a type value of https://credentials.example.com/identity_credential and the claims last_name, first_name, and address.street_address:

<{{examples/query_lang/simple.json}}

Additional, more complex examples can be found in (#more_dcql_query_examples).

Response {#response}

A VP Token is only returned if the corresponding Authorization Request contained a dcql_query parameter, a presentation_definition parameter, a presentation_definition_uri parameter, or a scope parameter representing a Presentation Definition (#vp_token_request).

A VP Token can be returned in the Authorization Response or the Token Response depending on the Response Type used. See (#response_type_vp_token) for more details.

If the Response Type value is vp_token, the VP Token is returned in the Authorization Response. When the Response Type value is vp_token id_token and the scope parameter contains openid, the VP Token is returned in the Authorization Response alongside a Self-Issued ID Token as defined in [@!SIOPv2].

If the Response Type value is code (Authorization Code Grant Type), the VP Token is provided in the Token Response.

The expected behavior is summarized in the following table:

response_type parameter value	Response containing the VP Token
vp_token	Authorization Response
vp_token id_token	Authorization Response
code	Token Response

Table 1: OpenID for Verifiable Presentations response_type values

The behavior with respect to the VP Token is unspecified for any other individual Response Type value, or a combination of Response Type values.

Response Parameters {#response-parameters}

When a VP Token is returned, the respective response includes the following parameters:

vp_token: : REQUIRED. The structure of this parameter depends on the query language used to request the presentations in the Authorization Request:

• If DCQL was used, this is a JSON-encoded object; the keys are the id values used for the Credential Queries in the DCQL query, and the values are the Verifiable Presentations that match the respective Credential Query. The Verifiable Presentations are represented as strings or objects depending on the format as defined in Appendix A of [@!OpenID.VCI]. The same rules as above apply for encoding the Verifiable Presentations.
• In case Presentation Exchange was used, it is a JSON String or JSON object that MUST contain a single Verifiable Presentation or an array of JSON Strings and JSON objects each of them containing a Verifiable Presentations. Each Verifiable Presentation MUST be represented as a JSON string (that is a base64url-encoded value) or a JSON object depending on a format as defined in Appendix A of [@!OpenID.VCI]. When a single Verifiable Presentation is returned, the array syntax MUST NOT be used. If Appendix A of [@!OpenID.VCI] defines a rule for encoding the respective Credential format in the Credential Response, this rules MUST also be followed when encoding Credentials of this format in the vp_token response parameter. Otherwise, this specification does not require any additional encoding when a Credential format is already represented as a JSON object or a JSON string.

presentation_submission: : REQUIRED if Presentation Exchange was used for the request; MUST NOT be used otherwise. The presentation_submission element as defined in [@!DIF.PresentationExchange]. It contains mappings between the requested Verifiable Credentials and where to find them within the returned VP Token. This is expressed via elements in the descriptor_map array, known as Input Descriptor Mapping Objects. These objects contain a field called path, which, for this specification, MUST have the value $ (top level root path) when only one Verifiable Presentation is contained in the VP Token, and MUST have the value $[n] (indexed path from root) when there are multiple Verifiable Presentations, where n is the index to select. Additional parameters can be defined by Credential Formats, see (#alternative_credential_formats) for details.

Other parameters, such as state or code (from [@!RFC6749]), or id_token (from [@!OpenID.Core]), and iss (from [@RFC9207]) can be included in the response as defined in the respective specifications. state values MUST only contain ASCII URL safe characters (uppercase and lowercase letters, decimal digits, hyphen, period, underscore, and tilde). For the implementation considerations of a state parameter, see (#state_management).

If Presentation Exchange was used for the request, the presentation_submission element MUST be included as a separate response parameter alongside the VP token. Clients MUST ignore any presentation_submission element included inside a Verifiable Presentation.

Including the presentation_submission parameter as a separate response parameter allows the Wallet to provide the Verifier with additional information about the format and structure in advance of the processing of the VP Token, and can be used even with the Credential formats that do not allow for the direct inclusion of presentation_submission parameters inside a Credential itself.

Additional response parameters MAY be defined and used, as described in [@!RFC6749]. The Client MUST ignore any unrecognized parameters.

The following is a non-normative example of an Authorization Response when the Response Type value in the Authorization Request was vp_token:

HTTP/1.1 302 Found
Location: https://client.example.org/cb#
  presentation_submission=...
  &vp_token=...

Examples (DCQL) {#response_dcql_query}

The following is a non-normative example of the contents of a VP Token containing a single Verifiable Presentation in the SD-JWT VC format after a request using DCQL like the one shown in (#dcql_query_example) (shortened for brevity):

{
  "my_credential": "eyJhbGci...QMA"
}

Examples (Presentation Exchange) {#response_presentation_exchange}

The following is a non-normative example of a VP Token containing a single Verifiable Presentation after a request using Presentation Exchange:

<{{examples/response/vp_token_raw_ldp_vp.json}}

The following is a non-normative example of a presentation_submission parameter sent alongside a VP Token in the example above. It corresponds to the second Presentation Definition example in (#request_presentation_definition):

<{{examples/response/presentation_submission.json}}

A descriptor_map element MUST contain a path_nested parameter referring to the actual Credential carried in the respective Verifiable Presentation.

The following is a non-normative example of a VP Token containing multiple Verifiable Presentations:

<{{examples/response/vp_token_multiple_vps.json}}

The following is a non-normative example of a presentation_submission parameter sent alongside a VP Token in the example above. It does not correspond to any Presentation Definition example in this specification:

<{{examples/response/presentation_submission_multiple_vps.json}}

Response Mode "direct_post" {#response_mode_post}

The Response Mode direct_post allows the Wallet to send the Authorization Response to an endpoint controlled by the Verifier via an HTTP POST request.

It has been defined to address the following use cases:

• Verifier and Wallet are located on different devices; thus, the Wallet cannot send the Authorization Response to the Verifier using a redirect.
• The Authorization Response size exceeds the URL length limits of user agents, so flows relying only on redirects (such as Response Mode fragment) cannot be used. In those cases, the Response Mode direct_post is the way to convey the Verifiable Presentations to the Verifier without the need for the Wallet to have a backend.

The Response Mode is defined in accordance with [@!OAuth.Responses] as follows:

direct_post: : In this mode, the Authorization Response is sent to the Verifier using an HTTP POST request to an endpoint controlled by the Verifier. The Authorization Response MUST be encoded in the request body using the format defined by the application/x-www-form-urlencoded HTTP content type. The parameters in the request body MUST all be encoded using UTF-8. The verifier can request that the wallet redirects the user to the verifier using the response as defined below.

The following new Authorization Request parameter is defined to be used in conjunction with Response Mode direct_post:

response_uri: : REQUIRED when the Response Mode direct_post is used. The URL to which the Wallet MUST send the Authorization Response using an HTTP POST request as defined by the Response Mode direct_post. The Response URI receives all Authorization Response parameters as defined by the respective Response Type. When the response_uri parameter is present, the redirect_uri Authorization Request parameter MUST NOT be present. If the redirect_uri Authorization Request parameter is present when the Response Mode is direct_post, the Wallet MUST return an invalid_request Authorization Response error. The response_uri value MUST be a value that the client would be permitted to use as redirect_uri when following the rules defined in (#client_metadata_management).

Note: When the specification text refers to the usage of Redirect URI in the Authorization Request, that part of the text also applies when Response URI is used in the Authorization Request with Response Mode direct_post.

Note: The Verifier's component providing the user interface (Frontend) and the Verifier's component providing the Response URI need to be able to map authorization requests to the respective authorization responses. The Verifier MAY use the state Authorization Request parameter to add appropriate data to the Authorization Response for that purpose, for details see (#implementation_considerations_direct_post).

Additional request parameters MAY be defined and used with the Response Mode direct_post. The Wallet MUST ignore any unrecognized parameters.

The following is a non-normative example of the payload of a Request Object with Response Mode direct_post:

{
  "client_id": "redirect_uri:https://client.example.org/post",
  "response_uri": "https://client.example.org/post",
  "response_type": "vp_token",
  "response_mode": "direct_post",
  "presentation_definition": {...},
  "nonce": "n-0S6_WzA2Mj",
  "state": "eyJhb...6-sVA"
}

The following non-normative example of an Authorization Request refers to the Authorization Request Object from above through the request_uri parameter. The Authorization Request can be displayed to the End-User either directly (as a link) or as a QR Code:

https://wallet.example.com?
  client_id=https%3A%2F%2Fclient.example.org%2Fcb
  &request_uri=https%3A%2F%2Fclient.example.org%2F567545564

The following is a non-normative example of the Authorization Response that is sent via an HTTP POST request to the Verifier's Response URI:

POST /post HTTP/1.1
Host: client.example.org
Content-Type: application/x-www-form-urlencoded

  presentation_submission=...&
  vp_token=...&
  state=eyJhb...6-sVA

The following is a non-normative example of an Authorization Error Response that is sent as an HTTP POST request to the Verifier's Response URI:

POST /post HTTP/1.1
Host: client.example.org
Content-Type: application/x-www-form-urlencoded

  error=invalid_request&
  error_description=unsupported%20client_id_scheme&
  state=eyJhb...6-sVA

If the Response URI has successfully processed the Authorization Response or Authorization Error Response, it MUST respond with an HTTP status code of 200 with Content-Type of application/json and a JSON object in the response body.

The following new parameter is defined for use in the JSON object returned from the Response Endpoint to the Wallet:

redirect_uri: : OPTIONAL. String containing a URI. When this parameter is present the Wallet MUST redirect the user agent to this URI. This allows the Verifier to continue the interaction with the End-User on the device where the Wallet resides after the Wallet has sent the Authorization Response to the Response URI. It can be used by the Verifier to prevent session fixation ((#session_fixation)) attacks. The Response URI MAY return the redirect_uri parameter in response to successful Authorization Responses or for Error Responses.

Additional response parameters MAY be defined and used. The Wallet MUST ignore any unrecognized parameters.

Note: Response Mode direct_post without the redirect_uri could be less secure than Response Modes with redirects. For details, see ((#session_fixation)).

The value of the redirect URI is an absolute URI as defined by [@!RFC3986] Section 4.3 and is chosen by the Verifier. The Verifier MUST include a fresh, cryptographically random value in the URL. This value is used to ensure only the receiver of the redirect can fetch and process the Authorization Response. The value can be added as a path component, as a fragment or as a parameter to the URL. It is RECOMMENDED to use a cryptographic random value of 128 bits or more. For implementation considerations see (#implementation_considerations_direct_post).

The following is a non-normative example of the response from the Verifier to the Wallet upon receiving the Authorization Response at the Response URI (using a response_code parameter from (#implementation_considerations_direct_post)):

HTTP/1.1 200 OK
Content-Type: application/json
Cache-Control: no-store

{
  "redirect_uri": "https://client.example.org/cb#response_code=091535f699ea575c7937fa5f0f454aee" 
}

If the response does not contain the redirect_uri parameter, the Wallet is not required to perform any further steps.

Note: In the Response Mode direct_post or direct_post.jwt, the Wallet can change the UI based on the Verifier's callback to the Wallet following the submission of the Authorization Response.

Additional parameters MAY be defined and used in the response from the Response Endpoint to the Wallet. The Wallet MUST ignore any unrecognized parameters.

Signed and/or Encrypted Responses {#jarm}

This section defines how an Authorization Response containing a VP Token can be signed and/or encrypted at the application level when the Response Type value is vp_token or vp_token id_token. Encrypting the Authorization Response can prevent personal data in the Authorization Response from leaking, when the Authorization Response is returned through the front channel (e.g., the browser).

To sign, encrypt, or both sign and encrypt the Authorization Response, implementations MUST use the JWT Secured Authorization Response Mode for OAuth 2.0 (JARM) [@!JARM], and when only encrypting, the JARM extension described below.

This specification also defines how to encrypt an unsigned Authorization Response by extending the mechanisms defined in [@!JARM]. The JSON containing the Authorization Response parameters can be encrypted as the payload of the JWE.

The advantage of an encrypted but not signed Authorization Response is that it prevents the signing key from being used as a correlation factor. It can also be a challenge to establish trust in the signing key to ensure authenticity. For security considerations with encrypted but unsigned responses, see (#encrypting_unsigned_response).

If the JWT is only a JWE, the following processing rules MUST be followed:

• iss, exp and aud MUST be omitted in the JWT Claims Set of the JWE, and the processing rules as per [@!JARM] Section 2.4 related to these claims do not apply.
• The processing rules as per [@!JARM] Section 2.4 related to JWS processing MUST be ignored.

The following is a non-normative example of the payload of a JWT used in an Authorization Response that is encrypted and not signed:

<{{examples/response/jarm_jwt_enc_only_vc_json_body.json}}

The JWT response document MUST include the vp_token and, if Presentation Exchange was used in the request, the presentation_submission parameters as defined in (#response-parameters).

The key material used for encryption and signing SHOULD be determined using existing metadata mechanisms.

To obtain Verifier's public key for the input to the key agreement to encrypt the Authorization Response, the Wallet MUST use jwks claim within the client_metadata request parameter, or within the metadata defined in the Entity Configuration when [@!OpenID.Federation] is used, or other mechanisms.

To sign the Authorization Response, the Wallet MUST use a private key that corresponds to a public key made available in its metadata.

Response Mode "direct_post.jwt" {#direct_post_jwt}

This specification also defines a new Response Mode direct_post.jwt, which allows for JARM to be used with Response Mode direct_post defined in (#response_mode_post).

The Response Mode direct_post.jwt causes the Wallet to send the Authorization Response using an HTTP POST request instead of redirecting back to the Verifier as defined in (#response_mode_post). The Wallet adds the response parameter containing the JWT as defined in Section 4.1. of [@!JARM] and (#jarm) in the body of an HTTP POST request using the application/x-www-form-urlencoded content type. The names and values in the body MUST be encoded using UTF-8.

The following is a non-normative example of a response using the presentation_submission and vp_token values from (#jwt_vc). (line breaks for display purposes only):

<{{examples/response/jarm_jwt_vc_json_post.txt}}

The following is a non-normative example of the payload of the JWT used in the example above before base64url encoding and signing:

<{{examples/response/jarm_jwt_vc_json_body.json}}

Transaction Data {#transaction_data}

The transaction data mechanism enables a binding between the user's identification/authentication and the user’s authorization, for example to complete a payment transaction, or to sign specific document(s) using QES (Qualified Electronic Signatures). This is achieved by signing the transaction data used for user authorization with the user-controlled key used for proof of possession of the Credential being presented as a means for user identification/authentication.

The Wallet that received the transaction_data parameter in the request MUST include in the response a transaction_data_hashes parameter defined below. If the wallet does not support transaction_data parameter, it MUST return an error.

Where to include thetransaction_data_hashes parameter in the response is specific to each credential format and is defined by the Credential Format Profile, such as those in (#alternative_credential_formats).

• transaction_data_hashes: Array of hashes, where each hash is calculated using a hash function over the strings received in the transaction_data request parameter. Each hash value ensures the integrity of, and maps to, the respective transaction data object. Where in the response this parameter is included is defined by each Credential Format Profile, but it has to be included in the mechanism used for the proof of possession of the Credential that is signed using the user-controlled key.
• transaction_data_hashes_alg: REQUIRED when this parameter was present in the transaction_data request parameter. String representing the hash algorithm identifier used to calculate hashes in transaction_data_hashes response parameter.

Error Response {#error-response}

The error response follows the rules as defined in [@!RFC6749], with the following additional clarifications:

invalid_scope:

• Requested scope value is invalid, unknown, or malformed.

invalid_request:

• The request contains more than one out of the following three options to communicate a requested Credential: a presentation_definition parameter, a presentation_definition_uri parameter, or a scope value representing a Presentation Definition.
• The request uses the vp_token Response Type but does not request a Credential using any of the three options
• Requested Presentation Definition does not conform to the DIF PEv2 specification [@!DIF.PresentationExchange].
• The Wallet does not support the Client Identifier Scheme passed in the Authorization Request.
• The Client Identifier passed in the request did not belong to its Client Identifier scheme, or requirements of a certain scheme was violated, for example an unsigned request was sent with Client Identifier scheme https.

invalid_client:

• client_metadata parameter defined in (#new_parameters) is present, but the Wallet recognizes Client Identifier and knows metadata associated with it.
• Verifier's pre-registered metadata has been found based on the Client Identifier, but client_metadata parameter is also present.

access_denied:

• The Wallet did not have the requested Credentials to satisfy the Authorization Request.
• The End-User did not give consent to share the requested Credentials with the Verifier.
• The Wallet failed to authenticate the End-User.

This document also defines the following additional error codes and error descriptions:

vp_formats_not_supported:

• The Wallet does not support any of the formats requested by the Verifier, such as those included in the vp_formats registration parameter.

invalid_presentation_definition_uri:

• The Presentation Definition URL cannot be reached.

invalid_presentation_definition_reference:

• The Presentation Definition URL can be reached, but the specified presentation_definition cannot be found at the URL.

invalid_request_uri_method:

• The value of the request_uri_method request parameter is neither get nor post (case-sensitive).

invalid_transaction_data:

• any of the following is true for at least one object in the transaction_data structure:
  • contains an unknown or unsupported transaction data type value,
  • is an object of known type but containing unknown fields,
  • contains fields of the wrong type for the transaction data type,
  • contains fields with invalid values for the transaction data type, or
  • is missing required fields for the transaction data type.
  • the credential_ids does not match
  • the referenced Credential(s) are not available in the Wallet

wallet_unavailable:

• The Wallet appears to be unavailable and therefore unable to respond to the request. It can be useful in situations where the user agent cannot invoke the Wallet and another component receives the request while the End-User wishes to continue the journey on the Verifier website. For example, this applies when using claimed HTTPS URIs handled by the Wallet provider in case the platform cannot or does not translate the URI into a platform intent to invoke the Wallet. In this case, the Wallet provider would return the Authorization Error Response to the Verifier and might redirect the user agent back to the Verifier website.

VP Token Validation

Verifiers MUST validate the VP Token in the following manner:

1. Validate the format of the VP Token as defined in (#response-parameters) and verify the contents depending on the language used in the Authorization Request:
   1. If DCQL was used, ensure that the set of VPs returned satisfies all required Credential Sets (and optionally other Credential Sets).
   2. If Presentation Exchange was used, determine the number of VPs returned in the VP Token and identify in which VP which requested VC is included, using the Input Descriptor Mapping Object(s) in the Presentation Submission.
2. Validate the integrity, authenticity, and Holder Binding of any Verifiable Presentation provided in the VP Token according to the rules of the respective Presentation format. See (#preventing-replay) for the checks required to prevent replay of a VP.
3. Perform the checks on the Credential(s) specific to the Credential Format (i.e., validation of the signature(s) on each VC).
4. Confirm that the returned Credential(s) meet all criteria defined in the query in the Authorization Request (e.g., Claims included in the presentation).
5. Perform the checks required by the Verifier's policy based on the set of trust requirements such as trust frameworks it belongs to (i.e., revocation checks), if applicable.

Note: Some of the processing rules of the Presentation Definition and the Presentation Submission are outlined in [@!DIF.PresentationExchange].

Wallet Invocation {#wallet-invocation}

The Verifier can use one of the following mechanisms to invoke a Wallet:

• Custom URL scheme as an authorization_endpoint (for example, openid4vp:// as defined in (#openid4vp-profile))
• Domain-bound Universal Links/App link as an authorization_endpoint
• no specific authorization_endpoint, End-User scanning a QR code with Authorization Request using a manually opened Wallet, instead of an arbitrary camera application on a user-device (neither custom URL scheme nor Universal/App link is used)

Wallet Metadata (Authorization Server Metadata) {#as_metadata_parameters}

This specification defines how the Verifier can determine Credential formats, proof types and algorithms supported by the Wallet to be used in a protocol exchange.

Additional Wallet Metadata Parameters

This specification defines new metadata parameters according to [@!RFC8414].

• presentation_definition_uri_supported: OPTIONAL. Boolean value specifying whether the Wallet supports the transfer of presentation_definition by reference, with true indicating support. If omitted, the default value is true.
• vp_formats_supported: REQUIRED. An object containing a list of name/value pairs, where the name is a string identifying a Credential format supported by the Wallet. Valid Credential format identifier values are defined in Appendix A of [@!OpenID.VCI]. Other values may be used when defined in the profiles of this specification. The value is an object containing a parameter defined below:
  • alg_values_supported: OPTIONAL. An object where the value is an array of case sensitive strings that identify the cryptographic suites that are supported. Parties will need to agree upon the meanings of the values used, which may be context-specific. For specific values that can be used depending on the Credential format, see (#alternative_credential_formats). If alg_values_supported is omitted, it is unknown what cryptographic suites the wallet supports.

The following is a non-normative example of a vp_formats_supported parameter:

"vp_formats_supported": {
  "jwt_vc_json": {
    "alg_values_supported": [
      "ES256K",
      "ES384"
    ]
  },
  "jwt_vp_json": {
    "alg_values_supported": [
      "ES256K",
      "EdDSA"
    ]
  }
}

client_id_schemes_supported: : OPTIONAL. Array of JSON Strings containing the values of the Client Identifier schemes that the Wallet supports. The values defined by this specification are pre-registered (which represents the behavior when no Client Identifier Scheme is used), redirect_uri, https, verifier_attestation, did, x509_san_dns, and x509_san_uri. If omitted, the default value is pre-registered. Other values may be used when defined in the profiles of this specification.

Additional wallet metadata parameters MAY be defined and used, as described in [@!RFC8414]. The Verifier MUST ignore any unrecognized parameters.

Obtaining Wallet's Metadata

Verifier utilizing this specification has multiple options to obtain Wallet's metadata:

• Verifier obtains Wallet's metadata dynamically, e.g., using [@!RFC8414] or out-of-band mechanisms. See (#as_metadata_parameters) for the details.
• Verifier has pre-obtained static set of Wallet's metadata. See (#openid4vp-profile) for the example.

Verifier Metadata (Client Metadata) {#client_metadata}

To convey Verifier metadata, Client metadata defined in Section 2 of [@!RFC7591] is used.

This specification defines how the Wallet can determine Credential formats, proof types and algorithms supported by the Verifier to be used in a protocol exchange.

Additional Verifier Metadata Parameters {#client_metadata_parameters}

This specification defines the following new Client metadata parameters according to [@!RFC7591], to be used by the Verifier:

vp_formats: : REQUIRED. An object defining the formats and proof types of Verifiable Presentations and Verifiable Credentials that a Verifier supports. For specific values that can be used, see (#alternative_credential_formats). Deployments can extend the formats supported, provided Issuers, Holders and Verifiers all understand the new format.

Additional Verifier metadata parameters MAY be defined and used, as described in [@!RFC7591]. The Wallet MUST ignore any unrecognized parameters.

Verifier Attestation JWT {#verifier_attestation_jwt}

The Verifier Attestation JWT is a JWT especially designed to allow a Wallet to authenticate a Verifier in a secure and flexible manner. A Verifier Attestation JWT is issued to the Verifier by a party that wallets trust for the purpose of authentication and authorization of Verifiers. The way this trust established is out of scope of this specification. Every Verifier is bound to a public key, the Verifier MUST always present a Verifier Attestation JWT along with the proof of possession for this key. In the case of the Client Identifier Scheme verifier_attestation, the authorization request is signed with this key, which serves as proof of possession.

A Verifier Attestation JWT MUST contain the following claims:

• iss: REQUIRED. This claim identifies the issuer of the Verifier Attestation JWT. The iss value MAY be used to retrieve the issuer's public key. How the trust is established between Wallet and Issuer and how the public key is obtained for validating the attestation's signature is out of scope of this specification.
• sub: REQUIRED. The value of this claim MUST be the client_id of the client making the credential request.
• iat: OPTIONAL. (number). The value of this claim MUST be the time at which the Verifier Attestation JWT was issued using the syntax defined in [RFC7519].
• exp: REQUIRED. (number). The value of this claim MUST be the time at which the Verifier Attestation JWT expires using the syntax defined in [RFC7519]. The Wallet MUST reject any Verifier Attestation JWT with an expiration time that has passed, subject to allowable clock skew between systems.
• nbf: OPTIONAL. The Verifier Attestation JWT MAY contain an "nbf" (not before) claim that identifies the time before which the token MUST NOT be accepted for processing.
• cnf: REQUIRED. This claim contains the confirmation method as defined in [@!RFC7800]. It MUST contain a JSON Web Key [@!RFC7517] as defined in Section 3.2 of [@!RFC7800]. This claim determines the public key for which's corresponding private key the Verifier MUST proof possession of when presenting the Verifier Attestation JWT. This additional security measure allows the Verifier to obtain a Verifier Attestation JWT from a trusted issuer and use it for a long time independent of that issuer without the risk of an adversary impersonating the Verifier by replaying a captured attestation.

Additional claims MAY be defined and used in the Verifier Attestation JWT, as described in [@!RFC7519]. The Wallet MUST ignore any unrecognized claims.

Verifier Attestation JWTs compliant with this specification MUST use the media type application/verifier-attestation+jwt as defined in (#va_media_type).

A Verifier Attestation JWT MUST set the typ JOSE header to verifier-attestation+jwt.

The Verifier Attestation JWT MAY be conveyed in the header of a JWS signed object (JOSE header).

This specification introduces a JOSE header, which can be used to add a JWT to such a header as follows:

• jwt: This JOSE header MUST contain a JWT.

In the context of this specification, such a JWT MUST set the typ JOSE header to verifier-attestation+jwt.

Implementation Considerations

Static Configuration Values of the Wallets

This document lists profiles that define static configuration values of the Wallets and defines one set of static configuration values that can be used by the Verifier when it is unable to perform Dynamic Discovery and is not using any of the profiles.

Profiles that Define Static Configuration Values

The following is a list of profiles that define static configuration values of Wallets:

• JWT VC Presentation Profile

A Set of Static Configuration Values bound to openid4vp:// {#openid4vp-profile}

The following is a non-normative example of a set of static configuration values that can be used with vp_token parameter as a supported Response Type, bound to a custom URL scheme openid4vp:// as an Authorization Endpoint:

{
  "authorization_endpoint": "openid4vp:",
  "response_types_supported": [
    "vp_token"
  ],
  "vp_formats_supported": {
    "jwt_vp_json": {
      "alg_values_supported": ["ES256"]
    },
    "jwt_vc_json": {
      "alg_values_supported": ["ES256"]
    }
  },
  "request_object_signing_alg_values_supported": [
    "ES256"
  ]
}

Nested Verifiable Presentations

Current version of this document does not support presentation of a Verifiable Presentation nested inside another Verifiable Presentation, even though [@!DIF.PresentationExchange] specification theoretically supports this by stating that the nesting of path_nested objects "may be any number of levels deep".

One level of nesting path_nested objects is sufficient to describe a Verifiable Credential included inside a Verifiable Presentation.

State Management {#state_management}

The state parameter defined in Section 4.1.1 of [@!RFC6749] may be used by a verifier to link requests and responses. Also see Section 3.6 and Section 5.3.5 of [@RFC6819], and [@I-D.ietf-oauth-security-topics].

When using Response Mode direct_post, also see (#security_considerations_direct_post).

Response Mode direct_post {#implementation_considerations_direct_post}

The design of the interactions between the different components of the Verifier (especially Frontend and Response URI) when using Response Mode direct_post is at the discretion of the Verifier since it does not affect the interface between the Verifier and the Wallet.

In order to support implementers, this section outlines a possible design that fulfills the Security Considerations given in (#security_considerations).

The design is illustrated in the following sequence diagram:

!---

+--------+   +------------+           +---------------------+                 +----------+
|End-User|   |  Verifier  |           |  Verifier           |                 |  Wallet  |
|        |   |            |           |  Response Endpoint  |                 |          |
+--------+   +------------+           +---------------------+                 +----------+  
    |              |                            |                                  |
    |   interacts  |                            |                                  |
    |------------->|                            |                                  |
    |              |  (1) create nonce          |                                  |
    |              |-----------+                |                                  |
    |              |           |                |                                  |
    |              |<----------+                |                                  |
    |              |                            |                                  |
    |              |  (2) initiate transaction  |                                  |
    |              |--------------------------->|                                  |
    |              |                            |                                  |
    |              |  (3) return transaction-id & request-id                       |
    |              |<---------------------------|                                  |
    |              |                            |                                  |
    |              |  (4) Authorization Request                                    |
    |              |      (response_uri, nonce, state)                             |
    |              |-------------------------------------------------------------->|
    |              |                            |                                  |
    |              End-User Authentication / Consent                               |
    |              |                            |                                  |
    |              |                            | (5) Authorization Response       |
    |              |                            |     (VP Token, state)            |
    |              |                            |<---------------------------------|
    |              |                            |                                  |
    |              |                            | (6) Response                     |
    |              |                            | (redirect_uri with response_code)|
    |              |                            |--------------------------------->|
    |              |                            |                                  |
    |              |  (7) Redirect to the redirect URI (response_code)             |
    |              |<--------------------------------------------------------------|
    |              |                            |                                  |
    |              |  (8) fetch response data   |                                  |
    |              |     (transaction-id, response_code)                           |
    |              |--------------------------->|                                  |
    |              |                            |                                  |
    |              |                            |                                  |
    |              |  (9) response data         |                                  |
    |              |     (VP Token, Presentation Submission)                       |
    |              |<---------------------------|                                  |
    |              |                            |                                  |
    |              |  (10) check nonce          |                                  |
    |              |-----------+                |                                  |
    |              |           |                |                                  |
    |              |<----------+                |                                  |

!--- Figure: Reference Design for Response Mode direct_post

(1) The Verifier produces a nonce value by generating at least 16 fresh, cryptographically random bytes with sufficient entropy, associates it with the session and base64url encodes it.

(2) The Verifier initiates a new transaction at its Response URI.

(3) The Response URI will set up the transaction and respond with two fresh, cryptographically random numbers with sufficient entropy designated as transaction-id and request-id. Those values are used in the process to identify the authorization response (request-id) and to ensure only the Verifier can obtain the Authorization Response data (transaction-id).

(4) The Verifier then sends the Authorization Request with the request-id as state and the nonce value created in step (1) to the Wallet.

(5) After authenticating the End-User and getting their consent to share the request Credentials, the Wallet sends the Authorization Response with the parameters vp_token, presentation_submission (optional) and state to the response_uri of the Verifier.

(6) The Verifier's Response URI checks whether the state value is a valid request-id. If so, it stores the Authorization Response data linked to the respective transaction-id. It then creates a response_code as fresh, cryptographically random number with sufficient entropy that it also links with the respective Authorization Response data. It then returns the redirect_uri, which includes the response_code to the Wallet.

Note: If the Verifier's Response URI does not return a redirect_uri, processing at the Wallet stops at that step. The Verifier is supposed to fetch the Authorization Response without waiting for a redirect (see step 8).

(7) The Wallet sends the user agent to the Verifier (redirect_uri). The Verifier receives the Request and extracts the response_code parameter.

(8) The Verifier sends the response_code and the transaction-id from its session to the Response URI.

• The Response URI uses the transaction-id to look the matching Authorization Response data up, which implicitly validates the transaction-id associated with the Verifier's session.
• If an Authorization Response is found, the Response URI checks whether the response_code was associated with this Authorization Response in step (6).

Note: If the Verifier's Response URI did not return a redirect_uri in step (6), the Verifier will periodically query the Response URI with the transaction-id to obtain the Authorization Response once it becomes available.

(9) The Response URI returns the VP Token and Presentation Submission for further processing to the Verifier.

(10) The Verifier checks whether the nonce received in the Credential(s) in the VP Token in step (9) corresponds to the nonce value from the session. The Verifier then consumes the VP Token and invalidates the transaction-id, request-id and nonce in the session.

Security Considerations {#security_considerations}

Preventing Replay of the VP Token {#preventing-replay}

An attacker could try to inject a VP Token (or an individual Verifiable Presentation), that was obtained from a previous Authorization Response, into another Authorization Response thus impersonating the End-User that originally presented that VP Token or the respective Verifiable Presentation.

Implementers of this specification MUST implement the controls as defined in this section to detect such an attack.

This specification assumes that a Verifiable Credential is always presented with a cryptographic proof of possession which can be a Verifiable Presentation. This cryptographic proof of possession MUST be bound by the Wallet to the intended audience (the Client Identifier of the Verifier) and the respective transaction (identified by the nonce parameter in the Authorization Request). The Verifier MUST verify this binding.

The Verifier MUST create a fresh, cryptographically random number with sufficient entropy for every Authorization Request, store it with its current session, and pass it in the nonce Authorization Request Parameter to the Wallet.

The Wallet MUST link every Verifiable Presentation returned to the Verifier in the VP Token to the client_id and the nonce values of the respective Authentication Request.

The Verifier MUST validate every individual Verifiable Presentation in an Authorization Response and ensure that it is linked to the values of the client_id and the nonce parameter it had used for the respective Authorization Request. If the response contains multiple Verifiable Presentations which do not contain the same nonce value, the response is rejected.

The client_id is used to detect the presentation of Verifiable Credentials to a party other than the one intended. This allows Verifiers take appropriate action in that case, such as not accepting the Verifiable Presentation. The nonce value binds the Presentation to a certain authentication transaction and allows the Verifier to detect injection of a Presentation in the flow, which is especially important in the flows where the Presentation is passed through the front-channel.

Note: Different formats for Verifiable Presentations and signature/proof schemes use different ways to represent the intended audience and the session binding. Some use claims to directly represent those values, others include the values into the calculation of cryptographic proofs. There are also different naming conventions across the different formats. In case Presentation Exchange is used in the Authorization Request, the format of the respective presentation is determined from the format information in the presentation submission in the Authorization Response. If DCQL was used, the format was defined by the Verifier in the request.

The following is a non-normative example of the payload of a Verifiable Presentation of a format identifier jwt_vp_json:

{
  "iss": "did:example:ebfeb1f712ebc6f1c276e12ec21",
  "jti": "urn:uuid:3978344f-8596-4c3a-a978-8fcaba3903c5",
  "aud": "s6BhdRkqt3",
  "nonce": "343s$FSFDa-",
  "nbf": 1541493724,
  "iat": 1541493724,
  "exp": 1573029723,
  "vp": {
    "@context": [
      "https://www.w3.org/2018/credentials/v1",
      "https://www.w3.org/2018/credentials/examples/v1"
    ],
    "type": ["VerifiablePresentation"],

    "verifiableCredential": [""]
  }
}

In the example above, the requested nonce value is included as the nonce and client_id as the aud value in the proof of the Verifiable Presentation.

The following is a non-normative example of a Verifiable Presentation of a format identifier ldp_vp without a proof property:

{
  "@context": [ ... ],
  "type": "VerifiablePresentation",
  "verifiableCredential": [ ... ],
  "proof": {
    "type": "RsaSignature2018",
    "created": "2018-09-14T21:19:10Z",
    "proofPurpose": "authentication",
    "verificationMethod": "did:example:ebfeb1f712ebc6f1c276e12ec21#keys-1",    
    "challenge": "343s$FSFDa-",
    "domain": "s6BhdRkqt3",
    "jws": "eyJhb...nKb78"
  }
}

In the example above, the requested nonce value is included as the challenge and client_id as the domain value in the proof of the Verifiable Presentation.

Session Fixation {#session_fixation}

To perform a Session Fixation attack, an attacker would start the process using a Verifier executed on a device under his control, capture the Authorization Request and relay it to the device of a victim. The attacker would then periodically try to conclude the process in his Verifier, which would cause the Verifier on his device to try to fetch and verify the Authorization Response.

Such an attack is impossible against flows implemented with the Response Mode fragment as the Wallet will always send the VP Token to the redirect endpoint on the same device where it resides. This means an attacker could extract a valid Authorization Request from a Verifier on his device and trick a Victim into performing the same Authorization Request on her device. But there is technically no way for an attacker to get hold of the resulting VP Token.

However, the Response Mode direct_post is susceptible to such an attack as the result is sent from the Wallet out-of-band to the Verifier's Response URI.

This kind of attack can be detected if the Response Mode direct_post is used in conjunction with the redirect URI, which causes the Wallet to redirect the flow to the Verifier's frontend at the device where the transaction was concluded. The Verifier's Response URI MUST include a fresh secret (Response Code) into the redirect URI returned to the Wallet and the Verifier's Response URI MUST require the frontend to pass the respective Response Code when fetching the Authorization Response. That stops session fixation attacks as long as the attacker is unable to get access to the Response Code.

Note that this protection technique is not applicable to cross-device scenarios because the browser used by the wallet will not have the original session. It is also not applicable in same-device scenarios if the wallet uses a browser different from the one used on the presentation request (e.g. device with multiple installed browsers), because the original session will also not be available there.

See (#implementation_considerations_direct_post) for more implementation considerations.

When using the Response Mode direct_post without the further protection provided by the redirect URI, there is no session context for the Verifier to detect session fixation attempts. It is RECOMMENDED for the Verifiers to implement mechanisms to strengthen the security of the flow. For more details on possible attacks and mitigations see [@I-D.ietf-oauth-cross-device-security].

Response Mode "direct_post" {#security_considerations_direct_post}

Validation of the Response URI

The Wallet MUST ensure the data in the Authorization Response cannot leak through Response URIs. When using pre-registered Response URIs, the Wallet MUST comply with best practices for redirect URI validation as defined in [@I-D.ietf-oauth-security-topics]. The Wallet MAY also rely on a Client Identifier Scheme in conjunction with Client Authentication and integrity protection of the request to establish trust in the Response URI provided by a certain Verifier.

Protection of the Response URI

The Verifier SHOULD protect its Response URI from inadvertent requests by checking that the value of the received state parameter corresponds to a recent Authorization Request. It MAY also use JARM [@!JARM] to authenticate the originator of the request.

Protection of the Authorization Response Data

This specification assumes that the Verifier's Response URI offers an internal interface to other components of the Verifier to obtain (and subsequently process) Authorization Response data. An attacker could try to obtain Authorization Response Data from a Verifier's Response URI by looking up this data through the internal interface. This could lead to leakage valid Verifiable Presentations containing PII.

Implementations of this specification MUST have security mechanisms in place to prevent inadvertent requests against this internal interface. Implementation options to fulfill this requirement include:

• Authentication between the different parts within the Verifier
• Two cryptographically random numbers. The first being used to manage state between the Wallet and Verifier. The second being used to ensure that only a legitimate component of the Verifier can obtain the Authorization Response data.

End-User Authentication using Verifiable Credentials

Clients intending to authenticate the End-User utilizing a claim in a Verifiable Credential MUST ensure this claim is stable for the End-User as well locally unique and never reassigned within the Credential Issuer to another End-User. Such a claim MUST also only be used in combination with the Credential Issuer identifier to ensure global uniqueness and to prevent attacks where an attacker obtains the same claim from a different Credential Issuer and tries to impersonate the legitimate End-User.

Encrypting an Unsigned Response {#encrypting_unsigned_response}

If an encrypted Authorization Response has no additional integrity protection, an attacker might be able to alter Authorization Response parameters such as presentation_submission and generate a new encrypted Authorization Response for the Verifier, as encryption is performed using the public key of the Verifier which is likely to be widely known. Note this includes injecting a new VP Token. Since the contents of the VP Token are integrity protected, tampering the VP Token is detectable by the Verifier. For details, see (#preventing-replay).

DIF Presentation Exchange 2.0.0

Fetching Presentation Definitions by Reference

In many instances the referenced server will be operated by a known federation or other trusted operator, and the URL's domain name will already be widely known. Wallets using this URI can mitigate request forgeries by having a pre-configured set of trusted domain names and only fetching Presentation Definition from these sources. In addition, the Presentation Definitions could be signed by a trusted authority, such as the federation operator.

JSONPath and Arbitrary Scripting

Implementers MUST make sure that JSONPath used as part of presentation_definition and presentation_submission parameters cannot be used to execute arbitrary scripts on a server. This can be achieved, for example, by implementing the entire syntax of the query without relying on the parsers of programming language engine. For details, see Section 4 of [@I-D.ietf-jsonpath-base].

Filters Property

Implementers should be careful with what is used as a filter property in [@!DIF.PresentationExchange]. For example, when using regular expressions or JSON Schemas as filters, implementers should ensure that computations and resource access are bounded with the security in mind to prevent attacks such as denial of service or unauthorized access.

TLS Requirements

Implementations MUST follow [@!BCP195].

Whenever TLS is used, a TLS server certificate check MUST be performed, per [@!RFC6125].

Privacy Considerations

Authorization Requests with Request URI

If the Wallet is acting within a trust framework that allows the Wallet to determine whether a 'request_uri' belongs to a certain 'client_id', the Wallet is RECOMMENDED to validate the Verifier's authenticity and authorization given by 'client_id' and that the 'request_uri' corresponds to this Verifier. If the link cannot be established in those cases, the Wallet SHOULD refuse the request or ask the End-User for advise.

If no End-User interaction is required before sending the request, it is easy to request on a large scale and in an automated fashion the wallet capabilities from all visitors of a website. Even without personally identifiable information (PII) this can reveal some information about End-Users, like their nationality (e.g., a Wallet with special capabilities only used in one EU member state).

Mandatory End-User interaction before sending the request, like clicking a button, unlocking the wallet or even just showing a screen of the app, can make this less attractive/likely to being exploited.

Requests from the Wallet to the Verifier SHOULD be sent with the minimal amount of information possible, and in particular, without any HTTP headers identifying the software used for the request (e.g., HTTP libraries or their versions). The Wallet MUST NOT send PII or any other data that could be used for fingerprinting to the Request URI in order to prevent End-User tracking.

Authorization Error Response with the wallet_unavailable error code

In the event that another component is invoked instead of the Wallet, the End-User MUST be informed and give consent before the invoked component returns the wallet_unavailable Authorization Error Response to the Verifier.

{backmatter}

<title>Verifiable Credentials Data Model 1.1</title> Digital Bazaar ConsenSys Digital Bazaar ConsenSys Evernym University of Kent <title>Self-Issued OpenID Provider V2</title> German Federal Agency for Disruptive Innovation (SPRIND) Self-Issued Consulting German Federal Agency for Disruptive Innovation (SPRIND) <title>OpenID Connect Core 1.0 incorporating errata set 2</title> NAT.Consulting Yubico Self-Issued Consulting Google Disney <title>Presentation Exchange 2.0.0</title> Microsoft Evernym Consensys Mesh Centre Consortium <title>Decentralized Identifiers (DIDs) v1.0</title> Digital Bazaar Digital Bazaar Danube Tech Evernym <title>OpenID Connect Dynamic Client Registration 1.0 incorporating errata set 2</title> NAT.Consulting Yubico Self-Issued Consulting <title>Hyperledger Indy Project</title> Hyperledger Indy Project <title>JWT Secured Authorization Response Mode for OAuth 2.0 (JARM)</title> yes.com Ping Identity <title>ISO/IEC 18013-5:2021 Personal identification — ISO-compliant driving license — Part 5: Mobile driving license (mDL) application</title> ISO/IEC JTC 1/SC 17 Cards and security devices for personal identification <title>ISO/IEC DTS 18013-7 Personal identification — ISO-compliant driving license — Part 7: Mobile driving license (mDL) add-on functions</title> ISO/IEC JTC 1/SC 17 Cards and security devices for personal identification <title>ISO/IEC DTS 23220-2 Personal identification — Building blocks for identity management via mobile devices, Part 2: Data objects and encoding rules for generic eID systems</title> ISO/IEC JTC 1/SC 17 Cards and security devices for personal identification <title>ISO/IEC CD TS 23220-4 Personal identification — Building blocks for identity management via mobile devices, Part 4: Protocols and services for operational phase</title> ISO/IEC JTC 1/SC 17 Cards and security devices for personal identification <title>BCP195</title> IETF <title>OAuth 2.0 Multiple Response Type Encoding Practices</title> Google Google Evernym Microsoft <title>OpenID for Verifiable Credential Issuance</title> German Federal Agency for Disruptive Innovation (SPRIND) German Federal Agency for Disruptive Innovation (SPRIND) Mattr <title>OpenID Federation 1.0</title> independent Self-Issued Consulting Sikt Yubico independent Connect2id <title>Digital Credentials API</title> Apple Inc. Google <title>OAuth Parameters</title> IANA <title>Media Types</title> IANA <title>Uniform Resource Identifier (URI) Schemes</title> IANA <title>JSON Object Signing and Encryption (JOSE)</title> IANA <title>Named Information Hash Algorithm Registry</title> IANA

OpenID4VP profile for the W3C Digital Credentials API

This section defines a profile of OpenID4VP for use with the W3C Digital Credentials API [@!w3c.digital_credentials_api].

The W3C Digital Credentials API defines a Web Platform API which allows web sites acting as Verifiers to request the presentation of Verifiable Credentials. The API itself does not define a Credential exchange protocol but can be used with multiple protocols. The Web Platform, working in conjunction with other layers, such as the app platform/operating system, and based on the permission of the End-User, will send the request data along with the web origin of the Verifier to the End-User's chosen Wallet.

This OpenID4VP profile utilizes the mechanisms of the W3C Digital Credentials API while also allowing to leverage advanced security features of OpenID4VP, if needed. It also defines the OpenID4VP request parameters that MAY be used with the W3C Digital Credentials API.

The Digital Credentials API offers several advantages for implementers of both Verifiers and Wallets.

Firstly, the API serves as a privacy-preserving alternative to invoking Wallets via URLs, particularly custom URL schemes. The underlying app platform will only invoke a Wallet if the End-User confirms the request based on contextual information about the Credential Request and the requestor (Verifier).

Secondly, the session with the End-User will always continue in the initial context, typically a web browser tab, when the request has been fulfilled (or aborted), which results in an improved user experience.

Thirdly, cross-device requests benefit from the use of secure transports with proximity checks, which are handled by the OS platform, e.g., using FIDO CTAP 2.2 with hybrid transports.

And lastly, as part of the request, the Wallet is provided with information about the Verifier's origin as authenticated by the user agent, which is important for phishing resistance.

Protocol

For the profile defined in this section, the value of the exchange protocol used with the W3C Digital Credentials API [@!w3c.digital_credentials_api], is openid4vp.

Request {#browser_api_request}

The Verifier MAY send all the OpenID4VP request parameters to the W3C Digital Credentials API as defined in [@!w3c.digital_credentials_api].

The following is a non-normative example of an unsigned OpenID4VP request (when advanced security features of OpenID4VP are not used) that can be sent over the W3C Digital Credentials API :

{
  response_type: "vp_token",
  response_mode: "w3c_dc_api",
  nonce: "n-0S6_WzA2Mj",
  client_metadata: {...},
  presentation_definition: {...}
}

Out of the Authorization Request parameters defined in [@!RFC6749] and (#vp_token_request), the following are supported with this profile:

• client_id
• response_type
• response_mode
• nonce
• presentation_definition
• client_metadata
• request

The client_id parameter MUST be omitted in unsigned requests defined in (#unsigned_request). The Wallet determines the effective Client Identifier from the origin as asserted by the Web Platform and/or app platform. The effective Client Identifier is composed of a synthetic Client Identifier Scheme of web-origin and the origin itself. For example, an origin of https://verifier.example.com would result in an effective Client Identifier of web-origin:https://verifier.example.com. The transport of the request and origin from the Web Platform and/or app platform to the Wallet is platform-specific and is out of scope of this profile.

The value of the response_mode parameter MUST be w3c_dc_api when the response is neither signed nor encrypted and w3c_dc_api.jwt when the response is signed and/or encrypted as defined in (#jarm).

In addition to the above-mentioned parameters, this profile introduces a new parameter:

• expected_origins: REQUIRED when signed requests defined in (#signed_request) are used with the W3C Digital Credentials API [@!w3c.digital_credentials_api]. An array of strings, each string representing an origin of the Verifier that is making the request. The Wallet can detect replay of the request from a malicious Verifier by comparing values in this parameter to the origin asserted by the Web Platform.

Additional request parameters MAY be defined and used with this profile for the W3C Digital Credentials API. The Wallet MUST ignore any unrecognized parameters.

Signed and Unsigned Requests

Any OpenID4VP request compliant to this section of this specification can be used with the W3C Digital Credentials API [@!w3c.digital_credentials_api]. Depending on the mechanism used to identify and authenticate the Verifier, the request can be signed or unsigned. This section defines signed and unsigned OpenID4VP requests for use with the W3C Digital Credentials API.

Unsigned Request {#unsigned_request}

The Verifier MAY send all the OpenID4VP request parameters as members in the request member passed to the API. In this case, the Wallet will use the Verifier's origin as asserted by the user agent to determine the Verifier's effective Client Identifier.

Signed Request {#signed_request}

The Verifier MAY send a signed request, for example, when identification and authentication of the Verifier is required.

The signed Request Object MAY contain all the parameters listed in (#browser_api_request), except request.

Below is a non-normative example of such a request sent over the W3C Digital Credentials API:

{ request: "eyJhbGciOiJF..." }

This is an example of the payload of a signed OpenID4VP request used with the W3C Digital Credentials API:

<{{examples/digital_credentials_api/signed_request_payload.json}}

The signed request allows the Wallet to authenticate the Verifier using a trust framework other than the Web PKI utilized by the browser. An example of such a trust framework is the Verifier (RP) management infrastructure set up in the context of the eIDAS regulation in the European Union, in which case, the Wallet can no longer rely only on the web origin of the Verifier. This web origin MAY still be used to further strengthen the security of the flow. The external trust framework could, for example, map the Client Identifier to registered web origins.

Response

Every OpenID4VP Authorization Request results in a response being provided through the W3C Digital Credentials API. The response is an instance of the DigitalCredential interface, as defined in [@!w3c.digital_credentials_api], and the OpenID4VP Authorization Response parameters as defined for the Response Type are represented as an object within the data attribute.

Credential Format Profiles {#alternative_credential_formats}

OpenID for Verifiable Presentations is Credential Format agnostic, i.e., it is designed to allow applications to request and receive Verifiable Presentations and Verifiable Credentials in any Credential Format. This section defines Credential Format Profiles for some of the known Credential Formats. Other specifications or deployments can define their own Credential Format Profiles.

W3C Verifiable Credentials

W3C Verifiable Credentials may use an additional parameter for the descriptor_map with the presentation_submission: The path_nested object inside an Input Descriptor Mapping Object is used to describe how to find a returned Credential within a Verifiable Presentation, and contains a format parameter with the Credential format identifier as a value and a path parameter with a relative path to the Verifiable Credential. Non-normative examples can be found further in this section.

VC signed as a JWT, not using JSON-LD {#jwt_vc}

This section illustrates presentation of a Credential conformant to [@VC_DATA] that is signed using JWS, and does not use JSON-LD.

The Credential format identifiers are jwt_vc_json for a W3C Verifiable Credential and jwt_vp_json for W3C Verifiable Presentation.

Cipher suites should use algorithm names defined in IANA JOSE Algorithms Registry.

Example Credential

The following is a non-normative example of the payload of a JWT-based W3C Verifiable Credential that will be used throughout this section:

<{{examples/credentials/jwt_vc.json}}

Presentation Request

The following is a non-normative example of an Authorization Request:

<{{examples/request/request.txt}}

The requirements regarding the Credential to be presented are conveyed in the presentation_definition parameter.

The following is a non-normative example of the contents of a presentation_definition parameter:

<{{examples/request/pd_jwt_vc.json}}

This presentation_definition parameter contains a single input_descriptor element, which sets the desired format to JWT VC and defines a constraint over the vc.type parameter to select Verifiable Credentials of type IDCredential.

Presentation Response

The following is a non-normative example of an Authorization Response:

<{{examples/response/response.txt}}

The following is a non-normative example of the content of the presentation_submission parameter:

<{{examples/response/ps_jwt_vc.json}}

The following is a non-normative example of the payload of the Verifiable Presentation in the vp_token parameter provided in the same response and referred to by the presentation_submission above:

<{{examples/response/jwt_vp.json}}

Note: The VP's nonce claim contains the value of the nonce of the presentation request and the aud claim contains the Client Identifier of the Verifier. This allows the Verifier to detect replay of a Presentation as recommended in (#preventing-replay).

LDP VCs

This section illustrates presentation of a Credential conformant to [@VC_DATA] that is secured using Data Integrity, using JSON-LD.

The Credential format identifiers are ldp_vc for a W3C Verifiable Credential and ldp_vp for W3C Verifiable Presentation.

Cipher suites should use signature suites names defined in Linked Data Cryptographic Suite Registry.

Example Credential

The following is a non-normative example of the payload of a Verifiable Credential that will be used throughout this section:

<{{examples/credentials/ldp_vc.json}}

Presentation Request

The following is a non-normative example of an Authorization Request:

<{{examples/request/request.txt}}

The following is a non-normative example of the contents of a presentation_definition parameter that contains the requirements regarding the Credential to be presented:

<{{examples/request/pd_ldp_vc.json}}

This presentation_definition parameter contains a single input_descriptor element, which sets the desired format to LDP VC and defines a constraint over the type parameter to select Verifiable Credentials of type IDCredential.

Presentation Response

The following is a non-normative example of an Authorization Response:

<{{examples/response/response.txt}}

The following is a non-normative example of the content of the presentation_submission parameter:

<{{examples/response/ps_ldp_vc.json}}

The following is a non-normative example of the Verifiable Presentation in the vp_token parameter provided in the same response and referred to by the presentation_submission above:

<{{examples/response/ldp_vp.json}}

Note: The VP's challenge claim contains the value of the nonce of the presentation request and the domain claims contains the Client Identifier of the Verifier. This allows the Verifier to detect replay of a presentation as recommended in (#preventing-replay).

AnonCreds

AnonCreds is a Credential format defined as part of the Hyperledger Indy project [@Hyperledger.Indy].

To be able to request AnonCreds, there needs to be a set of identifiers for Verifiable Credentials, Verifiable Presentations ("proofs" in Indy terminology) and crypto schemes.

Credential format identifier is ac_vc for a Credential, and ac_vp for a Presentation.

Identifier for a CL-signature crypto scheme used in the examples in this section is CLSignature2019.

Example Credential

The following is a non-normative example of an AnonCred Credential that will be used throughout this section.

<{{examples/credentials/ac_vc.json}}

The most important parts for the purpose of this section are scheme_id parameter and values parameter that contains the actual End-User claims.

Presentation Request

Request Example {#anoncreds_request}

The following is a non-normative example of an Authorization Request:

<{{examples/request/request.txt}}

The following is a non-normative example of the content of the presentation_definition parameter:

<{{examples/request/pd_ac_vc.json}}

The format object in the input_descrioptor element uses the format identifier ac_vc as defined above and sets the proof_type to CLSignature2019 to denote this descriptor requires a Credential in AnonCreds format signed with a CL signature (Camenisch-Lysyanskaya signature). The rest of the expressions operate on the AnonCreds JSON structure.

The constraints object requires the selected Credential to conform with the schema definition did:indy:idu:test:3QowxFtwciWceMFr7WbwnM:2:BasicScheme:0\\.1, which is denoted as a constraint over the AnonCred's schema_id parameter.

Request Example with Selective Release of Claims

The next example leverages the AnonCreds' capabilities for selective release by requesting a subset of the claims in the Credential to be disclosed to the Verifier.

A non-normative example of an Authorization Request would look the same as in (#anoncreds_request).

The following is a non-normative example of the difference is in the presentation_definition parameter:

<{{examples/request/pd_ac_vc_sd.json}}

This example is identical to the previous one with the following exceptions: It sets the element limit_disclosure of the constraint to require and adds two more constraints for the individual claims given_name and family_name. Since such claims are stored underneath a values container in an AnonCred, values is part of the path to identify the respective claims.

Presentation Response

A non-normative example of the Authorization Response would look the same as in the examples of other Credential formats. It would contain the presentation_submission and vp_token parameters.

The following is a non-normative example of the content of the presentation_submission parameter:

<{{examples/response/ps_ac_vc_sd.json}}

The descriptor_map refers to the input_descriptor element with an identifier id_credential and tells the Verifier that there is a proof of AnonCred Credential (format is ac_vp) directly in the vp_token (path is the root designated by $). Furthermore, it indicates using path_nested parameter that the End-User claims can be found embedded in the proof underneath requested_proof.revealed_attr_groups.id_card_credential.

The following is the content of the vp_token parameter:

<{{examples/response/ac_vp_sd.json}}

Mobile Documents or mdocs (ISO/IEC 18013 and ISO/IEC 23220 series) {#mdocs}

ISO/IEC 18013-5:2021 [@ISO.18013-5] defines a mobile driving license (mDL) Credential in the mobile document (mdoc) format. Although ISO/IEC 18013-5:2021 [@ISO.18013-5] is specific to mobile driving licenses (mDLs), the Credential format can be utilized with any type of Credential (or mdoc document types). The ISO/IEC 23220 series has extracted components from ISO/IEC 18013-5:2021 [@ISO.18013-5] and ISO/IEC TS 18013-7 [@ISO.18013-7] that are common across document types to facilitate the profiling of the specification for other document types. The core data structures are shared between ISO/IEC 18013-5:2021 [@ISO.18013-5], ISO/IEC 23220-2 [@ISO.23220-2], ISO/IEC 23220-4 [@ISO.23220-4] which are encoded in CBOR and secured using COSE_Sign1.

The Credential format identifier for Credentials in the mdoc format is mso_mdoc.

ISO/IEC TS 18013-7 Annex B [@ISO.18013-7] and ISO/IEC 23220-4 [@ISO.23220-4] Annex C define a profile of OpenID4VP for requesting and presenting Credentials in the mdoc format.

The profile includes the following elements:

• Rules for the presentation_definition Authorization Request parameter.
• Rules for the presentation_submission Authorization Response parameter.
• Wallet invocation using the mdoc-openid4vp:// custom URI scheme.
• Defines the OpenID4VP-specific Handover CBOR structure and how OpenID4VP Authorization Request and Request Object parameters apply to the SessionTranscript CBOR structure and DeviceResponse CBOR structure as specified in ISO/IEC 18013-5 [@ISO.18013-5] and ISO/IEC 23220-4 [@ISO.23220-4].
• Required Wallet and Verifier Metadata parameters and their values.
• Additional restrictions on Authorization Request and Authorization Response parameters to ensure compliance with ISO/IEC TS 18013-7 [@ISO.18013-7] and ISO/IEC 23220-4 [@ISO.23220-4]. For instance, to comply with ISO/IEC TS 18013-7 [@ISO.18013-7], only the same-device flow is supported, the request_uri Authorization Request parameter is required, and the Authorization Response has to be encrypted.

DCQL Query and Response

An example DCQL query using the mdoc format is shown in (#more_dcql_query_examples). The following is a non-normative example for a VP Token in the response:

{
  "my_credential": "<base64url-encoded DeviceResponse>"
}

Presentation Request

See ISO/IEC TS 18013-7 Annex B [@ISO.18013-7] and ISO/IEC 23220-4 Annex C [@ISO.23220-4] for the latest examples on how to use the presentation_definition parameter for requesting Credentials in the mdoc format.

Presentation Response

The VP Token contains the base64url-encoded DeviceResponse CBOR structure as defined in ISO/IEC 18013-5 [@ISO.18013-5] or ISO/IEC 23220-4 [@ISO.23220-4]. Essentially, the DeviceResponse CBOR structure contains a signature or MAC over the SessionTranscript CBOR structure including the OpenID4VP-specific Handover CBOR structure.

See ISO/IEC TS 18013-7 Annex B [@ISO.18013-7] and ISO/IEC 23220-4 Annex C [@ISO.23220-4] for the latest examples on how to use the presentation_submission parameter and how to generate the Authorizaton Response for presenting Credentials in the mdoc format.

IETF SD-JWT VC

This section defines how Credentials complying with [@!I-D.ietf-oauth-sd-jwt-vc] can be presented to the Verifier using this specification.

Format Identifier

The Credential format identifier is vc+sd-jwt.

Example Credential

The following is a non-normative example of the unsecured payload of an IETF SD-JWT VC that will be used throughout this section:

<{{examples/credentials/sd_jwt_vc_unsecured.json}}

The following is a non-normative example of an IETF SD-JWT VC using the unsecured payload above, containing claims that are selectively disclosable.

<{{examples/credentials/sd_jwt_vc.json}}

The following are disclosures belonging to the claims from the example above.

Claim given_name:

• SHA-256 Hash: jsu9yVulwQQlhFlM_3JlzMaSFzglhQG0DpfayQwLUK4
• Disclosure:
  WyIyR0xDNDJzS1F2ZUNmR2ZyeU5STjl3IiwgImdpdmVuX25hbWUiLCAiSm9o
biJd
• Contents: ["2GLC42sKQveCfGfryNRN9w", "given_name", "John"]

Claim family_name:

• SHA-256 Hash: TGf4oLbgwd5JQaHyKVQZU9UdGE0w5rtDsrZzfUaomLo
• Disclosure:
  WyJlbHVWNU9nM2dTTklJOEVZbnN4QV9BIiwgImZhbWlseV9uYW1lIiwgIkRv
ZSJd
• Contents: ["eluV5Og3gSNII8EYnsxA_A", "family_name", "Doe"]

Claim birthdate:

• SHA-256 Hash: tiTngp9_jhC389UP8_k67MXqoSfiHq3iK6o9un4we_Y
• Disclosure:
  WyI2SWo3dE0tYTVpVlBHYm9TNXRtdlZBIiwgImJpcnRoZGF0ZSIsICIxOTQw
LTAxLTAxIl0
• Contents: ["6Ij7tM-a5iVPGboS5tmvVA", "birthdate", "1940-01-01"]

Verifier Metadata

The format value in the vp_formats parameter of the Verifier metadata MUST have the key vc+sd-jwt, and the value is an object consisting of the following name/value pairs:

• sd-jwt_alg_values: OPTIONAL. A JSON array containing identifiers of cryptographic algorithms the Verifier supports for signing of an Issuer-signed JWT of an SD-JWT. If present, the alg JOSE header (as defined in [@!RFC7515]) of the Issuer-signed JWT of the presented SD-JWT MUST match one of the array values.
• kb-jwt_alg_values: OPTIONAL. A JSON array containing identifiers of cryptographic algorithms the Verifier supports for signing of a Key Binding JWT (KB-JWT). If present, the alg JOSE header (as defined in [@!RFC7515]) of the presented KB-JWT MUST match one of the array values.

The following is a non-normative example of client_metadata request parameter value in a request to present an IETF SD-JWT VC.

<{{examples/client_metadata/sd_jwt_vc_verifier_metadata.json}}

DCQL Query and Response

A non-normative example DCQL query using the SD-JWT VC format is shown in (#dcql_query_example). The respective response is shown in (#response_dcql_query).

Additional examples are shown in (#more_dcql_query_examples).

Presentation Request

The following is a non-normative example of an Authorization Request:

<{{examples/request/request.txt}}

The following is a non-normative example of the contents of a presentation_definition parameter that contains the requirements regarding the Credential to be presented:

<{{examples/request/pd_sd_jwt_vc.json}}

The presentation of an IETF SD-JWT VC is requested by adding an object named vc+sd-jwt to the format object of an input_descriptor. The input_descriptor value is applied to the unsecured payload of the IETF SD-JWT VC which correspond to the disclosures of the presented SD-JWT VC.

Setting limit_disclosure property defined in [@!DIF.PresentationExchange] to required enables selective release by instructing the Wallet to submit only the disclosures for the matching claims specified in the fields array. The unsecured payload of an IETF SD-JWT VC is used to perform the matching.

Presentation Response

A non-normative example of the Authorization Response would look the same as in the examples of other Credential formats in this Annex.

The transaction_data_hashes response parameter defined in (#transaction_data) MUST be included in the Key Binding JWT as a top level claim. This means that transaction data mechanism cannot be used with SD-JWT VCs without cryptographic key binding and, therefore, do not use KB JWT.

The following is a non-normative example of the content of the presentation_submission parameter:

<{{examples/response/ps_sd_jwt_vc.json}}

The following is a non-normative example of the vp_token parameter provided in the same response and referred to by the presentation_submission above:

<{{examples/response/token_response_vp_token_sd_jwt_vc.txt}}

In this example the vp_token contains only the disclosures for the claims specified in the presentation_submission, along with a Key Binding JWT.

The following is a non-normative example of the unsecured payload of the Key Binding JWT.

<{{examples/response/kb_jwt_unsecured.json}}

Note: The Key Binding JWT nonce claim contains the value of the nonce from the authorization request, and the aud claim contains the Client Identifier of the Verifier.

Combining this specification with SIOPv2

This section shows how SIOP and OpenID for Verifiable Presentations can be combined to present Verifiable Credentials and pseudonymously authenticate an End-User using subject controlled key material.

Request {#siop_request}

The following is a non-normative example of a request that combines this specification and [@!SIOPv2].

GET /authorize?
  response_type=vp_token%20id_token
  &scope=openid
  &id_token_type=subject_signed
  &client_id=https%3A%2F%2Fclient.example.org%2Fcb
  &redirect_uri=https%3A%2F%2Fclient.example.org%2Fcb
  &presentation_definition=...
  &nonce=n-0S6_WzA2Mj HTTP/1.1
Host: wallet.example.com

The differences to the example requests in the previous sections are:

• response_type is set to vp_token id_token. This means the Wallet returns the presentation_submission and vp_token parameters in the same response as the id_token parameter as described in (#response).
• The request includes the scope parameter with value openid making this an OpenID Connect request. Additionally, the request also contains the parameter id_token_type with value subject_signed requesting a Self-Issuer ID Token, i.e., the request is a SIOP request.

Response

The following is a non-normative example of a response sent upon receiving a request provided in (#siop_request):

HTTP/1.1 302 Found
Location: https://client.example.org/cb#
  id_token=
  &presentation_submission=...
  &vp_token=...

In addition to the presentation_submission and vp_token, it also contains an id_token.

The following is a non-normative example of the payload of a Self-Issued ID Token [@!SIOPv2] contained in the above response:

{
  "iss": "did:example:NzbLsXh8uDCcd6MNwXF4W7noWXFZAfHkxZsRGC9Xs",
  "sub": "did:example:NzbLsXh8uDCcd6MNwXF4W7noWXFZAfHkxZsRGC9Xs",
  "aud": "x509_san_uri:https://client.example.org/cb",
  "nonce": "n-0S6_WzA2Mj",
  "exp": 1311281970,
  "iat": 1311280970
}

Note: The nonce and aud are set to the nonce of the request and the Client Identifier of the Verifier, respectively, in the same way as for the Verifier, Verifiable Presentations to prevent replay.

Examples for DCQL Queries {#more_dcql_query_examples}

The following is a non-normative example of a DCQL query that requests a Verifiable Credential in the format mso_mdoc with the claims vehicle_holder and first_name:

<{{examples/query_lang/simple_mdoc.json}}

The following is a non-normative example of a DCQL query that requests multiple Verifiable Credentials; all of them must be returned:

<{{examples/query_lang/multi_credentials.json}}

The following shows a complex query where the Wallet is requested to deliver the pid credential, or the other_pid credential, or both pid_reduced_cred_1 and pid_reduced_cred_2. Additionally, the nice_to_have credential may optionally be delivered.

<{{examples/query_lang/credentials_alternatives.json}}

The following shows a query where an ID and an address are requested; either can come from an mDL or a photoid Credential.

<{{examples/query_lang/complex_mdoc.json}}

The following is a non-normative example of a DCQL query that requests

• the mandatory claims last_name and date_of_birth, and
• either the claim postal_code, or, if that is not available, both of the claims locality and region.

<{{examples/query_lang/claims_alternatives.json}}

The following example shows a query that uses the values constraints to request a credential with specific values for the last_name and postal_code claims:

<{{examples/query_lang/value_matching_simple.json}}

IANA Considerations

OAuth Authorization Endpoint Response Types Registry

This specification registers the following response_type values in the IANA "OAuth Authorization Endpoint Response Types" registry [@IANA.OAuth.Parameters] established by [@!RFC6749].

vp_token

• Response Type Name: vp_token
• Change Controller: OpenID Foundation Artifact Binding Working Group - [email protected]
• Specification Document(s): (#response) of this specification

vp_token id_token

• Response Type Name: vp_token id_token
• Change Controller: OpenID Foundation Artifact Binding Working Group - [email protected]
• Specification Document(s): (#response) of this specification

OAuth Parameters Registry

This specification registers the following OAuth parameters in the IANA "OAuth Parameters" registry [@IANA.OAuth.Parameters] established by [@!RFC6749].

presentation_definition

• Name: presentation_definition
• Parameter Usage Location: authorization request
• Change Controller: OpenID Foundation Artifact Binding Working Group - [email protected]
• Reference: (#vp_token_request) of this specification

presentation_definition_uri

• Name: presentation_definition_uri
• Parameter Usage Location: authorization request
• Change Controller: OpenID Foundation Artifact Binding Working Group - [email protected]
• Reference: (#vp_token_request) of this specification

client_metadata

• Name: client_metadata
• Parameter Usage Location: authorization request
• Change Controller: OpenID Foundation Artifact Binding Working Group - [email protected]
• Reference: (#vp_token_request) of this specification

request_uri_method

• Name: request_uri_method
• Parameter Usage Location: authorization request
• Change Controller: OpenID Foundation Artifact Binding Working Group - [email protected]
• Reference: (#vp_token_request) of this specification

wallet_nonce

• Name: wallet_nonce
• Parameter Usage Location: authorization request, token response
• Change Controller: OpenID Foundation Artifact Binding Working Group - [email protected]
• Reference: (#request_uri_method_post) of this specification

response_uri

• Name: response_uri
• Parameter Usage Location: authorization request
• Change Controller: OpenID Foundation Artifact Binding Working Group - [email protected]
• Reference: (#response_mode_post) of this specification

vp_token

• Name: vp_token
• Parameter Usage Location: authorization response, token response
• Change Controller: OpenID Foundation Artifact Binding Working Group - [email protected]
• Reference: (#response-parameters) of this specification

presentation_submission

• Name: presentation_submission
• Parameter Usage Location: authorization response, token response
• Change Controller: OpenID Foundation Artifact Binding Working Group - [email protected]
• Reference: (#response-parameters) of this specification

expected_origins

• Name: expected_origins
• Parameter Usage Location: authorization request
• Change Controller: OpenID Foundation Artifact Binding Working Group - [email protected]
• Reference: (#browser_api_request) of this specification

OAuth Extensions Error Registry

This specification registers the following errors in the IANA "OAuth Extensions Error" registry [@IANA.OAuth.Parameters] established by [@!RFC6749].

vp_formats_not_supported

• Name: vp_formats_not_supported
• Usage Location: authorization endpoint, token endpoint
• Protocol Extension: OpenID for Verifiable Presentations
• Change Controller: OpenID Foundation Artifact Binding Working Group - [email protected]
• Reference: (#error-response) of this specification

invalid_presentation_definition_uri

• Name: invalid_presentation_definition_uri
• Usage Location: authorization endpoint, token endpoint
• Protocol Extension: OpenID for Verifiable Presentations
• Change Controller: OpenID Foundation Artifact Binding Working Group - [email protected]
• Reference: (#error-response) of this specification

invalid_presentation_definition_reference

• Name: invalid_presentation_definition_reference
• Usage Location: authorization endpoint, token endpoint
• Protocol Extension: OpenID for Verifiable Presentations
• Change Controller: OpenID Foundation Artifact Binding Working Group - [email protected]
• Reference: (#error-response) of this specification

invalid_request_uri_method

• Name: invalid_request_uri_method
• Usage Location: authorization endpoint
• Protocol Extension: OpenID for Verifiable Presentations
• Change Controller: OpenID Foundation Artifact Binding Working Group - [email protected]
• Reference: (#error-response) of this specification

wallet_unavailable

• Name: wallet_unavailable
• Usage Location: authorization endpoint, token endpoint
• Protocol Extension: OpenID for Verifiable Presentations
• Change Controller: OpenID Foundation Artifact Binding Working Group - [email protected]
• Reference: (#error-response) of this specification

OAuth Authorization Server Metadata Registry

This specification registers the following authorization server metadata parameters in the IANA "OAuth Authorization Server Metadata" registry [@IANA.OAuth.Parameters] established by [@!RFC8414].

presentation_definition_uri_supported

• Metadata Name: presentation_definition_uri_supported
• Metadata Description: Boolean value specifying whether the Wallet supports the transfer of presentation_definition by reference
• Change Controller: OpenID Foundation Artifact Binding Working Group - [email protected]
• Reference: (#as_metadata_parameters) of this specification

vp_formats_supported

• Metadata Name: vp_formats_supported
• Metadata Description: An object containing a list of name/value pairs, where the name is a string identifying a Credential format supported by the Wallet
• Change Controller: OpenID Foundation Artifact Binding Working Group - [email protected]
• Reference: (#as_metadata_parameters) of this specification

OAuth Dynamic Client Registration Metadata Registry

This specification registers the following client metadata parameters in the IANA "OAuth Dynamic Client Registration Metadata" registry [@IANA.OAuth.Parameters] established by [@!RFC7591].

vp_formats

• Client Metadata Name: vp_formats
• Client Metadata Description: Boolean value specifying whether the Wallet supports the transfer of presentation_definition by reference
• Change Controller: OpenID Foundation Artifact Binding Working Group - [email protected]
• Reference: (#client_metadata_parameters) of this specification

Media Types Registry

This section registers the following media type [@RFC2046] in the IANA "Media Types" registry in the manner described in [@RFC6838].

application/verifier-attestation+jwt {#va_media_type}

The media type for a Verifier Attestation JWT is application/verifier-attestation+jwt.

• Type name: application
• Subtype name: verifier-attestation+jwt
• Required parameters: n/a
• Optional parameters: n/a
• Encoding considerations: Uses JWS Compact Serialization as defined in [@!RFC7515].
• Security considerations: See Security Considerations in in [@!RFC7519].
• Interoperability considerations: n/a
• Published specification: (#verifier_attestation_jwt) of this specification
• Applications that use this media type: Applications that issue, present, verify verifier attestation VCs
• Additional information:
  • Magic number(s): n/a
  • File extension(s): n/a
  • Macintosh file type code(s): n/a
• Person & email address to contact for further information: TBD
• Intended usage: COMMON
• Restrictions on usage: none
• Author: Oliver Terbu, [email protected]
• Change controller: OpenID Foundation Artifact Binding Working Group - [email protected]

JSON Web Signature and Encryption Header Parameters Registry {#jose_header}

This specification registers the following JWS header parameter in the IANA "JSON Web Signature and Encryption Header Parameters" registry [@IANA.JOSE] established by [@!RFC7515].

jwt

• Header Parameter Name: jwt
• Header Parameter Description: This header contains a JWT. Processing rules MAY depend on the typ header value of the respective JWT.
• Header Parameter Usage Location: JWS
• Change Controller: OpenID Foundation Artifact Binding Working Group - [email protected]
• Specification Document(s): (#verifier_attestation_jwt) of this specification

Uniform Resource Identifier (URI) Schemes Registry

This specification registers the following URI scheme in the IANA "Uniform Resource Identifier (URI) Schemes" registry [@IANA.URI.Schemes].

openid4vp

• URI Scheme: openid4vp
• Description: Custom scheme used for wallet invocation
• Status: Provisional
• Well-Known URI Support: -
• Change Controller: OpenID Foundation Artifact Binding Working Group - [email protected]
• Reference: (#openid4vp-profile) of this specification

Acknowledgements {#Acknowledgements}

We would like to thank Richard Barnes, Paul Bastian, Vittorio Bertocci, Christian Bormann, John Bradley, Marcos Caceres, Brian Campbell, Lee Campbell, Tim Cappalli, Gabe Cohen, David Chadwick, Andrii Deinega, Rajvardhan Deshmukh, Giuseppe De Marco, Mark Dobrinic, Daniel Fett, Pedro Felix, George Fletcher, Ryan Galluzzo, Timo Glasta, Sam Goto, Mark Haine, Martijn Haring, Fabian Hauck, Roland Hedberg, Joseph Heenan, Bjorn Hjelm, Alen Horvat, Andrew Hughes, Jacob Ideskog, Łukasz Jaromin, Edmund Jay, Michael B. Jones, Tom Jones, Judith Kahrer, Takahiko Kawasaki, Gaurav Khot, Niels Klomp, Ronald Koenig, Markus Kreusch, Adam Lemmon, Hicham Lozi, Daniel McGrogan, Jeremie Miller, Kenichi Nakamura, Gareth Oliver, Andreea Prian, Rolson Quadras, Javier Ruiz, Nat Sakimura, Arjen van Veen, Steve Venema, Jan Vereecken, David Waite, Jacob Ward, David Zeuthen for their valuable feedback and contributions to this specification.

Notices

Copyright (c) 2024 The OpenID Foundation.

The OpenID Foundation (OIDF) grants to any Contributor, developer, implementer, or other interested party a non-exclusive, royalty free, worldwide copyright license to reproduce, prepare derivative works from, distribute, perform and display, this Implementers Draft or Final Specification solely for the purposes of (i) developing specifications, and (ii) implementing Implementers Drafts and Final Specifications based on such documents, provided that attribution be made to the OIDF as the source of the material, but that such attribution does not indicate an endorsement by the OIDF.

The technology described in this specification was made available from contributions from various sources, including members of the OpenID Foundation and others. Although the OpenID Foundation has taken steps to help ensure that the technology is available for distribution, it takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this specification or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any independent effort to identify any such rights. The OpenID Foundation and the contributors to this specification make no (and hereby expressly disclaim any) warranties (express, implied, or otherwise), including implied warranties of merchantability, non-infringement, fitness for a particular purpose, or title, related to this specification, and the entire risk as to implementing this specification is assumed by the implementer. The OpenID Intellectual Property Rights policy requires contributors to offer a patent promise not to assert certain patent claims against other contributors and against implementers. The OpenID Foundation invites any interested party to bring to its attention any copyrights, patents, patent applications, or other proprietary rights that may cover technology that may be required to practice this specification.

Document History

[[ To be removed from the final specification ]]

-22

• Introduced the Digital Credentials Query Language
• add transaction data mechanism
• remove client_id_scheme and turn it into a prefix of the client_id; this addresses a security issue with the previous solution
• Clarified what can go in the client_metadata parameter
• Fixed #227: Enabled non-breaking extensibility.
• Fixed #383: Completed IANA Considerations section.

-21

• removed client_metadata_uri authorization parameter
• added how OpenID4VP request/response can be used over the browser API
• remove path_nested description from Response Parameters section and move it into W3C VC Annex
• fix indentation of examples
• added references to ISO/IEC 23220 and 18013 documents
• added post request method for Request URI
• Added IETF SD-JWT VC profile
• Added wallet_unavailable error

-20

• added "verifier_attestation" client id scheme value

-19

• added "x509_san_uri" and "x509_san_dns" client id scheme value

-18

• editorial update based on the 45 days review period prior to the Vote for proposed Second Implementer’s Draft

-17

• direct_post response mode uses state to identify response
• Added sequence diagrams for same and cross device flows to overview section

-16

• Added client_id_scheme parameter
• Defined that single VP Tokens must not use the array syntax for single Verifiable Presentations

-15

• Added definition of VP Token
• Editorial improvements for better readability (restructured request and response section, consistent terminology, and casing)

-14

• added support for signed and encrypted authorization responses based on JARM
• clarified response encoding for authorization responses
• moved invocation/just-in-time client metadata exchange/AS Discovery sections from siopv2 to openid4vp

-13

• added scope support

-12

• add Cross-Device flow (using SIOP v2 text)
• Added Client Metadata Section (based on SIOP v2 text)

-11

• changed base protocol to OAuth 2.0
• consolidated the examples

-10

• Added AnonCreds example
• Added ISO mobile Driving License (mDL) example

-09

• added support for passing presentation_definition by reference
• added description how to requset credential issued by a member of a federation

-08

• reflected editorial comments received during pre-implementer's draft review period

-07

• added text on other credential formats
• fixed inconsistency in security consideration regarding nonce

-06

• added additional security considerations
• removed support for embedding Verifiable Presentations in ID Token or UserInfo response
• migrated to Presentation Exchange 2.0

-05

• moved presentation submission parameters outside of Verifiable Presentations (ID Token or UserInfo)

-04

• added presentation submission support
• cleaned up examples to use nonce & client_id instead of vp_hash for replay detection
• fixed further nits in examples
• added and reworked references to other specifications

-03

• aligned with SIOP v2 spec

-02

• added presentation_definition as sub parameter of verifiable_presentation and VP Token

-01

• adopted DIF Presentation Exchange request syntax
• added security considerations regarding replay detection for Verifiable Credentials

-00

• initial revision