openid-4-vp February 2024
Terbu, et al. Standards Track [Page]
Workgroup:
connect
Published:
Authors:
O. Terbu
Mattr
T. Lodderstedt
sprind.org
K. Yasuda
Microsoft
T. Looker
Mattr

OpenID for Verifiable Presentations - draft 20

Abstract

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

Table of Contents

1. 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], 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].

1.1. 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].

2. 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" and the term "Base64url Encoding" 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].

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], [ISO.18013-5] (mdoc) 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], [ISO.18013-5] (mdoc) 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.
Claim-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. Claim-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 defined in this specification that contains a single Verifiable Presentation or an array of Verifiable Presentations as defined in Section 6.1.
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.

3. 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], [ISO.18013-5] (mdoc), 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 Appendix A.

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.

3.1. Same Device Flow

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.

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

3.2. Cross Device Flow

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 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.

+--------------+   +--------------+                                    +--------------+
|     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)                    |
        |                 |-------------------------------------------------->|
        |                 |                                                   |
        |   User Authentication / Consent                                     |
        |                 |                                                   |
        |                 |  (3)   Authorization Response as HTTP POST        |
        |                 |  (VP Token with Verifiable Presentation(s))       |
        |                 |<--------------------------------------------------|
Figure 2: 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.

4. Scope

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

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

5. Authorization 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 Request Object by value or by reference as defined in JWT-Secured Authorization Request (JAR) [RFC9101].

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].

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 using client_id_scheme parameter. This parameter 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 client_metadata and client_metadata_uri parameters that contain name/value pairs defined in Section 4.3 and Section 2.1 of the OpenID Connect Dynamic Client Registration 1.0 [OpenID.Registration] specification as well as [RFC7591]. The parameter names include a term client since the Verifier is acting as an OAuth 2.0 Client.

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

This specification defines the following new parameters:

presentation_definition:
A string containing a Presentation Definition JSON object. See Section 5.1 for more details. This parameter MUST be present when presentation_definition_uri parameter, or a scope value representing a Presentation Definition is not present.
presentation_definition_uri:
A string containing an HTTPS URL pointing to a resource where a Presentation Definition JSON object can be retrieved. This parameter MUST be present when presentation_definition parameter, or a scope value representing a Presentation Definition is not present. See Section 5.2 for more details.
client_id_scheme:
OPTIONAL. A string identifying the scheme of the value in the client_id Authorization Request parameter (Client Identifier scheme). The client_id_scheme parameter namespaces the respective Client Identifier. If an Authorization Request uses the client_id_scheme parameter, the Wallet MUST interpret the Client Identifier of the Verifier in the context of the Client Identifier scheme. If the parameter is not present, the Wallet MUST behave as specified in [RFC6749]. See Section 5.7 for the values defined by this specification. If the same Client Identifier is used with different Client Identifier schemes, those occurrences MUST be treated as different Verifiers. 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.
client_metadata:
OPTIONAL. A JSON object containing the Verifier metadata values. It MUST be UTF-8 encoded. It MUST NOT be present if client_metadata_uri parameter is present.
client_metadata_uri:
OPTIONAL. A string containing an HTTPS URL pointing to a resource where a JSON object with the Verifier metadata can be retrieved. The scheme used in the client_metadata_uri value MUST be https. The client_metadata_uri value MUST be reachable by the Wallet. It MUST NOT be present if client_metadata parameter is present.

A public key to be used by the Wallet as an input to the key agreement to encrypt Authorization Response (see Section 6.3). It MAY be passed by the Verifier using the jwks or the jwks_uri claim within the client_metadata or client_metadata_uri request parameter.

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 Section 12.1 for details.
scope:
OPTIONAL. Defined in [RFC6749]. The Wallet MAY allow Verifiers to request presentation of Verifiable Credentials by utilizing a pre-defined scope value. See Section 5.3 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 Section 6.2 for more details). It is also used to request signing and encrypting (see Section 6.3 for more details). If the parameter is not present, the default value is fragment.

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

  GET /authorize?
    response_type=vp_token
    &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

5.1. presentation_definition Parameter

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:

{
    "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"
                        }
                    }
                ]
            }
        }
    ]
}

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

{
    "id": "example with selective disclosure",
    "input_descriptors": [
        {
            "id": "ID card with constraints",
            "format": {
                "ldp_vc": {
                    "proof_type": [
                        "Ed25519Signature2018"
                    ]
                }
            },
            "constraints": {
                "limit_disclosure": "required",
                "fields": [
                    {
                        "path": [
                            "$.type"
                        ],
                        "filter": {
                            "type": "string",
                            "pattern": "IDCardCredential"
                        }
                    },
                    {
                        "path": [
                            "$.credentialSubject.given_name"
                        ]
                    },
                    {
                        "path": [
                            "$.credentialSubject.family_name"
                        ]
                    },
                    {
                        "path": [
                            "$.credentialSubject.birthdate"
                        ]
                    }
                ]
            }
        }
    ]
}

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

{
    "id": "alternative credentials",
    "submission_requirements": [
        {
            "name": "Citizenship Information",
            "rule": "pick",
            "count": 1,
            "from": "A"
        }
    ],
    "input_descriptors": [
        {
            "id": "id card credential",
            "group": [
                "A"
            ],
            "format": {
                "ldp_vc": {
                    "proof_type": [
                        "Ed25519Signature2018"
                    ]
                }
            },
            "constraints": {
                "fields": [
                    {
                        "path": [
                            "$.type"
                        ],
                        "filter": {
                            "type": "string",
                            "pattern": "IDCardCredential"
                        }
                    }
                ]
            }
        },
        {
            "id": "passport credential",
            "format": {
                "jwt_vc_json": {
                    "alg": [
                        "RS256"
                    ]
                }
            },
            "group": [
                "A"
            ],
            "constraints": {
                "fields": [
                    {
                        "path": [
                            "$.vc.type"
                        ],
                        "filter": {
                            "type": "string",
                            "pattern": "PassportCredential"
                        }
                    }
                ]
            }
        }
    ]
}

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 Section 8).

The formats supported by a Verifier may be set up using the metadata parameter vp_formats (see Section 9.1). 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.

5.2. presentation_definition_uri Parameter

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"
                        }
                    }
                ]
            }
        }
    ]
}

5.3. Using scope Parameter to Request Verifiable Credential(s)

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 Presentation Definition 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 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.

Such definition of a 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 Section 6.1.

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 Section 5.1:

  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

5.4. 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 Section 6 on how the response_type value determines the response used to return a VP Token.

5.5. 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 Section 6.2) in conjunction with request_uri is RECOMMENDED, since Authorization Request size might be large and might not fit in a QR code.

5.6. 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.

5.7. Verifier Metadata Management

The client_id_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_id_scheme is used since the Verifier is acting as an OAuth 2.0 Client.

This specification defines the following values for the client_id_scheme parameter, followed by the examples where applicable:

  • pre-registered: This value represents 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.

  • redirect_uri: This value indicates that the Verifier's redirect URI is also the value of the Client Identifier. In this case, the Authorization Request MUST NOT be signed, the Verifier MAY omit the redirect_uri Authorization Request parameter, and all Verifier metadata parameters MUST be passed using the client_metadata or client_metadata_uri parameter defined in Section 5.

The following is a non-normative example of a request when client_id equals redirect_uri.

  HTTP/1.1 302 Found
  Location: https://client.example.org/universal-link?
    response_type=vp_token
    &client_id=https%3A%2F%2Fclient.example.org%2Fcb
    &client_id_scheme=redirect_uri
    &redirect_uri=https%3A%2F%2Fclient.example.org%2Fcb
    &presentation_definition=...
    &nonce=n-0S6_WzA2Mj
    &client_metadata=%7B%22vp_formats%22:%7B%22jwt_vp%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
  • entity_id: This value indicates that the Client Identifier is an Entity Identifier defined in OpenID Federation [OpenID.Federation]. 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 or client_metadata_uri parameter, if present in the Authorization Request, MUST be ignored when this Client Identifier scheme is used.

  • did: This value indicates that the Client Identifier is a DID defined in [DID-Core]. 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 or the client_metadata_uri parameter as defined in Section 5.

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

{
    "typ": "oauth-authz-req+jwt",
    "alg": "RS256",
    "kid": "did:example:123#1"
}

Body

{
   "client_id": "did:example:123",
   "client_id_scheme": "did",
   "response_types": "vp_token",
   "redirect_uri": "https://client.example.org/callback",
   "nonce":"n-0S6_WzA2Mj",
   "presentation_definition": "...",
   "client_metadata": {
      "vp_formats": {
         "jwt_vp": {
            "alg": [
               "EdDSA",
               "ES256K"
            ]
         },
         "ldp_vp": {
            "proof_type": [
               "Ed25519Signature2018"
            ]
         }
      }
   }
}
  • 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 Section 10. 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 Section 10). 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 or or the client_metadata_uri parameter.

  • 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.

  • 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.

To use client_id_scheme values entity_id, 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 values for the client_id_scheme parameter. It is RECOMMENDED to use collision-resistant names for such values.

6. Response

A VP Token is only returned if the corresponding Authorization Request contained a presentation_definition parameter, a presentation_definition_uri parameter, or a scope parameter representing a Presentation Definition Section 5.

VP Token can be returned in the Authorization Response or the Token Response depending on the Response Type used. See Section 5.4 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:

Table 1
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.

6.1. Response Parameters

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

vp_token:
REQUIRED. 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. 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. 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 the value of the path field in it will ultimately depend on the credential format. Non-normative examples can be found further in this section.

Other parameters, such as state or code (from [RFC6749]), or id_token (from [OpenID.Core]), and iss (from [RFC9207]) MAY be included in the response as defined in the respective specifications.

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.

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=...

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

{
    "@context": [
        "https://www.w3.org/2018/credentials/v1"
    ],
    "type": [
        "VerifiablePresentation"
    ],
    "verifiableCredential": [
        {
            "@context": [
                "https://www.w3.org/2018/credentials/v1",
                "https://www.w3.org/2018/credentials/examples/v1"
            ],
            "id": "https://example.com/credentials/1872",
            "type": [
                "VerifiableCredential",
                "IDCardCredential"
            ],
            "issuer": {
                "id": "did:example:issuer"
            },
            "issuanceDate": "2010-01-01T19:23:24Z",
            "credentialSubject": {
                "given_name": "Fredrik",
                "family_name": "Strömberg",
                "birthdate": "1949-01-22"
            },
            "proof": {
                "type": "Ed25519Signature2018",
                "created": "2021-03-19T15:30:15Z",
                "jws": "eyJhb...JQdBw",
                "proofPurpose": "assertionMethod",
                "verificationMethod": "did:example:issuer#keys-1"
            }
        }
    ],
    "id": "ebc6f1c2",
    "holder": "did:example:holder",
    "proof": {
        "type": "Ed25519Signature2018",
        "created": "2021-03-19T15:30:15Z",
        "challenge": "n-0S6_WzA2Mj",
        "domain": "https://client.example.org/cb",
        "jws": "eyJhbG...IAoDA",
        "proofPurpose": "authentication",
        "verificationMethod": "did:example:holder#key-1"
    }
}

The following is a non-normative example of a presentation_submission parameter sent alongside a VP Token in the example above. It corresponds to a second Presentation Definition example in Section 5.1:

{
    "id": "Presentation example 1",
    "definition_id": "Example with selective disclosure",
    "descriptor_map": [
        {
            "id": "ID card with constraints",
            "format": "ldp_vp",
            "path": "$",
            "path_nested": {
                "format": "ldp_vc",
                "path": "$.verifiableCredential[0]"
            }
        }
    ]
}

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:

[
    {
        "@context": [
            "https://www.w3.org/2018/credentials/v1"
        ],
        "type": [
            "VerifiablePresentation"
        ],
        "verifiableCredential": [
            {
                "@context": [
                    "https://www.w3.org/2018/credentials/v1",
                    "https://www.w3.org/2018/credentials/examples/v1"
                ],
                "id": "https://example.com/credentials/1872",
                "type": [
                    "VerifiableCredential",
                    "IDCardCredential"
                ],
                "issuer": {
                    "id": "did:example:issuer"
                },
                "issuanceDate": "2010-01-01T19:23:24Z",
                "credentialSubject": {
                    "given_name": "Fredrik",
                    "family_name": "Strömberg",
                    "birthdate": "1949-01-22"
                },
                "proof": {
                    "type": "Ed25519Signature2018",
                    "created": "2021-03-19T15:30:15Z",
                    "jws": "eyJhb...IAoDA",
                    "proofPurpose": "assertionMethod",
                    "verificationMethod": "did:example:issuer#keys-1"
                }
            }
        ],
        "id": "ebc6f1c2",
        "holder": "did:example:holder",
        "proof": {
            "type": "Ed25519Signature2018",
            "created": "2021-03-19T15:30:15Z",
            "challenge": "n-0S6_WzA2Mj",
            "domain": "https://client.example.org/cb",
            "jws": "eyJhb...JQdBw",
            "proofPurpose": "authentication",
            "verificationMethod": "did:example:holder#key-1"
        }
    },
        "eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCIsImtpZCI6ImRpZDpleGFtcGxlOjB4YWJjI2tleTEifQ.
        eyJpc3MiOiJkaWQ6ZXhhbXBsZTplYmZlYjFmNzEyZWJjNmYxYzI3NmUxMmVjMjEiLCJqdGkiOiJ1cm46
        dXVpZDozOTc4MzQ0Zi04NTk2LTRjM2EtYTk3OC04ZmNhYmEzOTAzYzUiLCJhdWQiOiJkaWQ6ZXhhbXBs
        ZTo0YTU3NTQ2OTczNDM2ZjZmNmM0YTRhNTc1NzMiLCJuYmYiOjE1NDE0OTM3MjQsImlhdCI6MTU0MTQ5
        MzcyNCwiZXhwIjoxNTczMDI5NzIzLCJub25jZSI6IjM0M3MkRlNGRGEtIiwidnAiOnsiQGNvbnRleHQi
        OlsiaHR0cHM6Ly93d3cudzMub3JnLzIwMTgvY3JlZGVudGlhbHMvdjEiLCJodHRwczovL3d3dy53My5v
        cmcvMjAxOC9jcmVkZW50aWFscy9leGFtcGxlcy92MSJdLCJ0eXBlIjpbIlZlcmlmaWFibGVQcmVzZW50
        YXRpb24iLCJDcmVkZW50aWFsTWFuYWdlclByZXNlbnRhdGlvbiJdLCJ2ZXJpZmlhYmxlQ3JlZGVudGlh
        bCI6WyJleUpoYkdjaU9pSlNVekkxTmlJc0luUjVjQ0k2SWtwWFZDSXNJbXRwWkNJNkltUnBaRHBsZUdG
        dGNHeGxPbUZpWm1VeE0yWTNNVEl4TWpBME16RmpNamMyWlRFeVpXTmhZaU5yWlhsekxURWlmUS5leUp6
        ZFdJaU9pSmthV1E2WlhoaGJYQnNaVHBsWW1abFlqRm1OekV5WldKak5tWXhZekkzTm1VeE1tVmpNakVp
        TENKcWRHa2lPaUpvZEhSd09pOHZaWGhoYlhCc1pTNWxaSFV2WTNKbFpHVnVkR2xoYkhNdk16Y3pNaUlz
        SW1semN5STZJbWgwZEhCek9pOHZaWGhoYlhCc1pTNWpiMjB2YTJWNWN5OW1iMjh1YW5kcklpd2libUpt
        SWpveE5UUXhORGt6TnpJMExDSnBZWFFpT2pFMU5ERTBPVE0zTWpRc0ltVjRjQ0k2TVRVM016QXlPVGN5
        TXl3aWJtOXVZMlVpT2lJMk5qQWhOak0wTlVaVFpYSWlMQ0oyWXlJNmV5SkFZMjl1ZEdWNGRDSTZXeUpv
        ZEhSd2N6b3ZMM2QzZHk1M015NXZjbWN2TWpBeE9DOWpjbVZrWlc1MGFXRnNjeTkyTVNJc0ltaDBkSEJ6
        T2k4dmQzZDNMbmN6TG05eVp5OHlNREU0TDJOeVpXUmxiblJwWVd4ekwyVjRZVzF3YkdWekwzWXhJbDBz
        SW5SNWNHVWlPbHNpVm1WeWFXWnBZV0pzWlVOeVpXUmxiblJwWVd3aUxDSlZibWwyWlhKemFYUjVSR1Zu
        Y21WbFEzSmxaR1Z1ZEdsaGJDSmRMQ0pqY21Wa1pXNTBhV0ZzVTNWaWFtVmpkQ0k2ZXlKa1pXZHlaV1Vp
        T25zaWRIbHdaU0k2SWtKaFkyaGxiRzl5UkdWbmNtVmxJaXdpYm1GdFpTSTZJanh6Y0dGdUlHeGhibWM5
        SjJaeUxVTkJKejVDWVdOallXeGhkWExEcVdGMElHVnVJRzExYzJseGRXVnpJRzUxYmNPcGNtbHhkV1Z6
        UEM5emNHRnVQaUo5ZlgxOS5LTEpvNUdBeUJORDNMRFRuOUg3RlFva0VzVUVpOGpLd1hoR3ZvTjNKdFJh
        NTF4ck5EZ1hEYjBjcTFVVFlCLXJLNEZ0OVlWbVIxTklfWk9GOG9HY183d0FwOFBIYkYySGFXb2RRSW9P
        Qnh4VC00V05xQXhmdDdFVDZsa0gtNFM2VXgzclNHQW1jek1vaEVFZjhlQ2VOLWpDOFdla2RQbDZ6S1pR
        ajBZUEIxcng2WDAteGxGQnM3Y2w2V3Q4cmZCUF90WjlZZ1ZXclFtVVd5cFNpb2MwTVV5aXBobXlFYkxa
        YWdUeVBsVXlmbEdsRWRxclpBdjZlU2U2UnR4Snk2TTEtbEQ3YTVIVHphbllUV0JQQVVIRFpHeUdLWGRK
        dy1XX3gwSVdDaEJ6STh0M2twRzI1M2ZnNlYzdFBnSGVLWEU5NGZ6X1FwWWZnLS03a0xzeUJBZlFHYmci
        XX19.ft_Eq4IniBrr7gtzRfrYj8Vy1aPXuFZU-6_ai0wvaKcsrzI4JkQEKTvbJwdvIeuGuTqy7ipO-EY
        i7V4TvonPuTRdpB7ZHOlYlbZ4wA9WJ6mSVSqDACvYRiFvrOFmie8rgm6GacWatgO4m4NqiFKFko3r58L
        ueFfGw47NK9RcfOkVQeHCq4btaDqksDKeoTrNysF4YS89INa-prWomrLRAhnwLOo1Etp3E4ESAxg73CR
        2kA5AoMbf5KtFueWnMcSbQkMRdWcGC1VssC0tB0JffVjq7ZV6OTyV4kl1-UVgiPLXUTpupFfLRhf9Qpq
        MBjYgP62KvhIvW8BbkGUelYMetA"
]

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 examples in this specification:

{
    "id": "Presentation example 2",
    "definition_id": "Example with multiple VPs",
    "descriptor_map": [
        {
            "id": "ID Card with constraints",
            "format": "ldp_vp",
            "path": "$[0]",
            "path_nested": {
                "format": "ldp_vc",
                "path": "$[0].verifiableCredential[0]"
            }
        },
        {
            "id": "Ontario Health Insurance Plan",
            "format": "jwt_vp_json",
            "path": "$[1]",
            "path_nested": {
                "format": "jwt_vc_json",
                "path": "$[1].vp.verifiableCredential[0]"
            }
        }
    ]
}

6.2. Response Mode "direct_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 parameters are encoded in the body using the application/x-www-form-urlencoded content type. The flow can end with an HTTP POST request from the Wallet to the Verifier, or it can end with a redirect that follows the HTTP POST request, if the Verifier responds with a redirect URI to the Wallet.

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 Response URI 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 Section 5.7.

Note: The Verifier's component providing the user interface (Frontend) and the Verifier's component providing the Response URI (Response Endpoint) 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 Section 11.5.

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

{
   "client_id": "https://client.example.org/post",
   "client_id_scheme": "redirect_uri",
   "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 Endpoint:

  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 Endpoint:

  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 Endpoint has successfully processed the Authorization Response or Authorization Error Response, it MUST respond with HTTP status code 200.

The following new parameter is defined for use in the response from the endpoint:

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 Endpoint. It can be used by the Verifier to prevent session fixation (Section 12.2) attacks. The Response Endpoint MAY return the redirect_uri parameter in response to successful Authorization Responses or for Error Responses.

Note: Response Mode direct_post without the redirect_uri could be less secure than Response Modes with redirects. For details, see (Section 12.2).

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 Section 11.5.

The following is a non-normative example of the response from the Verifier to the Wallet upon receiving the Authorization Response at the Response Endpoint (using a response_code parameter from Section 11.5):

  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.

6.3. Signed and Encrypted Responses

This section defines how 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, or sign and encrypt the Authorization Response, implementations MAY use JWT Secured Authorization Response Mode for OAuth 2.0 (JARM) [JARM].

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 Section 12.5.

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:

{
    "vp_token": "eyJhb...YMetA",
    "presentation_submission": {
        "definition_id": "example_jwt_vc",
        "id": "example_jwt_vc_presentation_submission",
        "descriptor_map": [
            {
                "id": "id_credential",
                "path": "$",
                "format": "jwt_vp",
                "path_nested": {
                    "path": "$.vp.verifiableCredential[0]",
                    "format": "jwt_vc"
                }
            }
        ]
    }
}

The JWT response document MUST include vp_token and presentation_submission parameters as defined in Section 6.1.

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 or jwks_uri 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.

6.3.1. Response Mode "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 Section 6.2.

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 Section 6.2. The Wallet adds the response parameter containing the JWT as defined in Section 4.1. of [JARM] and Section 6.3 in the body of an HTTP POST request using the application/x-www-form-urlencoded content type.

The following is a non-normative example of a response using the presentation_submission and vp_token values from Appendix A.1.1. (line breaks for display purposes only):

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

    response=eyJra...9t2LQ

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

{
    "iss": "did:example:ebfeb1f712ebc6f1c276e12ec21",
    "aud": "https://client.example.org/cb",
    "exp": 1573029723,
    "vp_token": "eyJhb...YMetA",
    "presentation_submission": {
        "definition_id": "example_jwt_vc",
        "id": "example_jwt_vc_presentation_submission",
        "descriptor_map": [
            {
                "id": "id_credential",
                "path": "$",
                "format": "jwt_vp",
                "path_nested": {
                    "path": "$.vp.verifiableCredential[0]",
                    "format": "jwt_vc"
                }
            }
        ]
    }
}

6.4. 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_id_scheme value passed in the Authorization Request.
  • The Client Identifier passed in the request did not belong to the Client Identifier scheme indicated in the Authorization Request, or requirements of a certain scheme was violated, for example an unsigned request was sent with Client Identifier scheme entity_id.

invalid_client:

  • client_metadata or client_metadata_uri parameter defined in Section 5 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.

Usage of client_metadata or client_metadata_uri parameters with client_id that the Wallet might be seeing for the first time is mutually exclusive with the registration mechanism where Self-Issued OP assigns client_id to the Verifier after receiving Verifier metadata.

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.

6.5. VP Token Validation

Verifiers MUST validate the VP Token in the following manner:

  1. 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 Section 12.1 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 sent in the Presentation Definition in the Authorization Request.
  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].

7. Wallet Invocation

The Verifier has the choice of the following mechanisms to invoke a Wallet:

8. Wallet Metadata (Authorization Server Metadata)

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.

8.1. 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: 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 Appendix A.

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, redirect_uri, entity_id, did. If omitted, the default value is pre-registered. Other values may be used when defined in the profiles of this specification.

8.2. 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 Section 8 for the details.
  • Verifier has pre-obtained static set of Wallet's metadata. See Section 11.1.2 for the example.

9. Verifier 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.

9.1. Additional Verifier Metadata Parameters

This specification defines the following new 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 Appendix A. Deployments can extend the formats supported, provided Issuers, Holders and Verifiers all understand the new format.

10. 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_id_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:

The Verifier Attestation JWT MAY use any claim registered in the "JSON Web Token Claims" registry as defined in [RFC7519].

Verifier Attestation JWTs compliant with this specification MUST use the media type application/verifier-attestation+jwt as defined in Appendix B.2.1.

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:

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

11. Implementation Considerations

11.1. 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.

11.1.1. Profiles that Define Static Configuration Values

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

11.1.2. A Set of Static Configuration Values bound to openid4vp://

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"
  ]
}

11.2. Support for Federations/Trust Schemes

Often Verifiers will want to request Verifiable Credentials from a Credential Issuer who is a participant of a federation, or adheres to a known trust scheme, rather than from a specific Credential Issuer, for example, a "BSc Chemistry Degree" Credential from the hypothetical "eduCreds" trust scheme rather than from a specifically named university.

To facilitate this, federations will need to determine how a Credential Issuer can indicate in a Verifiable Credential that they are a member of one or more federations/trust schemes. Once this is done, the Verifier will be able to create a presentation_definition that includes this filtering criteria. This will enable the Wallet to select all the Verifiable Credentials that match this criteria and then by some means (for example, by asking the user) determine which matching Verifiable Credential to return to the Verifier. Upon receiving this Verifiable Credential, the Verifier will be able to call its federation API to determine if the Credential Issuer is indeed a member of the federation/trust scheme that it says it is.

Indicating the federations/trust schemes used by a Credential Issuer MAY be achieved by defining a termsOfUse property [VC_DATA].

Note: [VC_DATA] describes terms of use as "can be utilized by a Credential Issuer ... to communicate the terms under which a Verifiable Credential ... was issued."

The following is a non-normative example of the terms of use that may be defined:

{
   "termsOfUse":[
      {
         "type":"<uri that identifies this type of terms of use>",
         "federations":[
            "<list of federations/trust schemes the Credential Issuer asserts it is a member of>"
         ]
      }
   ]
}

Federations that conform to those specified in [OpenID.Federation] are identified by the type urn:ietf:params:oauth:federation. Individual federations are identified by the Entity Identifier of the trust anchor. If the federation decides to use trust marks as signs of whether an entity belongs to a federation or not then the federation is identified by the type urn:ietf:params:oauth:federation_trust_mark and individual federations are identified by the Entity Identifier of the trust mark issuer.

Trust schemes that conform to the TRAIN [TRAIN] trust scheme are identified by the type https://train.trust-scheme.de/info. Individual federations are identified by their DNS names.

The following is a non-normative example of a claims parameter containing a presentation_definition that filters VCs based on their federation memberships:

{
    "vp_token": {
        "presentation_definition": {
            "id": "32f54163-7166-48f1",
            "input_descriptors": [
                {
                    "id": "federationExample",
                    "purpose": "To pick a UK university that is a member of the UK academic federation",
                    "constraints": {
                        "fields": [
                            {
                                "path": [
                                    "$.termsOfUse.type"
                                ],
                                "filter": {
                                    "type": "string",
                                    "const": "https://train.trust-scheme.de/info"
                                }
                            },
                            {
                                "path": [
                                    "$.termsOfUse.federations"
                                ],
                                "filter": {
                                    "type": "string",
                                    "const": "ukuniversities.ac.uk"
                                }
                            }
                        ]
                    }
                }
            ]
        }
    }
}

This example will choose a Verifiable Credential that has been issued by a university that is a member of the ukuniversities.ac.uk federation and that uses the TRAIN terms of use specification for asserting federation memberships.

11.3. 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.

11.4. 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 Section 12.3.

11.5. Response Mode direct_post

The design of the interactions between the different components of the Verifier (especially Frontend and Response Endpoint) 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 Section 12.

The design is illustrated in the following sequence diagram:

+-------+   +------------+           +---------------------+                 +----------+
| 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)                             |
    |              |-------------------------------------------------------------->|
    |              |                            |                                  |
    |              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 3: Reference Design for Response Mode direct_post

(1) The Verifier selects a nonce value as fresh, cryptographically random number with sufficient entropy and associates it with the session.

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

(3) The Response Endpoint 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 her consent to share the request Credentials, the Wallet sends the Authorization Response with the parameters vp_token, presentation_submission and state to the response_uri of the Verifier.

(6) The Verifier's Response Endpoint 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 Endpoint 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 Endpoint.

  • The Response Endpoint 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 Endpoint checks whether the response_code was associated with this Authorization Response in step (6).

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

(9) The Response Endpoint 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.

12. Security Considerations

12.1. Preventing Replay of the VP Token

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 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.

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. The format of the respective presentation is determined from the format information in the presentation submission in the Authorization Response.

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.

12.2. 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 Endpoint.

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 Endpoint MUST include a fresh secret (Response Code) into the redirect URI returned to the Wallet and the Verifier's Response Endpoint 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.

See Section 11.5 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].

12.3. Response Mode "direct_post"

12.3.1. 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.

12.3.2. 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.

12.3.3. Protection of the Authorization Response Data

This specification assumes that the Verifier's Response Endpoint 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 Endpoint 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.

12.4. 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 user.

12.5. Encrypting an 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 Section 12.1.

12.6. DIF Presentation Exchange 2.0.0

12.6.1. 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.

12.6.2. 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].

12.6.3. 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.

12.7. TLS Requirements

Implementations MUST follow [BCP195].

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

13. Normative References

[BCP195]
IETF, "BCP195", , <https://www.rfc-editor.org/info/bcp195>.
[DID-Core]
Sporny, M., Guy, A., Sabadello, M., and D. Reed, "Decentralized Identifiers (DIDs) v1.0", , <https://www.w3.org/TR/2021/PR-did-core-20210803/>.
[DIF.PresentationExchange]
Buchner, D., Zundel, B., Riedel, M., and K. H. Duffy, "Presentation Exchange 2.0.0", <https://identity.foundation/presentation-exchange/spec/v2.0.0/>.
[JARM]
Lodderstedt, T. and B. Campbell, "JWT Secured Authorization Response Mode for OAuth 2.0 (JARM)", , <https://openid.net/specs/oauth-v2-jarm-final.html>.
[OAuth.Responses]
de Medeiros, B., Scurtescu, M., Tarjan, P., and M. Jones, "OAuth 2.0 Multiple Response Type Encoding Practices", , <https://openid.net/specs/oauth-v2-multiple-response-types-1_0.html>.
[OpenID.Core]
Sakimura, N., Bradley, J., Jones, M., de Medeiros, B., and C. Mortimore, "OpenID Connect Core 1.0 incorporating errata set 1", , <http://openid.net/specs/openid-connect-core-1_0.html>.
[OpenID.Registration]
Sakimura, N., Bradley, J., and M. B. Jones, "OpenID Connect Dynamic Client Registration 1.0 incorporating errata set 1", , <https://openid.net/specs/openid-connect-registration-1_0.html>.
[OpenID.VCI]
Lodderstedt, T., Yasuda, K., and T. Looker, "OpenID for Verifiable Credential Issuance", , <https://openid.net/specs/openid-4-verifiable-credential-issuance-1_0.html>.
[RFC2119]
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <https://www.rfc-editor.org/info/rfc2119>.
[RFC3986]
Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, DOI 10.17487/RFC3986, , <https://www.rfc-editor.org/info/rfc3986>.
[RFC5280]
Cooper, D., Santesson, S., Farrell, S., Boeyen, S., Housley, R., and W. Polk, "Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, , <https://www.rfc-editor.org/info/rfc5280>.
[RFC6125]
Saint-Andre, P. and J. Hodges, "Representation and Verification of Domain-Based Application Service Identity within Internet Public Key Infrastructure Using X.509 (PKIX) Certificates in the Context of Transport Layer Security (TLS)", RFC 6125, DOI 10.17487/RFC6125, , <https://www.rfc-editor.org/info/rfc6125>.
[RFC6749]
Hardt, D., Ed., "The OAuth 2.0 Authorization Framework", RFC 6749, DOI 10.17487/RFC6749, , <https://www.rfc-editor.org/info/rfc6749>.
[RFC7515]
Jones, M., Bradley, J., and N. Sakimura, "JSON Web Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, , <https://www.rfc-editor.org/info/rfc7515>.
[RFC7516]
Jones, M. and J. Hildebrand, "JSON Web Encryption (JWE)", RFC 7516, DOI 10.17487/RFC7516, , <https://www.rfc-editor.org/info/rfc7516>.
[RFC7519]
Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token (JWT)", RFC 7519, DOI 10.17487/RFC7519, , <https://www.rfc-editor.org/info/rfc7519>.
[RFC7591]
Richer, J., Ed., Jones, M., Bradley, J., Machulak, M., and P. Hunt, "OAuth 2.0 Dynamic Client Registration Protocol", RFC 7591, DOI 10.17487/RFC7591, , <https://www.rfc-editor.org/info/rfc7591>.
[RFC7800]
Jones, M., Bradley, J., and H. Tschofenig, "Proof-of-Possession Key Semantics for JSON Web Tokens (JWTs)", RFC 7800, DOI 10.17487/RFC7800, , <https://www.rfc-editor.org/info/rfc7800>.
[RFC8414]
Jones, M., Sakimura, N., and J. Bradley, "OAuth 2.0 Authorization Server Metadata", RFC 8414, DOI 10.17487/RFC8414, , <https://www.rfc-editor.org/info/rfc8414>.
[RFC9101]
Sakimura, N., Bradley, J., and M. Jones, "The OAuth 2.0 Authorization Framework: JWT-Secured Authorization Request (JAR)", RFC 9101, DOI 10.17487/RFC9101, , <https://www.rfc-editor.org/info/rfc9101>.
[SIOPv2]
Yasuda, K., Jones, M. B., and T. Lodderstedt, "Self-Issued OpenID Provider V2", , <https://openid.bitbucket.io/connect/openid-connect-self-issued-v2-1_0.html>.

14. Informative References

[Hyperledger.Indy]
Hyperledger Indy Project, "Hyperledger Indy Project", , <https://www.hyperledger.org/use/hyperledger-indy>.
[I-D.ietf-jsonpath-base]
Gössner, S., Normington, G., and C. Bormann, "JSONPath: Query expressions for JSON", Work in Progress, Internet-Draft, draft-ietf-jsonpath-base-21, , <https://datatracker.ietf.org/doc/html/draft-ietf-jsonpath-base-21>.
[I-D.ietf-oauth-cross-device-security]
Kasselman, P., Fett, D., and F. Skokan, "Cross-Device Flows: Security Best Current Practice", Work in Progress, Internet-Draft, draft-ietf-oauth-cross-device-security-04, , <https://datatracker.ietf.org/doc/html/draft-ietf-oauth-cross-device-security-04>.
[I-D.ietf-oauth-security-topics]
Lodderstedt, T., Bradley, J., Labunets, A., and D. Fett, "OAuth 2.0 Security Best Current Practice", Work in Progress, Internet-Draft, draft-ietf-oauth-security-topics-25, , <https://datatracker.ietf.org/doc/html/draft-ietf-oauth-security-topics-25>.
[ISO.18013-5]
ISO/IEC JTC 1/SC 17 Cards and security devices for personal identification, "ISO/IEC 18013-5:2021 Personal identification — ISO-compliant driving license — Part 5: Mobile driving license (mDL) application", , <https://www.iso.org/standard/69084.html>.
[OpenID.Federation]
Ed., R. H., Jones, M. B., Solberg, A., Bradley, J., Marco, G. D., and V. Dzhuvinov, "OpenID Federation 1.0", , <https://openid.net/specs/openid-connect-federation-1_0.html>.
[RFC6819]
Lodderstedt, T., Ed., McGloin, M., and P. Hunt, "OAuth 2.0 Threat Model and Security Considerations", RFC 6819, DOI 10.17487/RFC6819, , <https://www.rfc-editor.org/info/rfc6819>.
[RFC8252]
Denniss, W. and J. Bradley, "OAuth 2.0 for Native Apps", BCP 212, RFC 8252, DOI 10.17487/RFC8252, , <https://www.rfc-editor.org/info/rfc8252>.
[RFC9126]
Lodderstedt, T., Campbell, B., Sakimura, N., Tonge, D., and F. Skokan, "OAuth 2.0 Pushed Authorization Requests", RFC 9126, DOI 10.17487/RFC9126, , <https://www.rfc-editor.org/info/rfc9126>.
[RFC9207]
Meyer zu Selhausen, K. and D. Fett, "OAuth 2.0 Authorization Server Issuer Identification", RFC 9207, DOI 10.17487/RFC9207, , <https://www.rfc-editor.org/info/rfc9207>.
[TRAIN]
Jeyakumar, I. H. J., Chadwick, D. W., and M. Kubach, "A novel approach to establish trust in Verifiable Credential issuers in Self-Sovereign Identity ecosystems using TRAIN", , <https://oid2022.compute.dtu.dk/index.html>.
[VC_DATA]
Sporny, M., Noble, G., Longley, D., Burnett, D. C., Zundel, B., and D. Chadwick, "Verifiable Credentials Data Model 1.1", , <https://www.w3.org/TR/2022/REC-vc-data-model-20220303/>.

Appendix A. Examples with Credentials in Various 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 format, not limited to the formats defined in [VC_DATA]. This section aims to illustrate this with examples utilizing different Credential formats. Customization of OpenID for Verifiable Presentation for Credential formats other than those defined in [VC_DATA] uses extension points of Presentation Exchange [DIF.PresentationExchange].

A.1. W3C Verifiable Credentials

A.1.1. VC signed as a JWT, not using JSON-LD

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.

A.1.1.1. 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:

{
    "iss": "https://example.gov/issuers/565049",
    "nbf": 1262304000,
    "jti": "http://example.gov/credentials/3732",
    "sub": "did:example:ebfeb1f712ebc6f1c276e12ec21",
    "vc": {
        "@context": [
            "https://www.w3.org/2018/credentials/v1",
            "https://www.w3.org/2018/credentials/examples/v1"
        ],
        "type": [
            "VerifiableCredential",
            "IDCredential"
        ],
        "credentialSubject": {
            "given_name": "Max",
            "family_name": "Mustermann",
            "birthdate": "1998-01-11",
            "address": {
                "street_address": "Sandanger 25",
                "locality": "Musterstadt",
                "postal_code": "123456",
                "country": "DE"
            }
        }
    }
}
A.1.1.2. Presentation Request

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

  GET /authorize?
    response_type=vp_token
    &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 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:

{
    "id": "example_jwt_vc",
    "input_descriptors": [
        {
            "id": "id_credential",
            "format": {
                "jwt_vc_json": {
                    "proof_type": [
                        "JsonWebSignature2020"
                    ]
                }
            },
            "constraints": {
                "fields": [
                    {
                        "path": [
                            "$.vc.type"
                        ],
                        "filter": {
                            "type": "array",
                            "contains": {
                                "const": "IDCredential"
                            }
                        }
                    }
                ]
            }
        }
    ]
}

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.

A.1.1.3. Presentation Response

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

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

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

{
  "definition_id": "example_jwt_vc",
  "id": "example_jwt_vc_presentation_submission",
  "descriptor_map": [
    {
      "id": "id_credential",
      "path": "$",
      "format": "jwt_vp_json",
      "path_nested": {
        "path": "$.vp.verifiableCredential[0]",
        "format": "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:

{
    "iss": "did:example:ebfeb1f712ebc6f1c276e12ec21",
    "jti": "urn:uuid:3978344f-8596-4c3a-a978-8fcaba3903c5",
    "aud": "https://client.example.org/cb",
    "nbf": 1541493724,
    "iat": 1541493724,
    "exp": 1573029723,
    "nonce": "n-0S6_WzA2Mj",
    "vp": {
        "@context": [
            "https://www.w3.org/2018/credentials/v1"
        ],
        "type": [
            "VerifiablePresentation"
        ],
        "verifiableCredential": [
            "eyJhb...ssw5c"
        ]
    }
}

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 Section 12.1.

A.1.2. 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.

A.1.2.1. Example Credential

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

{
    "@context": [
        "https://www.w3.org/2018/credentials/v1",
        "https://www.w3.org/2018/credentials/examples/v1"
    ],
    "id": "https://example.com/credentials/1872",
    "type": [
        "VerifiableCredential",
        "IDCredential"
    ],
    "issuer": {
        "id": "did:example:issuer"
    },
    "issuanceDate": "2010-01-01T19:23:24Z",
    "credentialSubject": {
        "given_name": "Max",
        "family_name": "Mustermann",
        "birthdate": "1998-01-11",
        "address": {
            "street_address": "Sandanger 25",
            "locality": "Musterstadt",
            "postal_code": "123456",
            "country": "DE"
        }
    },
    "proof": {
        "type": "Ed25519Signature2018",
        "created": "2021-03-19T15:30:15Z",
        "jws": "eyJhb...JQdBw",
        "proofPurpose": "assertionMethod",
        "verificationMethod": "did:example:issuer#keys-1"
    }
}
A.1.2.2. Presentation Request

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

  GET /authorize?
    response_type=vp_token
    &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 following is a non-normative example of the contents of a presentation_definition parameter that contains the requirements regarding the Credential to be presented:

{
    "id": "example_ldp_vc",
    "input_descriptors": [
        {
            "id": "id_credential",
            "format": {
                "ldp_vc": {
                    "proof_type": [
                        "Ed25519Signature2018"
                    ]
                }
            },
            "constraints": {
                "fields": [
                    {
                        "path": [
                            "$.type"
                        ],
                        "filter": {
                            "type": "array",
                            "contains": {
                                "const": "IDCredential"
                            }
                        }
                    }
                ]
            }
        }
    ]
}

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.

A.1.2.3. Presentation Response

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

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

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

{
    "definition_id": "example_ldp_vc",
    "id": "example_ldp_vc_presentation_submission",
    "descriptor_map": [
        {
            "id": "id_credential",
            "path": "$",
            "format": "ldp_vp",
            "path_nested": {
                "format": "ldp_vc",
                "path": "$.verifiableCredential[0]"
            }
        }
    ]
}

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:

{
    "@context": [
        "https://www.w3.org/2018/credentials/v1"
    ],
    "type": [
        "VerifiablePresentation"
    ],
    "verifiableCredential": [
        {
            "@context": [
                "https://www.w3.org/2018/credentials/v1",
                "https://www.w3.org/2018/credentials/examples/v1"
            ],
            "id": "https://example.com/credentials/1872",
            "type": [
                "VerifiableCredential",
                "IDCredential"
            ],
            "issuer": {
                "id": "did:example:issuer"
            },
            "issuanceDate": "2010-01-01T19:23:24Z",
            "credentialSubject": {
                "given_name": "Max",
                "family_name": "Mustermann",
                "birthdate": "1998-01-11",
                "address": {
                    "street_address": "Sandanger 25",
                    "locality": "Musterstadt",
                    "postal_code": "123456",
                    "country": "DE"
                }
            },
            "proof": {
                "type": "Ed25519Signature2018",
                "created": "2021-03-19T15:30:15Z",
                "jws": "eyJhb...JQdBw",
                "proofPurpose": "assertionMethod",
                "verificationMethod": "did:example:issuer#keys-1"
            }
        }
    ],
    "id": "ebc6f1c2",
    "holder": "did:example:holder",
    "proof": {
        "type": "Ed25519Signature2018",
        "created": "2021-03-19T15:30:15Z",
        "challenge": "n-0S6_WzA2Mj",
        "domain": "https://client.example.org/cb",
        "jws": "eyJhb...IAoDA",
        "proofPurpose": "authentication",
        "verificationMethod": "did:example:holder#key-1"
    }
}

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 Section 12.1.

A.2. 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.

A.2.1. Example Credential

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

{
    "schema_id": "3QowxFtwciWceMFr7WbwnM:2:BasicScheme:0.1",
    "cred_def_id": "CsiDLAiFkQb9N4NDJKUagd:3:CL:4687:awesome_cred",
    "rev_reg_id": null,
    "values": {
        "given_name": {
            "raw": "Alice",
            "encoded": "6874ecdbdb214ee888e37c8c983e2f1c9c0ed16907b519704db42bb6"
        },
        "family_name": {
            "raw": "Wonderland",
            "encoded": "f5e16db78511f23bf2bcf0f450f20180951557cd75efe88b276988fd"
        },
        "email": {
            "raw": "alice@example.com",
            "encoded": "0fbaa7f92a47fe3c5201e97f063983c702432e90dd7bf0c723386543"
        }
    },
    "signature": {
        "p_credential": {
            "m_2": "99219524012997799443220800218760023447537107640621419137185629243278403921312",
            "a": "54855652574677988116650236306088516361537734570414909367032672219103444197205489674846545082012012711261249754371310495367475614729209653850720034913398482184757254920537051297936910125023613323255317515823974231493572903991640659741108603715378490408836507643191051986137793268856316333600932915078337920001692235029278931184173692694366223663131943657834349339828618978436402973046999961539444380116581314372906598415014528562207334745774098097000567515212222894771357044500544552372314335894883000614144994856702181141090905033428221403654636324918343808136750040908443212492359485782471636294013062295153997068252",
            "e": "259344723055062059907025491480697571938277889515152306249728583105665800713306759149981690559193987143012367913206299323899696942213235956742930239825562861075148170278284639129199",
            "v": "9774232256179658261610308745866736090602538333363396375105120427156273261155207775732400073422905045147609169788952804683922921383859274758479842100138659865591976937215264032734277416744113491766616076612368115891637834588143840477778776159325514034900968730327459279564615858068472282705529798808334108833124505594371791348317639533993310391511620579199112357959170076753792711700533312522910797352842323445933004238048599164039686432144165884599052061538014126710866075791210006585893465085621395503182710866197817129408546193805893321161372355187962990595781339533851533077334790530438016817333603675910702146635975282253747819810788129751055728368937483121363992748831475139233180853145906108476753713239644943541916540123456371366974874702598201796929261151925643543132170495933035112012082080893049915977209167597"
        },
        "r_credential": null
    },
    "signature_correctness_proof": {
        "se": "8986500246928105545119249693120482606913996376875337975817228090569777886100120575851444392132175485176800946276729875298747664099989412623249056022784348808658577491758644556594901203598819936532435225959211617545841036816799892165118015169512229910557670483101499028188851318984001732266955939801843049852569586066803442690248386970226324039561954050567607010646624132392374280640663854092050106203821468403658338788408023014151088931308776669398184180228869449717267624484235796469721889284094131533549692106113602342932288350356591343546227828642494647872633442330361211149649432468143339518371824496555067302935",
        "c": "93582993140981799598406702841334282100000866001274710165299804498679784215598"
    },
    "rev_reg": null,
    "witness": null
}

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

A.2.2. Presentation Request

A.2.2.1. Request Example

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

  GET /authorize?
    response_type=vp_token
    &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 following is a non-normative example of the content of the presentation_definition parameter:

{
    "id": "example_vc_ac",
    "input_descriptors": [
        {
            "id": "id_credential",
            "format": {
                "ac_vc": {
                    "proof_type": [
                        "CLSignature2019"
                    ]
                }
            },
            "constraints": {
                "fields": [
                    {
                        "path": [
                            "$.schema_id"
                        ],
                        "filter": {
                            "type": "string",
                            "const": "did:indy:idu:test:3QowxFtwciWceMFr7WbwnM:2:BasicScheme:0\\.1"
                        }
                    }
                ]
            }
        }
    ]
}

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.

A.2.2.2. 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 Appendix A.2.2.1.

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

{
   "id": "example_vc_ac_sd",
   "input_descriptors": [
      {
         "id": "id_credential",
         "format": {
            "ac_vc": {
               "proof_type": [
                  "CLSignature2019"
               ]
            }
         },
         "constraints": {
            "limit_disclosure": "required",
            "fields": [
               {
                  "path": [
                     "$.schema_id"
                  ],
                  "filter": {
                     "type": "string",
                     "const": "did:indy:idu:test:3QowxFtwciWceMFr7WbwnM:2:BasicScheme:0\\.1"
                  }
               },
               {
                  "path": [
                     "$.values.given_name"
                  ]
               },
               {
                  "path": [
                     "$.values.family_name"
                  ]
               }
            ]
         }
      }
   ]
}

This example is identic 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.

A.2.3. 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:

{
    "definition_id": "example_vc_ac_sd",
    "id": "example_vc_ac_sd_presentation_submission",
    "descriptor_map": [
        {
            "id": "id_credential",
            "path": "$",
            "format": "ac_vp",
            "path_nested": {
                "path": "$.requested_proof.revealed_attr_groups.id_card_credential",
                "format": "ac_vc"
            }
        }
    ]
}

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 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 presentation_definition parameter:

{
    "proof": {...},
    "requested_proof": {
        "revealed_attrs": {},
        "revealed_attr_groups": {
            "id_card_credential": {
                "sub_proof_index": 0,
                "values": {
                    "family_name": {
                        "raw": "Wonderland",
                        "encoded": "167908493…94017654562035"
                    },
                    "given_name": {
                        "raw": "Alice",
                        "encoded": "270346400…99344178781507"
                    }
                }
            }
        },
       …
    },
    "identifiers": [
        {
            "schema_id": "3QowxFtwciWceMFr7WbwnM:2:BasicScheme:0.1",
            "cred_def_id": "CsiDLAiFkQb9N4NDJKUagd:3:CL:4687:awesome_cred",
            "rev_reg_id": null,
            "timestamp": null
        }
    ]
}

A.3. ISO mobile Driving License (mDL)

This section illustrates how a mobile driving license (mDL) Credential expressed using a data model and data sets defined in [ISO.18013-5] encoded as CBOR can be presented from the End-User's device directly to the Verifier using this specification.

The Credential format identifier is mso_mdoc.

Cipher suites should use signature suites names defined in [ISO.18013-5].

A.3.1. Presentation Request

A non-normative example of an Authorization Request would look the same as in the examples of other Credential formats in this Annex. The difference is in the content of the presentation_definition parameter.

  GET /authorize?
    response_type=vp_token
    &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 following is a non-normative example of the content of the presentation_definition parameter:

{
    "id":"mDL-sample-req",
    "input_descriptors":[
        {
            "id":"org.iso.18013.5.1.mDL",
            "format":{
                "mso_mdoc":{
                    "alg":[
                        "EdDSA",
                        "ES256"
                    ]
                },
            },
            "constraints":{
                "limit_disclosure":"required",
                "fields":[
                    {
                        "path":[
                            "$['org.iso.18013.5.1']['family_name']"
                        ],
                        "intent_to_retain":false
                    },
                    {
                        "path":[
                            "$['org.iso.18013.5.1']['portrait']"
                        ],
                        "intent_to_retain":false
                    },
                    {
                        "path":[
                            "$['org.iso.18013.5.1']['driving_privileges']"
                        ],
                        "intent_to_retain":false
                    },
                    {
                        "path":[
                            "$['domestic_namespace']['domestic_data_element_id']"
                        ],
                        "intent_to_retain":false
                    }
                ]
            }
        }
    ]
}

To start with, the format parameter in the input_descriptor element is set to mso_mdoc, i.e., it requests presentation of an mDL in CBOR format.

To request user claims in ISO/IEC 18013-5:2021 mDL, a doctype and namespace of the claim needs to be specified. Moreover, the Verifiers needs to indicate whether it intends to retain obtained user claims or not, using intent_to_retain property.

Note: intent_to_retain is a property introduced in this example to meet requirements of [ISO.18013-5].

Setting limit_disclosure property defined in [DIF.PresentationExchange] to required enables selective release by instructing the Wallet to submit only the data parameters specified in the fields array. Selective release of claims is a requirement built into an ISO/IEC 18013-5:2021 mDL data model.

A.3.2. 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 following is a non-normative example of the content of the presentation_submission parameter:

{
    "definition_id": "mDL-sample-req",
    "id": "org.iso.18013.5.1.mDL",
    "descriptor_map": [
        {
            "id": "mDL",
            "format": "mso_mdoc",
            "path": "$"
        }
    ]
}

The descriptor_map refers to the input_descriptor element with an identifier mDL and tells the Verifier that there is an ISO/IEC 18013-5:2021 mDL (format is mso_mdoc) in CBOR encoding directly in the vp_token (path is the root designated by $).

When ISO/IEC 18013-5:2021 mDL is expressed in CBOR the path_nested parameter cannot be used to point to the location of the requested claims. The user claims will always be included in the issuerSigned item. path_nested parameter can be used, however, when a JSON-encoded ISO/IEC 18013-5:2021 mDL is returned.

The following is a non-normative example of an ISO/IEC 18013-5:2021 mDL encoded as CBOR in diagnostic notation (line wraps within values are for display purposes only) as conveyed in the vp_token parameter.

{
    "status": 0,
    "version": "1.0",
    "documents": [
        {
            "docType": "org.iso.18013.5.1.mDL",
            "deviceSigned": {
                "deviceAuth": {
                    "deviceMac": [
                        << {1: 5} >>,
                        {},
                        null, h'A574C64F18902BFE18B742F17C581218F88EA279AA96D0F5888123843461A3B6'
                    ]
                },
                "nameSpaces": 24(h'A0')
            },
            "issuerSigned": {
                "issuerAuth": [
                  << {1: -7} >>,
                    {
                        33: h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
                    },
                    <<
                      24(<<
                          {
                            "docType": "org.iso.18013.5.1.mDL",
                            "version": "1.0",
                            "validityInfo": {
                                "signed": 0("2022-04-15T06:23:56Z"),
                                "validFrom": 0("2022-04-15T06:23:56Z"),
                                "validUntil": 0("2027-01-02T00:00:00Z")
                            },
                            "valueDigests": {
                                "org.iso.18013.5.1": {
                                    1: h'0F1571A97FFB799CC8FCDF2BA4FC29099290AAD37AE37ACE3C3BAE85C6379AD5',
                                    2: h'0CDFE077400432C055A2B69596C90AAA47277C9678BFFC32BBC7F0CF82713B8E',
                                    3: h'E2382149255AE8E955AF9B8984395315F3A38427C267F910A637D3FC81F25BB4',
                                    4: h'BBC77E6CCA981A3AD0C3E544EDF8B68F19F4DACF1AF2AA0E6436401B4539ABA2',
                                    6: h'BB6E6C68D1B4B4EC5A2AE9206F5F976A32061FA878BD5B44476F96D35462F6B2',
                                    8: h'F8A5966E6DAC9970E0334D8F75E24DC63832E73A56AEF21C0D4B91487FC6AB03',
                                    9: h'EAD5E8B5E543BD31F3BE57DE4ED6CCF7BB635221725F80538165DA7DC0BF92BB',
                                    11: h'38CE9A09DC0121E1A9C2EF3EE2456530C2183AA8326FBE13B7D19A17DF77E980',
                                    12: h'DEFDF1AA746718016EF1B94BFE5FB7774B8665F57D48ADAB83ABE0B28C22DB59',
                                    13: h'A8868DF71AA4FB7D0AD3459C2E75E63767FE477B5A8FDF45537E936AFAB59C44',
                                    15: h'95B651F1BA60EF5867E63E8DB1B0328464E5B66775E213B743A1E31F8EFBD9CB',
                                    16: h'364E3C65D46D06FEDEB0E7293A86BA45FDFA99AA1A6DA3C3289B6E073B589922',
                                    17: h'B584E5D5EF4CFC93FDB1E4EE8F3996090EF0B1E8FD2AC594D7D8793093BB328F',
                                    18: h'677468F3E28CAAB521337E0FEF7FFEB067D2A2704F88B5D50D84CAF17209BA25',
                                    19: h'95501E3E769230DC945CFBDC707C45218459F1129EFD5088BDA672CEF5991598',
                                    20: h'677FACBBCA2EB9306BD649227B9AD66DF4A9AF6A5AB7D073F1BAAC23254B6D78',
                                    22: h'BCCFB15CB36125BF1ECBFDE32FF908BD3BAA2DC0BA949B673E96CBA26902059F',
                                    23: h'F9EE4D36F67DBD75E23311AC1C294C563992463A30B47039D25E03B6C6EFFCA3',
                                    25: h'AFC5A127BE44753172844B13491D880C3768691A4C9916E5257CEFA4BAA74654',
                                    26: h'1E1DA854356D3CFB7D983B8105F8A081057D4D01E910F263143BDC9AF1EF363C'
                                }
                            },
                            "deviceKeyInfo": {
                                "deviceKey": {
                                    1: 2,
                                    -1: 1,
                                    -2: h'B820963964E53AF064686DD9218303494A5B23A175C34CC54AD1D9244EFD0BA5',
                                    -3: h'0A6DA0AF437E2943F1836F31C678D89298E93D7E95057FD4D04E8E3EC2BBA935'
                                }
                            },
                            "digestAlgorithm": "SHA-256"
                          }
                      >>)
                    >>,
                    h'1AD0D6A7313EFDC38FCD765852FA2BD43DEBF48BF5A516960A685162B2B8242935861329ECB54F68234FC88A0228EC5DF22CB9689EC5053C80EDC59CC99EE80D'
                ],
                "nameSpaces": {
                    "org.iso.18013.5.1": [
                        24(<<
                            {
                              "digestID": 1,
                              "random": h'E0B70BCEFBD43686F345C9ED429343AA',
                              "elementIdentifier": "expiry_date",
                              "elementValue": 1004("2030-02-22")
                            }
                        >>),
                        24(<<
                            {
                              "digestID": 6,
                              "random": h'AE84834F389EE69888665B90A3E4FCCE',
                              "elementIdentifier": "given_name",
                              "elementValue": "Doe"
                            }
                        >>),
                        24(<<
                            {
                              "digestID": 11,
                              "random": h'960CB15A2EA9B68E5233CE902807AA95',
                              "elementIdentifier": "issuing_country",
                              "elementValue": "UT"
                            }
                        >>),
                        24(<<
                            {
                              "digestID": 13,
                              "random": h'9D3774BD5994CCFED248674B32A4F76A',
                              "elementIdentifier": "document_number",
                              "elementValue": "ES24689"
                            }
                        >>),
                        24(<<
                            {
                              "digestID": 15,
                              "random": h'EB12193DC66C6174530CDC29B274381F',
                              "elementIdentifier": "portrait",
                              "elementValue": 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
                            }
                        >>)),
                        24(<<
                            {
                              "digestID": 19,
                              "random": h'DB143143538F3C8D41DC024F9CB25C9D',
                              "elementIdentifier": "birth_date",
                              "elementValue": 1004("1980-02-05")
                            }
                        >>),
                        24(<<
                            {
                              "digestID": 20,
                              "random": h'6059FF1CE27B4997B4ADE1DE7B01DC60',
                              "elementIdentifier": "family_name",
                              "elementValue": "John"
                            }
                        >>),
                        24(<<
                            {
                              "digestID": 22,
                              "random": h'1E69C89C81B21A1BA56ACA3E026A2A3F',
                              "elementIdentifier": "issue_date",
                              "elementValue": 1004("2020-02-23")
                            }
                        >>),
                        24(<<
                            {
                              "digestID": 25,
                              "random": h'CAD1F6A38F603451F1FA653F81FF309D',
                              "elementIdentifier": "driving_privileges",
                              "elementValue": [
                                  {
                                      "issue_date": 1004("2018-08-09"),
                                      "expiry_date": 1004("2024-10-20"),
                                      "vehicle_category_code": "A"
                                  },
                                  {
                                      "issue_date": 1004("2017-02-20"),
                                      "expiry_date": 1004("2024-10-20"),
                                      "vehicle_category_code": "B"
                                  }
                              ]
                            }
                        >>),
                        24(<<
                            {
                              "digestID": 26,
                              "random": h'53C15C57B3B076E788795829190220B4',
                              "elementIdentifier": "issuing_authority",
                              "elementValue": "UTOPIA"
                            }
                        >>)
                    ]
                }
            }
        }
    ]
}

In the deviceSigned item, the deviceAuth item includes a signature by the deviceKey that belongs to the End-User. It is used to prove legitimate possession of the Credential, since the Issuer has signed over the deviceKey during the issuance of the Credential.

Note: The deviceKey does not have to be HW-bound.

In the issueSigned item, issuerAuth item includes Issuer's signature over the hashes of the user claims, and namespaces items include user claims within each namespace that the End-User agreed to reveal to the Verifier in that transaction.

Note: The user claims in the deviceSigned item correspond to self-attested claims inside a Self-Issued ID Token [SIOPv2] (none in the example below), and user claims in the issuerSigned item correspond to the user claims included in a VP Token signed by a trusted third party.

Note: The reason hashes of the user claims are included in the issuerAuth item lies in the selective release mechanism. Selective release of the user claims in an ISO/IEC 18013-5:2021 mDL is performed by the Issuer signing over the hashes of all the user claims during the issuance, and only the actual values of the claims that the End-User has agreed to reveal to the Verifier being included during the presentation.

The example in this section is also applicable to the electronic identification Verifiable Credentials expressed using data models defined in ISO/IEC TR 23220-2.

A.4. 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.

A.4.1. Request

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

  GET /authorize?
    response_type=id_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 id_token. If the request also includes a presentation_definition parameter, the Wallet is supposed to return the presentation_submission and vp_token parameters in the same response as the id_token parameter.
  • 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.

A.4.2. Response

The following is a non-normative example of a response sent upon receiving a request provided in Appendix A.4.1:

  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": "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.

Appendix B. IANA Considerations

B.1. Response Types

Note: Plan to register the following Response Types in the OAuth Authorization Endpoint Response Types IANA Registry.

B.2. Media Types

B.2.1. application/verifier-attestation+jwt

The Internet 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: : Compact Serialization as defined in [RFC7519].

Security considerations: : See Security Considerations in in [RFC7519].

Interoperability considerations: : n/a

  • Published specification: : TODO
  • 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: tbd TODO@email.com
    • Change controller: OpenID Foundation

B.3. JWS Headers

B.3.1. JWT

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

  • 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 - openid-specs-ab@lists.openid.net
  • Specification Document(s): Section 10

Appendix C. Acknowledgements

We would like to thank Richard Barnes, Paul Bastian, Vittorio Bertocci, Christian Bormann, John Bradley, Brian Campbell, Gabe Cohen, David Chadwick, Andrii Deinega, Giuseppe De Marco, Mark Dobrinic, Daniel Fett, Pedro Felix, George Fletcher, Timo Glasta, Mark Haine, Fabian Hauck, Roland Hedberg, Joseph Heenan, Alen Horvat, Andrew Hughes, Jacob Ideskog, Edmund Jay, Michael B. Jones, Tom Jones, Judith Kahrer, Takahiko Kawasaki, Gaurav Khot, Niels Klomp, Ronald Koenig, Markus Kreusch, Adam Lemmon, Daniel McGrogan, Jeremie Miller, Kenichi Nakamura, Rolson Quadras, Nat Sakimura, Arjen van Veen, David Waite, Jacob Ward for their valuable feedback and contributions to this specification.

Appendix D. Notices

Copyright (c) 2023 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.

Appendix E. Document History

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Authors' Addresses

Oliver Terbu
Mattr
Torsten Lodderstedt
sprind.org
Kristina Yasuda
Microsoft
Tobias Looker
Mattr