`/derive` Endpoint#

New in version 2.0.

Starting in version 2.0, ESS supports an authorization mechanism based on access requests and grants. In 2.0, the access requests and grants are serialized as a Verifiable Credentials (VCs).

To support access requests and grants, ESS provides an endpoint that derives VCs through query and return the matching VCs in a Verifiable Presentation.

`/derive` Endpoint#

The ESS VC service provides an endpoint with the following URL:

https://vc.<ESS DOMAIN>/derive

Note

Access to the /derive endpoint requires users to be authenticated.

To query for/derive VCs, clients can send a derivation request to the endpoint:

Method:	`POST`
Content-Type	`application/json`
Endpoint:	`https://vc.<ESS DOMAIN>/derive`
Payload:	Derivation request object. See Input: Verifiable Credential for details.

Behavior#

The ESS’ /derive endpoint implements the derive credential portion of the VC API specification [1] with the following exceptions:

ESS’ /derive endpoint returns a Verifiable Presentation instead of a VC.
ESS’ /derive endpoint, by default, excludes both expired VCs (i.e., VCs with expirationDate in the past) and future VCs (i.e., VCs with issuanceDate in the future). To override, see options.

The endpoint queries the user-associated VCs (regardless of revocation status) to return a Verifiable Presentation that contains the matching VCs. User-associated VCs are:

VCs that have been issued to the user; i.e., the credentialSubject.id of the VC(s) is the user’s WebID,
VCs that have been requested of the user; i.e., the user’s WebID matches the property credentialSubject.hasConsent.isConsentForDataSubject, and
VCs that have been granted to the user; i.e., the user’s WebID matches any of the following fields:
- "credentialSubject.providedConsent.isProvidedTo"
- "credentialSubject.providedConsent.isProvidedToPerson"
- "credentialSubject.providedConsent.isProvidedToController"

Input: Verifiable Credential#

The endpoint accepts a JSON document of the form:

{
  "verifiableCredential": <VC to filter/query by>,
  "options": {
    "include": "ExpiredVerifiableCredential"
  }
}

verifiableCredential

Specify a filter VC. The filter VC acts similarly to a “search-by-example” model and can be minimal (i.e., can be missing fields or have empty values such as an empty array, an empty document) or comprehensive. However, if any of the following field paths appear in the filter VC and are non-empty, ESS VC services uses these non-empty field paths to filter VCs:

id
credentialSubject
type
issuer

options

Optional. Specify the "include": "ExpiredVerifiableCredential" option to include expired VCs and future VCs in the returned VP.

"options": {
  "include": "ExpiredVerifiableCredential"
}

Omit to exclude the expired and future VCs.

If you specify a different option or value (such as "include": "ExpiredVerifiableCredentials" with an s), the endpoint ignores the option and excludes the expired and future VCs.

Output: Verifiable Presentation#

The /derive endpoint returns a Verifiable Presentation containing the matching VCs:

{
  "@context": [
    "https://www.w3.org/2018/credentials/v1"
  ],
  "holder": "https://vc.<ESS Domain>",
  "type": "VerifiablePresentation",
  "verifiableCredential": [
    { // Matching VC },
    { // Matching VC },
    ...
  ]
}

Filter Paths#

`id`#

"id": <value>

If the id field is present in the filter VC, the ESS VC service considers the field for filtering user-associated VCs.

`credentialSubject`#

If the credentialSubject field is present in the filter VC and is not empty (i.e., it is not an empty document and contains at least one non-empty field path), the ESS VC service considers the non-empty credentialSubject field path(s) to filter user-associated VCs.

For Access Request VCs#

Since credentialSubject.hasConsent only appears in access request VCs, a non-empty credentialSubject.hasConsent field path can be used to query access request VCs.

"credentialSubject": {
  "hasConsent": {
    "mode": <value or array of values>
    "hasStatus": <value>,
    "isConsentForDataSubject": <value>,
    "forPersonalData": <value or array of values>
  },
  "id": <value>
}

Note

For credentialSubject.hasConsent.mode and credentialSubject.hasConsent.forPersonalData fields that can be a single URL string or an array of URL strings,

A single URL string is equivalent to an array with a single element.
To filter by an array, matching VCs must include all elements in the provided array. However, the matching VCs can have additional elements in the array; that is, the matching VCs are not restricted to just the elements specified in the filter array.

That is:

<field>: "foo" condition would match:
- <field>: "foo"
- <field>: [ "foo" ]
- <field>: [ "foo", "other string" ]
<field>: [ "foo" ] condition would match:
- <field>: "foo"
- <field>: [ "foo" ]
- <field>: [ "foo", "other string" ]

For Access Grant VCs#

Since credentialSubject.providedConsent only appears in access grant VCs, a non-empty credentialSubject.providedConsent field path can be used to query access grant VCs.

"credentialSubject": {
  "providedConsent": {
    "mode":  <value(s)>,
    "hasStatus": <value>,
    "isProvidedToPerson": <value>,
    "forPersonalData": <value(s)>
  },
  "id": <value>
}

Note

For credentialSubject.providedConsent.mode and credentialSubject.providedConsent.forPersonalData fields that can be a single URL string or an array of URL strings,

A single URL string is equivalent to an array with a single element.
To filter by an array, matching VCs must include all elements in their array. However, the matching VCs can have additional elements in the array; that is, the matching VCs are not restricted to just the elements specified in the filter array.

That is:

<field>: "foo" (or <field>: ["foo"]) condition would match:
- <field>: "foo"
- <field>: [ "foo" ]
- <field>: [ "foo", "other string" ]
<field>: [ "foo", "bar" ] condition would match:
- <field>: [ "foo", "bar" ]
- <field>: [ "foo", "bar", "something else" ]

Empty `credentialSubject`#

ESS VC service only considers non-empty credentialSubject field path(s) to filter user-associated VCs. Empty credentialSubject field path(s) are not considered as part of the filter. Examples of empty credentialSubject field paths are:

"credentialSubject": {

}

"credentialSubject": {
   "hasConsent": {}
}

"credentialSubject": {
   "hasConsent": {
      "mode": [],
      "forPersonalData": []
   }
}

"credentialSubject": {
   "providedConsent": { }
}

"credentialSubject": {
   "providedConsent": {
       "mode": []
   }
}

`issuer`#

"issuer": <value>

If the issuer field is present in the filter VC, the ESS VC service considers the field for filtering user-associated VCs.

`type`#

"type": <value(s)>

If the type field is present in the filter VC, the ESS VC service considers the field for filtering user-associated VCs.

Note

If the type value is a non-empty array, matching VCs must include all elements in that array. The matching VCs can have additional elements in the array; that is, the matching VCs are not restricted to just the elements specified in the filter array.

Examples#

ESS VC service performs a match on non-empty id, credentialSubject, issuer, and type field paths present in the filter VCs.

Note

In the following examples, the VC payloads return user-associated VCs (both active and revoked) that that match the filter field paths. Because the payload does not specify the options: {“include”: “ExpiredVerifiableCredential” }, expired and future VCs are excluded from the results.

Example 1#

The filter VC queries for user-associated VCs where owliverowner grants Read access to requestingrabbit. The filter VC contains the following non-empty fields for matching:

credentialSubject.providedConsent.mode
credentialSubject.providedConsent.hasStatus
credentialSubject.providedConsent.isProvidedToPerson
credentialSubject.id
type

When the following payload is posted to the /derive endpoint,

{
   "verifiableCredential": {
      "credentialSubject": {
         "providedConsent": {
            "mode": ["http://www.w3.org/ns/auth/acl#Read" ],
            "hasStatus": "https://w3id.org/GConsent#ConsentStatusExplicitlyGiven",
            "isProvidedToPerson": "https://id.<ESS DOMAIN>/requestingrabbit"
          },
          "id": "https://id.<ESS DOMAIN>/owliverowner"
      },
      "type": [
          "VerifiableCredential",
          "SolidAccessGrant"
      ]
   }
}

The filter VC matches all user-associated VCs where:

credentialSubject.providedConsent.mode matches the value "http://www.w3.org/ns/auth/acl#Read" or contains the value "http://www.w3.org/ns/auth/acl#Read" as an array element, AND
credentialSubject.providedConsent.hasStatus matches the value "https://w3id.org/GConsent#ConsentStatusExplicitlyGiven", AND
credentialSubject.providedConsent.hasStatus matches the value "https://id.<ESS DOMAIN>/requestingrabbit", AND
credentialSubject.id matches the value "https://id.<ESS DOMAIN>/owliverowner", AND
type contains the values "VerifiableCredential" and "SolidAccessGrant" as array elements.

Upon completion, the endpoint returns a Verifiable Presentation with the matching VCs.

Example 2#

The following filter VC queries for user-associated VCs that grants Write access to the specified resource. The filter VC contains the following non-empty fields for matching:

credentialSubject.providedConsent.mode
credentialSubject.providedConsent.forPersonalData

When the following payload is posted to the /derive endpoint,

{
  "verifiableCredential": {
    "credentialSubject": {
      "providedConsent": {
        "mode": "http://www.w3.org/ns/auth/acl#Write",
        "forPersonalData": [
          "https://storage.<ESS Domain>/<Pod Identifier>/getting-started/readingList/myList"
        ]
      }
    }
  }
}

The filter VC matches all user-associated VCs where:

credentialSubject.providedConsent.mode matches the value "http://www.w3.org/ns/auth/acl#Write" or contains the value "http://www.w3.org/ns/auth/acl#Write" as an array element, AND
credentialSubject.providedConsent.forPersonalData matches the value "https://storage.<ESS Domain>/<Pod Identifier>/getting-started/readingList/myList" or contains the value as an array element.

Upon completion, the endpoint returns a Verifiable Presentation with the matching VCs.

Empty Filter Paths#

ESS VC service performs a match only on non-empty id, credentialSubject, issuer, type field paths. Otherwise, the service returns all VCs associated with the user.

For example, when the following payloads are posted to the /derive endpoint:

The filter VC is an empty document; i.e., the filter VC does not contain any of the fields used for matching:
```
{
  "verifiableCredential": { }
}
```
This would match all the VCs (access request VCs and access grant VCs) associated with the user.
The filter VC contains empty values for the query field “credentialSubject.hasConsent” and no other matching fields (i.e., id, type, credentialSubject.id fields). As such, the filter VC does not have any non-empty matching filter paths
```
{
  "verifiableCredential": {
     "credentialSubject": {
       "hasConsent": { }
     }
  }
}
```
This would match all the VCs (access request VCs and access grant VCs) associated with the user.

The VC filter contains empty values for the query field “credentialSubject.providedConsent” and no other matching fields (i.e., id, type, credentialSubject.id):

{
  "verifiableCredential": {
     "@context": [
       "https://www.w3.org/2018/credentials/v1",
       "https://w3id.org/security/suites/ed25519-2020/v1",
       "https://w3id.org/vc-revocation-list-2020/v1",
       "https://vc.<ESS DOMAIN>/credentials/v1"
     ],
     "credentialStatus": {
       "id": "https://vc./status/VfaR#98",
       "revocationListCredential": "https://vc.<ESS DOMAIN>/status/VfaR",
       "revocationListIndex": "98",
       "type": "RevocationList2020Status"
     },
     "credentialSubject": {
       "providedConsent": { }
     },
     "type": [ ]
  }
}

Upon completion, the endpoint returns a Verifiable Presentation with the matching VCs, in this case, all VCs associated with the user.

/derive Endpoint#

/derive Endpoint#

Behavior#

Input: Verifiable Credential#

Output: Verifiable Presentation#

Filter Paths#

id#

credentialSubject#

For Access Request VCs#

For Access Grant VCs#

Empty credentialSubject#

issuer#

type#

Examples#

Example 1#

Example 2#

Empty Filter Paths#

`/derive` Endpoint#

`/derive` Endpoint#

`id`#

`credentialSubject`#

Empty `credentialSubject`#

`issuer`#

`type`#