---
tags: Design
---
# Requesting Presentations

## Status Quo

Presentations can be requested by Credential Defintion IDs (CredDefId).
The Credential Definitions are hard coded in the frontend with a list for ILL and IDunion network. In addition it is possible to enter a CredDefId manually in "Expert mode".

 templates: {
        iil: [
          {
            credentialDefinitionId:
              "5mwQSWnRePrZ3oF67C4KqD:3:CL:1077:commercial register entry",
            label: "Commercial Registry Entry",
            issuer: "Commercial Registry",
          },
          {
            credentialDefinitionId:
              "M6Mbe3qx7vB4wpZF4sBRjt:3:CL:571:Bank Account V2",
            label: "Bank Account",
            issuer: "Bank",
          },
        ],
        idu: [
          {
            credentialDefinitionId:
              "R6WR6n7CQVDjvvmwofHK6S:3:CL:109:Commercial Registry Entry",
            label: "Commercial Registry Entry",
            issuer: "Trust Service Provider",
          },
          {
            credentialDefinitionId:
              "SCf4pK5PTvc1LnbUAF2aHD:3:CL:104:Bank Account V2",
            label: "Bank Account",
            issuer: "Bank",
          },
          {
            credentialDefinitionId:
              "3QowxFtwciWceMFr7WbwnM:3:CL:104:Bank Account",
            label: "Bank Account",
            issuer: "CommerzBank",
          },
        ],
      }
      

## Drawbacks

1. If the wallet db of an issuer gets lost a new credential defintion has to be registered on the ledger. Hence, we would need to update the CredDefId in the code.
2. Users of a BPA can't easily add additional credential definitions
3. Users can't easiliy add credential definitions of a ledger other than IIL and IDunion.
4. It's not possible to ask for a presention of a specified schema without specifying the issuer.
5. It's not possible to ask for/accept a document.

## Features / Requirements / User Stories

1. As a BPA admin I want to use another ledger
2. As a BPA admin I want to configure specific credential definition ids
3. As a user I want to ask for a specific schema and define 1..n accepted issuers
4. As a user I want to ask for a specific schema and I accept self-attested data ("asking for a document")
5. As a BPA admin I want to configure specific presentation definitions that users can select
6. As a BPA user I want to create a custom presentation request
7. As a BPA user I want to create a custom presentation request and store it as a presentation definition

## Solution Concept

**1. Configure credential definitions as part of schema configuration.**
(Optional) Use ledger explorer to simplify selection of credential definitions in the UI.
Each Schema can define 0...n credential definitions with a label.
Open Question: How to handle Issuer names?
Addresses: D1 by allowing to update the config, D2, D3
Implements US 1,2
**2. Request presentations based on schema and issuer** **(DECISION)**
Would allow being independent of a particular credential definition
Issuers
Addresses: D1, D4
Implements US 3
**3. Disable Auto-respond presentation request and fullfill "document request" in BPA**
Addresses: D5
Implements US 4

## Presentation Request Examples

### Bank Account Credential

Schema ID: M6Mbe3qx7vB4wpZF4sBRjt:2:bank_account:1.0
Attributes: iban, bic

**THIS IS NOT TESTED!**
Ask for the attributes from a schema. Issuer does not matter, but both attributes need to be from the same credential.

"name":"proof_req_1",
"version":"0.1",
"requested_attributes": {
    "attr1_referent": {
        "names":["iban", "bic"], 
        "restrictions": [{
            "schema_id": "M6Mbe3qx7vB4wpZF4sBRjt:2:bank_account:1.0"    
        }]                       
    }
}
"requested_predicates": {}

Ask for the attributes from a schema and issuer1 OR issuer2. Both attributes need to be from the same credentials

"name":"proof_req_2",
"version":"0.1",
"requested_attributes": {
    "attr1_referent": {
        "names":["iban", "bic"],
        "restrictions": [{
            "schema_id": "M6Mbe3qx7vB4wpZF4sBRjt:2:bank_account:1.0",
            "issuer_did": "issuer1"
        },
 {
            "schema_id": "M6Mbe3qx7vB4wpZF4sBRjt:2:bank_account:1.0",
            "issuer_did": "issuer2"
            }]
                     
    }]
}
"requested_predicates": {}

BPA API:

one of
{
request_by_schema: {
    schema_id: "",
    issuer_did: []
},
request_raw: {}
}

Allow for self-attestation, but communicate intend with schema_id

"name":"proof_req_2",
"version":"0.1",
"requested_attributes": {
    "attr1_referent": {
        "name":"iban",
        "restrictions": [
        {
            "schema_id": "M6Mbe3qx7vB4wpZF4sBRjt:2:bank_account:1.0"    
        }, {}]                       
    },
    "attr2_referent": {
        "name":"bic",
        "restrictions": [
        {
            "schema_id": "M6Mbe3qx7vB4wpZF4sBRjt:2:bank_account:1.0"    
        }, {}]                       
    }
}
"requested_predicates": {}

## Sequence Diagram (US 4)

@startuml
"BPA Requester"->"ACA-PY Requester": /present-proof/send-request
"ACA-PY Requester"->"ACA-PY Prover": DIDcomm: presentation request
"ACA-PY Prover"->"BPA Prover": Webhook: Presentation Request
opt Ask for permission
"BPA Prover"->"BPA Prover": Should presentation request be fullfilled?
end
"BPA Prover"->"ACA-PY Prover":  Look for VC of schema in wallet
alt VC with schema NOT found
    "BPA Prover"->"BPA Prover": Look for Document of schema
end
"BPA Prover"->"ACA-PY Prover": /present-proof/records/{pres_ex_id}/send-presentation
"ACA-PY Prover"->"ACA-PY Requester": DIDcomm: Presentation
"ACA-PY Requester"->"ACA-PY Requester": Verify Presentation (automatically due to --auto-verify-presentation)
"ACA-PY Requester"->"BPA Requester": "Webhook: Presentation Received & Verified"
@enduml

If neither a VC nor a Document is found we could send a `problem-report` message (can be added later on)