2025-11-10-presentation-request-service

Extraction of service for presentation requests

Decision

We will extract a service for requesting Verifiable Presentations from the DcpIdentityService. This new service will be responsible for fetching the SI token and making the presentation request when verifying a received token.

Rationale

Currently, the entire process for verifying a received token when using DCP is located in the DcpIdentityService's verifyJwtToken method. This on the one hand causes the method to be quite long and on the other hand does not allow for flexibility within the verification process. By extracting part of the process to a dedicated service, the method can be shortened and adopters gain more flexibility to extend the code for requesting the presentation with custom logic.

Approach

PresentationRequestService

We will create a new interface PresentationRequestService in the decentralized-claims-spi. This service will be responsible for requesting the Verifiable Presentation after receiving the counter-party's SI token, including the creation of the own SI token:

public interface PresentationRequestService {
    Result<List<VerifiablePresentationContainer>> requestPresentation(String participantContextId, String ownDid,
                                                                      String counterPartyDid, String counterPartySiToken,
                                                                      List<String> scopes);
}

The new interface will be used in the DcpIdentityService's verifyJwtToken method, where the calls to the SecureTokenService, the CredentialServiceUrlResolver and the CredentialServiceClient will be replaced with a call to the new service. The code replaced in the DcpIdentityService will be moved to the DefaultPresentationRequestService:

public class DefaultPresentationRequestService implements PresentationRequestService {
    // services & constructor

    @Override
    public Result<List<VerifiablePresentationContainer>> requestPresentation(String participantContextId, String ownDid,
                                                                             String counterPartyDid, String counterPartySiToken,
                                                                             List<String> requestedScopes) {
        Map<String, Object> siTokenClaims = Map.of(PRESENTATION_TOKEN_CLAIM, counterPartyToken,
                ISSUED_AT, Instant.now().getEpochSecond(),
                AUDIENCE, counterPartyDid,
                ISSUER, ownDid,
                SUBJECT, ownDid,
                EXPIRATION_TIME, Instant.now().plus(5, ChronoUnit.MINUTES).getEpochSecond());
        var siToken = secureTokenService.createToken(participantContextId, siTokenClaims, null);
        if (siToken.failed()) {
            return siToken.mapFailure();
        }
        var siTokenString = siToken.getContent().getToken();

        return credentialServiceUrlResolver.resolve(counterPartyDid)
                .compose(url -> credentialServiceClient.requestPresentation(url, siTokenString, requestedScopes));
    }
}

decentralized-claims lib module

As one of the goals of this refactoring is to allow adopters to extend the current logic for making the presentation request, the DefaultPresentationRequestService should be available in a lib module. We will therefore create a new lib module within the decentralized-claims module, which for now will only contain the DefaultPresentationRequestService.