Features

• Multiple Credential Formats: Support for Linked Data Proof (LDP) Verifiable Credentials/Presentations with extensible architecture for additional formats
• Policy-Based Verification: Configurable business rules and verification policies (e.g., required subject) to ensure compliance
• Cryptographic Flexibility: Works with pluggable verifiers and cryptosuites, including Ed25519
• Presentation Requests: Build requests describing required policies and credential constraints
• TypeScript Support: Full TypeScript definitions for enhanced developer experience and type safety

Installation

npm install @the-hashgraph-group-ag/verifier

Quick Start

Basic Usage

import {
  createCredentialVerifier,
  LdpHandler,
  LdpRequiredSubjectPolicy,
} from '@the-hashgraph-group-ag/verifier';
import { InternalEd25519Verifier } from '@the-hashgraph-group-ag/signer-internal-ed25519';
import { Ed25519ProofVerifier } from '@the-hashgraph-group-ag/cryptosuites-eddsa-v1';

// Create cryptographic components
const verifier = new InternalEd25519Verifier();
const cryptoSuites = [new Ed25519ProofVerifier()];

// Provide verifier options, including a way to resolve public keys
const verifierOptions = {
  verificationMethodResolver: async (verificationMethod: string) => {
    // Resolve and return the raw public key bytes for the verificationMethod
    // e.g., from DID Documents or your key registry
    return new Uint8Array(/* public key bytes */);
  },
};

// Create an LDP verification handler
const ldpHandler = new LdpHandler({
  cryptoSuites,
  verifier,
  verifierOptions,
});

// Create verification policies
const subjectPolicy = new LdpRequiredSubjectPolicy({
  subject: 'did:example:alice',
});

// Create the credential verifier
const credentialVerifier = createCredentialVerifier({
  handlers: [ldpHandler],
  policies: [subjectPolicy],
});

// Create a presentation request that references configured policies
const request = await credentialVerifier.createRequest({
  policies: ['LdpRequiredSubjectPolicy'],
});

// Verify a Verifiable Presentation (or a single Verifiable Credential)
const vp = {
  '@context': ['https://www.w3.org/2018/credentials/v1'],
  type: ['VerifiablePresentation'],
  holder: 'did:example:alice',
  verifiableCredential: [
    /* your LDP VC(s) here */
  ],
  proof: {
    /* LDP proof */
  },
};

const verification = await credentialVerifier.verify(vp, request);

if (verification.verified) {
  console.log(
    'Presentation verified. Policy results:',
    verification.policyResults,
  );
} else {
  console.error('Verification failed:', verification.error);
}

Contributing

Contributions are welcome! Please see the main project repository for contribution guidelines.

License

This SDK is licensed under the Apache License 2.0.

Support

For support and questions:

• Check the documentation
• Open an issue on GitHub
• Contact the development team