Verify Credentials

Tutorial: Verify a Verifiable Credential

This tutorial walks you through verifying a Verifiable Credential (VC) using LearnCard. Verification checks that:

1. The credential's cryptographic proof is valid

2. The credential hasn't been tampered with

3. The credential hasn't expired

Prerequisites

• Node.js (v18+)

• Basic familiarity with Verifiable Credentials

Installation

npm install @learncard/init

Basic Verification

import { initLearnCard } from '@learncard/init';

// Initialize LearnCard (no seed needed for verification-only)
const learnCard = await initLearnCard();

// Example signed credential (you'd receive this from an issuer)
const signedCredential = {
  "@context": ["https://www.w3.org/2018/credentials/v1"],
  "type": ["VerifiableCredential"],
  "issuer": "did:key:z6MkjZ...",
  "issuanceDate": "2024-01-01T00:00:00Z",
  "credentialSubject": {
    "id": "did:key:z6Mkp...",
    "achievement": "Completed Tutorial"
  },
  "proof": {
    "type": "Ed25519Signature2020",
    // ... proof details
  }
};

// Verify the credential
const result = await learnCard.invoke.verifyCredential(signedCredential);

console.log(result);
// { checks: ['proof', 'expiration'], warnings: [], errors: [] }

Understanding Results

Valid Credential

const result = await learnCard.invoke.verifyCredential(validCredential);

if (result.errors.length === 0) {
  console.log('✅ Credential is valid!');
  console.log('Checks passed:', result.checks);
} else {
  console.log('❌ Credential is invalid');
  console.log('Errors:', result.errors);
}

Human-Readable Output

For a more detailed, human-readable result, pass true as the third argument:

const result = await learnCard.invoke.verifyCredential(signedCredential, {}, true);

console.log(result);
// [
//   { status: "Success", check: "proof", message: "Valid" },
//   { status: "Success", check: "expiration", message: "Valid • Does Not Expire" }
// ]

Handling Invalid Credentials

// Tampered credential (modified after signing)
const tamperedCredential = { ...signedCredential };
tamperedCredential.credentialSubject.achievement = "Fake Achievement";

const result = await learnCard.invoke.verifyCredential(tamperedCredential);

console.log(result);
// {
//   checks: [],
//   warnings: [],
//   errors: ['signature error: Verification equation was not satisfied']
// }

Complete Example

import { initLearnCard } from '@learncard/init';

async function verifyCredentialFromIssuer(credential: any) {
  const learnCard = await initLearnCard();
  
  const result = await learnCard.invoke.verifyCredential(credential, {}, true);
  
  const isValid = result.every(check => check.status === 'Success');
  
  if (isValid) {
    console.log('✅ Credential verified successfully!');
    result.forEach(check => {
      console.log(`  ${check.check}: ${check.message}`);
    });
  } else {
    console.log('❌ Credential verification failed:');
    result.forEach(check => {
      if (check.status === 'Failed') {
        console.log(`  ${check.check}: ${check.details}`);
      }
    });
  }
  
  return isValid;
}

// Usage
const credential = /* ... received from issuer ... */;
await verifyCredentialFromIssuer(credential);

Next Steps

• Learn about Verifiable Presentations for sharing credentials

• Explore Trust Registries for validating issuers