A privacy-preserving credential verification platform built on Ethereum using Zero-Knowledge Proofs. Issuers can issue digital credentials on-chain, holders can prove ownership without revealing sensitive data, and verifiers can validate credentials trustlessly.
- Issuer Dashboard — Register as a trusted authority and issue credentials on-chain
- Holder Dashboard — View credentials and generate zero-knowledge proofs
- Verifier Dashboard — Verify proofs on-chain without accessing personal data
- ZK Proof Generation — Prove credential ownership without revealing private data
- On-Chain Verification — Smart contract validates proofs cryptographically
- MetaMask Integration — Auto-connects to the correct blockchain network
- Immutable Audit Trail — Every verification is recorded on the blockchain
┌──────────────────────────────────┐
│ React Frontend │
│ (Issuer / Holder / Verifier) │
└──────────────┬───────────────────┘
│ ethers.js + MetaMask
▼
┌──────────────────────────────────┐
│ Ethereum Blockchain │
│ ┌────────────────────────────┐ │
│ │ CredentialRegistry.sol │ │
│ │ (Issue, Revoke, Verify) │ │
│ └─────────────┬──────────────┘ │
│ │ calls │
│ ┌─────────────▼──────────────┐ │
│ │ Groth16Verifier.sol │ │
│ │ (ZK Proof Verification) │ │
│ └────────────────────────────┘ │
└──────────────────────────────────┘
blockchain/
├── contracts/
│ ├── CredentialRegistry.sol # Credential management + ZK verification
│ └── Groth16Verifier.sol # ZK-SNARK proof verifier
├── circuits/
│ └── credential.circom # Circom ZK circuit (Poseidon hash)
├── scripts/
│ └── deploy.js # Contract deployment + ABI export
├── test/
│ └── CredentialRegistry.test.js
├── frontend/
│ └── src/
│ ├── components/ # Issuer, Holder, Verifier dashboards
│ ├── utils/ # WalletContext, zkUtils
│ └── App.js # Router + contract loading
├── hardhat.config.js
└── package.json
cd blockchain
npm install
cd frontend
npm install
cd ..npx hardhat nodenpx hardhat run scripts/deploy.js --network localhostcd frontend
npm startThe app auto-switches MetaMask to the Hardhat network. Just click Connect and approve.
- Network: Hardhat Local
- RPC URL:
http://127.0.0.1:8545 - Chain ID:
31337
1. ISSUER → Register → Issue credential (hash stored on-chain)
2. HOLDER → Enter secret + data → Generate ZK Proof → Copy/Download
3. VERIFIER → Paste proof JSON → Verify on-chain → Valid ✓ / Invalid ✗
Key Concept: The verifier confirms the credential is authentic without ever seeing the credential data. Only a cryptographic proof is verified.
Holder knows: secret + credentialData
↓
Computes: hash = Poseidon(secret, credentialData)
↓
Generates: ZK Proof → "I know the preimage of this hash"
↓
Verifier: Checks proof on-chain → Valid/Invalid
(never learns secret or credentialData)
| Function | Description |
|---|---|
selfRegisterIssuer(name) |
Register as a credential issuer |
issueCredential(hash, holder, type, uri) |
Issue a credential on-chain |
revokeCredential(hash) |
Revoke a credential |
verifyCredentialProof(hash, a, b, c, input) |
Verify a ZK proof on-chain |
getHolderCredentials(address) |
Get all credentials for a holder |
Verifies that ZK proof elements are cryptographically linked, ensuring forged proofs are rejected.
npx hardhat test CredentialRegistry
✓ should auto-register deployer as issuer
✓ should allow self-registration as issuer
✓ should prevent duplicate issuer registration
✓ should issue a credential
✓ should prevent non-issuers from issuing
✓ should prevent duplicate credentials
✓ should track holder credentials
✓ should allow issuer to revoke
✓ should prevent non-issuer from revoking
9 passing
| Technology | Purpose |
|---|---|
| Solidity 0.8.19 | Smart contracts |
| Circom 2.0 | ZK circuit definition |
| Hardhat | Ethereum dev framework |
| React 18 | Frontend UI |
| Ethers.js v6 | Blockchain interaction |
| MetaMask | Wallet & transaction signing |
| SnarkJS | ZK proof generation |
MIT
Built with ❤️ using Ethereum, Zero-Knowledge Proofs, and React