@ajna-inc/zk-aadhar

Zero-knowledge proof system for India's Aadhaar offline KYC verification using STARK proofs.

Features

• 🔐 Zero-Knowledge Proofs - Prove age/attributes without revealing PII
• ⚡ STARK-based - Fast proof generation (~12ms) using Plonky3
• 🔒 Digital Signature Verification - Validates UIDAI's RSA signature
• 🌐 DIDComm Compatible - Proof-of-Execution format support
• 🚫 Replay Protection - Context binding prevents proof reuse

Installation

npm install @ajna-inc/zk-aadhar

Quick Start

const {
  parseAadharXml,
  proveAgeThreshold,
  verifyAgeThreshold,
  createDidcommAgeResponse,
  getVersion
} = require('@ajna-inc/zk-aadhar');

// 1. Parse Aadhaar XML (from offline KYC ZIP)
const aadhar = parseAadharXml(xmlString);
console.log('Name:', aadhar.name);
console.log('Age:', aadhar.age);
console.log('Commitment:', aadhar.commitment);

// 2. Create DIDComm context for proof
const context = {
  nonce: '0x' + randomBytes(32).toString('hex'),
  contextHash: '0x' + sha256(requestData).toString('hex'),
  sessionId: '0x' + randomBytes(16).toString('hex')
};

// 3. Generate age threshold proof (age >= 18)
const proof = proveAgeThreshold(xmlString, 18, context);

// 4. Create DIDComm response
const response = createDidcommAgeResponse(xmlString, proof, context, 18);

// 5. Verify proof
const isValid = verifyAgeThreshold(
  proof.proof,
  18,
  aadhar.commitment,
  context,
  proof.metadata.outputsHash
);

API Reference

parseAadharXml(xmlContent: string): AadharData

Parses Aadhaar offline KYC XML and verifies digital signature.

Returns:

{
  referenceId: string,
  name: string,
  dob: string,
  gender: string,
  age: number,
  commitment: number,
  signatureVerified: boolean
}

proveAgeThreshold(xmlContent: string, minAge: number, context: ProofContext): ProofResult

Generates a zero-knowledge proof that age >= minAge.

Parameters:

• xmlContent - Raw Aadhaar XML string
• minAge - Minimum age threshold
• context - DIDComm context (nonce, contextHash, sessionId)

Returns:

{
  proof: string,        // Base64-encoded STARK proof
  metadata: {
    circuitId: string,
    vkHash: string,
    outputsHash: string,
    proofSizeBytes: number,
    scheme: string,
    generationTimeMs: number
  }
}

proveAgeRange(xmlContent: string, minAge: number, maxAge: number, context: ProofContext): ProofResult

Generates proof that minAge <= age <= maxAge.

createDidcommAgeResponse(xmlContent: string, proof: ProofResult, context: ProofContext, minAge: number): DIDCommProofResponse

Creates a DIDComm-compatible proof response.

Returns:

{
  programId: string,
  result: string,
  public: {
    nonce: string,
    contextHash: string,
    sessionId: string,
    outputsHash: string,
    vkHash: string,
    commitment: number
  },
  zk: {
    scheme: string,
    circuitId: string,
    vkHash: string,
    proofB64: string
  }
}

verifyAgeThreshold(proofBase64: string, minAge: number, commitment: number, context: ProofContext, outputsHash: string): boolean

Verifies an age threshold proof.

Returns: true if proof is valid, throws error otherwise.

getVersion(): string

Returns the library version.

Performance

Benchmarked on Apple M-series (arm64):

| Operation | Time | Notes | |-----------|------|-------| | Parse XML | < 1ms | Includes signature verification | | Generate Proof (threshold) | ~12ms | STARK proof, 58KB | | Generate Proof (range) | ~68ms | STARK proof, 59KB | | Verify Proof | ~2ms | Very fast verification |

Security Features

• ✅ Digital Signature Verification - UIDAI's RSA-2048 signature
• ✅ Zero-Knowledge - No PII revealed in proofs
• ✅ Replay Protection - Context binding prevents reuse
• ✅ Commitment Binding - Proof tied to specific Aadhaar
• ✅ Tamper Detection - Invalid XML rejected

Platform Support

Pre-built binaries for:

• macOS (x64, arm64)
• Linux (x64, arm64, musl)
• Windows (x64, arm64)

Example Code

See example.js for complete usage examples including:

• XML parsing
• Proof generation
• DIDComm responses
• Proof verification

License

MIT

Links

• GitHub
• Issues
• DIDComm Spec

Warning

⚠️ Never commit real Aadhaar data to version control!

This library is for legitimate KYC verification only. Misuse of Aadhaar data is illegal under Indian law.