PrivAgent Service

Privacy-preserving payment proofs via Tempo MPP. Shielded deposits, transfers, and withdrawals using Groth16 ZK proofs over JoinSplit UTXO circuits.

Endpoints

Method	Path	Cost	Description
GET	/health	Free	Health check
GET	/pool	Free	Pool info & available circuits
GET	/openapi.json	Free	OpenAPI 3.1 spec
GET	/llms.txt	Free	Agent discovery
POST	/privacy/deposit	$0.03	Generate shielded deposit proof
POST	/privacy/transfer	$0.03	Generate private transfer proof
POST	/privacy/withdraw	$0.03	Generate withdrawal proof
POST	/verify	Free	Verify a proof

How It Works

PrivAgent generates Groth16 zero-knowledge proofs for a UTXO-based privacy system:

• Deposit: Shield funds from public to private (publicAmount > 0)
• Transfer: Move funds privately between UTXO commitments (publicAmount = 0)
• Withdraw: Unshield funds from private to public (publicAmount < 0, field-wrapped)

Each proof uses the JoinSplit circuit (1 input, 2 outputs, Merkle depth 20) with Poseidon hashing over the BN254 curve.

Usage

Deposit (shield funds)

curl -X POST https://himess-privagent-service.hf.space/privacy/deposit \
  -H "Content-Type: application/json" \
  -d '{"amount": "1000000"}'

Transfer (private payment)

curl -X POST https://himess-privagent-service.hf.space/privacy/transfer \
  -H "Content-Type: application/json" \
  -d '{"amount": "1000000", "recipientPubkey": "12345"}'

Withdraw (unshield funds)

curl -X POST https://himess-privagent-service.hf.space/privacy/withdraw \
  -H "Content-Type: application/json" \
  -d '{"amount": "1000000", "recipient": "0x4013AE1C1473f6CB37AA44eedf58BDF7Fa4068F7"}'

Verify a proof

curl -X POST https://himess-privagent-service.hf.space/verify \
  -H "Content-Type: application/json" \
  -d '{"proof": {...}, "publicSignals": [...]}'

Payment

Paid endpoints require USDC payment via Tempo MPP (automatic 402 flow). Use tempo request or any MPP-compatible client.

Local Development

npm install
NO_MPP=1 npx tsx src/server.ts

Architecture

• Runtime: Node.js + Hono
• Proof system: Groth16 via snarkjs
• Hash function: Poseidon (BN254) via circomlibjs
• Payment: Tempo MPP via mppx
• Circuits: JoinSplit 1x2 and 2x2 (shared with ZKProver)

License

MIT