# Shadow Protocol (ZK + x402)

> OVERVIEW ZK-powered payment protocol for NumPay with privacy, gasless transactions, phone-linked wallets, and x402 support.

NumPay Shadow Protocol is a privacy-preserving payment system that combines zero-knowledge proofs (Groth16 + ElGamal encryption) with NumPay's decentralized infrastructure to enable private, gasless, phone-to-wallet payments. Payment amounts are encrypted, sender identities are hidden, and all transaction fees are absorbed by NumPay's optimized token model.

**→ Privacy**: ElGamal-encrypted amounts + ZK proofs hide sender identity

**→ Phone-Linked**: Pay to phone numbers without revealing wallet addresses

**→ Zero-Fee**: NumPay absorbs network costs completely

**→ Gasless**: Smart contract relayers handle all on-chain operations

**→ x402 Protocol**: HTTP 402 Payment Required standard for APIs

**→ Decentralized**: No central authority, no data storage, no user tracking


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