Key Terms

• Payment ID: A human-readable identifier (like alice@binance) that maps to multiple blockchain addresses across different sources and networks.

• ZK Email: A privacy-preserving technology that uses zero-knowledge proofs to verify email ownership and content without revealing the actual email address on-chain, serving as the identity layer for Payment ID.

• Wallet: A deterministic smart contract wallet derived from a user's email address using zero-knowledge proofs. Each email maps to exactly one wallet, providing a consistent on-chain identity while keeping the email private and enabling transaction execution through ephemeral session keys.

• PID Token: An ERC-721 non-fungible token that represents ownership of a Payment ID, allowing for transfers and delegated management.

• Resolver: A smart contract that maps Payment IDs to blockchain addresses based on the source context (exchange/wallet/anything) and blockchain network.

• Source Type: An identifier for different sources of funds (exchanges, wallets, anything) that allows a single Payment ID to have different addresses for different contexts (e.g., @binance, @metamask, @mytopaccount).