Protocol Terms
| Term | Definition |
|---|---|
| b402 | A multichain payment protocol extending HTTP 402 for gasless, confidential crypto payments across EVM chains |
| x402 | The base HTTP 402 payment protocol specification that b402 extends |
| HTTP 402 | The 402 Payment Required HTTP status code, used to signal that a resource requires payment |
| Facilitator | Off-chain service that verifies payment signatures and submits on-chain settlements |
| Relayer | On-chain smart contract (B402Relayer) that executes transferWithAuthorization() for verified payments |
| Settlement | The on-chain execution of a verified payment transaction |
Wallet Terms
| Term | Definition |
|---|---|
| EOA | Externally Owned Account — a standard Ethereum wallet controlled by a private key |
| Smart Wallet | An ERC-7579 Nexus modular smart account with batched operations and paymaster support |
| ERC-7579 | Standard for modular smart accounts with pluggable validator/executor modules |
| Nexus | Biconomy’s ERC-7579 smart account implementation used by b402 |
| K1 Validator | ECDSA signature validation module installed on Nexus smart wallets |
| Master Wallet | The primary smart wallet for an owner, derived with a deterministic salt |
| Sub-wallet | Additional smart wallets created with custom salts for specific purposes |
Transaction Terms
| Term | Definition |
|---|---|
| EIP-712 | Ethereum standard for typed structured data signing, used for EOA payment authorization |
| TransferWithAuthorization | The EIP-712 message type that authorizes the Relayer to transfer tokens on the signer’s behalf |
| UserOperation (UserOp) | An ERC-4337 pseudo-transaction that encodes a smart wallet action for bundler execution |
| Bundler | An ERC-4337 service that packages UserOperations into on-chain transactions |
| Paymaster | An ERC-4337 contract that sponsors gas fees, deducting costs from the payment token |
| EntryPoint | The ERC-4337 singleton contract (v0.7) that validates and executes UserOperations |
| Nonce | A unique value preventing transaction replay; generated per-payment for EIP-712 signatures |
Privacy Terms
| Term | Definition |
|---|---|
| Incognito | b402’s privacy mode powered by b402’s zero-knowledge privacy pool |
| Shield | Depositing tokens into the b402 privacy pool, creating a commitment |
| Unshield | Withdrawing tokens from the b402 privacy pool back to a public address |
| Commitment | A Poseidon hash representing a shielded token deposit in the Merkle tree |
| Nullifier | A value published when spending a commitment, preventing double-spending |
| Merkle Proof | A cryptographic proof that a commitment exists in the privacy pool’s Merkle tree |
| Poseidon Hash | A ZK-friendly hash function used to create commitments and nullifiers |
Identity Terms
| Term | Definition |
|---|---|
| ERC-8004 | Ethereum standard for on-chain agent identity (identity NFTs, reputation, delegation) |
| Agent Identity | An on-chain NFT representing an AI agent’s identity, linked to a wallet |
| Delegation | One wallet acting on behalf of another via ERC-8004 identity linking |
API Terms
| Term | Definition |
|---|---|
| Verify | The first step in payment settlement — validates the signed payload and returns confirmation data |
| Settle | The second step — submits the verified payment for on-chain execution |
| X-PAYMENT | HTTP header containing the signed payment payload, sent by the buyer with the resource request |
| x-admin-api-key | Authentication header for admin-protected endpoints on the Facilitator API |
Network Terms
| Term | Definition |
|---|---|
| BNB Chain | An EVM-compatible blockchain supported by b402 (Chain ID: 56) |
| Base | An EVM-compatible L2 blockchain supported by b402 (Chain ID: 8453) |
| BSC | Binance Smart Chain — the legacy name for BNB Chain |