EIP-2612
EIP-2612 adds a permit function to an ERC-20 token, so a holder can grant a spending allowance with a signed message instead of a transaction. It removes the separate approval step, and with it the need for the holder to hold the chain's own fee token.
The standard's motivation is the cost of the pair it extends. Using a token inside a smart contract takes two transactions — the approval, then the call that spends against it — and even paying another person requires holding the network's native token for gas. permit sets the allowance from a signed message rather than from the sender of a transaction, and the signature is EIP-712 typed data. Its status is Final.
It is one of two ways an x402 payment avoids a separate approval, and the difference between them is worth keeping straight. This one still grants an allowance, which somebody then spends against; EIP-3009 authorises a specific transfer to a specific address instead. x402's own gas-sponsoring extension for this standard has the facilitator submit the signature and pay the fee.
→ The network and asset probe402's own settle leg will accept are set out in the method.
Sources
- ERC-2612: Permit Extension for EIP-20 Signed ApprovalsEthereum Improvement Proposals
- ERC-20: Token StandardEthereum Improvement Proposals
- Extension: eip2612GasSponsoringx402 Foundation