Overview

Permit2 combines two contracts, SignatureTransfer and AllowanceTransfer, into a unified system. The SignatureTransfer contract facilitates signature-based transfers, bypassing token allowances and granting spend permissions only for the duration of the transaction. Conversely, the AllowanceTransfer contract manages token allowances, granting spenders permission to use a specified amount for a defined duration. Transfers conducted through the AllowanceTransfer contract are contingent upon proper permissions being set.

Resources

For a comprehensive understanding of the Permit2 contract and its practical applications, refer to this explanation with examples.

Approving Permit2

Before contracts can request users' tokens through Permit2, users must approve the Permit2 contract via the specific token contract. This is typically achieved by calling something like:

USDC.approve(permit2Address, totalAmount);

To fully leverage the benefits of Permit2, users should perform a max approval on the contract, where:

totalAmount = type(uint256).max;