Function: permit(address owner, address spender, uint256 amount, uint256 deadline, uint8 v, byte[32] r, byte[32] s)

The permit function allows the owner of tokens to approve a spender to transfer a certain amount until a deadline, using a signature.

Inputs

• owner

  • Control: Controlled by the user.

  • Constraints: N/A.

  • Impact: Specifies the address from which the tokens will be deducted.

• spender

  • Control: Controlled by the user.

  • Constraints: N/A.

  • Impact: Specifies the address that will be granted the allowance to spend tokens on behalf of the owner.

• amount

  • Control: Controlled by the user.

  • Constraints: Must be less than or equal to the owner's balance.

  • Impact: Specifies the amount of tokens the spender will be allowed to spend.

• deadline

  • Control: Controlled by the user.

  • Constraints: Must be a future timestamp.

  • Impact: Specifies the time until which the permit message is valid. After this time, the message will not be accepted.

• v

  • Control: Generated as part of the signature of the off-chain permit message.

  • Constraints: Must be a valid part of an ECDSA signature (27 or 28).

  • Impact: Part of the signature for the permit message.

• r

  • Control: Generated as part of the signature of the off-chain permit message.

  • Constraints: Must be a valid part of an ECDSA signature.

  • Impact: Part of the signature for the permit message.

• s

  • Control: Generated as part of the signature of the off-chain permit message.

  • Constraints: Must be a valid part of an ECDSA signature.

  • Impact: Part of the signature for the permit message.

Branches and code coverage (including function calls)

Intended branches

• Successful permit call.

  Test coverage

Negative behavior

• Revert due to expired deadline.

  Negative test

• Revert due to invalid owner signature.

  Negative test

• Fail to do replay attack.

  Negative test