Remove EIP-712 (#63)

src/SpendPermissions.sol

@@ -5,16 +5,14 @@ import {IERC1271} from "openzeppelin-contracts/contracts/interfaces/IERC1271.sol
 import {IERC20} from "openzeppelin-contracts/contracts/token/ERC20/IERC20.sol";
 import {CoinbaseSmartWallet} from "smart-wallet/CoinbaseSmartWallet.sol";
 
-import {EIP712} from "./EIP712.sol";
-
 /// @title SpendPermissions
 ///
 /// @notice Allow spending native and ERC20 tokens with a recurring allowance.
 ///
 /// @dev Allowance and spend values capped at uint160 ~ 1e48.
 ///
 /// @author Coinbase (https://github.com/coinbase/smart-wallet-permissions)
-contract SpendPermissions is EIP712 {
+contract SpendPermissions {
     /// @notice A recurring allowance for an external spender to withdraw an account's tokens.
     struct RecurringAllowance {
         /// @dev Smart account this recurring allowance is valid for.
@@ -43,11 +41,6 @@ contract SpendPermissions is EIP712 {
         uint160 spend;
     }
 
-    /// @notice Hash of EIP-712 message type
-    bytes32 internal constant _RECURRING_ALLOWANCE_TYPEHASH = keccak256(
-        "RecurringAllowance(address account,address spender,address token,uint48 start,uint48 end,uint48 period,uint160 allowance)"
-    );
-
     /// @notice ERC-7528 address convention for ether (https://eips.ethereum.org/EIPS/eip-7528).
     address public constant ETHER = 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE;
 
@@ -169,7 +162,10 @@ contract SpendPermissions is EIP712 {
     /// @param signature Signed hash of the recurring allowance data.
     function permit(RecurringAllowance memory recurringAllowance, bytes memory signature) public {
         // validate signature over recurring allowance data
-        if (_isValidSignature(recurringAllowance.account, getHash(recurringAllowance), signature)) {
+        if (
+            IERC1271(recurringAllowance.account).isValidSignature(getHash(recurringAllowance), signature)
+                != IERC1271.isValidSignature.selector
+        ) {
             revert UnauthorizedRecurringAllowance();
         }
 
@@ -198,7 +194,7 @@ contract SpendPermissions is EIP712 {
     ///
     /// @return hash Hash of the recurring allowance and replay protection parameters.
     function getHash(RecurringAllowance memory recurringAllowance) public view returns (bytes32) {
-        return _eip712Hash(keccak256(abi.encode(_RECURRING_ALLOWANCE_TYPEHASH, recurringAllowance)));
+        return keccak256(abi.encode(recurringAllowance, block.chainid, address(this)));
     }
 
     /// @notice Return if recurring allowance is authorized i.e. approved and not revoked.
@@ -332,23 +328,4 @@ contract SpendPermissions is EIP712 {
     function _execute(address account, address target, uint256 value, bytes memory data) internal virtual {
         CoinbaseSmartWallet(payable(account)).execute({target: target, value: value, data: data});
     }
-
-    /// @notice Validate an EIP-1271 contract signature.
-    ///
-    /// @param account Address of the user account.
-    /// @param hash Hash of the message.
-    /// @param signature Bytes for the user signature.
-    ///
-    /// @return isValid True if signature is valid.
-    function _isValidSignature(address account, bytes32 hash, bytes memory signature) internal view returns (bool) {
-        return IERC1271(account).isValidSignature(hash, signature) != IERC1271.isValidSignature.selector;
-    }
-
-    /// @notice Returns the domain name and version to use when creating EIP-712 signatures.
-    ///
-    /// @return name    The user readable name of signing domain.
-    /// @return version The current major version of the signing domain.
-    function _domainNameAndVersion() internal pure override returns (string memory name, string memory version) {
-        return ("SpendPermissions", "1");
-    }
 }