move draft-EIP712 to utils/cryptography

Author: Amxx

contracts/mocks/EIP712External.sol

@@ -2,7 +2,7 @@
 
 pragma solidity ^0.8.0;
 
-import "../utils/draft-EIP712.sol";
+import "../utils/cryptography/draft-EIP712.sol";
 import "../utils/cryptography/ECDSA.sol";
 
 contract EIP712External is EIP712 {

contracts/token/ERC20/extensions/draft-ERC20Permit.sol

@@ -4,9 +4,9 @@ pragma solidity ^0.8.0;
 
 import "./draft-IERC20Permit.sol";
 import "../ERC20.sol";
+import "../../../utils/cryptography/draft-EIP712.sol";
 import "../../../utils/cryptography/ECDSA.sol";
 import "../../../utils/Counters.sol";
-import "../../../utils/draft-EIP712.sol";
 
 /**
  * @dev Implementation of the ERC20 Permit extension allowing approvals to be made via signatures, as defined in

contracts/utils/cryptography/ECDSA.sol

@@ -72,9 +72,9 @@ library ECDSA {
 
     /**
      * @dev Returns an Ethereum Signed Message, created from a `hash`. This
-     * replicates the behavior of the
-     * https://github.com/ethereum/wiki/wiki/JSON-RPC#eth_sign[`eth_sign`]
-     * JSON-RPC method.
+     * produces hash corresponding to the one signed with the
+     * https://eth.wiki/json-rpc/API#eth_sign[`eth_sign`]
+     * JSON-RPC method as part of EIP-191.
      *
      * See {recover}.
      */
@@ -83,4 +83,17 @@ library ECDSA {
         // enforced by the type signature above
         return keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n32", hash));
     }
+
+    /**
+     * @dev Returns an Ethereum Signed Typed Data, created from a
+     * `domainSeparator` and a `structHash`. This produces hash corresponding
+     * to the one signed with the
+     * https://eips.ethereum.org/EIPS/eip-712[`eth_signTypedData`]
+     * JSON-RPC method as part of EIP-712.
+     *
+     * See {recover}.
+     */
+    function toTypedDataHash(bytes32 domainSeparator, bytes32 structHash) internal pure returns (bytes32) {
+        return keccak256(abi.encodePacked("\x19\x01", domainSeparator, structHash));
+    }
 }

contracts/utils/draft-EIP712.sol renamed to contracts/utils/cryptography/draft-EIP712.sol

@@ -2,6 +2,8 @@
 
 pragma solidity ^0.8.0;
 
+import "./ECDSA.sol";
+
 /**
  * @dev https://eips.ethereum.org/EIPS/eip-712[EIP 712] is a standard for hashing and signing of typed structured data.
  *
@@ -95,6 +97,6 @@ abstract contract EIP712 {
      * ```
      */
     function _hashTypedDataV4(bytes32 structHash) internal view virtual returns (bytes32) {
-        return keccak256(abi.encodePacked("\x19\x01", _domainSeparatorV4(), structHash));
+        return ECDSA.toTypedDataHash(_domainSeparatorV4(), structHash);
     }
 }