Add tooling to verify signatures with support for ERC1271 (#2532)

Co-authored-by: Francisco Giordano <frangio.1@gmail.com>

contracts/utils/cryptography/SignatureChecker.sol

@@ -0,0 +1,29 @@
+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.0;
+
+import "./ECDSA.sol";
+import "../Address.sol";
+import "../../interfaces/IERC1271.sol";
+
+/**
+ * @dev Signature verification helper: Provide a single mechanism to verify both private-key (EOA) ECDSA signature and
+ * ERC1271 contract sigantures. Using this instead of ECDSA.recover in your contract will make them compatible with
+ * smart contract wallets such as Argent and Gnosis.
+ *
+ * Note: unlike ECDSA signatures, contract signature's are revocable, and the outcome of this function can thus change
+ * through time. It could return true at block N and false at block N+1 (or the opposite).
+ */
+library SignatureChecker {
+    function isValidSignatureNow(address signer, bytes32 hash, bytes memory signature) internal view returns (bool) {
+        if (Address.isContract(signer)) {
+            try IERC1271(signer).isValidSignature(hash, signature) returns (bytes4 magicValue) {
+                return magicValue == IERC1271(signer).isValidSignature.selector;
+            } catch {
+                return false;
+            }
+        } else {
+            return ECDSA.recover(hash, signature) == signer;
+        }
+    }
+}