Add Governor extension GovernorNoncesKeyed to use NoncesKeyed for vote by sig (#5574)

Co-authored-by: Hadrien Croubois <hadrien.croubois@gmail.com>
Co-authored-by: ernestognw <ernestognw@gmail.com>

contracts/governance/extensions/GovernorNoncesKeyed.sol

@@ -0,0 +1,90 @@
+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.24;
+
+import {Governor} from "../Governor.sol";
+import {Nonces} from "../../utils/Nonces.sol";
+import {NoncesKeyed} from "../../utils/NoncesKeyed.sol";
+import {SignatureChecker} from "../../utils/cryptography/SignatureChecker.sol";
+
+/**
+ * @dev An extension of {Governor} that extends existing nonce management to use {NoncesKeyed}, where the key is the first 192 bits of the `proposalId`.
+ * This is useful for voting by signature while maintaining separate sequences of nonces for each proposal.
+ *
+ * NOTE: Traditional (un-keyed) nonces are still supported and can continue to be used as if this extension was not present.
+ */
+abstract contract GovernorNoncesKeyed is Governor, NoncesKeyed {
+    function _useCheckedNonce(address owner, uint256 nonce) internal virtual override(Nonces, NoncesKeyed) {
+        super._useCheckedNonce(owner, nonce);
+    }
+
+    /**
+     * @dev Check the signature against keyed nonce and falls back to the traditional nonce.
+     *
+     * NOTE: This function won't call `super._validateVoteSig` if the keyed nonce is valid.
+     * Side effects may be skipped depending on the linearization of the function.
+     */
+    function _validateVoteSig(
+        uint256 proposalId,
+        uint8 support,
+        address voter,
+        bytes memory signature
+    ) internal virtual override returns (bool) {
+        if (
+            SignatureChecker.isValidSignatureNow(
+                voter,
+                _hashTypedDataV4(
+                    keccak256(
+                        abi.encode(BALLOT_TYPEHASH, proposalId, support, voter, nonces(voter, uint192(proposalId)))
+                    )
+                ),
+                signature
+            )
+        ) {
+            _useNonce(voter, uint192(proposalId));
+            return true;
+        } else {
+            return super._validateVoteSig(proposalId, support, voter, signature);
+        }
+    }
+
+    /**
+     * @dev Check the signature against keyed nonce and falls back to the traditional nonce.
+     *
+     * NOTE: This function won't call `super._validateExtendedVoteSig` if the keyed nonce is valid.
+     * Side effects may be skipped depending on the linearization of the function.
+     */
+    function _validateExtendedVoteSig(
+        uint256 proposalId,
+        uint8 support,
+        address voter,
+        string memory reason,
+        bytes memory params,
+        bytes memory signature
+    ) internal virtual override returns (bool) {
+        if (
+            SignatureChecker.isValidSignatureNow(
+                voter,
+                _hashTypedDataV4(
+                    keccak256(
+                        abi.encode(
+                            EXTENDED_BALLOT_TYPEHASH,
+                            proposalId,
+                            support,
+                            voter,
+                            nonces(voter, uint192(proposalId)),
+                            keccak256(bytes(reason)),
+                            keccak256(params)
+                        )
+                    )
+                ),
+                signature
+            )
+        ) {
+            _useNonce(voter, uint192(proposalId));
+            return true;
+        } else {
+            return super._validateExtendedVoteSig(proposalId, support, voter, reason, params, signature);
+        }
+    }
+}