Keep only curent signer

Author: ranchalp

scripts/foundry/InitializeL1ScrollOwner.s.sol

@@ -21,7 +21,7 @@ import {ScrollChain} from "../../src/L1/rollup/ScrollChain.sol";
 import {ScrollOwner} from "../../src/misc/ScrollOwner.sol";
 import {Whitelist} from "../../src/L2/predeploys/Whitelist.sol";
 
-import {SystemSignerRegistry} from "../../src/L1/system-contract/SystemSignerRegistry.sol";
+import {SystemConfig} from "../../src/L1/system-contract/SystemConfig.sol";
 
 
 // solhint-disable max-states-count
@@ -282,7 +282,7 @@ contract InitializeL1ScrollOwner is Script {
 
     function configSystemContract() internal {
         // If we already have deployed it, just do:
-        SystemSignerRegistry sys = SystemSignerRegistry(SYSTEM_CONTRACT_ADDR);
+        SystemConfig sys = SystemConfig(SYSTEM_CONTRACT_ADDR);
 
         // sys has a normal constructor that set the "owner" to `ScrollOwner`.
         // Now we want to let the Security Council call `addSigner(...)` with no delay.

src/L1/system-contract/SystemConfig.sol

@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: MIT
+pragma solidity =0.8.24;
+
+import "@openzeppelin/contracts/access/Ownable.sol";
+
+contract SystemConfig is Ownable {
+
+    address public currentSigner;
+
+    constructor(address _owner) {
+        _transferOwnership(_owner);
+    }
+
+    /**
+     * @dev Update the current signer.
+     *      Only the owner can call this function.
+     * @param _newSigner The address of the new authorized signer.
+     */
+    function updateSigner(address _newSigner) external onlyOwner {
+        currentSigner = _newSigner;
+    }
+
+    /**
+     * @dev Return the current authorized signer.
+     * @return The authorized signer address.
+     */
+    function getSigner() external view returns (address) {
+        return currentSigner;
+    }
+}