Implement validator registry

src/IValidatorRegistry.sol

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+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.20;
+
+interface IValidatorRegistry {
+    function register(
+        bytes memory registrationMessage,
+        bytes memory registrationSignature
+    ) external;
+
+    function deregister(
+        bytes memory deregistrationMessage,
+        bytes memory deregistrationSignature
+    ) external;
+
+    event Registration(bytes registrationMessage, bytes registrationSignature);
+    event Deregistration(
+        bytes deregistrationMessage,
+        bytes deregistrationSignature
+    );
+}

src/ValidatorRegistry.sol

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+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.20;
+
+import "src/IValidatorRegistry.sol";
+
+contract ValidatorRegistry is IValidatorRegistry {
+    function register(
+        bytes memory registrationMessage,
+        bytes memory registrationSignature
+    ) external {
+        emit Registration(registrationMessage, registrationSignature);
+    }
+
+    function deregister(
+        bytes memory deregistrationMessage,
+        bytes memory deregistrationSignature
+    ) external {
+        emit Deregistration(deregistrationMessage, deregistrationSignature);
+    }
+}

test/ValidatorRegistry.t.sol

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+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.20;
+
+import "forge-std/Test.sol";
+import "../src/IValidatorRegistry.sol";
+import "../src/ValidatorRegistry.sol";
+
+contract ValidatorRegistryTest is Test {
+    event Registration(bytes registrationMessage, bytes registrationSignature);
+    event Deregistration(
+        bytes deregistrationMessage,
+        bytes deregistrationSignature
+    );
+
+    IValidatorRegistry registry;
+
+    function setUp() public {
+        registry = new ValidatorRegistry();
+    }
+
+    function testRegistration() public {
+        bytes memory message = bytes("msg");
+        bytes memory signature = bytes("sig");
+
+        vm.expectEmit(address(registry));
+        emit Registration(message, signature);
+
+        registry.register(message, signature);
+    }
+
+    function testDeregistration() public {
+        bytes memory message = bytes("msg");
+        bytes memory signature = bytes("sig");
+
+        vm.expectEmit(address(registry));
+        emit Deregistration(message, signature);
+
+        registry.deregister(message, signature);
+    }
+}