diff --git a/test/Sign.t.sol b/test/Sign.t.sol
new file mode 100644
index 0000000..0474c1f
--- /dev/null
+++ b/test/Sign.t.sol
@@ -0,0 +1,32 @@
+// SPDX-License-Identifier: UNLICENSED
+pragma solidity ^0.8.20;
+
+import "forge-std/Test.sol";
+
+contract signTest is Test {
+    // private key = 123
+    // public key = vm.addr(private key)
+    // message = "secret message"
+    // message hash = keccak256(message)
+    // vm.sign(private key, message hash)
+
+    function testSignature() public {
+        uint privateKey = 123;
+        address pubKey = vm.addr(privateKey);
+
+        bytes32 messageHash = keccak256("secret message");
+
+        (uint8 v, bytes32 r, bytes32 s) = vm.sign(privateKey, messageHash);
+
+        address signer = ecrecover(messageHash, v, r, s);
+
+        assertEq(pubKey, signer);
+
+        bytes32 invalidMessageHash = keccak256("invalid Message");
+
+        signer = ecrecover(invalidMessageHash, v, r, s);
+        
+        assertTrue(signer != pubKey);
+    }
+
+}