From 44af80e5c12dc373181c07a9df4c3effd15bfb54 Mon Sep 17 00:00:00 2001
From: KOSASIH <kosasihg88@gmail.com>
Date: Sun, 20 Oct 2024 11:45:14 +0700
Subject: [PATCH] Create CryptoLib.sol

---
 .../contracts/libraries/CryptoLib.sol         | 44 +++++++++++++++++++
 1 file changed, 44 insertions(+)
 create mode 100644 blockchain_integration/pi_network/pi-network-layer2-scaling/contracts/libraries/CryptoLib.sol

diff --git a/blockchain_integration/pi_network/pi-network-layer2-scaling/contracts/libraries/CryptoLib.sol b/blockchain_integration/pi_network/pi-network-layer2-scaling/contracts/libraries/CryptoLib.sol
new file mode 100644
index 000000000..ff1657c91
--- /dev/null
+++ b/blockchain_integration/pi_network/pi-network-layer2-scaling/contracts/libraries/CryptoLib.sol
@@ -0,0 +1,44 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.0;
+
+library CryptoLib {
+    // Hash a message using keccak256
+    function hashMessage(bytes memory message) internal pure returns (bytes32) {
+        return keccak256(message);
+    }
+
+    // Verify a signature
+    function verifySignature(
+        bytes32 messageHash,
+        bytes memory signature,
+        address signer
+    ) internal pure returns (bool) {
+        bytes32 ethSignedMessageHash = getEthSignedMessageHash(messageHash);
+        return recoverSigner(ethSignedMessageHash, signature) == signer;
+    }
+
+    // Get the Ethereum signed message hash
+    function getEthSignedMessageHash(bytes32 messageHash) internal pure returns (bytes32) {
+        return keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n32", messageHash));
+    }
+
+    // Recover the signer from a signature
+    function recoverSigner(bytes32 ethSignedMessageHash, bytes memory signature) internal pure returns (address) {
+        (bytes32 r, bytes32 s, uint8 v) = splitSignature(signature);
+        return ecrecover(ethSignedMessageHash, v, r, s);
+    }
+
+    // Split the signature into r, s, and v
+    function splitSignature(bytes memory signature) internal pure returns (bytes32 r, bytes32 s, uint8 v) {
+        require(signature.length == 65, "CryptoLib: invalid signature length");
+        assembly {
+            r := mload(add(signature, 0x20))
+            s := mload(add(signature, 0x40))
+            v := byte(0, mload(add(signature, 0x60)))
+        }
+        // Adjust v value
+        if (v < 27) {
+            v += 27;
+        }
+    }
+}