Turupawn · May 22, 2025 15:45 · May 22, 2025
diff --git a/P256Verifier.sol b/P256Verifier.sol
@@ -0,0 +1,41 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.0;
+
+contract P256Verifier {
+    address constant P256_PRECOMPILE = address(0x0100);
+
+    /// @notice Verifies a secp256r1 signature using the EIP-7212 precompile.
+    /// @param hash The 32-byte message hash that was signed.
+    /// @param r The 32-byte r component of the signature.
+    /// @param s The 32-byte s component of the signature.
+    /// @param x The 32-byte x coordinate of the public key.
+    /// @param y The 32-byte y coordinate of the public key.
+    /// @return isValid True if the signature is valid, false otherwise.
+    function verifySignature(
+        bytes32 hash,
+        bytes32 r,
+        bytes32 s,
+        bytes32 x,
+        bytes32 y
+    ) external view returns (bool isValid) {
+        bytes memory input = abi.encodePacked(hash, r, s, x, y);
+        bytes memory output = new bytes(32);
+
+        assembly {
+            // Call the precompiled contract
+            let success := staticcall(
+                gas(),
+                0x0100,
+                add(input, 32),
+                160,
+                add(output, 32),
+                32
+            )
+            // Check if the call was successful and the output is 1
+            isValid := and(
+                success,
+                eq(mload(add(output, 32)), 1)
+            )
+        }
+    }
+}
diff --git a/package.json b/package.json
@@ -0,0 +1,15 @@
+{
+  "name": "p256-signature",
+  "version": "1.0.0",
+  "main": "index.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "keywords": [],
+  "author": "",
+  "license": "ISC",
+  "description": "",
+  "dependencies": {
+    "secp256r1": "^0.0.3"
+  }
+}
diff --git a/sign.js b/sign.js
@@ -0,0 +1,34 @@
+// sign.js
+const crypto = require('crypto');
+const secp256r1 = require('secp256r1');
+
+// Generate a random 32-byte message
+const message = crypto.randomBytes(32);
+
+// Generate a valid private key
+let privateKey;
+do {
+  privateKey = crypto.randomBytes(32);
+} while (!secp256r1.privateKeyVerify(privateKey));
+
+// Derive the public key (uncompressed)
+const publicKey = secp256r1.publicKeyCreate(privateKey, false); // 65 bytes: 0x04 || X || Y
+
+// Sign the message
+const signatureObj = secp256r1.sign(message, privateKey);
+const { signature } = signatureObj;
+
+// Extract r and s from the signature
+const r = signature.slice(0, 32);
+const s = signature.slice(32, 64);
+
+// Extract x and y from the public key
+const x = publicKey.slice(1, 33);
+const y = publicKey.slice(33, 65);
+
+// Output the components in hexadecimal format
+console.log('Message Hash:', message.toString('hex'));
+console.log('r:', r.toString('hex'));
+console.log('s:', s.toString('hex'));
+console.log('x:', x.toString('hex'));
+console.log('y:', y.toString('hex'));