feat: relayer signature auth

api/relayer_auth.ts

@@ -0,0 +1,31 @@
+import { ethers } from 'ethers';
+
+/**
+ * Get the address that signed a configuration update
+ * @param configPayload The configuration update payload
+ * @param signature The signature provided by the relayer
+ * @returns The Ethereum address that signed the payload
+ */
+async function getSignerAddress(
+  configPayload: Record<string, any>,
+  signature: string
+): Promise<string> {
+  try {
+    // Convert payload to string and hash it
+    const payloadStr = JSON.stringify(configPayload);
+    const messageHash = ethers.utils.keccak256(ethers.utils.toUtf8Bytes(payloadStr));
+
+    // Create signable message
+    const prefixedMessage = ethers.utils.arrayify(messageHash);
+
+    // Recover the address that signed the message
+    const recoveredAddress = ethers.utils.verifyMessage(prefixedMessage, signature);
+
+    // Convert to checksum format
+    return ethers.utils.getAddress(recoveredAddress);
+
+  } catch (error) {
+    console.error('Error recovering signer address:', error);
+    throw error;
+  }
+}