feat: relayer authentication verification method

api/relayer_auth_verification.ts

@@ -0,0 +1,67 @@
+import { utils } from 'ethers';
+import { getProvider } from '@/utils/provider';
+
+/**
+ * Verify a relayer's configuration update signature and nonce
+ * @param configPayload The configuration update payload
+ * @param signature The signature provided by the relayer 
+ * @param nonce The nonce value to prevent replay attacks
+ * @throws Error if signature is invalid or nonce has been used
+ */
+export async function verifyRelayerSignature(
+  configPayload: Record<string, any>,
+  signature: string,
+  nonce: number
+): Promise<void> {
+  try {
+    // Verify nonce hasn't been used before
+    if (await hasNonceBeenUsed(nonce)) {
+      throw new Error('Nonce has already been used');
+    }
+
+    // Add nonce to payload before verifying
+    const payloadWithNonce = {
+      ...configPayload,
+      nonce
+    };
+
+    // Convert payload to string and hash it
+    const payloadStr = JSON.stringify(payloadWithNonce);
+    const messageHash = utils.keccak256(utils.toUtf8Bytes(payloadStr));
+
+    // Create signable message
+    const prefixedMessage = utils.arrayify(messageHash);
+
+    // Recover the address that signed the message
+    const recoveredAddress = utils.verifyMessage(prefixedMessage, signature);
+    const checksumAddress = utils.getAddress(recoveredAddress);
+
+    // Verify signer is an authorized relayer
+    if (!await isAuthorizedRelayer(checksumAddress)) {
+      throw new Error('Signer is not an authorized relayer');
+    }
+
+    // Store nonce as used
+    await storeUsedNonce(nonce);
+
+  } catch (error) {
+    console.error('Error verifying relayer signature:', error);
+    throw error;
+  }
+}
+
+// Helper functions that would need to be implemented:
+async function hasNonceBeenUsed(nonce: number): Promise<boolean> {
+  // Check if nonce exists in storage
+  throw new Error('Not implemented');
+}
+
+async function isAuthorizedRelayer(address: string): Promise<boolean> {
+  // Check if address is in authorized relayer list
+  throw new Error('Not implemented'); 
+}
+
+async function storeUsedNonce(nonce: number): Promise<void> {
+  // Store nonce in persistent storage
+  throw new Error('Not implemented');
+}