some kinda

backend/services/wallet_service.py

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+from web3 import Web3
+from eth_account import Account
+from datetime import datetime
+import hashlib
+import secrets
+import os  # ✅ Add this missing import
+
+class WalletService:
+    def __init__(self, web3_provider_url):
+        self.w3 = Web3(Web3.HTTPProvider(web3_provider_url))
+        
+    def verify_wallet_signature(self, wallet_address, signature, message):
+        """Verify wallet signature for authentication"""
+        try:
+            # Recover the address from signature
+            message_hash = Web3.keccak(text=message)
+            recovered_address = self.w3.eth.account.recover_message_hash(message_hash, signature=signature)
+            
+            return recovered_address.lower() == wallet_address.lower()
+        except Exception as e:
+            print(f"Signature verification error: {e}")
+            return False
+    
+    def generate_auth_message(self, wallet_address, exam_code):
+        """Generate message for wallet signing"""
+        timestamp = int(datetime.now().timestamp())
+        nonce = secrets.token_hex(16)
+        
+        message = f"""OpenLearnX Exam Authentication
+
+Wallet: {wallet_address}
+Exam Code: {exam_code}
+Timestamp: {timestamp}
+Nonce: {nonce}
+
+Sign this message to join the coding exam."""
+        
+        return message, timestamp, nonce
+    
+    def create_wallet_session(self, wallet_address, exam_code, signature):
+        """Create authenticated wallet session"""
+        session_id = hashlib.sha256(f"{wallet_address}{exam_code}{datetime.now().timestamp()}".encode()).hexdigest()
+        
+        return {
+            "session_id": session_id,
+            "wallet_address": wallet_address,
+            "exam_code": exam_code,
+            "authenticated_at": datetime.now(),
+            "signature": signature
+        }
+
+# Create the service instance
+wallet_service = WalletService(os.getenv('WEB3_PROVIDER_URL', 'http://127.0.0.1:8545'))