Update app.py

app.py

@@ -13,12 +13,46 @@ from helpers.mongodbconnection import provideClient
 
 
 
-
-
 app = FastAPI()
 solana_client = Client("https://api.mainnet-beta.solana.com")
 
+SERVER_KEY = Keypair.from_base58_string("special_quantum_key")
+
+
+
+
+@app.post("/relay-txn")
+async def relay_txn(payload: dict):
+    # 1. Verification Math
+    proof = base58.b58decode(payload['winternitz_hash'])
+    anchor = base58.b58decode(payload['anchor']) # Stored in your DB
+    lap = payload['lap']
+
+    # Hash the proof 'lap' times to see if it hits the anchor
+    check = proof
+    for _ in range(lap):
+        check = hashlib.sha256(check).digest()
+
+    if check != anchor:
+        raise HTTPException(status_code=403, detail="Quantum Auth Failed")
+
+    # 2. Transaction Execution
+    # Deserialize the transaction sent from the UI
+    raw_tx = base58.b58decode(payload['txn'])
+    txn = Transaction.deserialize(raw_tx)
+
+    # ✅ THE MAGIC STEP: The server signs as the "Fee Payer"
+    # The 'From' address in the txn is still the user's wallet!
+    response = client.send_transaction(txn, SERVER_PAYER_KEY)
+        
+    #🏁 THIS IS IT: The actual on-chain signature!
+    actual_signature = str(response.value)
 
+    return {
+            "success": True, 
+            "signature": actual_signature,
+            "status": "Finalized on Solana"
+    }