Quantum Noisy Vault protects a randomly generated 64-bit secret key behind a quantum oracle that introduces depolarizing noise, idle cycle decay, and measurement errors. The attacker gets exactly one oracle query and one guess. The oracle prepares the key as a computational basis state on 64 data qubits, allows the attacker to apply a custom quantum circuit (subject to structural constraints), adds noise, and returns 4096 measurement shots. Despite the noise, the underlying state is classical (each qubit is deterministically |0> or |1>), which means a simple majority vote over the shots recovers each bit with high probability. The real challenge lies in satisfying the oracle's circuit validation constraints without disturbing the data qubits.

From server.py, the vault generates a random 64-bit key and prepares it on 64 data qubits:

self.secret_key = bin(secrets.randbits(self.visible_bits))[2:].zfill(self.visible_bits)
self.total_data_qubits = 64
self.ancilla_qubits = 16
self.total_qubits = 80     # 64 data + 16 ancilla

State preparation applies X gates to data qubits corresponding to '1' bits:

def _prepare_state(self, circuit):
    for idx, bit in enumerate(self.secret_key):
        if bit == "1":