examples/tensor_tamper_detection.py
| 1 | """Show that a single-bit flip in an encrypted tensor is detected. |
| 2 | |
| 3 | AES-256-GCM ties ciphertext and AAD (metadata + sequence number) into one |
| 4 | authentication tag. Any bit flip in ciphertext or tampering with metadata |
| 5 | causes decrypt_tensor() to raise DecryptionError. |
| 6 | |
| 7 | Run: |
| 8 | |
| 9 | python examples/tensor_tamper_detection.py |
| 10 | """ |
| 11 | |
| 12 | from __future__ import annotations |
| 13 | |
| 14 | import os |
| 15 | |
| 16 | from pqc_gpu_driver import DecryptionError, TensorMetadata, establish_channel |
| 17 | |
| 18 | |
| 19 | def main() -> None: |
| 20 | cpu, gpu = establish_channel() |
| 21 | tensor = os.urandom(512) |
| 22 | meta = TensorMetadata( |
| 23 | tensor_id="t-tamper", |
| 24 | name="model.fc.weight", |
| 25 | dtype="float32", |
| 26 | shape=(128,), |
| 27 | size_bytes=len(tensor), |
| 28 | ) |
| 29 | |
| 30 | print("[*] Encrypting tensor on CPU side ...") |
| 31 | enc = cpu.encrypt_tensor(tensor, meta) |
| 32 | print(f" original ciphertext prefix = {enc.ciphertext[:32]}...") |
| 33 | |
| 34 | print("\n[*] Attacker flips one byte of ciphertext over PCIe ...") |
| 35 | ct = bytearray(bytes.fromhex(enc.ciphertext)) |
| 36 | ct[0] ^= 0xFF |
| 37 | enc.ciphertext = bytes(ct).hex() |
| 38 | print(f" tampered ciphertext prefix = {enc.ciphertext[:32]}...") |
| 39 | |
| 40 | print("\n[*] GPU side attempts decryption ...") |
| 41 | try: |
| 42 | gpu.decrypt_tensor(enc) |
| 43 | print("[-] FAIL: tamper went undetected.") |
| 44 | except DecryptionError as exc: |
| 45 | print(f"[+] Tamper detected. DecryptionError: {exc}") |
| 46 | |
| 47 | |
| 48 | if __name__ == "__main__": |
| 49 | main() |
| 50 | |