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import os from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes from cryptography.hazmat.primitives.kdf.hkdf import HKDF from cryptography.hazmat.primitives import hashes from cryptography.hazmat.backends import default_backend # Placeholder for LWE-based key generation (simulated here) def lwe_key_generation(seed: bytes): """ Simulates LWE key generation using a seed. In practice, this would involve solving mathematical operations specific to LWE. """ kdf = HKDF( algorithm=hashes.SHA256(), length=32, salt=None, info=b"LWE Example", backend=default_backend() ) key = kdf.derive(seed) return key # File encryption function def encrypt_file(input_file: str, output_file: str, lwe_seed: bytes): key = lwe_key_generation(lwe_seed) iv = os.urandom(16) # Random initialization vector cipher = Cipher(algorithms.AES(key), modes.CFB(iv), backend=default_backend()) encryptor = cipher.encryptor() with open(input_file, 'rb') as f_in, open(output_file, 'wb') as f_out: f_out.write(iv) # Write IV at the beginning of the file while chunk := f_in.read(1024): f_out.write(encryptor.update(chunk)) f_out.write(encryptor.finalize()) # File decryption function def decrypt_file(input_file: str, output_file: str, lwe_seed: bytes): key = lwe_key_generation(lwe_seed) with open(input_file, 'rb') as f_in: iv = f_in.read(16) # Read IV from the file cipher = Cipher(algorithms.AES(key), modes.CFB(iv), backend=default_backend()) decryptor = cipher.decryptor() with open(output_file, 'wb') as f_out: while chunk := f_in.read(1024): f_out.write(decryptor.update(chunk)) f_out.write(decryptor.finalize()) # Example usage if __name__ == "__main__": # Generate a random seed for LWE seed = os.urandom(16) # Random seed for LWE input_file = "example_input.txt" encrypted_file = "example_encrypted.bin" decrypted_file = "example_decrypted.txt" # Create a sample input file with open(input_file, 'w') as f: f.write("This is a test file for encryption and decryption.") # Encrypt the file encrypt_file(input_file, encrypted_file, seed) print(f"File encrypted: {encrypted_file}") # Decrypt the file decrypt_file(encrypted_file, decrypted_file, seed) print(f"File decrypted: {decrypted_file}") # Verify the content with open(decrypted_file, 'r') as f: print("Decrypted content:", f.read())
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