apeng

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())