sio-2425/delivery1/lib/symmetric_encryption.py

import os
from cryptography.hazmat.primitives.kdf.pbkdf2 import PBKDF2HMAC
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
from cryptography.hazmat.backends import default_backend

# Function to encrypt a file using a salt
def encrypt_file(input_file, output_file=None):
	key = os.urandom(16)
	iv = os.urandom(16)

	cipher = Cipher(algorithms.AES(key), modes.CFB(iv))
	encryptor = cipher.encryptor()

	with open(input_file, 'rb') as f:
		plaintext = f.read()

	ciphertext = encryptor.update(plaintext) + encryptor.finalize()
	ciphertext = iv + ciphertext

	if output_file is not None:
		with open(output_file, 'wb') as f:
			f.write(ciphertext)

	print(iv.hex())

	return key, ciphertext, iv


# Function to decrypt a file
def decrypt_file(nonce, key, input_file, output_file=None):
	with open(input_file, 'rb') as f:
		encrypted_data = f.read()

	ciphertext = encrypted_data

	cipher = Cipher(algorithms.AES(key), modes.CFB(nonce))
	decryptor = cipher.decryptor()

	plaintext = decryptor.update(ciphertext) + decryptor.finalize()

	if output_file is not None:
		with open(output_file, 'wb') as f:
			f.write(plaintext)

	return plaintext.hex()