Implementing-cryptography-using-python

178 Chapter 6 ■ Using Cryptography with Images
file_data = file.read()
# encrypt data
encrypted_data = f.encrypt(file_data)
# write the encrypted file
with open(filename, "wb") as file:
file.write(encrypted_data)
def decrypt(filename, key):
# decrypts the file and writes it using the filename and key
f = Fernet(key)
with open(filename, "rb") as file:
# read the encrypted data
encrypted_data = file.read()
# decrypt data
decrypted_data = f.decrypt(encrypted_data)
# write the original file
with open(filename, "wb") as file:
file.write(decrypted_data)
if __name__ == "__main__":
import argparse
parser = argparse.ArgumentParser(description="Simple File Encryptor
Script")
parser.add_argument("file", help="File to encrypt/decrypt")
parser.add_argument("-g", "--generate-key", dest="generate_key",
action="store_true",
help="Whether to generate a new key or use
existing")
parser.add_argument("-e", "--encrypt", action="store_true",
help="Whether to encrypt the file, only -e or -d
can be specified.")
parser.add_argument("-d", "--decrypt", action="store_true",
help="Whether to decrypt the file, only -e or -d
can be specified.")
args = parser.parse_args()
file = args.file
generate_key = args.generate_key
if generate_key:
write_key()
# load the key
key = load_key()
encrypt_ = args.encrypt
decrypt_ = args.decrypt