File Encryption Tool
This utility encrypts and decrypts files using symmetric encryption provided by the cryptography library. It uses the Fernet implementation, which guarantees that a message encrypted using it cannot be manipulated or read without the key.
Modules Used:
cryptography: For generating keys and performing encryption/decryption.- argparse: To handle command-line arguments.
os: To check for file existence.
Installation
You need to install the cryptography library:
pip install cryptographyThe Code
Save this as encryptor.py.
from cryptography.fernet import Fernet
import argparse
import os
def generate_key(key_file="secret.key"):
"""Generates a key and saves it into a file."""
key = Fernet.generate_key()
with open(key_file, "wb") as kf:
kf.write(key)
print(f"Key generated and saved to {key_file}")
def load_key(key_file="secret.key"):
"""Loads the key from the current directory."""
return open(key_file, "rb").read()
def process_file(filename, key, mode):
"""Encrypts or Decrypts a file."""
f = Fernet(key)
with open(filename, "rb") as file:
file_data = file.read()
try:
if mode == 'encrypt':
processed_data = f.encrypt(file_data)
print(f"File '{filename}' encrypted.")
else:
processed_data = f.decrypt(file_data)
print(f"File '{filename}' decrypted.")
with open(filename, "wb") as file:
file.write(processed_data)
except Exception as e:
print(f"Error processing file (Invalid Key?): {e}")
if __name__ == "__main__":
parser = argparse.ArgumentParser(description="File Encryptor/Decryptor")
parser.add_argument("action", choices=['generate', 'encrypt', 'decrypt'], help="Action to perform")
parser.add_argument("filename", nargs="?", help="File to encrypt/decrypt")
parser.add_argument("--key", default="secret.key", help="Key file path (default: secret.key)")
args = parser.parse_args()
if args.action == "generate":
generate_key(args.key)
elif args.action in ["encrypt", "decrypt"]:
if not args.filename:
print("Error: Filename required for encryption/decryption.")
elif not os.path.exists(args.filename):
print(f"Error: File '{args.filename}' not found.")
elif not os.path.exists(args.key):
print(f"Error: Key file '{args.key}' not found. Generate one first.")
else:
key = load_key(args.key)
process_file(args.filename, key, args.action)Usage
# 1. Generate a key (do this once)
python encryptor.py generate
# 2. Encrypt a file
python encryptor.py encrypt confidential.txt
# 3. Decrypt a file
python encryptor.py decrypt confidential.txtWarning: If you lose secret.key, you will not be able to decrypt your files.