This script is a demonstration of how to use RSA and Fernet to encrypt files. For performance reasons this script uses fernet, a symmetric encryption standard, to encrypt the contents of the file and then RSA to encrypt the key that fernet uses to encrypt the file. Public key cryptography is computationally expensive so this way of encrypting files is a better practice.
When encrypting, a fernet key will first be generated and then the file specified will be encrypted using this key. Once complete the fernet key will be encrypted using your RSA public key and then added to the file 256 bytes of the encrypted file. Then, for the decryption process, the Fernet key will be extracted and then decrypted using your RSA private key. Once the key has extracted the file will be decrypted and written to the same file. This way the only keys you have to manage are your own RSA keys and you still maintain the performance of symmetric encryption.
Install cryptography library
pip install cryptography
python file_encryptor.py [-h] [-f FILE] [-k KEY] [-g] [-e] [-d]
-for--file- Specify the file you want to encrypt or decrypt
-kor--key- RSA key
- Public Key for encrpytion
- Private Key for decryption
-g- Generate RSA Keys if you do not already have them
-e- Specify that you want to encrypt
-d- Specify that you want to decrypt
File Encryption:
python file_encryptor.py -e -f file.txt -k public_key.pem
File Decryption:
python file_encryptor.py -d -f file.txt -k private_key.pem