file_encryptor.py

# https://pyshark.com/encrypt-and-decrypt-files-using-python/
from cryptography.fernet import Fernet

class Encryptor():

    def key_create(self):
        return Fernet.generate_key()
    
    def key_write(self, key, key_name):
        with open(key_name, 'wb') as mykey:
            mykey.write(key)
    
    def key_load(self, key_name):
        with open(key_name, 'rb') as mykey:
            key = mykey.read()
        return key

    def file_encrypt(self, key, original_file, encrypted_file):
        f = Fernet(key)

        with open(original_file, 'rb') as file:
            original = file.read()
        
        encrypted = f.encrypt(original)
    
        with open(encrypted_file, 'wb') as file:
            file.write(encrypted)
        
    
    def file_decrypt(self, key, encrypted_file, decrypted_file):
        f = Fernet(key)
        
        with open(encrypted_file, 'rb') as file:
            encrypted = file.read()
        
        decrypted = f.decrypt(encrypted)

        with open(decrypted_file, 'wb') as file:
            file.write(decrypted)
    

if __name__=='__main__':
    encryptor = Encryptor()
    mykey = encryptor.key_create()
    encryptor.key_write(mykey, mykey)
    loaded_key = encryptor.key_load('mykey.key')
    encryptor.file_encrypt(loaded_key, 'grades.csv', 'enc_grades.csv')
    encryptor.file_decrypt(loaded_key, 'enc_grades.csv', 'dec_grades.csv')