# Symmetric crypto lib
from cryptography.fernet import Fernet

key = Fernet.generate_key() 

file = open('key.key', 'wb')
file.write(key) # The key is type bytes still
file.close() 

message = "my deep dark secret".encode()

f = Fernet(key)
encrypted = f.encrypt(message)

print(encrypted)

decrypted = f.decrypt(encrypted) 

print(decrypted)