The cryptography module is one of the most actively maintained libraries for secure cryptographic operations. It provides high-level, easy-to-use interfaces for encryption, hashing, key management, and digital signatures, while still exposing low-level primitives for advanced users. One of its most popular components is cryptography.fernet, a symmetric encryption system that guarantees that data cannot be read or modified without the correct key. It handles everything: key generation, AES encryption, HMAC authentication, timestamps, and safe serialization - making.

from cryptography.fernet import Fernet

key = Fernet.generate_key() # generating a new key (do this once)

# Saving the key to a file
with open("secret.key", "wb") as key_file:
    key_file.write(key)

# Loading the key later
with open("secret.key", "rb") as key_file:
    loaded_key = key_file.read()

cipher = Fernet(loaded_key)

# Encrypting a message
message = "Top secret message".encode()
token = cipher.encrypt(message)
print(token)

# Decrypting the message
plaintext = cipher.decrypt(token)
print(plaintext.decode())