Can you explain what is meant by symmetric data encryption?

Symmetric encryption is a method of data encryption where the same key is used for both encryption and decryption. This means that the sender and receiver must agree on a secret key in advance and keep it secure.

Main features:

• Fast encryption and decryption.
• A secure channel is required for key exchange.

Example algorithms: AES, DES.

Example in Python using the cryptography library:

from cryptography.fernet import Fernet

# Generate a key
key = Fernet.generate_key()
cipher = Fernet(key)

# Encryption
text = b"Hello, world!"
cipher_text = cipher.encrypt(text)

# Decryption
plain_text = cipher.decrypt(cipher_text)
print(plain_text.decode())  # Outputs: Hello, world!

Here, key is used for both encryption and decryption.