One of the most popular and reliable standards today is AES (Advanced Encryption Standard).
What is AES?
AES is a symmetric block encryption algorithm.
- The same key is used for encryption and decryption.
- Data is processed in fixed-length blocks (usually **128 bits**).
AES became a standard in 2001 and is still considered attack-resistant when implemented correctly.
Key length
AES supports keys of length:
- 128 bits (16 bytes)
- 192 bits (24 bytes)
- 256 bits (32 bytes)
The longer the key, the higher the resistance to attacks.
How does AES work?
1. The data is divided into blocks of 128 bits.
2. Each block goes through several rounds of encryption:
- Byte substitution
- Row shuffling
- Column
shuffling - Key overlay
3. The number of rounds depends on the length of the key.:
- 128 bits → 10 rounds
- 192 bits → 12 rounds
- 256 bits → 14 rounds
Unlike DES, AES does not use bit permutations — it operates at the byte and matrix levels.
An example of using AES in Python
We use the PyCryptodome library to work with AES.:
Python:
from Crypto.Cipher import AES
from Crypto.Random import get_random_bytes
from Crypto.Util.Padding import pad, unpad
# Generating a random 16-byte key
key = get_random_bytes(16)
# Creating an AES object in CBC mode (Cipher Block Chaining)
cipher = AES.new(key, AES.MODE_CBC)
# Data for encryption
data = b"Hello, this is a secret message!"
# Padding the data to a multiple of 16
padded_data = pad(data, AES.block_size)
# Encrypt
encrypted_data = cipher.encrypt(padded_data)
print("Encrypted data:", encrypted_data)
# For decryption, you need to save IV (initialization vector)
iv = cipher.iv
# Decryption
cipher_dec = AES.new(key, AES.MODE_CBC, iv)
decrypted_data = unpad(cipher_dec.decrypt(encrypted_data), AES.block_size)
print("Decrypted data:", crypted_data.decode()), Please note:
key — the secret key (must be kept secret).
iv (initialization vector) is needed for decryption, it can be transmitted in plain text.
Padding is used so that the text is a multiple of the block size.
Why AES?
Safe — there are no known practical attacks.
Faster than DES and 3DES.
It is widely supported in all modern protocols (TLS, SSH, VPN, ZIP, WhatsApp).
, Important recommendations
Never use the same key and IV for multiple messages.
Keep your keys in a secure vault.
Use secure protocols when transmitting data.
AES is the gold standard of symmetric encryption. It is used everywhere: from HTTPS and VPN to messengers.
Using Python and the PyCryptodome library, it can be easily integrated into your projects.
