AES (Advanced Encryption Standard) is a symmetric block cipher algorithm used to encrypt and decrypt data. It is widely used due to its efficiency and security. AES operates on fixed-size blocks of data (128 bits) and uses keys of varying lengths (128, 192, or 256 bits) to perform encryption and decryption.

How AES Works

AES follows a series of steps to encrypt data. These steps include:

1. Add Round Key: The initial block of data is XORed with the first key.

2. SubBytes: Each byte in the block is substituted using a substitution box (S-Box).

3. ShiftRows: Rows of the block are shifted cyclically.

4. MixColumns: Columns of the block are mixed using matrix multiplication (skipped in the last round).

5. Add Round Key: The block is XORed with the round key.

These steps are repeated for a number of rounds depending on the key length (10 rounds for 128-bit keys, 12 rounds for 192-bit keys, and 14 rounds for 256-bit keys).

Python Code Example

Here is a Python example using the pycryptodome library to perform AES encryption and decryption: