AES is one of the implementations of #Data Encryption Standard (DES) invented by Joan Daemen and Vincent Rijmen, which was once called Rijndael. It could use either 128-, 192-, or 256-bit keys to encrypt 128 bit of data with an iterative manner (operates on entire block every round) rather than adopting Feistel Cipher Structure#. There were three initial criteria for AES evaluation: security, computational cost, and algorithm and implementation characteristics. Final criteria for AES evaluation were: general security, software and hardware implementation ease, implementation attacks (practical attacks on the actual implementation), and flexibility (in terms of encryption, decryption, keying etc.).
AES processes data as block of 4 columns of 4 bytes. It will then operate on the entire data block in every round (up to 9, 11, 13 rounds) with byte substitution#, shift rows#, mix columns (substitution using matrix multiply of group), and add round key (XOR the data block with key) which view the data block as alternate XOR key and scramble data bytes. Decryption is done in reverse to encryption process.
Note: Initially, a round key will be produced based on the data block and key input in encryption and decryption.
AES utilises the properties of Galois Field#.
It sees wide adoption from US government, and becomes the fundamental data encryption standard used by the Wi-Fi Protected Access 2 (WPA2) in order to secure wireless networks.