The Advanced Encryption Standard (AES) was announced by the National Institute of Standards and Technology (NIST) in November 2001. It is the successor of Data Encryption Standard (DES), which cannot be considered as safe any longer, because of its short key with a length of only 56 bits.

To determine which algorithm would follow DES, NIST called for different algorithm proposals in a sort of competition. The best of all suggestions would become the new AES. In the final round of this competition the algorithm Rijndael, named after its Belgian inventors Joan Daemen and Vincent Rijmen, won because of its security, ease of implementation, and low memory requirements.

There are three different versions of AES. All of them have a block length of 128 bits, whereas, the key length is allowed to be 128, 192, or 256 bits. In this application report, only a key length of 128 bits is discussed.