Introduction - If you have any usage issues, please Google them yourself
AES is the group key, the algorithm 128-bit data input, is 128-bit key length. Nr expressed by a number of rounds of data packet encryption (encryption rounds relationship with the key length as listed in Table 1). Each round requires a length of the input packet has the same extension key Expandedkey (i) participation. As external input the length of the encryption key K is limited, so use a key in the algorithm extension (Keyexpansion) extend the external key K into a longer bit strings to generate each round of encryption and decryption key.