Q37,paper2, D 12.AES is a round cipher based on the Rijndal Algorithm that uses a 128-bit block of data. AES has three different configurations. ______ rounds with a key size of 128 bits, ______ rounds with a key size of 192 bits and ______ rounds with a key size of 256 bits.

(A) 5, 7, 15
(B) 10, 12, 14
(C) 5, 6, 7
(D) 20, 12, 14
Answer(B)
The Rijndael algorithm is a new generation symmetric block cipher that supports key sizes of 128, 192 and 256 bits, with data handled in 128-bit blocks - however, in excess of AES design criteria, the block sizes can mirror those of the keys. Rijndael uses a variable number of rounds, depending on key/block sizes, as follows:
9 rounds if the key/block size is 128 bits .
11 rounds if the key/block size is 192 bits .
13 rounds if the key/block size is 256 bits .