$1-[4$ marks$]$ Use the key $1010011100111011$ to show the results of the steps referred to in the figure below. The plaintext is the word $"$ok$"$ as expressed in ASCII, that is $0110111101101011.$

S$-$AES refers to Simplified$-$AES $($see figure below$).$ In fact, the structure of S$-$AES is exactly the same as AES. The differences are in the key size $(16$ bits$),$ the block size $(16$ bits$)$ and the number of rounds $(2$ rounds$).$