What is the concept used to verify the identity of the remote host with ssh connections?

Asequential circuit contains a register of four flip-flops. initially a binary number n (0000 ≤ n ≤ 1100) is stored in the flip-flops. after a single clock pulse is applied to the circuit, the register should contain n + 0011. in other words, the function of the sequential circuit is to add 3 to the contents of a 4-bit register. design and implement this circuit using j-k flip-flops.