Input: Ciphertext stored in four w-bit input registers A, B, C, D Number r of rounds w-bit round keys S[0;: : : ; 2r + 3] Output: Plaintext stored in A,B,C,D Procedure: Draw the special purpose hardware organization for the following algorithm: C = C-S[2r +3] A = A -S[2r +2] for i = r downto 1 do wwwwwww { } D = D-S[1] B=B-S[0] (A;B;C;D) = (D; A;B;C) u= (D * (2D + 1)) < < >t) + u A = ((A - S[21])>>>u) + t