fk.m

This program applies Simplified DES (S-DES) Ciphering Algorithm Developed by Maimouna Al-ammar 5t

% FK function for key k
function [xor2,R]=fk(in,key)
Right=[];
Right=[Right in(5) in(6) in(7) in(8)];
Left=[];
Left=[Left in(1) in(2) in(3) in(4)];
% Expansion and permutation
EP=[in(8) in(5) in(6) in(7) in(6) in(7) in(8) in(5)];
% Extarcting S0 and S1 matrices
SS=xor(EP,key);
% Definig S0 and S1
S0=[1 0 3 2;3 2 1 0;0 2 1 3;3 1 0 2];
S1=[0 1 2 3;2 0 1 3;3 0 1 3;2 1 0 3];

S0output=dec2binvec(S0(binvec2dec([SS(1) SS(4)])+1,binvec2dec([SS(2) SS(3)])+1),2);
S1output=dec2binvec(S1(binvec2dec([SS(5) SS(8)])+1,binvec2dec([SS(6) SS(7)])+1),2);
SSout=[S0output S1output];
% Perumtation4
PSSout=[SSout(2) SSout(4) SSout(3) SSout(1)];
% result of F using k1
xor2=xor(Left,PSSout);
R=Right;