Chaotic_code/decryptionprocess2_CBC.m

   1 function dimg =decryptionprocess2_CBC(img,h,RK,Inv_SubBytes,Inv_Pbox,r,IV)\r
   2 %%%%%%%%%%%%%% convert image to a vector seq\r
   3 %seq=double(reshape(img,1,[]));\r
   4 seq_bin=double(byte2bit(uint8(img))) ;\r
   5 decr_seq_binary=zeros(1,length(seq_bin));\r
   6 %%%%%%%%%%%%%%%%%%%% calculate the number of blocks%%%%%%%%%%%%%%%%%%%%%%%%\r
   7 nb= floor(length(seq_bin)/(8*h));\r
   8 RKB=byte2bit(RK);\r
   9 RKB=RKB(1:r*h*8);\r
  10 %RK_bin=double(reshape(byte2bit(RK),r,[]));\r
  11 RK_bin=double(reshape(RKB,r,[]));\r
  12 %RK_bin=double(reshape(byte2bit(RK),r,[]));\r
  13 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\r
  14 %%%%%%%%%%% Convert S-box to binary representation to avoid repeat the\r
  15 %%%%%%%%%%% byte2bit conversion\r
  16 Bin_Sbox  =double(Convert_Sbox_Bin(Inv_SubBytes));\r
  17 \r
  18 iv=[];\r
  19 for i=1:h\r
  20     iv=[iv byte2bit(IV(i))];\r
  21 end\r
  22 IV=double(iv);\r
  23 \r
  24 \r
  25 %%%%%%%%%%%%%%%%%%%% Applied the confusion process (r rounds)\r
  26 for it=1:nb\r
  27      temp=seq_bin((it-1)*8*h+1:it*h*8);\r
  28      temp_IV=temp;\r
  29     for itr=r:-1:1       \r
  30         temp= temp(Inv_Pbox);\r
  31         temp=reshape(Bin_Sbox (double(bit2byte(temp))+1,:)',1,[]);\r
  32         temp=bitxor(temp,RK_bin(itr,1:h*8));   \r
  33     end\r
  34     temp=bitxor(temp,IV);\r
  35     decr_seq_binary((it-1)*8*h+1:it*h*8)=temp;\r
  36     IV= temp_IV;\r
  37 end\r
  38 \r
  39 % Convert to Byte representation\r
  40 \r
  41 %valbin=reshape(valbin,Tb/8,8);\r
  42 dimg=uint8(bit2byte(decr_seq_binary));