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DESALGORITHM.cpp
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DESALGORITHM.cpp
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#include<iostream>
#include<string.h>
#include<stdio.h>
#include <string>
#include <cstdlib>
#include<stdlib.h>
#include <sstream>
#include <bits/stdc++.h>
using namespace std;
//From key generation program
string keyval[]={
"000110110000001011101111111111000111000001110010",
"011110011010111011011001110110111100100111100101",
"010101011111110010001010010000101100111110011001",
"011100101010110111010110110110110011010100011101",
"011111001110110000000111111010110101001110101000",
"011000111010010100111110010100000111101100101111",
"111011001000010010110111111101100001100010111100",
"111101111000101000111010110000010011101111111011",
"111000001101101111101011111011011110011110000001",
"101100011111001101000111101110100100011001001111",
"001000010101111111010011110111101101001110 000110",
"011101010111000111110101100101000110011111101001",
"100101111100010111010001111110101011101001000001",
"010111110100001110110111111100101110011100111010",
"101111111001000110001101001111010011111100001010",
"110010110011110110001011000011100001011111110101"
};
int s[8][4][16]=
{{
14,4,13,1,2,15,11,8,3,10,6,12,5,9,0,7,
0,15,7,4,14,2,13,1,10,6,12,11,9,5,3,8,
4,1,14,8,13,6,2,11,15,12,9,7,3,10,5,0,
15,12,8,2,4,9,1,7,5,11,3,14,10,0,6,13
},
{
15,1,8,14,6,11,3,4,9,7,2,13,12,0,5,10,
3,13,4,7,15,2,8,14,12,0,1,10,6,9,11,5,
0,14,7,11,10,4,13,1,5,8,12,6,9,3,2,15,
13,8,10,1,3,15,4,2,11,6,7,12,0,5,14,9
},
{
10,0,9,14,6,3,15,5,1,13,12,7,11,4,2,8,
13,7,0,9,3,4,6,10,2,8,5,14,12,11,15,1,
13,6,4,9,8,15,3,0,11,1,2,12,5,10,14,7,
1,10,13,0,6,9,8,7,4,15,14,3,11,5,2,12
},
{
7,13,14,3,0,6,9,10,1,2,8,5,11,12,4,15,
13,8,11,5,6,15,0,3,4,7,2,12,1,10,14,9,
10,6,9,0,12,11,7,13,15,1,3,14,5,2,8,4,
3,15,0,6,10,1,13,8,9,4,5,11,12,7,2,14
},
{
2,12,4,1,7,10,11,6,8,5,3,15,13,0,14,9,
14,11,2,12,4,7,13,1,5,0,15,10,3,9,8,6,
4,2,1,11,10,13,7,8,15,9,12,5,6,3,0,14,
11,8,12,7,1,14,2,13,6,15,0,9,10,4,5,3
},
{
12,1,10,15,9,2,6,8,0,13,3,4,14,7,5,11,
10,15,4,2,7,12,9,5,6,1,13,14,0,11,3,8,
9,14,15,5,2,8,12,3,7,0,4,10,1,13,11,6,
4,3,2,12,9,5,15,10,11,14,1,7,6,0,8,13
},
{
4,11,2,14,15,0,8,13,3,12,9,7,5,10,6,1,
13,0,11,7,4,9,1,10,14,3,5,12,2,15,8,6,
1,4,11,13,12,3,7,14,10,15,6,8,0,5,9,2,
6,11,13,8,1,4,10,7,9,5,0,15,14,2,3,12
},
{
13,2,8,4,6,15,11,1,10,9,3,14,5,0,12,7,
1,15,13,8,10,3,7,4,12,5,6,11,0,14,9,2,
7,11,4,1,9,12,14,2,0,6,10,13,15,3,5,8,
2,1,14,7,4,10,8,13,15,12,9,0,3,5,6,11
}};
string bin2hex(string p){
string op="";
string bits_COL[]={"0000","0001","0010","0011","0100","0101","0110","0111","1000","1001","1010","1011","1100","1101","1110","1111"};
for(int i=0;i<64;i+=4)
{
string a,b,c,d;
int j;
a=p[i];
b=p[i+1];
c=p[i+2];
d=p[i+3];
string text = a+b+c+d;
//cout<<endl<<"TEXT "<<text<<endl;
int lc;
for(j=0; j<=15;j++)
{
if(text==bits_COL[j])
{
if(j<=9)
{
string out_string;
stringstream ss;
ss << j;
out_string = ss.str();
//cout<<"oustring"<<out_string;
op+=out_string;
}
else if(j>9){
if(j==10)
op+="A";
if(j==11)
op+="B";
if(j==12)
op+="C";
if(j==13)
op+="D";
if(j==14)
op+="E";
if(j==15)
op+="F";
}
}
}
}
return op;
}
string hex2bin(string p)//hexadecimal to binary
{
string ap="";
int l=p.length();
for(int i=0;i<l;i++)
{
string st="";
if(p[i]>='0'&&p[i]<='9')
{
int te=int(p[i])-48;
while(te>0)
{
st+=char(te%2+48);
te/=2;
}
while(st.length()!=4)
st+='0';
for(int j=3;j>=0;j--)
ap+=st[j];
}
else
{
int te=p[i]-'A'+10;
while(te>0)
{
st+=char(te%2+48);
te/=2;
}
for(int j=3;j>=0;j--)
ap+=st[j];
}
}
return ap;
}
string initial_permuation( string inputval){
int p64[64]={
58, 50, 42, 34, 26, 18, 10, 2,
60, 52, 44, 36, 28, 20, 12, 4,
62, 54, 46, 38, 30, 22, 14, 6,
64, 56, 48, 40, 32, 24, 16, 8,
57, 49, 41, 33, 25, 17, 9, 1,
59, 51, 43, 35, 27, 19, 11, 3,
61, 53, 45, 37, 29, 21, 13, 5,
63, 55, 47, 39, 31, 23, 15, 7
};
string out_p="";
for(int i=0; i<64;i++)
{
out_p+=inputval[p64[i]-1];
}
return out_p;
}
string inv_perm(string text)
{
int p64[64]= {
40, 8, 48, 16, 56, 24, 64, 32,
39, 7, 47, 15, 55, 23, 63, 31,
38, 6, 46, 14, 54, 22, 62, 30,
37, 5, 45, 13, 53, 21, 61, 29,
36, 4, 44, 12, 52, 20, 60, 28,
35, 3, 43, 11, 51, 19, 59, 27,
34, 2, 42, 10, 50, 18, 58, 26,
33, 1, 41, 9, 49, 17, 57, 25};
string out_p="";
for(int i=0; i<64;i++)
{
out_p+=text[p64[i]-1];
}
return out_p;
}
string expn(string key)
{
int p48[48]= {
32, 1, 2, 3, 4, 5,
4, 5, 6, 7, 8, 9,
8, 9, 10, 11, 12, 13,
12, 13, 14, 15, 16, 17,
16, 17, 18, 19, 20, 21,
20, 21, 22, 23, 24, 25,
24, 25, 26, 27, 28, 29,
28, 29, 30, 31, 32, 1};
string out_p="";
for(int i=0; i<48;i++)
{
out_p+=key[p48[i]-1];
}
return out_p;
}
string after_sbox(string inp)
{
int p32[32]= {
16, 7, 20, 21,
29, 12, 28, 17,
1, 15, 23, 26,
5, 18, 31, 10,
2, 8, 24, 14,
32, 27, 3, 9,
19, 13, 30, 6,
22, 11, 4, 25};
string out_p="";
for(int i=0; i<32;i++)
{
out_p+=inp[p32[i]-1];
}
return out_p;
}
string s_box(string value)
{
int n=0;
int i,j, lr, lc;
int conv;
string op="";
string bits_ROW[]={"00","01","10","11"};
int k=0;
string bits_COL[]={"0000","0001","0010","0011","0100","0101","0110","0111","1000","1001","1010","1011","1100","1101","1110","1111"};
while(k<48)
{
string row="";
string col="";
string a,b,c,d,e,f;
a=value[k];
b=value[k+5];
c=value[k+1];
d=value[k+2];
e=value[k+3];
f=value[k+4];
row= a+b;
col= c+d+e+f;
for(i=0;i<4;i++){
if(row == bits_ROW[i])
lr=i;
}
for(j=0; j<16;j++){
if(col==bits_COL[j])
lc=j;
}
int n=k/6;
conv=s[n][lr][lc];
op+=bits_COL[conv];
k=k+6;
}
//cout<<value<<endl;
op= after_sbox(op);
return op;
}
string XOR(string a,string b)
{
string output = "";
for(int i=0;i<a.size();i++){
if(a[i] == b[i])
output += "0";
else
output += "1";
}
return output;
}
string function_encrypt(string left, string right, string key)
{
string left_val= right;
string right_val;
string total_val;
string exp_key= expn(right);
string output;
string res;
output= XOR(exp_key, key);
//cout<<"RIGHT VALUE "<<output<<endl;
output= s_box(output);
right_val= XOR(output,left);
total_val= left_val +right_val;
return total_val;
}
string decrypt( string p)
{
p = initial_permuation(p);
cout<<endl<<"Initial Permutation:"<<endl<<p;
string left_tot, right_tot;
string total_text;
for(int i=1;i<=16;i++)
{
left_tot= p.substr(0,32);
right_tot= p.substr(32,64);
total_text=left_tot+right_tot;
p = function_encrypt(left_tot, right_tot, keyval[16-i]);
}
string left= p.substr(32,64);
string right= p.substr(0,32);
string decrypt= left+right;
decrypt = inv_perm(decrypt);
cout<<endl<<endl<<"Decrypted Data is:"<<endl<<decrypt;
string plain_text= bin2hex(decrypt);
cout<<endl<<endl<<"PLAIN TEXT IS:"<<endl<<plain_text;
}
string split_key(string text)
{
string left_tot, right_tot;
string total_text;
for(int i=1;i<=16;i++)
{
left_tot= text.substr(0,32);
right_tot= text.substr(32,64);
text = function_encrypt(left_tot, right_tot, keyval[i-1]);
}
string left= text.substr(32,64);
string right= text.substr(0,32);
string encrypt= left+right;
encrypt = inv_perm(encrypt);
cout<<endl<<"Encrypted Data is:"<<endl<<encrypt;
string cipher= bin2hex(encrypt);
cout<<endl<<endl<<"CIPHER TEXT:"<<endl<<cipher;
//DES DECRYPTION
cout<<endl<<endl<<"------------DECRYPTION------------"<<endl;
decrypt(encrypt);
}
int main()
{
string key_value;
string plaintext;
cout<<"-------------DES ENCRYPTION AND DECRYPTION--------------------";
cout<<endl<<endl<<"Enter the plain text value: ";
cin>>plaintext;
string convtext = hex2bin(plaintext);
cout<<endl<<"Binary Format"<<endl<<convtext;
cout<<endl<<endl<<"------------ENCRYPTION------------";
string func_value = initial_permuation(convtext);
cout<<endl<<endl<<"Initial permutation:"<<endl<<func_value<<endl;
split_key(func_value);
}