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FourSquareCipher.cpp
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FourSquareCipher.cpp
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#include<iostream>
#include<string.h>
using namespace std;
string key1, key2;
char TL[5][5], TR[5][5], BL[5][5], BR[5][5], agg[10][10];
void makeTableau(string key1,string key2)
{
for(int i=0;i<2;i++)
for(int j=0;j<5;j++)
{
char ch = (i*5+j+65);
TL[i][j]=ch;
BR[i][j]=ch;
}
TL[1][4]='K';
BR[1][4]='K';
for(int i=2;i<5;i++)
for(int j=0;j<5;j++)
{
char ch = (i*5+j+66);
TL[i][j]=ch;
BR[i][j]=ch;
}
for(int i=0;i<5;i++)
for(int j=0;j<5;j++)
TR[i][j]=key1[(i*5+j)];
for(int i=0;i<5;i++)
for(int j=0;j<5;j++)
BL[i][j]=key2[(i*5+j)];
string seq = "";
for(int i=0;i<5;i++)
for(int j=0;j<10;j++)
{
if(j>4){
int k = j-5;
string s(1,TR[i][k]);
seq=seq+s;
}
else
{
string s(1,TL[i][j]);
seq=seq+s;
}
}
for(int i=0;i<5;i++)
for(int j=0;j<10;j++)
{
if(j>4)
{
int k = j-5;
string s(1,BR[i][k]);
seq=seq+s;
}
else
{
string s(1,BL[i][j]);
seq=seq+s;
}
}
int n = seq.length();
char char_arr[n+1];
strcpy(char_arr,seq.c_str());
for(int
i=0;i<10;i++)
for(int j=0;j<10;j++)
agg[i][j] = char_arr[(i*10+j)];
}
string encrypt(string pt)
{
string encpt="";
int length = pt.length();
char pt_char[length+1];
strcpy(pt_char,pt.c_str());
for(int i=0;i<pt.length();i=i+2)
{
int row1,col1,
row2,col2;
for(int j=0;j<5;j++)
for(int k=0;k<5;k++)
{
if(pt_char[i]==TL[j][k])
{
row1=j;
col2=k;
}
}
for(int j=0;j<5;j++)
for(int k=0;k<5;k++)
{
if(pt_char[i+1]==BR[j][k])
{
row2=j+5;
col1=k+5;
}
}
string s1(1,agg[row1][col1]), s2(1,agg[row2][col2]);
encpt=encpt+s1+s2;
}
return encpt;
}
string decrypt(string encpt)
{
string decpt="";
int length = encpt.length();
char encpt_char[length+1];
strcpy(encpt_char,encpt.c_str());
for(int
i=0;i<encpt.length();i=i+2)
{
int row1,col1,row2,col2;
for(int j=0;j<5;j++)
for(int k=0;k<5;k++)
{
if(encpt_char[i]==TR[j][k])
{
row1=j;
col2=k+5;
}
}
for(int j=0;j<5;j++)
for(int k=0;k<5;k++)
{
if(encpt_char[i+1]==BL[j][k])
{
row2=j+5;
col1=k;
}
}
string s1(1,agg[row1][col1]), s2(1,agg[row2][col2]);
decpt=decpt+s1+s2;
}
return decpt;
}
int main()
{
string pt, encpt, decpt;
cout<<"Enter plaintext: ";
cin>>pt;
cout
<<"Enter Key 1: ";
cin>>key1;
cout<<"Enter Key 2: ";
cin>>key2;
makeTableau(key1,key2);
encpt = encrypt(pt);
cout<<"Encrypted text: "<<encpt<<endl;
decpt = decrypt(encpt);
cout<<"Decrypted text: "<<decpt;
return 0;
}