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vigenere_cipher.cpp
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vigenere_cipher.cpp
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#include<bits/stdc++.h>
using namespace std;
class vigenere
{
string ip;
string cipher;
string key;
public:
void encrypt();
void decrypt();
};
void vigenere :: encrypt()
{
cout<<"\n\tEnter Message:";
cin>>ip;
cout<<"\tEnter Key:";
cin>>key;
cipher.clear();
cout<<"\n\tText Mapping:\n";
cout<<"\t\tInput:";
//Encripts the text according to algorithm
for(int i=0;i<ip.size();i++)
cout<<" "<<ip[i];
cout<<"\n\t\tKey :";
for(int i=0,j=0;i<ip.size();i++,j++)
{
if(key.size() == j)
j=0;
cout<<" "<<key[j];
}
cout<<endl;
for(int i = 0,j = 0;i<ip.size();i++,j++)
{
if(key.size() == j)
j=0;
int tmp = (ip[i] + (key[j] - 'a'));
tmp = ((tmp > 'z') ? (tmp - 26) : tmp);
cipher += tmp;
}
cout<<"\n\tCipher Text:"<<cipher<<endl;
}
void vigenere :: decrypt()
{
cout<<"\n\tEnter Key:";
cin>>key;
cout<<"\n\tCipher Text:"<<cipher<<endl;
ip.clear();
//Decrypts the text according to alogrithm.
for(int i = 0,j = 0;i<cipher.size();i++,j++)
{
if(key.size() == j)
j=0;
char tmp = (cipher[i] - (key[j] - 'a'));
tmp = tmp < 'a' ? (tmp + 26) : tmp;
ip += tmp;
}
cout<<"\n\tDecrypted text :"<<ip<<endl;
}
int main()
{
//Menu
cout<<"\t------Vigenere Cipher--------";
int opt;
vigenere vg;
while(1)
{
cout<<"\n\tSelect the following option\n\t1.Encrypt a message\n\t2.Decrypt the message\n\t3.Exit\n\tOption:";
cin>>opt;
if(opt>2)
break;
switch(opt)
{
case 1:
vg.encrypt();
break;
case 2:
vg.decrypt();
break;
}
}
}