Code:
#include iostream
#include string
using namespace std;
class Vigenere
{
public:
string key;
Vigenere(string key)
{
for (int i = 0; i < key.size(); ++i)
{
if (key[i] >= 'A' && key[i] <= 'Z')
this->key += key[i];
else if (key[i] >= 'a' && key[i] <= 'z')
this->key += key[i] + 'A' - 'a';
}
}
string encrypt(string text)
{
string out;
for (int i = 0, j = 0; i < text.length(); ++i)
{
char c = text[i];
if (c >= 'a' && c <= 'z')
c += 'A' - 'a';
else if (c < 'A' || c > 'Z')
continue;
out += (c + key[j] - 2 * 'A') % 26 + 'A';
j = (j + 1) % key.length();
}
return out;
}
string decrypt(string text)
{
string out;
for (int i = 0, j = 0; i < text.length(); ++i)
{
char c = text[i];
if (c >= 'a' && c <= 'z')
c += 'A' - 'a';
else if (c < 'A' || c > 'Z')
continue;
out += (c - key[j] + 26) % 26 + 'A';
j = (j + 1) % key.length();
}
return out;
}
};
int main()
{
Vigenere cipher("VIGENERECIPHER");
string original =
"Beware the Jabberwock, my son! The jaws that bite, the claws that catch!";
string encrypted = cipher.encrypt(original);
string decrypted = cipher.decrypt(encrypted);
cout << original << endl;
cout << "Encrypted: " << encrypted << endl;
cout << "Decrypted: " << decrypted << endl;
}
Output:
Beware the Jabberwock, my son! The jaws that bite, the claws that catch!
Encrypted: WMCEEIKLGRPIFVMEUGXQPWQVIOIAVEYXUEKFKBTALVXTGAFXYEVKPAGY
Decrypted: BEWARETHEJABBERWOCKMYSONTHEJAWSTHATBITETHECLAWSTHATCATCH
------------------
(program exited with code: 0)
Press return to continue
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