#include <bits/stdc++.h>
using namespace std;
//Shift cipher
//Lowercase alphabets
//Modulo 26
string encrypt (string message , int key) {
string cipherText;
for (int i = 0; i < message.size(); i++)
cipherText += ((((((message[i] - 97) + key) % 26) + 26) % 26) + 97);
return cipherText;
}
string decrypt (string cipherText , int key) {
string message;
for (int i = 0; i < cipherText.size(); i++)
message += ((((((cipherText[i] - 97) - key) % 26) + 26) % 26) + 97);
return message;
}
int main() {
string message = "wewillmeetatmidnight";
string cipherText = "hphtwwxppelextoytrse";
int key = 11;
cout << encrypt (message , key) << endl;
cout << decrypt (cipherText , key) << endl ;
return 0;
}#include <bits/stdc++.h>
using namespace std;
//Affine cipher
//Lowercase alphabets
//Modulo 26
int getInverse (int key) {
for (int i = 0; i < 26; i++) {
if ( (key * i) % 26 == 1 )
return i;
}
return -1;
}
string encrypt (string message , int key1 , int key2) {
string cipherText;
for (int i = 0; i < message.size(); i++)
cipherText += ((((((message[i] - 97) * key1) + key2) % 26) + 26) % 26 + 97);
return cipherText;
}
string decrypt (string cipherText , int inverseOfKey1 , int key2) {
string message;
for (int i = 0; i < cipherText.size(); i++)
message += ((( inverseOfKey1 * ( (cipherText[i] - 97) - key2) % 26) + 26) % 26 + 97);
return message;
}
int main() {
string message = "hot";
string cipherText = "axg";
int key1 = 7;
int key2 = 3;
int inverseOfKey1 = getInverse(key1);
cout << encrypt (message , key1 , key2) << endl;
cout << ( inverseOfKey1 != -1 ? decrypt (cipherText , inverseOfKey1 , key2) : "There is no inverse for key1") << endl ;
}#include <bits/stdc++.h>
using namespace std;
//Substitution cipher
//Lowercase alphabets
//Modulo 26
string encrypt (string message , string key) {
string cipherText;
for (int i = 0; i < message.size(); i++)
cipherText += key[message[i] - 97] ;
return cipherText;
}
string decrypt (string cipherText , string key) {
string message;
for (int i = 0; i < cipherText.size(); i++)
message += key[cipherText[i] - 97] ;
return message;
}
int main() {
string message = "right";
string cipherText = "czogm";
string encryptionKey = "xnyahpogzqwbtsflrcvmuekjdi";
string decryptionKey = "diryvohezxqptbgfjqnmuskaci";
cout << encrypt (message , encryptionKey) << endl;
cout << decrypt (cipherText , decryptionKey) << endl ;
}#include <bits/stdc++.h>
using namespace std;
//Vigenere cipher
//Lowercase alphabets
//Modulo 26
string encrypt (string message , string key) {
string cipherText;
for (int i = 0; i < message.size(); i += key.size()) {
for (int j = 0; j < key.size(); j++)
cipherText += (((message[j + i] - 97) + (key[j] - 97)) % 26) + 97;
}
return cipherText;
}
string decrypt (string cipherText , string key) {
string message;
for (int i = 0; i < cipherText.size(); i += key.size()) {
for (int j = 0; j < key.size(); j++)
message += (((((cipherText[j + i] - 97) - (key[j] - 97)) % 26) + 26 ) % 26) + 97;
}
return message;
}
int main() {
string message = "tomorrowatthesunset";
string cipherText = "vtnylttxknvmfcopxfd";
string key = "cfbku";
cout << "Encryption = " << encrypt (message , key) << endl;
cout << "Decryption = " << decrypt (cipherText , key) << endl ;
}
#include <bits/stdc++.h>
using namespace std;
//Hill cipher
//Lowercase alphabets
//Modulo 26
int getInverse (int key) {
for (int i = 0; i < 26; i++) {
if ( (key * i) % 26 == 1 )
return i;
}
return -1;
}
vector <vector<int>> getInverseMat (vector <vector <int> > key) {
vector <vector<int>> inverseKey(2);
int det = ((((key[0][0] * key[1][1]) - (key[0][1] * key[1][0])) % 26) + 26) % 26;
int inverseDet = getInverse(det);
inverseKey[0].push_back ((key[1][1]) * inverseDet);
inverseKey[0].push_back ((((key[0][1] * -1 % 26) + 26) * inverseDet) % 26);
inverseKey[1].push_back ((((key[1][0] * -1 % 26) + 26) * inverseDet) % 26);
inverseKey[1].push_back ((key[0][0]) * inverseDet);
return inverseKey;
}
string encrypt (string message, vector <vector <int> > key) {
string cipherText;
for (int i = 0; i < message.size(); i += 2) {
int col = 0;
for (int j = 0; j < 2; j++) {
cipherText += ((((message[i] - 97) * (key[0][col])) + ((message[i + 1] - 97) * (key[1][col]))) % 26) + 97;
col++;
}
}
return cipherText;
}
string decrypt (string cipherText, vector <vector <int>> key) {
string message;
for (int i = 0; i < cipherText.size(); i += 2) {
int col = 0;
for (int j = 0; j < 2; j++) {
message += ((((cipherText[i] - 97) * (key[0][col])) + ((cipherText[i + 1] - 97) * (key[1][col]))) % 26) + 97;
col++;
}
}
return message;
}
int main() {
string message = "july";
string cipherText = "delw";
vector <vector<int>> encryptionKey = {{ 11, 8 } , { 3, 7 }};
vector <vector<int>> decryptionKey = getInverseMat(encryptionKey);
cout << encrypt (message, encryptionKey) << endl;
cout << decrypt (cipherText, decryptionKey) << endl ;
}
#include <bits/stdc++.h>
using namespace std;
//Permutation cipher
//Lowercase alphabets
//Modulo 26
string encrypt (string message , vector<int> key) {
string cipherText;
for (int i = 0; i < message.size(); i += key.size()) {
for (int j = 0; j < key.size(); j++)
cipherText += message[(key[j]) - 1 + i];
}
return cipherText;
}
string decrypt (string cipherText , vector<int> key) {
string message;
for (int i = 0; i < cipherText.size(); i += key.size()) {
for (int j = 0; j < key.size(); j++)
message += cipherText[(key[j]) - 1 + i];
}
return message;
}
int main() {
string message = "shesellsseashellsbytheseashore";
string cipherText = "esaleshleshsselresetloebhsysah";
vector<int> encryptionKey = { 14 , 9 , 11 , 7 , 5 , 1 , 13 , 15 , 3 , 12 , 2 , 4 , 8 , 10 , 6};
vector<int> decryptionKey = { 6 , 11 , 9 , 12 , 5 , 15 , 4 , 13 , 2 , 14 , 3 , 10 , 7 , 1 , 8};
cout << "Encryption = " << encrypt (message , encryptionKey) << endl;
cout << "Decryption = " << decrypt (cipherText , decryptionKey) << endl ;
}