I have been working on a Playfair Cipher in C++ for a final Project in a Cryptography class. I was hoping for some feedback on the project so far. I recently got a job programming before I've even graduated and I feel like I've already learned so much.
I would just like some feedback on my code style, comments, formatting, and structure.
The code below is the PlayfairCipher class. The code is fairly simple.
#include "PlayfairCipher.h"
#include "Sanitizer.h"
#include <iostream>
#include <string>
using namespace std;
PlayfairCipher :: PlayfairCipher(void)
{
playfairMatrix.resize(5);
for (int i = 0; i < 5; ++i) {
playfairMatrix[i].resize(5);
}
}
void PlayfairCipher :: createKeyMatrix(string &key)
{
string alphabet = "abcdefghiklmnopqrstuvwxyz";
string sanitizedKey = Sanitizer :: sanitizeInputKey(key);
for(unsigned int i = 0; i < sanitizedKey.size(); i++) {
for(int j = 0; j < alphabet.size(); j++) {
if(sanitizedKey[i] == alphabet[j]) {
alphabet.erase(j, 1);
}
}
}
sanitizedKey.append(alphabet);
int index = 0;
for(int row = 0; row < 5; row++) {
for(int column = 0; column < 5; column++) {
playfairMatrix[row][column] = sanitizedKey[index];
index++;
}
}
}
void PlayfairCipher :: print()
{
for(int row = 0; row < 5; row++) {
for(int column = 0; column < 5; column++) {
cout << playfairMatrix[row][column] << " ";
}
cout << endl;
}
}
Point * PlayfairCipher :: getPointOfLetter(char letter)
{
for(int row = 0; row < 5; row++) {
for(int column = 0; column < 5; column++) {
if(playfairMatrix[row][column] == letter) {
return new Point(row, column);
}
}
}
return NULL;
}
char PlayfairCipher :: getLetterOfPoint(Point * a)
{
return playfairMatrix[a->row][a->column];
}
/////////////////////////////////////////////////////////////////////////////////
/// First, a key matrix is created using the supplied key. ///
/// Then the plaintext is sanitized to remove invalid characters. ///
/// For each pair of characters in plainText, retrieve their coordinates from ///
/// the key Matrix. The coordinates are then transformed. Finally, the newly ///
/// transformed coordinates are used to retrieve the corresponding letter. ///
/////////////////////////////////////////////////////////////////////////////////
string PlayfairCipher :: Encrypt(string plainText, string key)
{
createKeyMatrix(key);
Sanitizer :: sanitizePlainText(plainText);
for(unsigned int i = 0; i < plainText.size() - 1; i+=2) {
Point * a = getPointOfLetter(plainText[i]);
Point * b = getPointOfLetter(plainText[i + 1]);
encryptCoordinates(a, b);
plainText[i] = getLetterOfPoint(a);
plainText[i+1] = getLetterOfPoint(b);
}
return plainText;
}
/////////////////////////////////////////////////////////////////////////////////
/// First, a key matrix is created using the supplied key. ///
/// Then the plaintext is sanitized to remove invalid characters. ///
/// For each pair of characters in plainText, retrieve their coordinates from ///
/// the key Matrix. The coordinates are then transformed. Finally, the newly ///
/// transformed coordinates are used to retrieve the corresponding letter. ///
/////////////////////////////////////////////////////////////////////////////////
string PlayfairCipher :: Decrypt(string cipherText, string key)
{
createKeyMatrix(key);
for(unsigned int i = 0; i < cipherText.size() - 1; i+=2) {
Point * a = getPointOfLetter(cipherText[i]);
Point * b = getPointOfLetter(cipherText[i + 1]);
decryptCoordinates(a, b);
cipherText[i] = getLetterOfPoint(a);
cipherText[i+1] = getLetterOfPoint(b);
}
return cipherText;
}
void PlayfairCipher :: encryptCoordinates(Point * a, Point * b) {
if(a->column == b->column) {
a->row = (a->row + 1) % 5;
b->row = (b->row + 1) % 5;
}
else if(a->row == b->row) {
a->column = (a->column + 1) % 5;
b->column = (b->column + 1) % 5;
}
else {
int temp = a->column;
a->column = b->column;
b->column = temp;
}
}
void PlayfairCipher :: decryptCoordinates(Point * a, Point * b) {
if(a->column == b->column) {
a->row = Mod(a->row - 1, 5);
b->row = Mod(b->row - 1, 5);
}
else if(a->row == b->row) {
a->column = Mod(a->column - 1, 5);
b->column = Mod(b->column - 1, 5);
}
else {
int temp = a->column;
a->column = b->column;
b->column = temp;
}
}
int PlayfairCipher :: Mod(int x, int m)
{
int r = x % m;
return r < 0 ? r+m : r;
}
PlayfairCipher :: ~PlayfairCipher(void)
{
}
I have added the header file code as well:
#include <string>
#include <vector>
#include "Point.h"
using namespace std;
class PlayfairCipher
{
public:
PlayfairCipher(void);
string Encrypt(string plainText, string key);
string Decrypt(string cipherText, string key);
void print();
private:
vector<vector<char>> playfairMatrix;
void createKeyMatrix(string &key);
void encryptCoordinates(Point * a, Point * b);
void decryptCoordinates(Point * a, Point * b);
char getLetterOfPoint(Point * a);
Point * getPointOfLetter(char letter);
int Mod(int x, int m);
virtual ~PlayfairCipher(void);
};
