PlayFair Cipher

PlayFair Cipher Java:

Code:

1-----> PlayFair.java

package com.nearur;

import java.awt.*;

public class PlayFair {
   
   private String key="Monarchy";
   private char[] keyarraay=key.toUpperCase().toCharArray();
   private char[] alpha={'A','B','C','D','E','F','G','H','I','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'};
   char[][] matrix=new char[5][5];
   StringBuffer buffer=new StringBuffer();

   public PlayFair(){
      int j=0,k=0;
      for (int i=0;i<keyarraay.length;i++){
         if(k!=5){
            if(!check(keyarraay[i])){
            matrix[j][k++]=keyarraay[i];
            }
         }else {
            i--;
            k=0;j++;
         }
      }

      for (int i=0;i<alpha.length;i++){
         if(k!=5){
            if(!check(alpha[i])){
               matrix[j][k++]=alpha[i];
            }
         }else {
            i--;
            k=0;j++;
         }
      }

   }

//  function to view matrix   public void show(){
      for (int i=0;i<5;i++) {
         for (int j = 0; j < 5; j++) {
            System.out.print(matrix[i][j]);
         }
         System.out.println();
      }
   }

// function to check for duplicate characters   private boolean check(char a){
      for (int i=0;i<5;i++) {
         for (int j = 0; j < 5; j++) {
            if(matrix[i][j]==a){
               return true;
            }
         }
      }
      return false;
   }


   // function to encrypt   public String encrypt(String msg){

      msg=msg.toUpperCase();
      msg=msg.replaceAll(" ","");
      msg=msg.replaceAll("J","I");
      if(msg.length()%2!=0){
         msg=msg.concat("X");
      }
      char[] msgs=msg.toCharArray();

      for (int i=0;i<msgs.length;i++){
         Point x1=find(msgs[i++]);
         Point x2=find(msgs[i]);

         if(x1.x==x2.x){
//same row            if(x1.y+1==5){
               x1.y=0;
            }
            else {
               x1.y++;
            }
            if(x2.y+1==5){
               x2.y=0;
            }else {
               x2.y++;
            }
            buffer.append(matrix[x1.x][x1.y]);
            buffer.append(matrix[x2.x][x2.y]);
         }else if(x1.y==x2.y){
//same column            if(x1.x+1==5){
               x1.x=0;
            }
            else {
               x1.x++;
            }
            if(x2.x+1==5){
               x2.x=0;
            }else {
               x2.x++;
            }
            buffer.append(matrix[x1.x][x1.y]);
            buffer.append(matrix[x2.x][x2.y]);
         }else{
            //diagonal            if(x2.x>x1.x) {
               int d=x2.x-x1.x;
               x2.x=x2.x-d;
               x1.x=x1.x+d;
            }else{
               int d=x1.x-x2.x;
               x2.x=x2.x+d;
               x1.x=x1.x-d;
            }
            buffer.append(matrix[x2.x][x2.y]);
            buffer.append(matrix[x1.x][x1.y]);

         }

      }

      return buffer.toString();
   }

   // function to decrypt   public String decrypt(String msg){

      buffer.delete(0,buffer.length());
      msg=msg.toUpperCase();

      char[] msgs=msg.toCharArray();

      for (int i=0;i<msgs.length;i++){
         Point x1=find(msgs[i++]);
         Point x2=find(msgs[i]);

         if(x1.x==x2.x){   //same row            if(x1.y-1<0){
               x1.y=4;
            }
            else {
               x1.y--;
            }
            if(x2.y-1<0){
               x2.y=4;
            }else {
               x2.y--;
            }
            buffer.append(matrix[x1.x][x1.y]);
            buffer.append(matrix[x2.x][x2.y]);
         }else if(x1.y==x2.y){   //same column
            if(x1.x-1<0){
               x1.x=4;
            }
            else {
               x1.x--;
            }
            if(x2.x-1<0){
               x2.x=4;
            }else {
               x2.x--;
            }
            buffer.append(matrix[x1.x][x1.y]);
            buffer.append(matrix[x2.x][x2.y]);
         }else{  //diagonal                        if(x2.x>x1.x) {
               int d=x2.x-x1.x;
               x2.x=x2.x-d;
               x1.x=x1.x+d;
            }else{
               int d=x1.x-x2.x;
               x2.x=x2.x+d;
               x1.x=x1.x-d;
            }
            buffer.append(matrix[x2.x][x2.y]);
            buffer.append(matrix[x1.x][x1.y]);

         }

      }

      return buffer.toString();
   }


// function  to return positon of character in matrix   private Point find(char c){
      Point p=null;
      for (int i=0;i<5;i++) {
         for (int j = 0; j < 5; j++) {
            if(matrix[i][j]==c){
               p=new Point(i,j);
               return p;
            }
         }
      }
      return p;
   }

}

2.-------> Encyption.java

package com.nearur;

public class Encryption {

   public static void main(String[] args) {


      PlayFair playFair=new PlayFair();
      String x=playFair.encrypt("key square");
      System.out.println("Cipher : "+x);
      System.out.println("Plain  : "+playFair.decrypt(x));

   }

}

Output:

For Project Click Here  (GitHub Link "https://github.com/mrdishant/Cryptography")