import java.io.*;
import java.util.*;
class Playfair {
String key;
String plainText;
char[][] matrix = new char[5][5];
public Playfair(String key, String plainText)
{
this.key = key.toLowerCase();
this.plainText = plainText.toLowerCase();
}
public void cleanPlayFairKey()
{
LinkedHashSet<Character> set
= new LinkedHashSet<Character>();
String newKey = "";
for (int i = 0; i < key.length(); i++)
set.add(key.charAt(i));
Iterator<Character> it = set.iterator();
while (it.hasNext())
newKey += (Character)it.next();
key = newKey;
}
public void generateCipherKey()
{
Set<Character> set = new HashSet<Character>();
for (int i = 0; i < key.length(); i++)
{
if (key.charAt(i) == 'j')
continue;
set.add(key.charAt(i));
}
String tempKey = new String(key);
for (int i = 0; i < 26; i++)
{
char ch = (char)(i + 97);
if (ch == 'j')
continue;
if (!set.contains(ch))
tempKey += ch;
}
for (int i = 0, idx = 0; i < 5; i++)
for (int j = 0; j < 5; j++)
matrix[i][j] = tempKey.charAt(idx++);
&
nbsp;System.out.println("Playfair Cipher Key Matrix:");
for (int i = 0; i < 5; i++)
System.out.println(Arrays.toString(matrix[i]));
}
public String formatPlainText()
{
String message = "";
int len = plainText.length();
for (int i = 0; i < len; i++)
{
if (plainText.charAt(i) == 'j')
message += 'i';
else
message += plainText.charAt(i);
}
for (int i = 0; i < message.length(); i += 2)
{
if (message.charAt(i) == message.charAt(i + 1))
message = message.substring(0, i + 1) + 'x'
+ message.substring(i + 1);
}
if (len % 2 == 1)
message += 'x';
return message;
}
public String[] formPairs(String message)
{
int len = message.length();
String[] pairs = new String[len / 2];
for (int i = 0, cnt = 0; i < len / 2; i++)
pairs[i] = message.substring(cnt, cnt += 2);
return pairs;
}
public int[] getCharPos(char ch)
{
int[] keyPos = new int[2];
for (int i = 0; i < 5; i++)
{
for (int j = 0; j < 5; j++)
{
<
p style="text-align:justify"> if (matrix[i][j] == ch)
{
keyPos[0] = i;
keyPos[1] = j;
break;
}
}
}
return keyPos;
}
public String encryptMessage()
{
String message = formatPlainText();
String[] msgPairs = formPairs(message);
String encText = "";
for (int i = 0; i < msgPairs.length; i++)
{
char ch1 = msgPairs[i].charAt(0);
char ch2 = msgPairs[i].charAt(1);
int[] ch1Pos = getCharPos(ch1);
int[] ch2Pos = getCharPos(ch2);
if (ch1Pos[0] == ch2Pos[0]) {
ch1Pos[1] = (ch1Pos[1] + 1) % 5;
ch2Pos[1] = (ch2Pos[1] + 1) % 5;
}
else if (ch1Pos[1] == ch2Pos[1])
{
ch1Pos[0] = (ch1Pos[0] + 1) % 5;
ch2Pos[0] = (ch2Pos[0] + 1) % 5;
}
else {
int temp = ch1Pos[1];
ch1Pos[1] = ch2Pos[1];
ch2Pos[1] = temp;
}
encText = encText + matrix[ch1Pos[0]][ch1Pos[1]]
+ matrix[ch2Pos[0]][ch2Pos[1]];
&
nbsp; }
return encText;
}
}
public class GFG {
public static void main(String[] args)
{
System.out.println("Example-1\n");
String key1 = "Problem";
String plainText1 = "Playfair";
System.out.println("Key: " + key1);
System.out.println("PlainText: " + plainText1);
Playfair pfc1 = new Playfair(key1, plainText1);
pfc1.cleanPlayFairKey();
pfc1.generateCipherKey();
String encText1 = pfc1.encryptMessage();
System.out.println("Cipher Text is: " + encText1);
System.out.println("\nExample-2\n");
String key2 = "Problem";
String plainText2 = "Hello";
System.out.println("Key: " + key2);
System.out.println("PlainText: " + plainText2);
Playfair pfc2 = new Playfair(key2, plainText2);
pfc2.cleanPlayFairKey();
pfc2.generateCipherKey();
String encText2 = pfc2.encryptMessage();
System.out.println("Cipher Text is: " + encText2);
}
}