Program Java untuk Encode Pesan Menggunakan Playfair Cipher

Ini adalah program java untuk menerapkan algoritma cipher Playfair. The Playfair cipher adalah teknik enkripsi simetris manual dan merupakan yang pertama dari literal cipher substitusi.

Berikut adalah kode / source code dari program Java untuk Encode Pesan Menggunakan Playfair Cipher. Program Java berhasil dikompilasi dan dijalankan pada sistem Windows dan Linux. Output 

Program ini juga ditunjukkan di bawah.

import java.util.Scanner;

public class PlayfairCipherEncryption

{

    private String KeyWord        = new String();

    private String Key            = new String();

    private char   matrix_arr[][] = new char[5][5];

   public void setKey(String k)

    {

        String K_adjust = new String();

        boolean flag = false;

        K_adjust = K_adjust + k.charAt(0);

        for (int i = 1; i < k.length(); i++)

        {

            for (int j = 0; j < K_adjust.length(); j++)

           {

                if (k.charAt(i) == K_adjust.charAt(j))

                {

                    flag = true;

                }

            }

            if (flag == false)

                K_adjust = K_adjust + k.charAt(i);

            flag = false;

        }

        KeyWord = K_adjust;

    }

    public void KeyGen()

    {

        boolean flag = true;

        char current;

        Key = KeyWord;

        for (int i = 0; i < 26; i++)

        {

            current = (char) (i + 97);

            if (current == 'j')

                continue;

            for (int j = 0; j < KeyWord.length(); j++)

            {

                if (current == KeyWord.charAt(j))

                {

                    flag = false;

                    break;

                }

            }

            if (flag)

                Key = Key + current;

            flag = true;

        }

        System.out.println(Key);

        matrix();

    }

    private void matrix()

    {

        int counter = 0;

        for (int i = 0; i < 5; i++)

        {

            for (int j = 0; j < 5; j++)

            {

                matrix_arr[i][j] = Key.charAt(counter);

                System.out.print(matrix_arr[i][j] + " ");

                counter++;

            }

            System.out.println();

        }

    }

    private String format(String old_text)

    {

        int i = 0;

        int len = 0;

        String text = new String();

        len = old_text.length();

        for (int tmp = 0; tmp < len; tmp++)

        {

            if (old_text.charAt(tmp) == 'j')

          {

                text = text + 'i';

            }

            else

                text = text + old_text.charAt(tmp);

        }

        len = text.length();

        for (i = 0; i < len; i = i + 2)

        {

            if (text.charAt(i + 1) == text.charAt(i))

            {

                text = text.substring(0, i + 1) + 'x' + text.substring(i + 1);

            }

        }

       return text;

    }

    private String[] Divid2Pairs(String new_string)

    {

        String Original = format(new_string);

        int size = Original.length();

        if (size % 2 != 0)

        {

            size++;

            Original = Original + 'x';

        }

        String x[] = new String[size / 2];

        int counter = 0;

        for (int i = 0; i < size / 2; i++)

        {

            x[i] = Original.substring(counter, counter + 2);

            counter = counter + 2;

        }

        return x;

    }

                 

    public int[] GetDiminsions(char letter)

    {

        int[] key = new int[2];

        if (letter == 'j')

            letter = 'i';

        for (int i = 0; i < 5; i++)

       {

            for (int j = 0; j < 5; j++)

            {

                if (matrix_arr[i][j] == letter)

                {

                    key[0] = i;

                    key[1] = j;

                    break;

                }

            }

        }

        return key;

    }

    public String encryptMessage(String Source)

    {

        String src_arr[] = Divid2Pairs(Source);

        String Code = new String();

        char one;

        char two;

        int part1[] = new int[2];

        int part2[] = new int[2];

        for (int i = 0; i < src_arr.length; i++)

        {

          one = src_arr[i].charAt(0);

            two = src_arr[i].charAt(1);

            part1 = GetDiminsions(one);

            part2 = GetDiminsions(two);

            if (part1[0] == part2[0])

            {

                if (part1[1] < 4)

                    part1[1]++;

                else

                    part1[1] = 0;

                if (part2[1] < 4)

                    part2[1]++;

                else

                   part2[1] = 0;

           }

           else if (part1[1] == part2[1])

            {

                if (part1[0] < 4)

                    part1[0]++;

                else

                    part1[0] = 0;

                if (part2[0] < 4)

                    part2[0]++;

                else

                    part2[0] = 0;

            }

            else

            {

                int temp = part1[1];

                part1[1] = part2[1];

                part2[1] = temp;

            }

            Code = Code + matrix_arr[part1[0]][part1[1]]

                   + matrix_arr[part2[0]][part2[1]];

        }

        return Code;

    }

   public static void main(String[] args)

    {

        PlayfairCipherEncryption x = new PlayfairCipherEncryption();

        Scanner sc = new Scanner(System.in);

        System.out.println("Enter a keyword:");

        String keyword = sc.next();

        x.setKey(keyword);

        x.KeyGen();

        System.out

                .println("Enter word to encrypt: (Make sure length of message is even)");

        String key_input = sc.next();

        if (key_input.length() % 2 == 0)

       {

           System.out.println("Encryption: " + x.encryptMessage(key_input));

        }

        else

       {

           System.out.println("Message length should be even");

        }

        sc.close();

    }

}

Output:

$ javac PlayfairCipherEncryption.java

$ java PlayfairCipherEncryption

Enter a keyword:

Sanfoundry

Sanfoudrybceghiklmpqstvwxz

S a n f o

u d r y b

c e g h i

k l m p q

s t v w x

Enter word to encrypt: (Make sure length of message is even)

Learningcenter

Encryption: acndogrmegavgd