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Contoh Hill Cipher dalam Java

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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiVL-_pxf-adXK9-0iMSja6VnT3oDdplNT9spCsGscLs8CG-jAL9Idmy5tLoCI9_eknela5-DqjBfteIsk5XvUhe_o0XJ4dq2N1ZFPbU835xJY_oIH7wgXxy_8NMI2CV5bgs-CI6N6bsAQ/s1600/hill.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="287" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiVL-_pxf-adXK9-0iMSja6VnT3oDdplNT9spCsGscLs8CG-jAL9Idmy5tLoCI9_eknela5-DqjBfteIsk5XvUhe_o0XJ4dq2N1ZFPbU835xJY_oIH7wgXxy_8NMI2CV5bgs-CI6N6bsAQ/s400/hill.png" width="400" /></a></div>
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<span style="font-family: Verdana, sans-serif;">Dalam kriptografi klasik, Hill cipher adalah
cipher substitusi polygraphic berdasarkan aljabar linier. Diciptakan oleh Lester
S. Hill pada tahun 1929. Hill cipher adalah cipher polygraphic pertama di dunia
yang bisa mengenkripsi / mendekripsi 3 atau lebih huruf dalam satu waktu.</span><br />
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<span style="font-family: Verdana, sans-serif;">Teknik
kriptografi ini diciptakan dengan maksud untuk dapat menciptakan cipher (kode)
yang tidak dapat dipecahkan menggunakan teknik analisis frekuensi.</span></div>
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<span style="font-family: "verdana" , sans-serif;">Hill Cipher
tidak mengganti setiap abjad yang sama pada plaintext dengan abjad lainnya yang
sama pada ciphertext karena menggunakan perkalian matriks pada dasar enkripsi
dan dekripsinya. </span></div>
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<span style="font-family: "verdana" , sans-serif;">Setiap
huruf diwakili oleh sejumlah modulo 26. Skema yang digunakannya cukup sederhana,
dimana yang digunakan huruf A = 0, B = 1, ..., Z = 25, namun sebenarnya bukan
ini fitur atau kemampuan utama dari Hill cipher . Untuk mengenkripsi pesan,
setiap blok n huruf (dianggap sebagai vektor n-komponen) dikalikan dengan n × n
matriks, terhadap modulus 26. Untuk mendekripsi pesan, setiap blok dikalikan
dengan kebalikan dari matriks yang digunakan untuk enkripsi.</span></div>
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<span style="font-family: "verdana" , sans-serif;">Matriks yang
digunakan untuk enkripsi adalah kunci cipher, dan itu harus dipilih secara acak
dari himpunan n × n matriks (modulo 26). Kenapa menggunakan modulo 26? Cipher harus
disesuaikan dengan alfabet dengan jumlah huruf.</span></div>
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<span style="font-family: "verdana" , sans-serif;">Dalam rangka untuk
mendekripsi, kita beralih ciphertext kembali ke dalam vektor, maka cukup
kalikan dengan matriks inverse dari matriks kunci. Ada metode standar untuk
menghitung invers matriks, lihat matriks inversi untuk rincian.</span></div>
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<span style="font-family: "verdana" , sans-serif;">Dalam hal ini memang
sangat dibutuhkan pengetahuan untuk persamaan matematika perkalian matrik dan
bagaimana mencari matrik invers dari matrik kunci, termasuk bagaiamana mencari
modular invers dari sebuah matrik.</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">package ciphers;</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">import java.io.*;</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">import java.lang.*;</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">public class hillcipher</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">{</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">public static void main(String []arg)throws Exception</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">{</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">    int
k[][]={{17,17,5}, {21,18,21}, {2,2,19}};</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">    int p[]=new
int[300];</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">    int c[]=new
int[300];</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">    int i=0;    </span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">   
//System.out.println("enter key");</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">    BufferedReader
br=new BufferedReader(new InputStreamReader(System.in));</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">   
/*for(i=0;i<3;i++)</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">    {</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">    for(int
j=0;j<3;j++)</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">    {</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">    String
str=br.readLine();</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">   
k[i][j]=Integer.parseInt(str);</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">    }</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">    }*/</span></div>
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<br /></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">   
System.out.println("enter plain text");</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">    String
str=br.readLine();</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">    </span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">    for(
i=0;i<str.length();i++)</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">    {</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">        int
c1=str.charAt(i);</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">       
//System.out.println(c1);</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">        p[i]=(c1)-97;</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">    }</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">               
i=0;int zz=0;</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">        for( int
b=0;b<str.length()/3;b++)</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">        {</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">        for(int
j=0;j<3;j++)</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">        {</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">        for(int
x=0;x<3;x++)</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">        {</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">        c[i]+=k[j][x]*p[x+zz];</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">        }i++;</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">        }</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">        zz+=3;</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">        }</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">               
System.out.println("Encrypted Text : ");</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">        for(int
z=0;z<str.length();z++)</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">       
System.out.print((char)((c[z]%26)+97));</span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">    </span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">    </span></div>
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<span style="color: blue; font-family: "verdana" , sans-serif;">}</span></div>
<br />
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<span style="color: blue; font-family: "verdana" , sans-serif;">}</span></div>

Dalam kriptografi klasik, Hill cipher adalah cipher substitusi polygraphic berdasarkan aljabar linier. Diciptakan oleh Lester S. Hill...

Program Java untuk Encode Pesan Menggunakan Playfair Cipher

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<span style="font-family: Verdana, sans-serif;"><br /></span></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjmHqzB5aUgkBaQYN0KcALGUgGV6-zunn6bhhfRfMUCcVki3vdwmMwpXP33vfVli5aKaoyIKOcEJDLfQ_g_1oKTaavfkEymt9vA4LUe5ewWdjCQ3lPGzmIczMRCuxCmC4MmUlX4RDKDZso/s1600/playfair_cipher.png" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="96" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjmHqzB5aUgkBaQYN0KcALGUgGV6-zunn6bhhfRfMUCcVki3vdwmMwpXP33vfVli5aKaoyIKOcEJDLfQ_g_1oKTaavfkEymt9vA4LUe5ewWdjCQ3lPGzmIczMRCuxCmC4MmUlX4RDKDZso/s320/playfair_cipher.png" width="320" /></a><span style="font-family: Verdana, sans-serif;">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.</span></div>
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<span style="font-family: Verdana, sans-serif;">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 </span></div>
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<span style="font-family: Verdana, sans-serif;">Program ini juga ditunjukkan di bawah.</span></div>
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<span style="color: blue;">import java.util.Scanner;</span></div>
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<span style="color: blue;">public class PlayfairCipherEncryption</span></div>
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<span style="color: blue;">{</span></div>
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<span style="color: blue;">    private String KeyWord        = new String();</span></div>
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<span style="color: blue;">    private String Key            = new String();</span></div>
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<span style="color: blue;">    private char   matrix_arr[][] = new char[5][5];</span></div>
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<br /></div>
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<span style="color: blue;">   public void setKey(String k)</span></div>
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<span style="color: blue;">    {</span></div>
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<span style="color: blue;">        String K_adjust = new
String();</span></div>
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<span style="color: blue;">        boolean flag = false;</span></div>
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<span style="color: blue;">        K_adjust = K_adjust +
k.charAt(0);</span></div>
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<span style="color: blue;">        for (int i = 1; i <
k.length(); i++)</span></div>
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<span style="color: blue;">        {</span></div>
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<span style="color: blue;">            for (int j = 0; j
< K_adjust.length(); j++)</span></div>
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<span style="color: blue;">           {</span></div>
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<span style="color: blue;">                if (k.charAt(i)
== K_adjust.charAt(j))</span></div>
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<span style="color: blue;">                {</span></div>
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<span style="color: blue;">                    flag = true;</span></div>
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<span style="color: blue;">                }</span></div>
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<span style="color: blue;">            }</span></div>
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<span style="color: blue;">            if (flag == false)</span></div>
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<span style="color: blue;">                K_adjust =
K_adjust + k.charAt(i);</span></div>
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<span style="color: blue;">            flag = false;</span></div>
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<span style="color: blue;">        }</span></div>
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<span style="color: blue;">        KeyWord = K_adjust;</span></div>
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<span style="color: blue;">    }</span></div>
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<br /></div>
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<span style="color: blue;">    public void KeyGen()</span></div>
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<span style="color: blue;">    {</span></div>
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<span style="color: blue;">        boolean flag = true;</span></div>
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<span style="color: blue;">        char current;</span></div>
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<span style="color: blue;">        Key = KeyWord;</span></div>
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<span style="color: blue;">        for (int i = 0; i <
26; i++)</span></div>
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<span style="color: blue;">        {</span></div>
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<span style="color: blue;">            current = (char) (i +
97);</span></div>
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<span style="color: blue;">            if (current == 'j')</span></div>
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<span style="color: blue;">                continue;</span></div>
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<span style="color: blue;">            for (int j = 0; j
< KeyWord.length(); j++)</span></div>
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<span style="color: blue;">            {</span></div>
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<span style="color: blue;">                if (current ==
KeyWord.charAt(j))</span></div>
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<span style="color: blue;">                {</span></div>
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<span style="color: blue;">                    flag = false;</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">                    break;</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">                }</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">            }</span></div>
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<span style="color: blue;">            if (flag)</span></div>
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<span style="color: blue;">                Key = Key +
current;</span></div>
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<span style="color: blue;">            flag = true;</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        }</span></div>
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<span style="color: blue;">        System.out.println(Key);</span></div>
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<span style="color: blue;">        matrix();</span></div>
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<span style="color: blue;">    }</span></div>
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<br /></div>
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<span style="color: blue;">    private void matrix()</span></div>
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<span style="color: blue;">    {</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        int counter = 0;</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        for (int i = 0; i < 5;
i++)</span></div>
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<span style="color: blue;">        {</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">            for (int j = 0; j
< 5; j++)</span></div>
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<span style="color: blue;">            {</span></div>
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<span style="color: blue;">                matrix_arr[i][j]
= Key.charAt(counter);</span></div>
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<span style="color: blue;">               
System.out.print(matrix_arr[i][j] + " ");</span></div>
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<span style="color: blue;">                counter++;</span></div>
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<span style="color: blue;">            }</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">            System.out.println();</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        }</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">    }</span></div>
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<br /></div>
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<span style="color: blue;">    private String format(String
old_text)</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">    {</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        int i = 0;</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        int len = 0;</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        String text = new
String();</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        len = old_text.length();</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        for (int tmp = 0; tmp
< len; tmp++)</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        {</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">            if
(old_text.charAt(tmp) == 'j')</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">          {</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">                text = text +
'i';</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">            }</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">            else</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">                text = text +
old_text.charAt(tmp);</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        }</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        len = text.length();</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        for (i = 0; i < len; i
= i + 2)</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        {</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">            if (text.charAt(i +
1) == text.charAt(i))</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">            {</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">                text =
text.substring(0, i + 1) + 'x' + text.substring(i + 1);</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">            }</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        }</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">       return text;</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">    }</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<br /></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">    private String[]
Divid2Pairs(String new_string)</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">    {</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        String Original =
format(new_string);</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        int size =
Original.length();</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        if (size % 2 != 0)</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        {</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">            size++;</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">            Original = Original +
'x';</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        }</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        String x[] = new
String[size / 2];</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        int counter = 0;</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        for (int i = 0; i <
size / 2; i++)</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        {</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">            x[i] =
Original.substring(counter, counter + 2);</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">            counter = counter +
2;</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        }</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        return x;</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">    }</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">                 </span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">    public int[]
GetDiminsions(char letter)</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">    {</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        int[] key = new int[2];</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        if (letter == 'j')</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">            letter = 'i';</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        for (int i = 0; i < 5;
i++)</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">       {</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">            for (int j = 0; j
< 5; j++)</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">            {</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">                if
(matrix_arr[i][j] == letter)</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">                {</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">                    key[0] = i;</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">                    key[1] = j;</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">                    break;</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">                }</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">            }</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        }</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        return key;</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">    }</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<br /></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">    public String
encryptMessage(String Source)</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">    {</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        String src_arr[] =
Divid2Pairs(Source);</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        String Code = new
String();</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        char one;</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        char two;</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        int part1[] = new int[2];</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        int part2[] = new int[2];</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        for (int i = 0; i <
src_arr.length; i++)</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        {</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">          one =
src_arr[i].charAt(0);</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">            two =
src_arr[i].charAt(1);</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">            part1 =
GetDiminsions(one);</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">            part2 = GetDiminsions(two);</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">            if (part1[0] ==
part2[0])</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">            {</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">                if (part1[1] <
4)</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">                    part1[1]++;</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">                else</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">                    part1[1] = 0;</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">                if (part2[1] <
4)</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">                    part2[1]++;</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">                else</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">                   part2[1] = 0;</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">           }</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">           else if (part1[1] ==
part2[1])</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">            {</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">                if (part1[0] <
4)</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">                    part1[0]++;</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">                else</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">                    part1[0] = 0;</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">                if (part2[0] <
4)</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">                    part2[0]++;</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">                else</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">                    part2[0] = 0;</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">            }</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">            else</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">            {</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">                int temp =
part1[1];</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">                part1[1] =
part2[1];</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">                part2[1] = temp;</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">            }</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">            Code = Code +
matrix_arr[part1[0]][part1[1]]</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">                   +
matrix_arr[part2[0]][part2[1]];</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        }</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        return Code;</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">    }</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<br /></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">   public static void
main(String[] args)</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">    {</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        PlayfairCipherEncryption
x = new PlayfairCipherEncryption();</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        Scanner sc = new
Scanner(System.in);</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">       
System.out.println("Enter a keyword:");</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        String keyword =
sc.next();</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        x.setKey(keyword);</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        x.KeyGen();</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        System.out</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">                .println("Enter
word to encrypt: (Make sure length of message is even)");</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        String key_input =
sc.next();</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        if (key_input.length() %
2 == 0)</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">       {</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">          
System.out.println("Encryption: " +
x.encryptMessage(key_input));</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        }</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        else</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">       {</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">          
System.out.println("Message length should be even");</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        }</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">        sc.close();</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">    }</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;">}</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;"><br /></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue;"><br /></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<b><span style="font-family: Verdana, sans-serif;">Output:</span></b></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="font-family: Verdana, sans-serif;">$ javac PlayfairCipherEncryption.java</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="font-family: Verdana, sans-serif;">$ java PlayfairCipherEncryption</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<br /></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="font-family: Verdana, sans-serif;">Enter a keyword:</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="font-family: Verdana, sans-serif;">Sanfoundry</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="font-family: Verdana, sans-serif;">Sanfoudrybceghiklmpqstvwxz</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="font-family: Verdana, sans-serif;">S a n f o </span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="font-family: Verdana, sans-serif;">u d r y b </span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="font-family: Verdana, sans-serif;">c e g h i </span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="font-family: Verdana, sans-serif;">k l m p q </span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="font-family: Verdana, sans-serif;">s t v w x </span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="font-family: Verdana, sans-serif;">Enter word to encrypt: (Make sure length of message is even)</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="font-family: Verdana, sans-serif;">Learningcenter</span></div>
<br />
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="font-family: Verdana, sans-serif;">Encryption: acndogrmegavgd</span></div>
<div>
<br /></div>

Ini adalah program java untuk menerapkan algoritma cipher Playfair. The Playfair cipher adalah teknik enkripsi simetris manual dan merupa...

Kode Program Vigenere Cypher pada Bahasa Pemrograman Java

<div class="MsoNormal" style="text-align: justify;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh-5LrvldZ-aZl8dDilw_T4GoMhI-c0VeAUjQwYD53BNO6O4YrWJRtEgBB53XJnWsOHlz_QZQSUIT-aCV6FLYmT0LLw8i9cjqWUt3dhMp9VtNDM_k-0A9xoe_4XpGcHYWdUO8lKMEMyhTE/s1600/vigenere.png" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh-5LrvldZ-aZl8dDilw_T4GoMhI-c0VeAUjQwYD53BNO6O4YrWJRtEgBB53XJnWsOHlz_QZQSUIT-aCV6FLYmT0LLw8i9cjqWUt3dhMp9VtNDM_k-0A9xoe_4XpGcHYWdUO8lKMEMyhTE/s320/vigenere.png" width="320" /></a><span style="font-family: Verdana, sans-serif;">Berikut ini saya coba sajikan satu rutin aplikasi ciphering dalam
bahasa / program Java untuk melakukan enkripsi dan dekripsi  Vigenere cipher. </span></div>
<div class="MsoNormal" style="text-align: justify;">
<span style="font-family: Verdana, sans-serif;">Vigenère cipher adalah metode enkripsi teks abjad dengan
menggunakan serangkaian cipher Caesar berbeda berdasarkan suatu kata kunci. Boleh
dikatakan bahwa  Vigenère  merupakan bentuk sederhana substitusi
polyalphabetic.</span></div>
<div class="MsoNormal" style="text-align: justify;">
<span style="font-family: Verdana, sans-serif;"><br /></span></div>
<div class="MsoNormal" style="text-align: justify;">
<span style="font-family: Verdana, sans-serif;"><br /></span></div>
<div class="MsoNormal" style="text-align: justify;">
<span style="font-family: Verdana, sans-serif;">The Vigenère cipher, ditemukan oleh seorang Prancis, Blaise
de Vigenère di abad ke-16. Ini adalah cipher polyalphabetic karena menggunakan
dua atau lebih huruf cipher untuk mengenkripsi data. Dengan kata lain, huruf-
huruf dalam cipher Vigenère diubah berdasarkan lompatan  yang berbeda, biasanya dilakukan dengan
menggunakan kata atau frase sebagai kunci enkripsi.</span></div>
<div class="MsoNormal" style="text-align: justify;">
<span style="font-family: Verdana, sans-serif;">Berbeda dengan cipher monoalphabetic, cipher polyalphabetic
tidak rentan terhadap analisis frekuensi, karena lebih dari satu huruf dalam
plaintext dapat diwakili oleh satu huruf di enkripsi.</span></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
               <span style="color: blue; font-family: Trebuchet MS, sans-serif;"> package
com.darto.vigenecipher;</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue; font-family: Trebuchet MS, sans-serif;">                public class
VigenereCipher</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue; font-family: Trebuchet MS, sans-serif;">                {</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue; font-family: Trebuchet MS, sans-serif;">                    public static String encrypt(String text,
final String key)</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue; font-family: Trebuchet MS, sans-serif;">                    {</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue; font-family: Trebuchet MS, sans-serif;">                        String res = "";</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue; font-family: Trebuchet MS, sans-serif;">                        text = text.toUpperCase();</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue; font-family: Trebuchet MS, sans-serif;">                        for (int i = 0, j = 0; i <
text.length(); i++)</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue; font-family: Trebuchet MS, sans-serif;">                        {</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue; font-family: Trebuchet MS, sans-serif;">                            char c = text.charAt(i);</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue; font-family: Trebuchet MS, sans-serif;">                            if (c < 'A' || c > 'Z')</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue; font-family: Trebuchet MS, sans-serif;">                                continue;</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue; font-family: Trebuchet MS, sans-serif;">                            res += (char) ((c + key.charAt(j) -
2 * 'A') % 26 + 'A');</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue; font-family: Trebuchet MS, sans-serif;">                            j = ++j % key.length();</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue; font-family: Trebuchet MS, sans-serif;">                        }</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue; font-family: Trebuchet MS, sans-serif;">                        return res;</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue; font-family: Trebuchet MS, sans-serif;">                    }</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue; font-family: Trebuchet MS, sans-serif;">                 </span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue; font-family: Trebuchet MS, sans-serif;">                    public static String decrypt(String text,
final String key)</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue; font-family: Trebuchet MS, sans-serif;">                    {</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue; font-family: Trebuchet MS, sans-serif;">                        String res = "";</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue; font-family: Trebuchet MS, sans-serif;">                        text = text.toUpperCase();</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue; font-family: Trebuchet MS, sans-serif;">                        for (int i = 0, j = 0; i <
text.length(); i++)</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue; font-family: Trebuchet MS, sans-serif;">                        {</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue; font-family: Trebuchet MS, sans-serif;">                            char c = text.charAt(i);</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue; font-family: Trebuchet MS, sans-serif;">                            if (c < 'A' || c > 'Z')</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue; font-family: Trebuchet MS, sans-serif;">                                continue;</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue; font-family: Trebuchet MS, sans-serif;">                            res += (char) ((c - key.charAt(j) + 26) % 26 +
'A');</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue; font-family: Trebuchet MS, sans-serif;">                            j = ++j % key.length();</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue; font-family: Trebuchet MS, sans-serif;">                        }</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue; font-family: Trebuchet MS, sans-serif;">                        return res;</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue; font-family: Trebuchet MS, sans-serif;">    }</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<br /></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue; font-family: Trebuchet MS, sans-serif;">                    public static void main(String[] args)</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue; font-family: Trebuchet MS, sans-serif;">                    {</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue; font-family: Trebuchet MS, sans-serif;">                        String key =
"MYJAVALAMP";</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue; font-family: Trebuchet MS, sans-serif;">                        String message = "Blog saya ada di blogspot !";</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue; font-family: Trebuchet MS, sans-serif;">                        String encryptedMsg = encrypt(message,
key);</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue; font-family: Trebuchet MS, sans-serif;">                        System.out.println("String: "
+ message);</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue; font-family: Trebuchet MS, sans-serif;">                        System.out.println("Encrypted
message: " + encryptedMsg);</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue; font-family: Trebuchet MS, sans-serif;">                        System.out.println("Decrypted
message: " + decrypt(encryptedMsg, key));</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue; font-family: Trebuchet MS, sans-serif;">                    }</span></div>
<br />
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: blue; font-family: Trebuchet MS, sans-serif;">                }</span></div>

Berikut ini saya coba sajikan satu rutin aplikasi ciphering dalam bahasa / program Java untuk melakukan enkripsi dan dekripsi Vigenere cip...

Kriptografi Substitusi Caesar Chiper dalam Bahasa Pemrograman Java

<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg4YHF6nUqCQMot1RpTMEIBE9zVzLdqYAadeQi2o0IfO9UXtrv5TrnbqBHxfiTZmtX1Tunp1dfoCt0fv2hgOWqMhuM7u1OSIsbCm883MeE2VtLbDe5kXRFsjr6DAW3slwB_97yLWKvPK2Y/s1600/Caesar+Chiper+Java+Code.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="168" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg4YHF6nUqCQMot1RpTMEIBE9zVzLdqYAadeQi2o0IfO9UXtrv5TrnbqBHxfiTZmtX1Tunp1dfoCt0fv2hgOWqMhuM7u1OSIsbCm883MeE2VtLbDe5kXRFsjr6DAW3slwB_97yLWKvPK2Y/s400/Caesar+Chiper+Java+Code.png" width="400" /></a></div>
<div class="MsoNormal" style="text-align: justify;">
<span style="font-family: Verdana, sans-serif;"><br /></span></div>
<div class="MsoNormal" style="text-align: justify;">
<span style="font-family: Verdana, sans-serif;"><br /></span></div>
<div class="MsoNormal" style="text-align: justify;">
<span style="font-family: Verdana, sans-serif;">Dalam kriptografi, cipher Caesar, juga dikenal sebagai cipher
pergeseran, kode Caesar (Caesar Code) atau pergeseran Caesar (Caesar Shift) ,
adalah salah satu teknik enkripsi yang paling sederhana dan paling banyak
dikenal. </span></div>
<div class="MsoNormal" style="text-align: justify;">
<span style="font-family: Verdana, sans-serif;"><br /></span></div>
<div class="MsoNormal" style="text-align: justify;">
<span style="font-family: Verdana, sans-serif;">Ini adalah jenis cipher substitusi dimana setiap huruf dalam plaintext
diganti dengan huruf lain yang berada di beberapa huruf setelahnya. Misalnya,
dengan pergeseran kiri 3, D akan digantikan oleh A, E akan menjadi B, dan
sebagainya. Metode ini dinamai Julius Caesar, yang pertama kali menggunakan kriptografi ini.
</span></div>
<div class="MsoNormal" style="text-align: justify;">
<span style="font-family: Verdana, sans-serif;"><br /></span></div>
<div class="MsoNormal" style="text-align: justify;">
<span style="font-family: Verdana, sans-serif;">L</span><span style="font-family: Verdana, sans-serif;">angkah enkripsi didalam cipher Caesar sering dimasukkan
sebagai bagian dari skema kriptografi yang lebih kompleks, seperti cipher
Vigenère, dan dalam aplikasi modern sistem ROT13. Cipher Caesar mudah dipecahkan
apabila kunci pergeseran sudah ditemukan.</span></div>
<div class="MsoNormal" style="text-align: justify;">
<span style="font-family: Verdana, sans-serif;"><br /></span></div>
<div class="MsoNormal" style="text-align: justify;">
<span style="font-family: Verdana, sans-serif;">Transformasi dapat direpresentasikan dengan menyelaraskan
dua huruf; alfabet cipher adalah alfabet biasa diputar ke kiri atau kanan
dengan beberapa posisi. Misalnya, di sini adalah cipher Caesar menggunakan
rotasi kiri tiga tempat, setara dengan pergeseran kanan 23 (parameter
pergeseran digunakan sebagai kunci):</span></div>
<div class="MsoNormal" style="text-align: justify;">
<span style="font-family: Verdana, sans-serif;"><br /></span></div>
<div class="MsoNormal" style="text-align: justify;">
<span style="background-color: white; color: red; font-family: Verdana, sans-serif;">Plain:    ABCDEFGHIJKLMNOPQRSTUVWXYZ</span></div>
<div class="MsoNormal" style="text-align: justify;">
<span style="background-color: white; color: red; font-family: Verdana, sans-serif;">Cipher:  DEFGHIJKLMNOPQRSTUVWXYZABC</span></div>
<div class="MsoNormal" style="text-align: justify;">
<span style="font-family: Verdana, sans-serif;"><br /></span></div>
<div class="MsoNormal" style="text-align: justify;">
<span style="font-family: Verdana, sans-serif;">Ketika melakukan enkripsi, seseorang mengubah setiap huruf
dari pesan asli  (plaintext)  dan menuliskan huruf yang sesuai dalam
"cipher" line. Sedangkan saat mendeskripsi, dilakukan secara terbalik
/ membalik proses enkripsi yaitu dengan pergeseran kanan 3.</span></div>
<div class="MsoNormal" style="text-align: justify;">
<span style="font-family: Verdana, sans-serif;"><br /></span></div>
<div class="MsoNormal" style="text-align: justify;">
<span style="font-family: Verdana, sans-serif;">Jadi kalimat plainteks THE QUICK BROWN FOX JUMPS OVER THE
LAZY DOG akan diubah menjadi kalimat chiperteks GLGXNXQJ TXLFN EURZQ IRA MXPSV
RYHU GLGXNXQJ ODCB GRJ</span></div>
<div class="MsoNormal" style="text-align: justify;">
<span style="font-family: Verdana, sans-serif;"><br /></span></div>
<div class="MsoNormal" style="text-align: justify;">
<span style="font-family: Verdana, sans-serif;">Berikut ini disajikan contoh code sandi / kriptgrafi
tersebut diatas dengan bahasa Pemrograman Java</span></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<span style="color: blue; font-family: Verdana, sans-serif;">public class Cipher {</span></div>
<div class="MsoNormal">
<span style="color: blue; font-family: Verdana, sans-serif;">    public static void
main(String[] args) {</span></div>
<div class="MsoNormal">
<span style="color: blue; font-family: Verdana, sans-serif;">         String str = "The quick brown fox
Jumped over the lazy Dog";</span></div>
<div class="MsoNormal">
<span style="color: blue; font-family: Verdana, sans-serif;">         System.out.println( Cipher.encode( str,
12 ));</span></div>
<div class="MsoNormal">
<span style="color: blue; font-family: Verdana, sans-serif;">       
System.out.println( Cipher.decode( Cipher.encode( str, 12), 12 ));</span></div>
<div class="MsoNormal">
<span style="color: blue; font-family: Verdana, sans-serif;">    }</span></div>
<div class="MsoNormal">
<span style="color: blue; font-family: Verdana, sans-serif;">     public static String decode(String enc, int
offset) {</span></div>
<div class="MsoNormal">
<span style="color: blue; font-family: Verdana, sans-serif;">        return
encode(enc, 26-offset);</span></div>
<div class="MsoNormal">
<span style="color: blue; font-family: Verdana, sans-serif;">    }</span></div>
<div class="MsoNormal">
<span style="color: blue; font-family: Verdana, sans-serif;">     public static String encode(String enc, int
offset) {</span></div>
<div class="MsoNormal">
<span style="color: blue; font-family: Verdana, sans-serif;">        offset =
offset % 26 + 26;</span></div>
<div class="MsoNormal">
<span style="color: blue; font-family: Verdana, sans-serif;">        StringBuilder
encoded = new StringBuilder();</span></div>
<div class="MsoNormal">
<span style="color: blue; font-family: Verdana, sans-serif;">        for (char i :
enc.toCharArray()) {</span></div>
<div class="MsoNormal">
<span style="color: blue; font-family: Verdana, sans-serif;">            if
(Character.isLetter(i)) {</span></div>
<div class="MsoNormal">
<span style="color: blue; font-family: Verdana, sans-serif;">                if
(Character.isUpperCase(i)) {</span></div>
<div class="MsoNormal">
<span style="color: blue; font-family: Verdana, sans-serif;">                    encoded.append((char) ('A' + (i - 'A' +
offset) % 26 ));</span></div>
<div class="MsoNormal">
<span style="color: blue; font-family: Verdana, sans-serif;">                } else
{</span></div>
<div class="MsoNormal">
<span style="color: blue; font-family: Verdana, sans-serif;">                   
encoded.append((char) ('a' + (i - 'a' + offset) % 26 ));</span></div>
<div class="MsoNormal">
<span style="color: blue; font-family: Verdana, sans-serif;">                }</span></div>
<div class="MsoNormal">
<span style="color: blue; font-family: Verdana, sans-serif;">            } else {</span></div>
<div class="MsoNormal">
<span style="color: blue; font-family: Verdana, sans-serif;">               
encoded.append(i);</span></div>
<div class="MsoNormal">
<span style="color: blue; font-family: Verdana, sans-serif;">            }</span></div>
<div class="MsoNormal">
<span style="color: blue; font-family: Verdana, sans-serif;">        }</span></div>
<div class="MsoNormal">
<span style="color: blue; font-family: Verdana, sans-serif;">        return
encoded.toString();</span></div>
<div class="MsoNormal">
<span style="color: blue; font-family: Verdana, sans-serif;">    }</span></div>
<br />
<div class="MsoNormal">
<span style="color: blue; font-family: Verdana, sans-serif;">}</span></div>

Dalam kriptografi, cipher Caesar, juga dikenal sebagai cipher pergeseran, kode Caesar (Caesar Code) atau pergeseran Caesar (Caesar Sh...