ADFGVX cipher: Difference between revisions
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(Technically, we do not need the Polybius square to recover the spaces, but it's passed as an argument here for symmetry.)
=={{header|Java}}==
<syntaxhighlight lang="java">
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.stream.Collectors;
public final class ADFGVXCipher {
public static void main(String[] args) throws IOException {
final char[][] polybius = initialisePolybiusSquare();
System.out.println("The 6 x 6 Polybius square:");
System.out.println(" | A D F G V X");
System.out.println("--------------");
for ( int row = 0; row < 6; row++ ) {
System.out.print(ADFGVX.charAt(row) + "|");
for ( int column = 0; column < 6; column++ ) {
System.out.print(" " + polybius[row][column]);
}
System.out.println();
}
System.out.println();
final String key = createKey(9);
System.out.println("The key is " + key);
System.out.println();
final String plainText = "ATTACKAT1200AM";
System.out.println("Plaintext: " + plainText);
System.out.println();
final String encryptedText = encrypt(plainText, polybius, key);
System.out.println("Encrypted: " + encryptedText);
System.out.println();
final String decryptedText = decrypt(encryptedText, polybius, key);
System.out.println("Decrypted: " + decryptedText);
}
private static String encrypt(String plainText, char[][] polybius, String key) {
String code = "";
for ( char ch : plainText.toCharArray() ) {
for ( int row = 0; row < 6; row++ ) {
for ( int column = 0; column < 6; column++ ) {
if ( polybius[row][column] == ch ) {
code += ADFGVX.charAt(row) + "" + ADFGVX.charAt(column);
}
}
}
}
String encrypted = "";
for ( char ch : key.toCharArray() ) {
for ( int i = key.indexOf(ch); i < code.length(); i += key.length() ) {
encrypted += code.charAt(i);
}
encrypted += " ";
}
return encrypted;
}
private static String decrypt(String encryptedText, char[][] polybius, String key) {
final int codeSize = encryptedText.replace(" ", "").length();
String code = "";
for ( int i = 0; code.length() < codeSize; i++ ) {
for ( String block : encryptedText.split(" ") ) {
if ( code.length() < codeSize ) {
code += block.charAt(i);
}
}
}
String plainText = "";
for ( int i = 0; i < codeSize - 1; i += 2 ) {
int row = ADFGVX.indexOf(code.substring(i, i + 1));
int column = ADFGVX.indexOf(code.substring(i + 1, i + 2));
plainText += polybius[row][column];
}
return plainText;
}
// Create a key using a word from "unixdict.txt"
private static String createKey(int size) throws IOException {
if ( size < 7 || size > 12 ) {
throw new AssertionError("Key should contain between 7 and 12 letters, both inclusive.");
}
List<String> candidates = Files.lines(Path.of("unixdict.txt"))
.filter( word -> word.length() == size )
.filter( word -> word.chars().distinct().count() == word.length() )
.filter( word -> word.chars().allMatch(Character::isLetterOrDigit) )
.collect(Collectors.toList());
Collections.shuffle(candidates);
return candidates.get(0).toUpperCase();
}
private static char[][] initialisePolybiusSquare() {
List<String> letters = Arrays.asList("ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789".split(""));
Collections.shuffle(letters);
char[][] result = new char[6][6];
for ( int row = 0; row < 6; row++ ) {
for ( int column = 0; column < 6; column++ ) {
result[row][column] = letters.get(6 * row + column).charAt(0);
}
}
return result;
}
private static final String ADFGVX = "ADFGVX";
}
</syntaxhighlight>
{{ out }}
<pre>
The 6 x 6 Polybius square:
| A D F G V X
--------------
A| 2 K 4 Q 9 8
D| W C I M V A
F| 5 S 0 Y B D
G| F T O U J E
V| 6 1 R X 3 G
X| H L Z P 7 N
The key is DISHWATER
Plaintext: ATTACKAT1200AM
Encrypted: DDAG XAA GDF DDF GXF DGF DDD XVX DDD
Decrypted: ATTACKAT1200AM
</pre>
=={{header|Julia}}==
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