Task: Chaocipher




Go: package main

import(
    "fmt"
    "strings"
    "unicode/utf8"
)

type Mode int

const(
    Encrypt Mode = iota
    Decrypt
)

const(
    lAlphabet = "HXUCZVAMDSLKPEFJRIGTWOBNYQ"
    rAlphabet = "PTLNBQDEOYSFAVZKGJRIHWXUMC"
)

func Chao(text string, mode Mode, showSteps bool) string {
    len := len(text)
    if utf8.RuneCountInString(text) != len {
        fmt.Println("Text contains non-ASCII characters")
        return ""
    }
    left  := lAlphabet
    right := rAlphabet
    eText := make([]byte, len)
    temp  := make([]byte, 26)

    for i := 0; i < len; i++ {
        if showSteps {
            fmt.Println(left, " ", right)
        }
        var index int
        if mode == Encrypt {
            index = strings.IndexByte(right, text[i])
            eText[i] = left[index]
        } else {
            index = strings.IndexByte(left, text[i])
            eText[i] = right[index]
        }
        if i == len - 1 {
            break
        }

        
        for j := index; j < 26; j++ {
            temp[j - index] = left[j]
        }
        for j := 0; j < index; j++ {
            temp[26 - index + j] = left[j]
        }
        store := temp[1]
        for j := 2; j < 14; j++ {
            temp[j - 1] = temp[j]
        }
        temp[13] = store
        left = string(temp[:])

        

        for j := index; j < 26; j++ {
            temp[j - index] = right[j]
        }
        for j := 0; j < index; j++ {
            temp[26 - index + j] = right[j]
        }
        store = temp[0]
        for j := 1; j < 26; j++ {
            temp[j - 1] = temp[j]
        }
        temp[25] = store
        store = temp[2]
        for j := 3; j < 14; j++ {
            temp[j - 1] = temp[j]
        }
        temp[13] = store
        right = string(temp[:])
    }

    return string(eText[:])
}

func main() {
    plainText := "WELLDONEISBETTERTHANWELLSAID"
    fmt.Println("The original plaintext is :", plainText)
    fmt.Print("\nThe left and right alphabets after each permutation ")
    fmt.Println("during encryption are :\n")
    cipherText := Chao(plainText, Encrypt, true)
    fmt.Println("\nThe ciphertext is :",  cipherText)
    plainText2 := Chao(cipherText, Decrypt, false)
    fmt.Println("\nThe recovered plaintext is :", plainText2)
}


Java: import java.util.Arrays;

public class Chaocipher {
    private enum Mode {
        ENCRYPT,
        DECRYPT
    }

    private static final String L_ALPHABET = "HXUCZVAMDSLKPEFJRIGTWOBNYQ";
    private static final String R_ALPHABET = "PTLNBQDEOYSFAVZKGJRIHWXUMC";

    private static int indexOf(char[] a, char c) {
        for (int i = 0; i < a.length; ++i) {
            if (a[i] == c) {
                return i;
            }
        }
        return -1;
    }

    private static String exec(String text, Mode mode) {
        return exec(text, mode, false);
    }

    private static String exec(String text, Mode mode, Boolean showSteps) {
        char[] left = L_ALPHABET.toCharArray();
        char[] right = R_ALPHABET.toCharArray();
        char[] eText = new char[text.length()];
        char[] temp = new char[26];

        for (int i = 0; i < text.length(); ++i) {
            if (showSteps) {
                System.out.printf("%s  %s\n", new String(left), new String(right));
            }
            int index;
            if (mode == Mode.ENCRYPT) {
                index = indexOf(right, text.charAt(i));
                eText[i] = left[index];
            } else {
                index = indexOf(left, text.charAt(i));
                eText[i] = right[index];
            }
            if (i == text.length() - 1) {
                break;
            }

            

            if (26 - index >= 0) System.arraycopy(left, index, temp, 0, 26 - index);
            System.arraycopy(left, 0, temp, 26 - index, index);
            char store = temp[1];
            System.arraycopy(temp, 2, temp, 1, 12);
            temp[13] = store;
            left = Arrays.copyOf(temp, temp.length);

            

            if (26 - index >= 0) System.arraycopy(right, index, temp, 0, 26 - index);
            System.arraycopy(right, 0, temp, 26 - index, index);
            store = temp[0];
            System.arraycopy(temp, 1, temp, 0, 25);
            temp[25] = store;
            store = temp[2];
            System.arraycopy(temp, 3, temp, 2, 11);
            temp[13] = store;
            right = Arrays.copyOf(temp, temp.length);
        }

        return new String(eText);
    }

    public static void main(String[] args) {
        String plainText = "WELLDONEISBETTERTHANWELLSAID";
        System.out.printf("The original plaintext is : %s\n", plainText);
        System.out.println("\nThe left and right alphabets after each permutation during encryption are:");
        String cipherText = exec(plainText, Mode.ENCRYPT, true);
        System.out.printf("\nThe cipher text is : %s\n", cipherText);
        String plainText2 = exec(cipherText, Mode.DECRYPT);
        System.out.printf("\nThe recovered plaintext is : %s\n", plainText2);
    }
}