Task: Chaocipher
C#: using System;

namespace Chaocipher {
    enum Mode {
        ENCRYPT,
        DECRYPT,
    }

    class Program {
        const string L_ALPHABET = "HXUCZVAMDSLKPEFJRIGTWOBNYQ";
        const string R_ALPHABET = "PTLNBQDEOYSFAVZKGJRIHWXUMC";

        static string Exec(string text, Mode mode, bool showSteps = false) {
            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) Console.WriteLine("{0} {1}", string.Join("", left), string.Join("", right));
                int index = 0;
                if (mode == Mode.ENCRYPT) {
                    index = Array.IndexOf(right, text[i]);
                    eText[i] = left[index];
                } else {
                    index = Array.IndexOf(left, text[i]);
                    eText[i] = right[index];
                }
                if (i == text.Length - 1) break;

                

                for (int j = index; j < 26; ++j) temp[j - index] = left[j];
                for (int j = 0; j < index; ++j) temp[26 - index + j] = left[j];
                var store = temp[1];
                for (int j = 2; j < 14; ++j) temp[j - 1] = temp[j];
                temp[13] = store;
                temp.CopyTo(left, 0);

                

                for (int j = index; j < 26; ++j) temp[j - index] = right[j];
                for (int j = 0; j < index; ++j) temp[26 - index + j] = right[j];
                store = temp[0];
                for (int j = 1; j < 26; ++j) temp[j - 1] = temp[j];
                temp[25] = store;
                store = temp[2];
                for (int j = 3; j < 14; ++j) temp[j - 1] = temp[j];
                temp[13] = store;
                temp.CopyTo(right, 0);
            }

            return new string(eText);
        }

        static void Main(string[] args) {
            var plainText = "WELLDONEISBETTERTHANWELLSAID";
            Console.WriteLine("The original plaintext is : {0}", plainText);
            Console.WriteLine("\nThe left and right alphabets after each permutation during encryption are :\n");
            var cipherText = Exec(plainText, Mode.ENCRYPT, true);
            Console.WriteLine("\nThe ciphertext is : {0}", cipherText);
            var plainText2 = Exec(cipherText, Mode.DECRYPT);
            Console.WriteLine("\nThe recovered plaintext is : {0}", plainText2);
        }
    }
}

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)
}