C# ile basit kriptoloji

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace WindowsFormsApplication23
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private **** button1_Click(object sender, EventArgs e)
        {
            label1.Text = "";
            char[] k = { 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h','ı', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',' '};
            char[] b = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I','İ', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',' '};
            char[] a = { '.', '^', 'é', '*', '#', '\'', '1', '2','3', '4', '_', '+', '%', '!', '?', '5', '6', '7', '8', '"', '@', '[', ']', '$', '9', '0', ',',' '};
            string t = textBox1.Text;
            char[] karakter = t.ToCharArray();
            foreach (char d in karakter)
            {
                for (int i = 0; i < 28; i++)
                {
                    if (d == k[i])
                    {
                        label1.Text = label1.Text + a[i];
                    }
                    else
                    {
                        if (d == b[i])
                        {
                            label1.Text = label1.Text + a[i];
                        }
                    }
                }
            }
            foreach (char d in karakter)
            {
                for (int i = 0; i < 28; i++)
                {
                    if (d == a[i])
                    {
                        label1.Text = label1.Text + k[i];
                    }

                }
            }
        }
    }
}