using System;
using System.Text;
namespace conn
{
	
	public class code_en_de
	{
		private static char[] key = "yA36zA48dEhfrvghGRg57h5UlDv3".ToCharArray();
		 
		public static string Decode(string x)
		{
			System.Text.StringBuilder sb = new System.Text.StringBuilder();
			char[] ca = x.ToCharArray();
			for (int i = 0; i < (ca.Length - 2); i += 2)
			{
				string s1 = "" + ca[i + 2] + ca[i + 3];
				string s2 = "" + System.Convert.ToString((byte) key[(i / 2) % 13], 16);
				string s3 = "" + ca[i] + ca[i + 1];
				int m = (System.Convert.ToInt32(s1, 16) ^ System.Convert.ToInt32(s2, 16)) - System.Convert.ToInt32(s3, 16);
				if (m < 0)
				{
					m += 255;
				}
				sb.Append((char) ((short) m));
			}
			return sb.ToString();
		}

		public static string Encode(string x)
		{
			char[] ca = x.ToCharArray();
			int k = new System.Random().Next(255);
			System.Text.StringBuilder sb = null;
			if (k > 15)
			{
				sb = new System.Text.StringBuilder("" + System.Convert.ToString(k, 16));
			}
			else
			{
				sb = new System.Text.StringBuilder("0" + System.Convert.ToString(k, 16));
			}
			int m = System.Convert.ToInt32(sb.ToString(), 16);
			for (int i = 0; i < ca.Length; i++)
			{
				if ((ca[i] + m) > 255)
				{
					m = ((ca[i] + m) - 255) ^ key[i % 13];
				}
				else
				{
					m = (ca[i] + m) ^ key[i % 13];
				}
				if (m > 15)
				{
					sb.Append(System.Convert.ToString(m, 16));
				}
				else
				{
					sb.Append("0" + System.Convert.ToString(m, 16));
				}
			}
			return sb.ToString().ToUpper();
		}
	}


}