实现MD5加密算法

using System;
using System.Text;
using System.Security.Cryptography;

namespace Common
{
    /// <summary>   
    /// 一个实现MD5散列字符串的类   
    /// </summary>   
    public sealed class MD5Hashing
    {
        private static MD5 md5 = MD5.Create();
        //私有化构造函数   
        private MD5Hashing()
        {
        }
        /// <summary>   
        /// 使用utf8编码将字符串散列   
        /// </summary>   
        /// <param name="sourceString">要散列的字符串</param>   
        /// <returns>散列后的字符串</returns>   
        public static string HashString(string sourceString)
        {
            return HashString(Encoding.UTF8, sourceString);
        }
        /// <summary>   
        /// 使用指定的编码将字符串散列   
        /// </summary>   
        /// <param name="encode">编码</param>   
        /// <param name="sourceString">要散列的字符串</param>   
        /// <returns>散列后的字符串</returns>   
        public static string HashString(Encoding encode, string sourceString)
        {
            byte[] source = md5.ComputeHash(encode.GetBytes(sourceString));
            StringBuilder sBuilder = new StringBuilder();
            for (int i = 0; i < source.Length; i++)
            {
                sBuilder.Append(source[i].ToString("x2"));
            }
            return sBuilder.ToString();
        }
        public static void Main(string[] args) 
        {
            string reStr = MD5Hashing.HashString("xulong");
            string reStr2 = MD5Hashing.HashString(Encoding.UTF8, "xulong");

        }
    }
}

　MD5很难解密