.NETで文字列MD 5の暗号解読を実現

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Security.Cryptography;

namespace BLL
{
    public class md5Manger
    {
        #region MD5                  
        /// <summary>
        /// MD5  
        /// </summary>
        /// <param name="strSource">        </param>
        /// <returns>MD5       </returns>
        public static string Md5Encrypt(string strSource)
        {
            //      byte   
            byte[] bytIn = System.Text.Encoding.Default.GetBytes(strSource);
            //                     
            byte[] iv = { 102, 16, 93, 156, 78, 4, 218, 32 };//     
            byte[] key = { 55, 103, 246, 79, 36, 99, 167, 3 };//    
            //  DES   
            DESCryptoServiceProvider mobjCryptoService = new DESCryptoServiceProvider();
            mobjCryptoService.Key = iv;
            mobjCryptoService.IV = key;
            ICryptoTransform encrypto = mobjCryptoService.CreateEncryptor();
            //  MemoryStream      
            System.IO.MemoryStream ms = new System.IO.MemoryStream();
            CryptoStream cs = new CryptoStream(ms, encrypto, CryptoStreamMode.Write);
            cs.Write(bytIn, 0, bytIn.Length);
            cs.FlushFinalBlock();
            return System.Convert.ToBase64String(ms.ToArray());
        }
        #endregion

        #region MD5                 
        /// <summary>
        /// MD5  
        /// </summary>
        /// <param name="Source">        </param>
        /// <returns>MD5       </returns>
        public static string Md5Decrypt(string Source)
        {
            //             
            byte[] bytIn = System.Convert.FromBase64String(Source);
            //           ，                     
            byte[] iv = { 102, 16, 93, 156, 78, 4, 218, 32 };//     
            byte[] key = { 55, 103, 246, 79, 36, 99, 167, 3 };//    
            DESCryptoServiceProvider mobjCryptoService = new DESCryptoServiceProvider();
            mobjCryptoService.Key = iv;
            mobjCryptoService.IV = key;
            //       
            System.IO.MemoryStream ms = new System.IO.MemoryStream(bytIn, 0, bytIn.Length);
            ICryptoTransform encrypto = mobjCryptoService.CreateDecryptor();
            CryptoStream cs = new CryptoStream(ms, encrypto, CryptoStreamMode.Read);
            StreamReader strd = new StreamReader(cs, Encoding.Default);
            return strd.ReadToEnd();
        }
        #endregion
    }

}