/// <summary>
    /// 加密
    /// </summary>
    /// <param name="Text">要加密的文本</param>
    /// <param name="sKey">秘钥</param>
    /// <returns></returns>
    public static string Encrypt(string Text, string sKey="test")
    {
      DESCryptoServiceProvider des = new DESCryptoServiceProvider();
      byte[] inputByteArray;
      inputByteArray = Encoding.Default.GetBytes(Text);
      des.Key = ASCIIEncoding.ASCII.GetBytes(Md5Hash(sKey).Substring(0,8));
      des.IV = ASCIIEncoding.ASCII.GetBytes(Md5Hash(sKey).Substring(0, 8));
      System.IO.MemoryStream ms = new System.IO.MemoryStream();
      CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write);
      cs.Write(inputByteArray, 0, inputByteArray.Length);
      cs.FlushFinalBlock();
      StringBuilder ret = new StringBuilder();
      foreach (byte b in ms.ToArray())
      {
        ret.AppendFormat("{0:X2}", b);
      }
      md4j= ret.ToString();
      return ret.ToString();
    }

/// <summary>
    /// 解密
    /// </summary>
    /// <param name="Text"></param>
    /// <param name="sKey"></param>
    /// <returns></returns>
    public static string Decrypt(string Text, string sKey = "test")
    {
      DESCryptoServiceProvider des = new DESCryptoServiceProvider();
      int len;
      len = Text.Length / 2;
      byte[] inputByteArray = new byte[len];
      int x, i;
      for (x = 0; x < len; x++)
      {
        i = Convert.ToInt32(Text.Substring(x * 2, 2), 16);
        inputByteArray[x] = (byte)i;
      }
      des.Key = ASCIIEncoding.ASCII.GetBytes(Md5Hash(sKey).Substring(0, 8));
      des.IV = ASCIIEncoding.ASCII.GetBytes(Md5Hash(sKey).Substring(0, 8));
      System.IO.MemoryStream ms = new System.IO.MemoryStream();
      CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write);
      cs.Write(inputByteArray, 0, inputByteArray.Length);
      cs.FlushFinalBlock();
      return Encoding.Default.GetString(ms.ToArray());
    }

/// <summary>
    /// 32位MD5加密
    /// </summary>
    /// <param name="input"></param>
    /// <returns></returns>
    private static string Md5Hash(string input)
    {
      MD5CryptoServiceProvider md5Hasher = new MD5CryptoServiceProvider();
      byte[] data = md5Hasher.ComputeHash(Encoding.Default.GetBytes(input));
      StringBuilder sBuilder = new StringBuilder();
      for (int i = 0; i < data.Length; i++)
      {
        sBuilder.Append(data[i].ToString("x2"));
      }
      return sBuilder.ToString();
    }

public static string md4j = "";
static void Main(string[] args)
  {
      //加密
     Encrypt("123456");
     Decrypt(md4j);
 }