1:  private void button1_Click(object sender, EventArgs e)

   2:  {

   3:      string source = "Test String";

   4:   

   5:      // Method 1: FormsAuthentication.HashPasswordForStoringInConfigFile

   6:      string m1 = FormsAuthentication.HashPasswordForStoringInConfigFile(source, "MD5").ToLower();

   7:      string m2 = GetMD5(source);

   8:      string m3 = MD5Sql(source);

   9:   

  10:      MessageBox.Show(string.Format("source: {0}, m1:{1}, m22:{2}, m3:{3}", source, m1, m2, m3));

  11:  }

  12:   

  13:  // Method 2: MD5CryptoServiceProvider

  14:  private string GetMD5(string source)

  15:  {

  16:      MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider();

  17:      byte[] bytValue = Encoding.UTF8.GetBytes(source);

  18:      byte[] bytHash = md5.ComputeHash(bytValue);

  19:      md5.Clear();

  20:   

  21:      StringBuilder sb = new StringBuilder();

  22:      for (int i = 0; i < bytHash.Length; i++)

  23:      {

  24:          sb.Append(bytHash[i].ToString("X").PadLeft(2, '0'));

  25:      }

  26:   

  27:      return sb.ToString().ToLower();

  28:  }

  29:   

  30:  // Method 3: SQL Server 2005 MD5

  31:  public string MD5Sql(string source)

  32:  {

  33:      string strConn = @"Connectionstring";

  34:      SqlConnection conn = new SqlConnection(strConn);

  35:      SqlCommand cmd = new SqlCommand("select master.sys.fn_VarBinToHexStr(hashbytes('MD5', @sDataIn))", conn);

  36:      cmd.Parameters.Add("@sDataIn", SqlDbType.VarChar);

  37:      cmd.Parameters["@sDataIn"].Value = source;

  38:   

  39:      conn.Open();

  40:      string s = cmd.ExecuteScalar().ToString().Substring(2).ToLower();

  41:      conn.Close();

  42:   

  43:      return s;

  44:  }