public static string Encode(string str, string key){DESCryptoServiceProvider provider = new DESCryptoServiceProvider();provider.Key = Encoding.ASCII.GetBytes(key.Substring(0, 8));provider.IV = Encoding.ASCII.GetBytes(key.Substring(0, 8));byte[] bytes = Encoding.UTF8.GetBytes(str);MemoryStream stream = new MemoryStream();CryptoStream stream2 = new CryptoStream(stream, provider.CreateEncryptor(), CryptoStreamMode.Write);stream2.Write(bytes, 0, bytes.Length);stream2.FlushFinalBlock();StringBuilder builder = new StringBuilder();foreach (byte num in stream.ToArray()){builder.AppendFormat("{0:X2}", num);}stream.Close();return builder.ToString();}

public static string Decode(string str, string key){DESCryptoServiceProvider provider = new DESCryptoServiceProvider();provider.Key = Encoding.ASCII.GetBytes(key.Substring(0, 8));provider.IV = Encoding.ASCII.GetBytes(key.Substring(0, 8));byte[] buffer = new byte[str.Length / 2];for (int i = 0; i < (str.Length / 2); i++){int num2 = Convert.ToInt32(str.Substring(i * 2, 2), 0x10);buffer[i] = (byte)num2;}MemoryStream stream = new MemoryStream();CryptoStream stream2 = new CryptoStream(stream, provider.CreateDecryptor(), CryptoStreamMode.Write);stream2.Write(buffer, 0, buffer.Length);stream2.FlushFinalBlock();stream.Close();return Encoding.GetEncoding("GB2312").GetString(stream.ToArray());}

<asp:TextBox ID="txtbox" runat="server"></asp:TextBox><asp:Button ID="btnok" runat="server" onclick="btnok_Click" Text="加密" /><asp:Button ID="btncanel" runat="server" Text="解密" onclick="btncanel_Click" />

  protected void btnok_Click(object sender, EventArgs e){txtbox.Text = Helper.Encode(txtbox.Text.Trim(), "Rainight").Trim(}protected void btncanel_Click(object sender, EventArgs e){txtbox.Text = Helper.Decode(txtbox.Text.Trim(), "Rainight").Trim();Response.Write(Helper.Decode(txtbox.Text.Trim(), "Rainight"));}