public class Encrypt

{

    internal string ToEncrypt(string encryptKey, string str)

    {

        try

        {

            byte[] P_byte_key = //将密钥字符串转换为字节序列

                Encoding.Unicode.GetBytes(encryptKey);

            byte[] P_byte_data = //将字符串转换为字节序列

                Encoding.Unicode.GetBytes(str);

            MemoryStream P_Stream_MS = //创建内存流对象

                new MemoryStream();

            CryptoStream P_CryptStream_Stream = //创建加密流对象

                new CryptoStream(P_Stream_MS, new DESCryptoServiceProvider().

               CreateEncryptor(P_byte_key, P_byte_key), CryptoStreamMode.Write);

            P_CryptStream_Stream.Write(//向加密流中写入字节序列

                P_byte_data, , P_byte_data.Length);

            P_CryptStream_Stream.FlushFinalBlock();//将数据压入基础流

            byte[] P_bt_temp =//从内存流中获取字节序列

                P_Stream_MS.ToArray();

            P_CryptStream_Stream.Close();//关闭加密流

            P_Stream_MS.Close();//关闭内存流

            return //方法返回加密后的字符串

                Convert.ToBase64String(P_bt_temp);

        }

        catch (CryptographicException ce)

        {

            throw new Exception(ce.Message);

        }

    }

    internal string ToDecrypt(string encryptKey, string str)

    {

        try

        {

            byte[] P_byte_key = //将密钥字符串转换为字节序列

                Encoding.Unicode.GetBytes(encryptKey);

            byte[] P_byte_data = //将加密后的字符串转换为字节序列

                Convert.FromBase64String(str);

            MemoryStream P_Stream_MS =//创建内存流对象并写入数据

                new MemoryStream(P_byte_data);

            CryptoStream P_CryptStream_Stream = //创建加密流对象

                new CryptoStream(P_Stream_MS, new DESCryptoServiceProvider().

                CreateDecryptor(P_byte_key, P_byte_key), CryptoStreamMode.Read);

            byte[] P_bt_temp = new byte[];//创建字节序列对象

            MemoryStream P_MemoryStream_temp =//创建内存流对象

                new MemoryStream();

            int i = ;//创建记数器

            while ((i = P_CryptStream_Stream.Read(//使用while循环得到解密数据

                P_bt_temp, , P_bt_temp.Length)) > )

            {

                P_MemoryStream_temp.Write(//将解密后的数据放入内存流

                    P_bt_temp, , i);

            }

            return //方法返回解密后的字符串

                Encoding.Unicode.GetString(P_MemoryStream_temp.ToArray());

        }

        catch (CryptographicException ce)

        {

            throw new Exception(ce.Message);

        }

    }

}

private void btn_Encrypt_Click(object sender, EventArgs e)

        {

            if (txt_password.Text.Length == )//判断加密密钥长度是否正确

            {

                try

                {

                    txt_EncryptStr.Text = //调用实例ToEncrypt方法得到加密后的字符串

                        new Encrypt().ToEncrypt(

                        txt_password.Text, txt_str.Text);

                    //Encrypt P_Encrypt = new Encrypt();

                    //P_Encrypt.ToEncrypt(""

                }

                catch (Exception ex)//捕获异常

                {

                    MessageBox.Show(ex.Message);//输出异常信息

                }

            }

            else

            {

                MessageBox.Show("密钥长度不符！", "提示");//提示用户输入密钥长度不正确

            }

        }

        private void btn_UnEncrypt_Click(object sender, EventArgs e)

        {

            if (txt_password2.Text.Length == )//判断加密密钥长度是否正确

            {

                try

                {

                    txt_str2.Text = //调用ToDecrypt方法得到解密后的字符串

                        new Encrypt().ToDecrypt(

                        txt_password2.Text, txt_EncryptStr2.Text);

                }

                catch (Exception ex)//捕获异常

                {

                    MessageBox.Show(ex.Message);//输出异常信息

                }

            }

            else

            {

                MessageBox.Show("密钥长度不符！", "提示");//提示用户输入密钥长度不正确

            }

        }