[C#]DES再一例(转)

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, 0, 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[200];//创建字节序列对象  
            MemoryStream P_MemoryStream_temp =//创建内存流对象  
                new MemoryStream();
            int i = 0;//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, 0, P_bt_temp.Length)) > 0)
            {
                P_MemoryStream_temp.Write(//将解密后的数据放入内存流  
                    P_bt_temp, 0, 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);
        }
    }
}

调用

private void btn_Encrypt_Click(object sender, EventArgs e)
        {
            if (txt_password.Text.Length == 4)//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 == 4)//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
            }
        }

转自 

http://blog.csdn.net/finlay_liu/article/details/8272855