DES文件字符加密解密

class DES
    {
        /// <summary>
        /// Call this function to remove the key from memory after use for security
        /// </summary>
        /// <param name="Destination"></param>
        /// <param name="Length"></param>
        /// <returns></returns>
        [System.Runtime.InteropServices.DllImport("KERNEL32.DLL", EntryPoint = "RtlZeroMemory")]
        public static extern bool ZeroMemory(IntPtr Destination, int Length);

        /// <summary>
        /// Function to Generate a 64 bits Key.
        /// </summary>
        /// <returns>返回生成的密钥</returns>
        public static string GenerateKey()
        {
            // Create an instance of Symetric Algorithm. Key and IV is generated automatically.
            DESCryptoServiceProvider desCrypto = (DESCryptoServiceProvider)DESCryptoServiceProvider.Create();
            // Use the Automatically generated key for Encryption.
            return ASCIIEncoding.ASCII.GetString(desCrypto.Key);
        }

        #region 加密文件

        /// <summary>
        /// 加密文件
        /// </summary>
        /// <param name="sInputFilename">要加密的文件</param>
        /// <param name="sOutputFilename">加密后保存的文件</param>
        /// <param name="sKey">密钥</param>
        public static void EncryptFile(string sInputFilename, string sOutputFilename, string sKey)
        {
            using (FileStream fsInput = new FileStream(sInputFilename, FileMode.Open, FileAccess.Read))
            {
                byte[] bytearrayinput = new byte[fsInput.Length];
                fsInput.Read(bytearrayinput, 0, bytearrayinput.Length);
                fsInput.Close();

                FileStream fsEncrypted = new FileStream(sOutputFilename,
                   FileMode.OpenOrCreate,
                   FileAccess.Write);
                DESCryptoServiceProvider DES = new DESCryptoServiceProvider();

                DES.Key = ASCIIEncoding.ASCII.GetBytes(sKey);
                DES.IV = ASCIIEncoding.ASCII.GetBytes(sKey);

                ICryptoTransform desencrypt = DES.CreateEncryptor();
                CryptoStream cryptostream = new CryptoStream(fsEncrypted, desencrypt, CryptoStreamMode.Write);
                cryptostream.Write(bytearrayinput, 0, bytearrayinput.Length);
                cryptostream.Close();
                fsEncrypted.Close();
            }
        }

        #endregion

        #region 解密文件

        /// <summary>
        /// 解密文件
        /// </summary>
        /// <param name="sInputFilename">要解密的文件</param>
        /// <param name="sOutputFilename">解决后保存的文件</param>
        /// <param name="sKey">密钥</param>
        public static void DecryptFile(string sInputFilename, string sOutputFilename, string sKey)
        {
            DESCryptoServiceProvider DES = new DESCryptoServiceProvider();
            //A 64 bit key and IV is required for this provider.
            //Set secret key For DES algorithm.
            DES.Key = ASCIIEncoding.ASCII.GetBytes(sKey);
            //Set initialization vector.
            DES.IV = ASCIIEncoding.ASCII.GetBytes(sKey);

            //Create a file stream to read the encrypted file back.
            using (FileStream fsread = new FileStream(sInputFilename, FileMode.Open, FileAccess.Read))
            {
                //Create a DES decryptor from the DES instance.
                ICryptoTransform desdecrypt = DES.CreateDecryptor();
                //Create crypto stream set to read and do a
                //DES decryption transform on incoming bytes.
                CryptoStream cryptostreamDecr = new CryptoStream(fsread, desdecrypt, CryptoStreamMode.Read);
                //Print the contents of the decrypted file.
                StreamWriter fsDecrypted = new StreamWriter(sOutputFilename);
                fsDecrypted.Write(new StreamReader(cryptostreamDecr).ReadToEnd());
                fsDecrypted.Flush();
                fsDecrypted.Close();
            }
        }

        /// <summary>
        /// 解密文件并返回内容
        /// </summary>
        /// <param name="sInputFilename">要解密的文件路径</param>
        /// <param name="sKey">密钥</param>
        /// <returns>返回内容</returns>
        public static string DecryptFile(string sInputFilename, string sKey)
        {
            try
            {
                DESCryptoServiceProvider DES = new DESCryptoServiceProvider();
                //A 64 bit key and IV is required for this provider.
                //Set secret key For DES algorithm.
                DES.Key = ASCIIEncoding.ASCII.GetBytes(sKey);
                //Set initialization vector.
                DES.IV = ASCIIEncoding.ASCII.GetBytes(sKey);

                //Create a file stream to read the encrypted file back.
                using (FileStream fsread = new FileStream(sInputFilename, FileMode.Open, FileAccess.Read))
                {
                    byte[] byt = new byte[fsread.Length];
                    fsread.Read(byt, 0, byt.Length);
                    fsread.Flush();
                    fsread.Close();
                    //Create a DES decryptor from the DES instance.
                    ICryptoTransform desdecrypt = DES.CreateDecryptor();
                    MemoryStream ms = new MemoryStream();
                    CryptoStream cryptostreamDecr = new CryptoStream(ms, desdecrypt, CryptoStreamMode.Write);
                    cryptostreamDecr.Write(byt, 0, byt.Length);
                    cryptostreamDecr.FlushFinalBlock();
                    cryptostreamDecr.Close();
                    return Encoding.UTF8.GetString(ms.ToArray()).Trim();
                }
            }
            catch
            {
                return "";
            }
        }

        #endregion

        #region DES加密
        /// <summary>
        /// DES加密
        /// </summary>
        /// <param name="pToEncrypt">需要加密的字符串</param>
        /// <returns>加密后的字符串</returns>
        public static string DESEncrypt(string pToEncrypt, string DesKeyStr)
        {
            try
            {
                DESCryptoServiceProvider des = new DESCryptoServiceProvider();
                byte[] inputByteArray = Encoding.Default.GetBytes(pToEncrypt);
                des.Key = ASCIIEncoding.ASCII.GetBytes(DesKeyStr);
                des.IV = ASCIIEncoding.ASCII.GetBytes(DesKeyStr);
                MemoryStream ms = new 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);
                }
                ret.ToString();
                return ret.ToString();
            }
            catch
            {
                System.Windows.Forms.MessageBox.Show("输入注册码错误，请重新输入！！");
                return "";
            }


        }
        #endregion

        #region DES解密

        /// <summary>
        /// DES解密
        /// </summary>
        /// <param name="pToDecrypt">加密后的字符串</param>
        /// <returns>解密后的字符串</returns>
        public static string DESDecrypt(string pToDecrypt, string DesKeyStr)
        {
            try
            {
                DESCryptoServiceProvider des = new DESCryptoServiceProvider();

                byte[] inputByteArray = new byte[pToDecrypt.Length / 2];
                for (int x = 0; x < pToDecrypt.Length / 2; x++)
                {
                    int i = (Convert.ToInt32(pToDecrypt.Substring(x * 2, 2), 16));
                    inputByteArray[x] = (byte)i;
                }

                des.Key = ASCIIEncoding.ASCII.GetBytes(DesKeyStr);
                des.IV = ASCIIEncoding.ASCII.GetBytes(DesKeyStr);
                MemoryStream ms = new MemoryStream();
                CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write);
                cs.Write(inputByteArray, 0, inputByteArray.Length);
                cs.FlushFinalBlock();

                StringBuilder ret = new StringBuilder();

                return System.Text.Encoding.Default.GetString(ms.ToArray());
            }
            catch
            {
                System.Windows.Forms.MessageBox.Show("输入注册码错误，请重新输入！！");
                return "";
            }
        }
        #endregion
    }