public static bool EncryptFile(byte[] buffer, string sOutputFilename, string sKey)
        {
            bool IsSuccess = true;
            FileStream fsEncrypted = null;
            CryptoStream cryptostream = null;
            try
            {
                FileInfo f = new FileInfo(sOutputFilename);
                if (!Directory.Exists(f.Directory.FullName))
                {
                    Directory.CreateDirectory(f.Directory.FullName);
                }
  
                fsEncrypted = new FileStream(sOutputFilename,
                                                        FileMode.Create,
                                                        FileAccess.Write);
                DESCryptoServiceProvider DES = new DESCryptoServiceProvider();
                //DES.BlockSize = 64;
                DES.Key = ASCIIEncoding.ASCII.GetBytes(sKey);
                DES.IV = ASCIIEncoding.ASCII.GetBytes(sKey);
                ICryptoTransform desencrypt = DES.CreateEncryptor();
                cryptostream = new CryptoStream(fsEncrypted,
                                                            desencrypt,
                                                            CryptoStreamMode.Write);
                cryptostream.Write(buffer, 0, buffer.Length);
                cryptostream.Close();
                fsEncrypted.Close();
                IsSuccess = true;
            }
            catch (Exception ex)
            {
                IsSuccess = false;
            }
            finally
            {
                try
                {
                    if (cryptostream != null) cryptostream.Close();
                    if (fsEncrypted != null) fsEncrypted.Close();
                }
                catch
                {
                }
            }
            return IsSuccess;
        }

 public static XDocument DecryptFile(string sInputFilename, string sKey)
        {
            FileStream fsread = null;
            StreamWriter fsDecrypted = null;
            XDocument xdData = null;
            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.
                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);

                xdData = XDocument.Load(new StreamReader(cryptostreamDecr));
            }
            catch (Exception ex)
            {
                throw ex;
            }
            finally
            {
                try
                {
                    if (fsread != null) fsread.Close();
                    if (fsDecrypted != null) fsDecrypted.Close();
                }
                catch
                {
                }
            }
            return xdData;
        }