Xamarin.ios NSData.FromStream（）-文件大小加倍，文件已损坏

我正在尝试使用以下代码动态加密文件：

NSError oError = null;
using ( FileStream oStream = File.Open ( sSourcePathAndFile, FileMode.Open ) )
{
  NSData oData = NSData.FromStream ( oStream );
  // Save and encrypt.
  oData.Save ( sDestPathAndFile, NSDataWritingOptions.FileProtectionAlways, out oError );
}

没有错误，但所有保存的文件大小大约都增加了一倍，并且已损坏。即使我设置了写入选项“FileProtectionNone”，这根本不会改变文件，我也会得到相同的结果

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知道发生了什么事吗？

像这样的东西会有帮助吗？还没有在monotouch上尝试过这一点，但mtouch堆栈中包含了一个AIK所需的名称空间

using System.Security;
using System.Security.Cryptography;
using System.Runtime.InteropServices;

// Function to Generate a 64 bits Key.
      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);
      }

      static void EncryptFile(string sInputFilename,
         string sOutputFilename, 
         string sKey) 
      {
         FileStream fsInput = new FileStream(sInputFilename, 
            FileMode.Open, 
            FileAccess.Read);

         FileStream fsEncrypted = new FileStream(sOutputFilename, 
            FileMode.Create, 
            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); 

         byte[] bytearrayinput = new byte[fsInput.Length];
         fsInput.Read(bytearrayinput, 0, bytearrayinput.Length);
         cryptostream.Write(bytearrayinput, 0, bytearrayinput.Length);
         cryptostream.Close();
         fsInput.Close();
         fsEncrypted.Close();
      }

      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.
         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();
      } 

      static void Main()
      {
         // Must be 64 bits, 8 bytes.
         // Distribute this key to the user who will decrypt this file.
         string sSecretKey;

         // Get the Key for the file to Encrypt.
         sSecretKey = GenerateKey();

         // For additional security Pin the key.
         GCHandle gch = GCHandle.Alloc( sSecretKey,GCHandleType.Pinned );

         // Encrypt the file.        
         EncryptFile(@"C:\MyData.txt", 
            @"C:\Encrypted.txt", 
            sSecretKey);

         // Decrypt the file.
         DecryptFile(@"C:\Encrypted.txt", 
            @"C:\Decrypted.txt", 
            sSecretKey);
      } 

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也许吧，但如果iOS和iPhone3GS+内置了硬件加密，我为什么要这么做呢？呵呵，是的，我知道，但如果你急于将应用程序投入生产，作为一种解决办法：）我测试了你的代码，是的，我的文件也被破坏了，我想我们应该提交一个错误。我曾经尝试在这个奇怪的Novell网站上提交一个错误，但失败了。如果你有经验，请提交一个错误！我设法放了一只虫子！我得到了一些404，被重定向到最奇怪的页面，但最后我做到了！是 啊让我们看看会发生什么。