Trying to encrypt a save file crashes system

Hi All,
I',m trying to use System.Security.Cryptography to read write a binaryformatted file. However when I try to read it crashes game ( no error appears in console ). How I read the file is

Code (csharp):

1.  
2.         CryptoStream enc = new CryptoStream( file, unencryptor, CryptoStreamMode.Read );
3.  
4.         //T x = ( T )this.bf.Deserialize( file );
5.  
6.         T x = ( T )this.bf.Deserialize( enc );
7.  
8.         return( x );
9.     }
10.  

however when I Serialize the output this."bf.Serialize( enc, testObject );" it crahses the game.
Can anyone advise please, I've searched google without luck.
The whole code is below

Code (csharp):

1.  
2. using System.Collections;
3. using System.Collections.Generic;
4. using UnityEngine;
5. using System.IO;
6. using System.Runtime.Serialization.Formatters.Binary;
7. using System.Security.Cryptography;
8. public class FileControl
9. {
10.     BinaryFormatter bf;
11.     RijndaelManaged rm;
12.  
13.     ICryptoTransform encryptor,unencrytor;
14.     FileStream file;
15.     string filepath;
16.     byte[] Key = {0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
17.                 0x08, 0x09, 0x10, 0x11, 0x12, 0x13, 0x14,
18.                 0x15, 0x16};
19.     byte[] IV = {0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
20.                 0x08, 0x09, 0x10, 0x11, 0x12, 0x13, 0x14,
21.                 0x15, 0x16};
22.     public void setSavePath( string game_path )
23.     {
24.         this.filepath = Application.persistentDataPath + "/" + game_path;
25.     }
26.     public bool openFile( string game_path )
27.     {
28.         this.setSavePath( game_path );
29.         this.bf = new BinaryFormatter( );
30.         rm = new RijndaelManaged();
31.      
32.         encryptor = rm.CreateEncryptor(Key, IV);
33.         unencrytor = rm.CreateDecryptor(Key, IV);
34.  
35.         if( !File.Exists( filepath ) )
36.         {
37.             this.file = File.Create( filepath );
38.             this.file.Flush( );
39.             return( false );
40.         }
41.         else file = File.Open( filepath, FileMode.Open );
42.         this.file.Flush( );
43.         return( true );
44.     }
45.     public void closeFile( )
46.     {
47.         if( this.file != null )this.file.Close( );
48.     }
49.     public void writeFile< T >( T testObject )
50.     {
51.         file.Seek(0, SeekOrigin.Begin);
52.         CryptoStream enc = new CryptoStream(file,  encryptor, CryptoStreamMode.Write );
53.         //this.bf.Serialize( file, testObject );
54.         this.bf.Serialize( enc, testObject );
55.         this.file.Flush( );
56.         //this.file.Close( );
57.     }
58.     public T readFile< T >(  )
59.     {
60.         file.Seek(0, SeekOrigin.Begin);
61.         CryptoStream enc = new CryptoStream( file, unencryptor, CryptoStreamMode.Read );
62.         //T x = ( T )this.bf.Deserialize( file );
63.         T x = ( T )this.bf.Deserialize( enc );
64.         return( x );
65.     }
66. }
67.