int anInteger = System::Convert::ToInt32(textBox1->Text);

using namespace System::IO;

FileStream* fs = new FileStream(S"c:\\file.txt", FileMode::Open,
FileAccess::Read, FileShare::Read);

FileStream* fs = new FileStream(S"c:\\file.txt", FileMode::Open,
FileAccess::ReadWrite, FileShare::Read);

FileStream* fs = new FileStream(S"c:\\file.txt", FileMode::Open,
FileAccess::Write, FileShare::Read);

FileStream *source_file = new FileStream(textBox1->Text, FileMode::Open, FileAccess::Read);
FileStream *output_file= new FileStream(textBox2->Text,  FileMode::Open, FileAccess::Write);
BinaryReader *w = new BinaryReader(source_file);                    
BinaryWriter *s = new BinaryWriter(output_file);

ch=w->ReadByte(); // Побайтное чтение из source_file
byte

unsigned char ch = w->ReadByte();
s->Write(ch);

while(1)
		     {
			   ch=w->ReadByte();
               if(ch!=NULL)
			   {
               byte=ch^crypt_key[2]^crypt_key[3];
			   s->Write(byte);
			   }
			   else
			     break;
			   
			 }