hammy:
I think the Arduino will also be far too slow.
It seems that serial transfer speed might be not bad at all
http://forum.arduino.cc/index.php?topic=21497.0
hammy:
Virus definitions take a lot of space...you need check file headers too, when you look at file types.
As I said before (at least) I want to get file extension and mime type and compare it with the allowed list. Is it possible to do with arduino usb host shield?