Make a custom card reader

Hi folks, I really want to implement a rather interesting project that might be very useful everyone (for e.g. to protect your own PC from hacking). I have some experience with arduino but I need your help.

What is the idea? I want to make custom card reader based on arduino microcontroller to read files from any usb flash drive programmatically and send processed (verified) data to my PC. So this thing should work as a buffer between my PC and possibly malicious distrustful usb unit. It can be rubber ducky or just usb killer or even simple flash drive with malicious software, but nothing will happen if I insert this usb unit not to the motherboard directly. Also I want to recognize file extensions and mime types programmatically and preset some "white list".

Maybe I'm behind the life and this thing already exists on the market or described DIY?

It seems that I need to use arduino usb host shield for this purpose or make custom pcb with MAX3421E controller. At least I want to check file extensions and mime types. Is there any code samples or tutorials? How do you think how much time will it take to transfer the file (for e.g. less than 10mb) to PC using for e.g. atmega328? Maybe worth a look ARM microcontrollers? And one more pressing question: what is the best way to transfer verified files to PC from such custom card reader?

Any advice will be appreciated 8)

I can't see this working - how will you check the files are ok? Virus definitions take a lot of space . I think the Arduino will also be far too slow. Bear in mind too infected files can have false extensions, you need check file headers too, when you look at file types .

Consider using a raspberry pi or clone. But it must have at least 1 host port and at least 1 gadget port.

It should protect your PC from USB port killers, rubber ducky attacks, autoexec issues, etc. But filtering out malicious software is very difficult.

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?

gdsports: Consider using a raspberry pi or clone. But it must have at least 1 host port and at least 1 gadget port.

It should protect your PC from USB port killers, rubber ducky attacks, autoexec issues, etc. But filtering out malicious software is very difficult.

I guess raspberry pi can be hacked as usual PC since it has os or it should be configured very sophistically. But in this case there are some advantages with the exception of the price. For e.g. it is possible to use some online file checker (virustotal) to make protection more advanced rather than just checking file extension and headers.