hi,everybody,i work on a embedded linux system , now i want modify some function, such as with i insert a special usb disk (like a usbkey) to start system some special function. the usb disk should not be copy without authorization. anyboby can give some suggestion,thanks .

If the "copy without authorization" is your main problem you could search for "copy protection" but I doubt you will find a way that is a) uncrackable and b) cost-effective. I don't know any. If the en/decryption part is your main problem you could search for "digital restriction management" (yes even GNU/Linux has a DRM standard AFAIK). If the disk is encrypted then copying would not pose a risk until somebody retrieves the key or gains access to the contents while they are in a decrypted state. And how do you provide the key? It can't reside on the medium itself and it can't be placed on the system. That leaves only secured client-server transactions which sounds costly to me for an embedded system.