New attacks and security model of the secure flash disk

Nowadays, the secure flash disk is the most common secure mobile storage device. Two conventional schemes, flash encryption and identity authentication, are used to ensure the security of the information stored in it, but there is no comprehensive security model. We summarize three shortcomings of it: the USB cable is very easy to be monitored; the disk is not applicable to a big group and does not resist the corruption attack. In this paper, a new attack named USB cable monitor attack is proposed and implemented. In order to overcome the existing shortcomings, we give a notion of ‘secure group flash disk’ and its security model. Accordingly, a set of universal cryptographic strategies and a concrete authenticated key exchange protocol are devised, whose security can be proved via the universally composable security model. Based on the strategies, the system architecture of this USB flash disk is designed. An IP core of the USB device controller is implemented and verified on a FPGA, so that the performance superiority can be given. Our experiment shows that our strategies can perfectly solve the problems of USB cable monitor, group application, and resistance to corruption.