1. A system comprising a carrier media and an interface, the interface being connectable to a computer to enable communication between the computer and the carrier media, wherein the carrier media encodes a secure computing environment and a boot system and preconfigured parameters, upon connection of the system via the interface to a computer system and booting of the computer system, the boot system being operative to take over the boot process of the computer system and to authenticate the user, wherein upon successful authentication, the boot system is arranged to load the secure computing environment on the computer system, the secure computing environment using the preconfigured parameters to prevent predetermined interaction from outside the secure computing environment when it is running; and a system monitor arranged to monitor operation of the computer system whilst under the control of the secure computing environment and arranged to install a memory wiping process in physical memory of the computer system, the memory wiping process, upon determining no other processes are running, being operative to wipe physical memory not occupied by itself so as to erase data stores in volatile memory of the computer system upon shut down of the computer system.