Self destructing solid state store for secret information - uses solid state memories to store data and requires access code to match stored code supply fuse is not to be melted

摘要

The device has a logic circuit (10) which, under microprocessor control, must be matched by an access code in the reading device. A swith (20) in the power supply to the memory is not to be permanently opened, removing supply and thus erasing the memory contents. The access code is compared (5,8) against a code stored in memory (1). If an error occurs a logic gate (9) drives the base of a transistor (11), which, in conjunction with a fuse (12) is connected in a crowbar circuit configuration, the conduction of the transistor shorting the supply and melting the fusible link. The contacts utilised to programme the memory are sealed. The interfaces are made such that they cannot withstand the voltage required to re-programme the memory. Thus, no direct link can exist with the memory and external circuits.