US Patent 7266848 Integrated circuit security and method therefor

The invention relates to an integrated circuit (IC), and more particularly to security to protect an IC (10) against unauthorized accesses. In one embodiment, an identifier is provided external to IC 10. A corresponding input IC security key (52) is then provided to IC 10 and compared to a stored IC security key (30). If the input IC security key (52) and the stored IC security key (30) do not match, access to protected functional circuitry (12) is prohibited. The present invention may use any debug interface, including standard debug interfaces using the JTAG 1149.1 interface defined by the IEEE.