Data protection circuit

A data-protection circuit (32) selectively allows access to data stored in a memory (14). Specifically, the circuit (32) receives an authorization key and allows access to the data if the authorization key equals a predetermined value. Such a circuit (32) can be used to prevent an unauthorized agent such as an unauthorized update package, a virus, or a hacker from reading or corrupting data such as firmware because the agent presumably will not have or be able to obtain the authorization key. Furthermore, by disposing the data-protection circuit (32) and memory (14) on separate integrated circuits (ICs), one can implement data protection without altering the design of the memory IC. This allows one to implement data protection for off-the-shelf memory ICs that include no integrated protection circuit. For example, one can implement the data-protection circuit (32) in a field-programmable gate array (FPGA) that is coupled to but separate from the memory IC (14).