Patent ID: 7270275

Claim:
A tamper detection circuit for a secured key-based entry device for a computer system comprising: a keypad having a plurality of keycaps that initiate one or more electronic signals when depressed, the signals are used in a computer system; a frame securing the keypad to the entry device; a circuit board having electrical contacts that are coupled to a portion of one or more keycaps on the keypad when the keycaps are depressed, the one or more electronic signals are initiated by one or more electrical components on the circuit board based on the particular keycap being depressed; a tamper detection contact on the circuit board comprising a first conductive pattern and a second conductive pattern, the tamper detection contact initiating a signal when the first and the second conductive patterns are not connected by an electrical switch applied between the first and second patterns; a third conductive pattern surrounding a predetermined area around the first and second conductive patterns, the third conductive pattern coupled to a predetermined voltage level; and a non-conductive moat separating the third conductive pattern and either the first or the second conductive patterns, the non-conductive moat initiating a tamper detection response protocol by a transmission of electrical signals between the third conductive pattern and either the first or second conductive pattern.