Secure Integrated Circuit with Physical Attack Detection based on Reconfigurable Top Metal Shield

Abstract

Invasive physical attacks on integrated circuits (ICs), such as de-packaging, focused ion beam (FIB) chip editing, and micro-probing attempts, constitute security threats for chips with potentially valuable information, such as smart cards. Using a state-of-the-art circuit-editing technique, an attacker can remove an IC's top metal layer, leaving its secure information exposed to micro-probing attacks. Security ICs can be seriously threatened by such attacks and thus require on-chip countermeasures. Conventional active shields, however, have difficulty coping with physical attacks based on FIB chip editing (i.e., bypassing the top metal shield). This study presents a novel countermeasure against physical attacks based on the use of a reconfigurable metal shield for both top metal removal and micro-probing attack detection. This shield consists of two circuits: an FIB chip editing detection circuit consisting of a random number generator and a micro-probing attempt detection circuit consisting of two conditionally synchronized ring oscillators. Both circuits share a randomly reconfigured top metal shield, which represents a promising solution for security against state-of-the-art invasive attacks.