Cryptographically secure shields

Probing attacks are serious threats on integrated circuits. Security products often include a protective layer called shield that acts like a digital fence. In this article, we demonstrate a new shield structure that is cryptographically secure. This shield is based on the newly proposed SIMON lightweight block cipher and independent mesh lines to ensure the security against probing attacks of the hardware located behind the shield. Such structure can be proven secure against state-of-the-art invasive attacks. For the first time in the open literature, we describe a chip designed with a digital shield, and give an extensive report of its cost, in terms of power, metal layer(s) to sacrifice and of logic (including the logic to connect it to the CPU). Also, we explain how "Through Silicon Vias" (TSV) technology can be used for the protection against both frontside and backside probing.