A Miniaturized and Ultra-Low-Power Tamper Detection Sensor for Portable Applications

Abstract

This article presents a tamper detection sensor complementing cryptographic techniques in order to protect data from unauthorized access and/or from data falsification. Both the mechanical and electronic parts of the systems are described. The proposed architecture targets portable devices and can be realized using commercially available components, widely available materials and known manufacturing and assembly techniques. The tamper detection circuit is based on a capacitive sensing principle and uses ultra-low-power electronic components, leading to an overall consumed current below <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10~\mu \text{A}$ </tex-math></inline-formula> . Autonomy is a crucial reported drawback of miniaturized battery backed-up anti-tampering hardware systems: the presented architecture and implementation ensures a lifetime of at least 3 years when powered by one CR2032 coin cell battery. The paper also assesses the sensitivity of the tamper detection: measurements show that the system is able to detect a variation of at least one percent of the capacitance of the tamper layer, resulting from an attempt to breach the outer shell surrounding the circuit for accessing the sensitive data.