Randomized Switching SAR (RS-SAR) ADC for Power and EM Side-Channel Security

Abstract

Successive Approximation Register (SAR) Analog to Digital Converters (ADCs) are used in many edge Internet of Things (IoT) devices to digitize analog inputs before further processing. These inputs can be private, requiring physical side channel security to protect the data being converted. Previous work jeongs2adc2020-1, mikirandom2020 has found vulnerabilities in the power side channels of SAR ADCs and proposed limited fixes. Whereas power side channel attacks require cutting the power trace and introducing a shunt resistor for measurement, electromagnetic (EM) side channel attacks are possible to perform non-invasively external to packaging. In this work, we present a randomized switching SAR (RS-SAR) ADC protection that is effective against both power and EM side channel attacks, reducing the attack efficacy by 32x for EM attacks and 82x for power attacks.