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

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 works (Jeong et al., 2021), (Miki et al., 2020) have found vulnerabilities in the power side channels of SAR ADCs and proposed limited fixes. Whereas power side-channel attacks (SCAs) require cutting the power trace and introducing a shunt resistor for measurement, electromagnetic (EM) SCAs are possible to perform noninvasively external to packaging. In this work, we present a randomized switching SAR (RS-SAR) ADC protection that is effective against both power and EM SCAs, reducing the attack efficacy by
$32\times $
for EM attacks and
$82\times $
for power attacks.