On measuring the parasitic backscatter of sensor-enabled UHF RFID tags

Radio-frequency identification (RFID) tags have found their way into many applications. When tags implement cryptographic algorithms, side-channel analysis (SCA) attacks become a concern. Especially tags in the ultra-high frequency (UHF) range are susceptible to so-called parasitic-backscatter attacks that can be applied from a distance. Whereas it is known that such attacks are a threat for passive low-cost tags, no results are so far available for sensor-enabled tags. In this work, we evaluate the parasitic backscatter of wireless identification and sensing platform (WISP) tags by conducting differential electromagnetic analysis (DEMA) attacks. We apply the attacks on a passively as well as a semi-passively operated WISP tag from a distance of 30 cm and compare the results with an attack on a commercial low-cost tag. The results show that the evaluated WISP tags are less susceptible to DEMA attacks based on the parasitic backscatter than the evaluated commercial low-cost tag. Moreover, we present a measurement approach that allows to detect the weak parasitic backscatter modulated on the strong reader field without the need for an expensive hardware receiver or a dedicated demodulation circuit.