Towards Sound Approaches to Counteract Power-Analysis Attacks

Side channel cryptanalysis techniques, such as the analysis of instantaneous power consumption, have been extremely e ective in attacking implementations on simple hardware platforms. There are several proposed solutions to resist these attacks, most of which are ad{hoc and can easily be rendered ine ective. A scienti c approach is to create a model for the physical characteristics of the device, and then design implementations provably secure in that model, i.e, they resist generic attacks with an a priori bound on the number of experiments. We propose an abstract model which approximates power consumption in most devices and in particular small single{chip devices. Using this, we propose a generic technique to create provably resistant implementations for devices where the power model has reasonable properties, and a source of randomness exists. We prove a lower bound on the number of experiments required to mount statistical attacks on devices whose physical characteristics satisfy reasonable properties.