Towards Sound Approaches to Counteract Power-Analysis Attacks

Abstract

Side channel cryptanalysis techniques, such as the analysis of instantaneous power consumption, have been extremely e ective i n 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 l o wer bound on the number of experiments required to mount statistical attacks on devices whose physical characteristics satisfy reasonable properties.

Power Analysis, What Is Now Possible...

“…Unfortunately, DiPA attacks can counteract masking countermeasures mentioned in ( [Mes00,CJRR99b]). The reason is the following: in their security proof, they are assuming that the information is extracted from several messages.…”

“…random permutations; -transformations of the data: i.e. public key blinding, Duplication method [GP99], masking methods [Mes00,CJRR99b].…”

Mathematics under the Microscope

“…Moreover, brain scan techniques where the activities of various parts of the brain are studied by measuring the blood flow (which correlates with the energy consumption) also have an analog in cryptanalysis-namely power trace analysis: the secret key on a credit card is deduced from the pattern of its energy consumption when it is plugged into the card reader [264,307].…”

Provably Secure S-Box Implementation Based on Fourier Transform

“…The first attack consists in directly interpreting power consumption measurements and the second attack also involves statistical tests. From then on, many papers describing either countermeasures or attack improvements have been published (see [1,4,6,21] for example).…”

“…To protect the calculus of the output of an S-Box against DPA, three main kinds of methods have been proposed in the literature. The first one, called the duplication method [6,13], consists in randomly splitting every piece of sensitive data in a constant number of blocks. Then, the computation can be securely carried out by performing calculations with these random blocks.…”