Paper 2012/728 Original: eprint.iacr.org/2012/728 ↗

Defensive Leakage Camouflage

Abstract

This paper considers the transfer of digital data over {\sl leaky and noisy} communication channels. We develop defensive strategies exploiting the fact that noise prevents the attacker from accurately measuring leakage. The defense strategy described in this paper pairs each useful data element $k$ with a camouflage value $v$ and simultaneously transmits both $k$ and $v$ over the channel. This releases an emission $e(k,v)$. We wish to select the camouflage values $v(k)$ as a function of $k$ in a way that makes the quantities $e(k,v(k))$ as {\sl indistinguishable} as possible from each other. We model the problem and show that optimal camouflage values can be computed from side-channels under very weak physical assumptions. The proposed technique is hence applicable to a wide range of readily available technologies. We propose algorithms for computing optimal camouflage values when the number of samples per trace is moderate (typically $\leq 6$) and justify our models by a statistical analysis. We also provide experimental results obtained using FPGAs.