International audience

International audience

Side-channel based instruction disassembly (SCBD) is a family of side-channel attacks that aims at recovering the code executed by a device from physical measurements. Over past decades researches have proved that instruction-level disassembly is feasible on simple controllers. Simultaneously, the computing power and architectural complexity of processors are increasing, even in constrained devices. Performing side-channel attacks on mid or high-end devices is inherently harder because of complex concurrent activities and an important amount of noise. While broad pattern identification, such as cryptographic primitives, has been proved possible, the feasibility of precise SCBD remains an open question on a complex System-on-Chip (SoC). In this work, we address some of the technical challenges involved in performing SCBD on SoCs. We propose an experimental setup and measurement methodology that enables reliable characterization of instruction-level electromagnetic (EM) leakages. We study the feasibility of three code reconstruction granularities: functional unit recognition, opcode recognition and full instruction recovery. Under a controlled experimental environment, our results show that functional unit recognition is achievable (100% classification accuracy) as well as opcode recognition (with evidence of leakage). In our setup, full instruction recovery (i.e., bit-level encoding) turned out to be more challenging. We show that the classification accuracy on instruction bits is better than random guesses and can be improved by combining multiple EM probe positions, but it is not high enough to foresee an attack in a real environment.

International audience

In order to synthesize the noise of internal combustion engines at arbitrary speed variations, an overlap-add-based method is proposed to be applied to sound samples extracted from a prerecorded engine noise at a continuously-varying speed. The objective of this new method is to minimize the phase discontinuities between a finite number of harmonics of the sample sounds likely to be concatenated. The harmonicity of the synthesized signal is then preserved which greatly enhances the acoustic quality of the restitution. Moreover, the synthesis stage is well suited for real time applications due to a low computational load compared to existing approaches. The proposed analysis-synthesis method can be applied to any harmonic sound whose spectral content depends solely on its fundamental frequency. By analogy to existing overlap-and-add methods, the method introduced here is referred to as Harmonic Synchronous Overlap and Add (HSOLA).