A Sliding Window Phase-Only Correlation Method for Side-Channel Alignment in a Smartphone

Abstract

Future wireless embedded devices will be increasingly powerful, supporting many more applications including one of the most crucial, security. Although many embedded devices offer resistance to bus probing attacks due to their compact size and high levels of integration, susceptibility to attacks on their electromagnetic side channel must be analyzed. This side channel is often quite complex to analyze due to the complexities of the embedded device including operating system, interrupts, and so forth. This article presents a new methodology for analyzing a complex system's vulnerability to the EM side channel. The methodology proposes a sliding window phase-only correlation method for aligning electromagnetic emanations from a complex smartphone running native code utilizing an on-chip cache. Unlike previous research, experimental results demonstrate that data written to on-chip cache within an advanced 312MHz 0.13um processor executing AES can be attacked utilizing this new methodology. Furthermore, for the first time, it has been shown that the point of side-channel attack is not a spike of increased EM but an area of low EM amplitude, unlike what is noted in previous findings. This research is important for advancing side-channel analysis understanding in complex embedded processors and ensuring secure implementations in future embedded ubiquitous devices.