On the Complexity Reduction of Laser Fault Injection Campaigns using OBIC Measurements

Abstract—Laser Fault Injection (LFI) is one of the most powerful methods of inducing a fault as it allows targeting only specific areas down to sin-gle transistors. The downside compared to non-invasive methods like introducing clock glitches is the largely increased search space. An ex-haustive search through all parameters including dimensions for correct timing, intensity, or length might not be not feasible. Existing solutions to this problem are either not directly applicable to the fault location or require additional device preparation and access to expensive equipment. Our method utilizes measuring the Optical Beam Induced Current (OBIC) as imaging technique to find target areas like flip-flops and thus, reducing the search space drastically. This measurement is possible with existing laser scanning microscopes or well-equipped LFI setups. We provide exper-imental results targeting the Advanced Encryp-tion Standard (AES) hardware accelerator of an Atmel ATXMega microcontroller. Keywords-fault injection, laser fault injection, optical beam induced current, laser scanning, AES, ATXMega I