This work measures the performance of a synchronous sampling system attacking a modern microcontroller running a software AES implementation. This attack is characterized under four conditions: with a stable crystal-oscillator based clock, with a clock that is randomly varied between 3.9 MHz - 13 MHz, with an internal oscillator that is randomly varied between 7.2 MHz - 8.1 MHz, and with an internal oscillator that has slight random variation due to natural `drift' in the oscillator.
Traces captured with the synchronous sampling technique can be processed with a standard Differential Power Analysis (DPA) style attack in all four cases, whereas when an oscilloscope is used only the stable oscillator setup is successful. This work also develops the hardware to recover the internal clock of a device which does not have an externally available clock. It is possible to implement this scheme in software only, allowing it to work with existing oscilloscope-based test environments.Category / Keywords: implementation / side-channel analysis, acquisition, synchronization, DPA Original Publication (in the same form): Journal of Cryptographic Engineering (JCEN)