Path swapping method to improve DPA resistance of quasi delay insensitive asynchronous circuits

Abstract

This paper presents a Path Swapping (PS) method which enables to enhance the security of Quasi Delay Insensitive Asynchronous Circuits against Power Analysis (PA) attack. This approach exploits the logical symmetries of the QDI asynchronous blocks, particularly its data-path redundancies, to make all electrical curves used when implementing a PA attacks useless. Indeed, the idea is to average the electrical signatures of a block by randomly exchanging its data-paths during processing. To be able to implement this approach, we adopted a formal model of QDI circuits. Firstly, this formal model enables the designer to formally verify the symmetry of all paths in order to apply a path swapping method. Secondly, it offers the possibility to model the electrical signature of QDI asynchronous circuits. Finally, applying DPA on this formal model allows us to evaluate, in an early phase of the design, the circuit's sensitivity to the relevancy of the approach. Electrical simulations performed on a DES crypto-processor confirm the efficiency of the technique. © International Association for Cryptologic Research 2006.