Successful attack on an FPGA-based WDDL DES cryptoprocessor without place and route constraints

In this paper, we propose a preprocessing method to improve side channel attacks (SCAs) on dual-rail with precharge logic (DPL) countermeasure family. The strength of our method is that it uses intrinsic characteristics of the countermeasure: classical methods fail when the countermeasure is perfect, whereas our method still works and enables us to perform advanced attacks. We have experimentally validated the proposed method by attacking a DES cryptoprocessor embedded in a field programmable gates array (FPGA), and protected by the wave dynamic differential logic (WDDL) countermeasure. This successful attack, unambiguous as the full key is retrieved, is the first to be reported.