Date Added: Jan 2012
Inserting random delays in cryptographic implementations is often used as a countermeasure against side-channel attacks. Most previous works on the topic focus on improving the statistical distribution of these delays. For example, efficient random delay generation algorithms have been proposed at CHES 2009/2010. These solutions increase security against attacks that solve the lack of synchronization between different leakage traces by integrating them. In this paper, the authors demonstrate that integration may not be the best tool to evaluate random delay insertions. For this purpose, they first describe different attacks exploiting pattern recognition techniques and Hidden Markov Models.