Improvement of Side-Channel Attacks on Mitaka
摘要
Mitaka is a variant of Falcon, which is one of the three post-quantum signature schemes selected by the NIST for standardization. Introduced in 2021, Mitaka offers a simpler, parallelizable, and maskable version of Falcon. Our article focuses on its physical security, and our results are threefold. Firstly, we enhance a known profiled side-channel attack on an unprotected Mitaka implementation by a factor of 512. Secondly, we analyze the masked implementation of Mitaka described in the reference article, which incorporates a different sampler and a protective gadget. We expose the first side-channel flaw on this sampler. This flaw enables to break the masked implementation with a first-order side-channel attack. In this scenario, the key can be recovered using only three times more traces compared to the attack on the unprotected implementation. Finally, we discuss and recommend new countermeasures to mitigate these attacks.