Defeating state-of-the-art white-box countermeasures with advanced gray-box attacks

• DOI: 10.13154/tches.v2020.i3.454-482
• Publication Date: 2020-01-01
• Authors: Louis Goubin; Matthieu Rivain; Junwei Wang
• Keywords: Gray (unit); White box; White (mutation); S-box; Box Office

The goal of white-box cryptography is to protect secret keys embedded in a cryptographic software deployed in an untrusted environment. In this article, we revisit state-of-the-art countermeasures employed in white-box cryptography, and we discuss possible ways to combine them. Then we analyze the different gray-box attack paths and study their performances in terms of required traces and computation time. Afterward, we propose a new paradigm for the gray-box attack against white-box cryptography, which exploits the data-dependency of the target implementation. We demonstrate that our approach provides substantial complexity improvements over the existing attacks. Finally, we showcase this new technique by breaking the three winning AES-128 white-box implementations from WhibOx 2019 white-box cryptography competition.