Advanced Encoding Techniques for Secure White-Box Implementations 🔐

Authors: Alberto Battistello, Laurent Castelnovi and Thomas Chabrier
Conference: CARDIS 2021, Nov 11-12 2021

Abstract:
Designing a robust white-box implementation against state-of-the-art algebraic and differential computational analysis attacks is a challenging problem. The study of white-box security was revamped by recent advances involving grey box attacks. Since then, many authors have struggled to protect implementations against such new attacks. New designs as well as new security notions appeared, and white-box research in general seems to have greatly benefited from such advances. The current research aims at finding the best encodings and masking schemes to resist tracing attacks. In this perspective we suggest a new encoding scheme that can be applied to white-box designs. By using a modified version of the Benaloh cryptosystem, our design introduces semi-homomorphic properties to the encoding. To the best of our knowledge, this is the first time such properties are applied to an encoding design. This allows reducing the memory requirements and providing a better resistance against tracing attacks. Our encoding is versatile and can be adapted to different ciphers, and in most cases it provides performance improvements with respect to the state-of-the-art.