讲座题目: How can alpha-information theory formally prove that your sensitive circuits are protected against side-channel attacks?

讲座摘要: Cryptographic algorithms are ubiquitous in our digital society. Principles (such as Kerckhoffs’) and mathematical techniques for securing data against cryptanalysis are well established, even with future quantum computers: the best attacks of this type are essentially brute force, which takes several times the age of the universe.

However, one real threat is that algorithm implementations are vulnerable to side-channel attacks, that exploit sensitive information leaks to recover the secret in a “divide and conquer” approach. Some attacks only require a few queries (leakage measurements). Thus, the question is not whether you are secure or not, since it is only a matter of time. The question is how much you can be secure, e.g. with a protected implementation that use data masking.

For that, we need a formal evaluation.

In this talk, I present such a formal evaluation using alpha-information theory, based on Rényi alpha-divergence and alpha-entropy, and Sibson’s alpha-information. The parameter alpha can be positive or negative, and the limiting case alpha = minus infinity is related to the important notion of Doeblin coefficient, which can be used to reduce the noisy leakage model to a random probing model. Fano and data processing inequalities, as well as Mrs. Gerber’s lemma in the case of additive masking, are used to establish lower bounds on the number of queries that any attacker has to make to achieve a given level of success. In this way, it is possible to be proactive, for example with ephemeral keys, to maintain the security of an implementation.

讲座时间：2025年7月15日（周二）上午9:30

讲座方式：线下举办（综合大楼-806）

嘉宾简介：Olivier Rioul现任法国巴黎理工学院（Institut Polytechnique de Paris）下属巴黎高等电信学院（Télécom Paris）通信与电子系教授。他毕业于法国巴黎综合理工学院（École Polytechnique）及巴黎国立高等电信学院（École Nationale Supérieure des Télécommunications），并获博士学位。其研究领域涵盖应用数学，尤其聚焦信息论在统计学不等式、硬件安全及实验心理学等多元场景的创新应用。论文总引用量达到九千多，h指数32。二十年来，他持续在多所高校讲授信息论与统计学课程，其编著的教科书已成为该领域法文文献中的经典著作。