Title: Assessing the vulnerability of cryptographic countermeasures.

Abstract: Thanks to the mathematical robustness of modern cryptosystems, the classic pen-and-paper-based cryptanalyis techniques fail to breach their security. Nowadays, the most dangerous vulnerabilities are due to side channel attacks, based on the statistical analysis of data leaking from the physical implementation of a cryptosystem (e.g., power consumption, electromagnetic radiation and sound). Countermeasures can then be designed, by randomly masking the sensitive variables to make them statistically independent from the input data. In this talk, by way of example, we first introduce Advanced Encryption Standard (AES), the most commonly used symmetric key cryptographic algorithm. Next, we describe a tool for assessing the effective protection order in the implementation of a specific type of countermeasures (Boolean-additive masking). To achieve this goal, we promote the search for vulnerabilities from a statistical problem to a purely symbolic analysis of the variables involved.