EN INFORMATIQUE

iii Cryptanalysis is the science which evaluates the security of a cryptosystem and detects its weaknesses and flaws. Initially confined to the black-box model, where only the input and output data were considered, cryptanalysis is now broadened to the security evaluation of the physical implementation of a cryptosystem. The implementation attacks which compose physical cryptanalysis are divided into fault attacks, exploiting the effect of disruption of the normal functioning of the device, and side-channel attacks, exploiting the dependency between the instructions and data (including key bits) processed by a device and its physical characteristics (e.g. execution time, power consumption, electromagnetic (EM) radiations). In the scope of this thesis, we particularly focus on the latter attacks. “Every computation leaks information ” and lowering the physical leakages of an implementation is indeed a complex task both from cryptographic and engineering viewpoints, especially when performance and cost enter the equation. The develop