Side channel cryptanalysis

Cryptology includes cryptography and cryptanalysis technics. Cryptography is managed by Kerckhoffs principles, so any information related to a cryptosystem can be public except the keys. The cryptanalysis is the sum of a lot of very advanced technics in order to find these keys. The controversy about the Data Encryption Standard security has highly contributed to the development of new cryptanalysis methods based on mathematics. The linear and differentials analysis are the most convincing examples. Although these techniques often require great quantities of plain texts and ciphered texts, there are other very powerful methods based on the involuntary "information leakage". Indeed a cryptosystem can leak information in various manners, thus significant data can be extracted from physical signals emitted by the ciphering device. which can be extremely dangerous. It is then possible to define side channel. The side channel cryptanalysis has been the speciality of secret services for a long time, but ten years ago, the scientific world started contributing to develop new side channel very effective technics.