turkmath.org

Fault cryptanalysis, is based on the fact that computing devices (by chance or forced) can do faulty computations; that is, in a computation or process unpredictable factor can cause errors in in the process itself or the values that are involved in the process. This attack, originally proposed by Boneh, Dellimo and Lipton from Bellcore, can be divided into two steps: first making a system to blunder and second abuse the information produced by this blunder. Each iteration consisted of these two steps may give different information for different systems; e.g. in RSA it may cause to factorize the modulus and in DSA it may give one bit of secret key. So depending on the target system, attacker may have to apply the mentioned two steps just once or many times and again depending on the target system, the attack may be done easily with low time complexity or may be done hard with high time complexity. An important issue about vulnerability or immunity of a system to the attack is the implementation of the systems; factors like speed of the algorithm or being, so to say, hardware friendly, changes the algorithms behavior to the attack. In this presentation we talk about different fault cryptanalysis technics on smart-card like devices, their vulnerabilities toward this technic as well as possible precautions.