Analysis on the parameter selection method for FLUSH+RELOAD based cache timing attack on RSA

FLUSH+RELOAD attack is recently proposed as a new type of Cache timing attacks. There are three essential factors in this attack, which are monitored instructions, threshold and waiting interval. However, existing literature seldom exploit how and why they could affect the system. This paper aims to study the impacts of these three parameters, and the method of how to choose optimal values. The complete rules for choosing the monitored instructions based on necessary and sufficient condition are proposed. How to select the optimal threshold based on Bayesian binary signal detection principal is also proposed. Meanwhile, the time sequence model of monitoring is constructed and the calculation of the optimal waiting interval is specified. Extensive experiments are conducted on RSA implemented with binary square-and-multiply algorithm. The results show that the average success rate of full RSA key recovery is 89.67%.