The amount of information leakage of decryption keys through timing attacks on RSA decryption system

摘要

The running time of an RSA decryption program indicates a certain information of the concealed decryption key due to the correlation between the running time and the key. However, it is not easy to estimate the amount of leaked information because practical decryption programs are complicated in general. This study focuses on two simple RSA decryption algorithms, and derives well-defined formulas of the mutual information between the running time and the decryption key. The formulas contribute to the quantitative discussion of the possible risk of passive timing attacks.