INFORMATION SECURITY DEVICE, INFORMATION SECURITY METHOD, COMPUTER PROGRAM, COMPUTER-READABLE RECORDING MEDIUM, AND INTEGRATED CIRCUIT

摘要

Provided is an information security device for protection against a simple power attack (SPA) to a security device such as the RSA encryption. The information security device uses multiplication with 1 in the Montgomery region. 1 in the Montgomery region is decided depending on an integer k greater than the bit quantity of modulus p and the modulus. Accordingly, an attacker not knowing the p and the k cannot easily perform analysis. Even if the analyzer can predict the Hamming weight, it is possible to further improve the safety against the SPA by modifying the k or the modulus at random.