A New Approach for Implementing the MPL Method toward Higher SPA Resistance

The information security is emphasized with a development of Internet systems. In the measures as securing digital information, there are cryptosystems that protect secrecy of digital documents and digital signature scheme that ensure validity of digital documents. In the case of reality, i.e. hardware devices are used in cryptosystems, there is a possibility that secret information leaks via side-channel. Simple power analysis (SPA) attacks are one of the side-channel attacks. To prevent a SPA, one of the side-channel attacks, the Montgomery powering ladder (MPL) method has been considered as one of the countermeasures. In this paper, we show that a naive implementation of the MPL method is vulnerable for SPA attacks by observing the power consumption of the controller block of the RSA hardware. Furthermore, in order to avoid such information leakage, we propose a new hardware architecture for RSA using the MPL method to enhance SPA resistance.