Hardware-fault attack handling in RNS-based Montgomery multipliers

Hardware-fault attacks have become a prominent threat against secure cipher implementations. Faults are deliberately introduced during the operation of cryptographic hardware so that, based on the faulty outputs, secret keys may be recovered. This work focuses on the RSA-CRT algorithm, which, although famous and widely exploited, is known to be vulnerable to hardware-fault attacks. Most of the counter measures, proposed in the literature for this algorithm, are based on number theory techniques that apply at a protocol level. In these cases, security is offered at the cost of extra operations in the RSA-CRT protocol. Unlike these solutions, this work examines the security potential offered by hardware implementations. It attempts to prove that the use of a well-designed, residue-arithmetic, Montgomery multiplier overcomes hardware-fault attack threats, with no need to alter the basic RSA-CRT protocol.