Technical Report TR-98-3, LCIS, Tamkang University, Taiwan, R.O.C., March 1998.

Abstract. This report presents a simple method of protection against fault analysis when the underpinning cryptosystem uses modular arithmetic. The proposed method applies whatever the modular function to be evaluated and the used algorithms. Moreover, it only requires a very little overhead of extra computations, especially when the modulus is represented in diminished-radix form or when at least one factor of the modulus is known.