A Method for Preventing ”Skipping” Attacks

Abstract—Until recently, known fault attacks against (non-CRT) exponentiation-based cryptosystems were supposed to be of rather theoretical nature, as they require a precise fault injection, e.g., a bit flip. However, Schmidt and Herbst (FDTC 2008) reported practical fault-attacks against RSA in standard mode using low-cost equipment. Although their attacks were described against RSA, they readily extend to any other exponentiation-based cryptosystem. This paper describes an efficient method to prevent those new attacks. Keywords-RSA cryptosystem; exponentiation-based cryp-tosystems; fault attacks; skipping attacks; countermeasures. I