To infinity and beyond: Combined attack on ECC using points of low order

Abstract

We present a novel combined attack against ECC implementations that exploits specially crafted, but valid input points. The core idea is that after fault injection, these points turn into points of very low order. Using side channel information we deduce when the point at infinity occurs during the scalar multiplication, which leaks information about the secret key. In the best case, our attack breaks a simple and differential side channel analysis resistant implementation with input/output point validity and curve parameter checks using a single query. © 2011 International Association for Cryptologic Research.