This paper analyzes the resistance of smart-card implementations of elliptic curve cryptography against side-channel attacks, and more specifically against attacks using differential power analysis (DPA) and variants thereof. The use of random curve isomorphisms is a promising way (in terms of efficiency) for thwarting DPA-type for elliptic curve cryptosystems but its implementation needs care.
Various generalized DPA-type attacks are presented against improper implementations. Namely, a second-order DPA-type attack is mounted against an additive variant of randomized curve isomorphisms and a “refined” DPA-type attack against a more general variant. Of independent interest, this paper also provides an exact analysis of second-order DPA-type attacks.