Evaluation Criterion of Side-Channel Countermeasures for Elliptic Curve Cryptography Devices

The Elliptic Curve Cryptography (ECC) is widely deployed into embedded cryptographic devices. However, straightforward implementations of ECC are prone to side-channel analysis attacks. A number of countermeasures against side-channel analysis attacks exist with different effectiveness and efficiency. How to evaluate these countermeasures with a unified and quantitative criterion becomes a challenging task. This paper presents an evaluation criterion using the ratio between the security factor and the computational cost, to assess the efficiency and effectiveness of side-channel countermeasures. The security factor statistically measures the similarity between operations processing bit `0´ and those processing bit `1´. The computation cost measures the number of atomic operations in the scalar multiplication. Experiment results on smart cards with three different countermeasures demonstrate the feasibility of the proposed evaluation criterion.