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.