Microcontroller Implementation of Simultaneous Protections Against Observation and Perturbation Attacks for ECC

Scalar multiplication is the main operation in elliptic curve cryptography. In embedded systems, it is vulnerable to both observation and perturbation attacks. Most of protections only target one of these two types of attacks. Unfortunately, many protections against one type of attack may reduce the protection against the other one. In this paper, we simultaneously deal with protections against both types of attacks. Two countermeasures are presented for scalar multiplication and implemented on a Cortex-M0 microcontroller. The first one protects finite field operations over point coordinates. The second one protects the scalar (or key) bits.