Polynomial multiplication algorithms such as Toom-Cook and the Number Theoretic Transform are fundamental building blocks for lattice-based post-quantum cryptography. In this work we present correlation power-analysis-based side-channel analysis methodologies targeting every polynomial multiplication strategy for all lattice-based post-quantum key encapsulation mechanisms in the final round of the NIST post-quantum standardization procedure. We perform practical experiments on real side-channel measurements, demonstrating that our method allows to extract the secret key from all lattice-based post-quantum key encapsulation mechanisms. Our analysis shows that the used polynomial multiplication strategy can significantly impact the time complexity of the attack.

This paper is the first to present an implementation of a cryptographic circuit in 28nm FD-SOI using near-threshold design. The implemented cipher, Ketje Jr, is a lightweight authenticated encryption algorithm. The energy consumption of representative authenticated encryption operations as well as the information leakage through the power consumption side-channel are evaluated. The results show that an ultra-low energy implementation can be achieved, and that the near-threshold design has little influence on the Signal to Noise Ratio in the power measurements of our chip.