Paper 2024/1968

SoK: Pseudorandom Generation for Masked Cryptographic Implementation

Abstract

This paper investigates pseudorandom generation in the context of masked cryptographic implementation. Although masking and pseudorandom generators (PRGs) have been distinctly studied for a long time, little literature studies how the randomness in the masked implementation should be generated. The lack of analysis on mask-bits generators makes the practical security of masked cryptographic implementation unclear, and practitioners (e.g., designer, implementer, and evaluator) may be confused about how to realize it. This paper provides a novel viewpoint and comprehensive analyses by developing new three models, which correspond to respective practical scenarios of leakage assessment, quantitative evaluation of side-channel security (e.g., success rate), and practical deployment. We reveal what properties are required for each scenario. In particular, we support a long-held belief/folklore with a proof: for the output of PRG for masking, cryptographic security (i.e., randomness and unpredictability) is sufficient but not necessary, but only a statistical uniformity is necessary. In addition, we thoroughly investigate the SCA security of PRGs in the wild in the masking context. We conclude this paper with some recommendations for practitioners, with a proposal of leakage-resilient method of comparative performance.