International Association
for Cryptologic Research

The key encapsulation mechanism FrodoKEM is a post-quantum algorithm based on plain LWE. While it has not been selected by the NIST for standardization, FrodoKEM shares a lot of similarities with the lattice-based standard ML-KEM and offers strong security assumptions by relying on the unstructured version of the LWE problem. This leads FrodoKEM to be recommended by European agencies ANSSI and BSI as a possible choice to obtain post-quantum security. In this paper, we discuss the practical aspects of incorporating side-channel protections in FrodoKEM by describing a fully masked version of the scheme based on several previous works on LWE-based KEMs. Furthermore, we propose an arbitrary order C implementation based on the reference code and a Cortex-M4 implementation with gadgets specialized at order 1 in low level assembly code that incorporates bespoke modifications to thwart (micro-)architectural leakages. Finally, we validate our order 1 gadgets by performing TVLA on a ChipWhisperer.