Paper 2021/396

LESS-FM: Fine-tuning Signatures from the Code Equivalence Problem

Alessandro Barenghi, Jean-Francois Biasse, Edoardo Persichetti, and Paolo Santini

Abstract

Code-based cryptographic schemes are highly regarded among the quantum-safe alternatives to current standards. Yet, designing code-based signatures using traditional methods has always been a challenging task, and current proposals are still far from the target set by other post-quantum primitives (e.g. lattice-based). In this paper, we revisit a recent work using an innovative approach for signing, based on the hardness of the code equivalence problem. We introduce some optimizations and provide a security analysis for all variants considered. We then show that the new parameters produce instances of practical interest.

Note: This is the extended version of a work published at PQCrypto 2021. Several parts of this manuscript, most notably those concerning a detailed security analysis (e.g. Section 4, as well as Appendices E and F) have not yet appeared in literature, and are to be considered original work.