LEDAkem: a post-quantum key encapsulation mechanism based on QC-LDPC codes

TL;DR

LEDAkem is a new post-quantum key encapsulation mechanism based on QC-LDPC codes, offering high speed, compact keys, and quantum-resistant security, with improved decoding algorithms and practical implementation results.

Contribution

It introduces LEDAkem, a novel code-based KEM utilizing QC-LDPC codes with faster decoding and quantum security considerations, advancing post-quantum cryptography.

Findings

Achieves high decoding speeds with a new decoding algorithm.

Provides compact key sizes suitable for practical deployment.

Demonstrates security against classical and quantum attacks.

Abstract

This work presents a new code-based key encapsulation mechanism (KEM) called LEDAkem. It is built on the Niederreiter cryptosystem and relies on quasi-cyclic low-density parity-check codes as secret codes, providing high decoding speeds and compact keypairs. LEDAkem uses ephemeral keys to foil known statistical attacks, and takes advantage of a new decoding algorithm that provides faster decoding than the classical bit-flipping decoder commonly adopted in this kind of systems. The main attacks against LEDAkem are investigated, taking into account quantum speedups. Some instances of LEDAkem are designed to achieve different security levels against classical and quantum computers. Some performance figures obtained through an efficient C99 implementation of LEDAkem are provided.