Analysis of the error correction capability of LDPC and MDPC codes under parallel bit-flipping decoding and application to cryptography

TL;DR

This paper develops a theoretical framework to accurately bound the error correction capabilities of LDPC and MDPC codes under parallel bit-flipping decoding, crucial for cryptography applications requiring guaranteed low error rates.

Contribution

It introduces a rigorous, assumption-free analysis method for error correction bounds, especially for codes with small girth, applicable to cryptography security assessments.

Findings

Derived tight bounds on error rates for LDPC and MDPC codes

Provided guaranteed error correction capability for single-iteration decoding

Applied bounds to enhance cryptographic security analysis

Abstract

Iterative decoders used for decoding low-density parity-check (LDPC) and moderate-density parity-check (MDPC) codes are not characterized by a deterministic decoding radius and their error rate performance is usually assessed through intensive Monte Carlo simulations. However, several applications, like code-based cryptography, need guaranteed low values of the error rate, which are infeasible to assess through simulations, thus requiring the development of theoretical models for the error rate of these codes under iterative decoding. Some models of this type already exist, but become computationally intractable for parameters of practical interest. Other approaches approximate the code ensemble behaviour through some assumptions, which may not hold true for a specific code. We propose a theoretical analysis of the error correction capability of LDPC and MDPC codes that allows deriving tight bounds on the error rate at the output of parallel bit-flipping decoders. Special attention is devoted to the case of codes with small girth; moreover, single-iteration decoding is investigated through a rigorous approach, which does not require any assumption and hence results in a guaranteed error correction capability for any single code. We show an example of application of the new bound to the context of code-based cryptography, where guaranteed error rates are needed to achieve some strong security levels.