On Galois LCD codes and LCPs of codes over mixed alphabets

TL;DR

This paper characterizes Galois LCD codes over mixed alphabets, provides enumeration formulas, classifies specific cases, and explores applications in security and communication channels.

Contribution

It introduces new characterizations, enumeration methods, and classifications of Galois LCD and LCP codes over mixed alphabets, with applications in security and communication.

Findings

Monomial equivalence to Euclidean and Galois LCD codes under certain conditions

Enumeration formulas for Euclidean and Hermitian LCD codes

Classification of specific LCD codes over mixed alphabets

Abstract

Let $\mathtt{R}$ be a finite commutative chain ring with the maximal ideal $\gamma\mathtt{R}$ of nilpotency index $e\geq 2,$ and let $\check{\mathtt{R}}=\mathtt{R}/\gamma^{s}\mathtt{R}$ for some positive integer $ s< e.$ In this paper, we study and characterize Galois $\mathtt{R}\check{\mathtt{R}}$-LCD codes of an arbitrary block-length. We show that each weakly-free $\mathtt{R}\check{\mathtt{R}}$-linear code is monomially equivalent to a Galois $\mathtt{R}\check{\mathtt{R}}$-LCD code when $|\mathtt{R}/\gamma\mathtt{R}|>4,$ while it is monomially equivalent to a Euclidean $\mathtt{R}\check{\mathtt{R}}$-LCD code when $|\mathtt{R}/\gamma\mathtt{R}|>3.$ We also obtain enumeration formulae for all Euclidean and Hermitian $\mathtt{R}\check{\mathtt{R}}$-LCD codes of an arbitrary block-length. With the help of these enumeration formulae, we classify all Euclidean $\mathbb{Z}_4 \mathbb{Z}_{2}$-LCD codes and $\mathbb{Z}_9 \mathbb{Z}_{3}$-LCD codes of block-lengths $(1,1),$ $(1,2),$ $(2,1),$ $(2,2),$ $(3,1)$ and $(3,2)$ and all Hermitian $\frac{\mathbb{F}_{4}[u]}{\langle u^2\rangle} \;\mathbb{F}_{4}$-LCD codes of block-lengths $(1,1),$ $(1,2),$ $(2,1)$ and $(2,2)$ up to monomial equivalence. Apart from this, we study and characterize LCPs of $\mathtt{R}\check{\mathtt{R}}$-linear codes. We further study a direct sum masking scheme constructed using LCPs of $\mathtt{R}\check{\mathtt{R}}$-linear codes and obtain its security threshold against fault injection and side-channel attacks. We also discuss another application of LCPs of $\mathtt{R}\check{\mathtt{R}}$-linear codes in coding for the noiseless two-user adder channel.