7 research outputs found
Construction of isodual codes from polycirculant matrices
Double polycirculant codes are introduced here as a generalization of double
circulant codes. When the matrix of the polyshift is a companion matrix of a
trinomial, we show that such a code is isodual, hence formally self-dual.
Numerical examples show that the codes constructed have optimal or
quasi-optimal parameters amongst formally self-dual codes. Self-duality, the
trivial case of isoduality, can only occur over \F_2 in the double circulant
case. Building on an explicit infinite sequence of irreducible trinomials over
\F_2, we show that binary double polycirculant codes are asymptotically good
Constructing formally self-dual codes from block ƛ-circulant matrices
In this work, construction methods for formally self-dual codes are generalized in the form of block lambda-circulant matrices. The constructions are applied over the rings F_2,R1 = F_2 + uF_2 and S = F_2[u]=(u^3-1). Using n-block lambda-circulant matrices for suitable integers n and units lambda, many binary FSD codes (as Gray images) with a higher minimum distance than best known self-dual codes of lengths 34, 40, 44, 54, 58, 70, 72 and 74 were obtained. In particular, ten new even FSD [72, 36, 14] codes were constructed together with eight new near-extremal FSD even codes of length 44 and twentyfive new near-extremal FSD even codes of length 36
Formally Unimodular Packings for the Gaussian Wiretap Channel
This paper introduces the family of lattice-like packings, which generalizes
lattices, consisting of packings possessing periodicity and geometric
uniformity. The subfamily of formally unimodular (lattice-like) packings is
further investigated. It can be seen as a generalization of the unimodular and
isodual lattices, and the Construction A formally unimodular packings obtained
from formally self-dual codes are presented. Recently, lattice coding for the
Gaussian wiretap channel has been considered. A measure called secrecy function
was proposed to characterize the eavesdropper's probability of correctly
decoding. The aim is to determine the global maximum value of the secrecy
function, called (strong) secrecy gain.
We further apply lattice-like packings to coset coding for the Gaussian
wiretap channel and show that the family of formally unimodular packings shares
the same secrecy function behavior as unimodular and isodual lattices. We
propose a universal approach to determine the secrecy gain of a Construction A
formally unimodular packing obtained from a formally self-dual code. From the
weight distribution of a code, we provide a necessary condition for a formally
self-dual code such that its Construction A formally unimodular packing is
secrecy-optimal. Finally, we demonstrate that formally unimodular
packings/lattices can achieve higher secrecy gain than the best-known
unimodular lattices.Comment: Accepted for publication in IEEE Transactions on Information Theory.
arXiv admin note: text overlap with arXiv:2111.0143
Complementary Dual Codes for Counter-measures to Side-Channel Attacks
We recall why linear codes with complementary duals (LCD codes) play a role in counter-measures to passive and active side-channel analyses on embedded cryptosystems. The rate and the minimum distance of such LCD codes must be as large as possible. We investigate primary constructions of such codes, in particular with cyclic codes, specifically with generalized residue codes, and we study their idempotents. We study those secondary constructions which preserve the LCD property, and we characterize conditions under which codes obtained by puncturing, shortening or extending codes, or obtained by the Plotkin sum, can be LCD
Self-dual codes, subcode structures, and applications.
The classification of self-dual codes has been an extremely active area in coding theory since 1972 [33]. A particularly interesting class of self-dual codes is those of Type II which have high minimum distance (called extremal or near-extremal). It is notable that this class of codes contains famous unique codes: the extended Hamming [8,4,4] code, the extended Golay [24,12,8] code, and the extended quadratic residue [48,24,12] code. We examine the subcode structures of Type II codes for lengths up to 24, extremal Type II codes of length 32, and give partial results on the extended quadratic residue [48,24,12] code. We also develop a generalization of self-dual codes to Network Coding Theory and give some results on existence of self-dual network codes with largest minimum distance for lengths up to 10. Complementary Information Set (CIS for short) codes, a class of classical codes recently developed in [7], have important applications to Cryptography. CIS codes contain self-dual codes as a subclass. We give a new classification result for CIS codes of length 14 and a partial result for length 16