75 research outputs found
Two classes of LCD BCH codes over finite fields
BCH codes form an important subclass of cyclic codes, and are widely used in
compact discs, digital audio tapes and other data storage systems to improve
data reliability. As far as we know, there are few results on -ary BCH codes
of length . This is because it is harder to deal with
BCH codes of such length. In this paper, we study -ary BCH codes with
lengths and . These two classes of BCH codes
are always LCD codes. For , the dimensions of
narrow-sense BCH codes of length with designed distance are determined, where and .
Moreover, the largest coset leader is given for and the first two largest
coset leaders are given for . The parameters of BCH codes related to the
first few largest coset leaders are investigated. Some binary BCH codes of
length have optimal parameters. For ternary narrow-sense
BCH codes of length , a lower bound on the minimum distance of their
dual codes is developed, which is good in some cases
New binary and ternary LCD codes
LCD codes are linear codes with important cryptographic applications.
Recently, a method has been presented to transform any linear code into an LCD
code with the same parameters when it is supported on a finite field with
cardinality larger than 3. Hence, the study of LCD codes is mainly open for
binary and ternary fields. Subfield-subcodes of -affine variety codes are a
generalization of BCH codes which have been successfully used for constructing
good quantum codes. We describe binary and ternary LCD codes constructed as
subfield-subcodes of -affine variety codes and provide some new and good LCD
codes coming from this construction
Euclidean and Hermitian LCD MDS codes
Linear codes with complementary duals (abbreviated LCD) are linear codes
whose intersection with their dual is trivial. When they are binary, they play
an important role in armoring implementations against side-channel attacks and
fault injection attacks. Non-binary LCD codes in characteristic 2 can be
transformed into binary LCD codes by expansion. On the other hand, being
optimal codes, maximum distance separable codes (abbreviated MDS) have been of
much interest from many researchers due to their theoretical significant and
practical implications. However, little work has been done on LCD MDS codes. In
particular, determining the existence of -ary LCD MDS codes for
various lengths and dimensions is a basic and interesting problem. In
this paper, we firstly study the problem of the existence of -ary
LCD MDS codes and completely solve it for the Euclidean case. More
specifically, we show that for there exists a -ary Euclidean
LCD MDS code, where , or, , and . Secondly, we investigate several constructions of new Euclidean
and Hermitian LCD MDS codes. Our main techniques in constructing Euclidean and
Hermitian LCD MDS codes use some linear codes with small dimension or
codimension, self-orthogonal codes and generalized Reed-Solomon codes
Constructions of optimal LCD codes over large finite fields
In this paper, we prove existence of optimal complementary dual codes (LCD
codes) over large finite fields. We also give methods to generate orthogonal
matrices over finite fields and then apply them to construct LCD codes.
Construction methods include random sampling in the orthogonal group, code
extension, matrix product codes and projection over a self-dual basis.Comment: This paper was presented in part at the International Conference on
Coding, Cryptography and Related Topics April 7-10, 2017, Shandong, Chin
On Hull-Variation Problem of Equivalent Linear Codes
The intersection () of a linear code and its Euclidean dual (Hermitian dual ) is called the Euclidean
(Hermitian) hull of this code. The construction of an entanglement-assisted
quantum code from a linear code over or depends
essentially on the Euclidean hull or the Hermitian hull of this code. Therefore
it is natural to consider the hull-variation problem when a linear code is transformed to an equivalent code . In this paper
we introduce the maximal hull dimension as an invariant of a linear code with
respect to the equivalent transformations. Then some basic properties of the
maximal hull dimension are studied. A general method to construct
hull-decreasing or hull-increasing equivalent linear codes is proposed. We
prove that for a nonnegative integer satisfying , a
linear self-dual code is equivalent to a linear -dimension hull
code. On the opposite direction we prove that a linear LCD code over satisfying and is equivalent to a linear
one-dimension hull code under a weak condition. Several new families of
negacyclic LCD codes and BCH LCD codes over are also constructed.
Our method can be applied to the generalized Reed-Solomon codes and the
generalized twisted Reed-Solomon codes to construct arbitrary dimension hull
MDS codes. Some new EAQEC codes including MDS and almost MDS
entanglement-assisted quantum codes are constructed. Many EAQEC codes over
small fields are constructed from optimal Hermitian self-dual codes.Comment: 33 pages, minor error correcte
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