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Permutation polynomials with low boomerang uniformity have wide applications in cryptography. In this paper, by utilizing the Weil sums technique and solving some certain equations over 픽2n, we determine the boomerang uniformity of these permutation polynomials: (1) f1(x) = (x2m + x + δ)22m+1 + x, where n = 3m, δ ∈ 픽2n with Trmn(δ) = 1; (2) f2(x) = (x2m + x + δ)22m−1+2m−1 + x, where n = 3m, δ ∈ 픽2n with Trmn(δ) = 0; (3) f3(x) = (x2m + x + δ)23m−1+2m−1 + x, where n = 3m, δ ∈ 픽2n with Trmn(δ) = 0. The results show that the boomerang uniformity of f1(x), f2(x) and f3(x) can attain 2n. [ABSTRACT FROM AUTHOR]

In this study, we proposed a novel method that integrates density functional theory (DFT) with the finite field method to accurately estimate the polarizability and dielectric constant of polymers. Our approach effectively accounts for the influence of electronic and geometric conformation changed on the dielectric constant. We validated our method using polyethylene (PE) and polytetrafluoroethylene (PTFE) as benchmark materials, and found that it reliably predicted their dielectric constants. Furthermore, we explored the impact of conformation variations in poly(vinylidene fluoride) (PVDF) on its dielectric constant and polarizability. The resulting dielectric constants of α- and γ-PVDF (3.0) showed excellent agreement with crystalline PVDF in experiments. Our findings illuminate the relationship between PVDF's structural properties and its electrical behavior, offering valuable insights for material design and applications. [ABSTRACT FROM AUTHOR]

Permutation polynomials over finite fields constitute an active research area and have important applications in many areas of science and engineering. In this paper, several classes of permutation polynomials with trace functions are presented over F p n (p = 2 , 3) by investigating the number of solutions to special equations. [ABSTRACT FROM AUTHOR]

Our goal of this paper is to find a construction of all ℓ-quasi-cyclic self-dual codes over a finite field $ {\mathbb F}_q $ F q of length $ m\ell $ mℓ for every positive even integer ℓ. In this paper, we study the case where $ x^m-1 $ x m − 1 has an arbitrary number of irreducible factors in $ {\mathbb F}_q [x] $ F q [ x ] ; in the previous studies, only some special cases where $ x^m-1 $ x m − 1 has exactly two or three irreducible factors in $ {\mathbb F}_q [x] $ F q [ x ] , were studied. Firstly, the binary code case is completed: for any even positive integer ℓ, every binary ℓ-quasi-cyclic self-dual code can be obtained by our construction. Secondly, we work on the q-ary code cases for an odd prime power q. We find an explicit method for construction of all ℓ-quasi-cyclic self-dual codes over $ {\mathbb F}_q $ F q of length $ m\ell $ mℓ for any even positive integer ℓ, where we require that $ q \equiv 1 \pmod {4} $ q ≡ 1 (mod 4) if the index $ \ell \ge 6 $ ℓ ≥ 6. By implementation of our method, we obtain a new optimal binary self-dual code $ [172, 86, 24] $ [ 172 , 86 , 24 ] , which is also a quasi-cyclic code of index 4. [ABSTRACT FROM AUTHOR]

Let F q denote the finite field of order q. In this paper, we investigate the permutation property of the quadrinomial f (x) = x + a 1 x q (q − 1) + 1 + a 2 x q + a 3 x 2 (q − 1) + 1 over F q 2 , where q is odd and a 1 , a 2 , a 3 ∈ F q * . More precisely, we obtain the necessary and sufficient conditions for f (x) to be a permutation polynomial over F q 2 . [ABSTRACT FROM AUTHOR]

Let \mathbb {F}_q denote the finite field of characteristic p and order q. Let \mathbb {Z}_q denote the unramified extension of the p-adic rational integers \mathbb {Z}_p with residue field \mathbb {F}_q. Given two positive integers m,n, define a box \mathcal B_m to be a subset of \mathbb {Z}_q^n with q^{nm} elements such that \mathcal B_m modulo p^m is equal to (\mathbb {Z}_q/p^m \mathbb {Z}_q)^n. For a collection of nonconstant polynomials f_1,\dots,f_s\in \mathbb {Z}_q[x_1,\ldots,x_n] and positive integers m_1,\dots,m_s, define the set of common zeros inside the box \mathcal B_m to be \begin{equation*} V=\{X\in \mathcal B_m:\; f_i(X)\equiv 0\mod {p^{m_i}}\text { for all } 1\leq i\leq s\}. \end{equation*} It is an interesting problem to give the sharp estimates for the p-divisibility of |V|. This problem has been partially solved for the three cases: (i) m=m_1=\cdots =m_s=1, which is just the Ax-Katz theorem, (ii) m=m_1=\cdots =m_s>1, which was solved by Katz [Proc. Amer. Math. Soc. 137 (2009), pp. 4065–4075; Amer. J. Math. 93 (1971), pp. 485–499], Marshal and Ramage [Proc. Amer. Math. Soc. 49 (1975), pp. 35–38], and (iii) m=1, and m_1,\dots,m_s\geq 1, which was recently solved by Cao, Wan [Finite Fields Appl. 91 (2023), p. 25] and Grynkiewicz [ A generalization of the Chevalley-Warning and Ax-Katz theorems with a view towards combinatorial number theory , Preprint, arXiv: 2208.12895 , 2022]. Based on the multi-fold addition and multiplication of the finite Witt rings over \mathbb {F}_q, we investigate the remaining unconsidered case of m>1 and m\neq m_j for some 1\leq j\leq s, and finally provide a complete answer to this problem. [ABSTRACT FROM AUTHOR]

Given a prime power q and a positive integer n, let 픽 q n {\mathbb{F}_{q^{n}}} represent a finite extension of degree n of the finite field 픽 q {{\mathbb{F}_{q}}} . In this article, we investigate the existence of m elements in arithmetic progression, where every element is primitive and at least one is normal with prescribed norms. Moreover, for n ≥ 6 {n\geq 6} , q = 3 k {q=3^{k}} , m = 2 {m=2} we establish that there are only 10 possible exceptions. [ABSTRACT FROM AUTHOR]

This paper is aimed at using a lookup table method to improve the scalar multiplication performance of elliptic curve cryptography. The lookup table must be divided into two polynomials and requires two iterations of point doubling operation, for which negation operations are needed. It is well known that an inversion operation requires a lot of multiplication time. The advantage of this paper is that we are able to reduce one inverse element calculation for this problem and also improve the basic operations of finite fields through segmentation methods. If the normal basis method is used in the design of the inverse element operation, it must be converted to the normal basis through the standard basis. However, the conversion process requires a lot of matrix operations. Though the anti-element operation has good speed performance, it also increases the computational complexity. Using number theory and grouping methods will greatly improve the performance of inverse element operations. With application of the two-time point doubling operation in the hardware implementation, the developed approach reduces the computing time by 48% as compared with the conventional approach. The computational time of the scalar multiplication using the presented method is further improved by 67% over the traditional algorithm with only an area increase of 12%. Finally, the proposed lookup table-based technique can be utilized for software and hardware implementation, as the developed arithmetic operations are simple and are consistent in their execution. [ABSTRACT FROM AUTHOR]

The best known asymptotic bit complexity bound for factoring univariate polynomials over finite fields grows with d 1.5 + o (1) for input polynomials of degree d, and with the square of the bit size of the ground field. It relies on a variant of the Cantor–Zassenhaus algorithm which exploits fast modular composition. Using techniques by Kaltofen and Shoup, we prove a refinement of this bound when the finite field has a large extension degree over its prime field. We also present fast practical algorithms for the case when the extension degree is smooth. [ABSTRACT FROM AUTHOR]

For a finite field Fqn and a rational function f = f1/f2 ∈ Fqn(x), we present a sufficient condition for the existence of a primitive normal element α ∈ Fqn in such a way f(α) is also primitive in Fqn, where f(x) is a rational function in Fqn(x) of degree sum m (degree sum of f(x) = f1(x)/f2(x) is defined to be the sum of the degrees of f1(x) and f2(x)). Additionally, for rational functions of degree sum 4, we proved that there are only 37 and 16 exceptional values of (q, n) when q = 2k and q = 3k respectively. [ABSTRACT FROM AUTHOR]

By further exploring some ideas in Ding and Yin, the results on preimage distributions of a class of zero-difference balanced functions are extended and the parameters of a class of partitioned difference families are determined by means of self-conjugate Gauss sums over finite fields. [ABSTRACT FROM AUTHOR]

The rapid development of information technology puts forward new demands for signal sampling technology. Compressed sensing is a novel signal sampling theory that can realize signal sampling and compression simultaneously. The measurement matrix is the decisive factor affecting the reconstruction ability of compressed sensing. Therefore, the construction of measurement matrices is the key problem of compressed sensing theory. Taking full advantage of the finite field structure of the polynomial measurement matrix, a novel method for the deterministic measurement matrix based on two finite fields is proposed. In this paper, for more available choices of polynomial matrix and flexible signal length, a new expansion of polynomial sensing matrix is proposed by using two finite field. Experiments show that, the improved matrix offers more options of sensing matrix and overcome the shortcoming of fixed length measurement. Further comparisons to the block-polynomial method, show that the proposed two finite field polynomial matrix can improve the PSNR of reconstructed image by 10% ~ 15%. [ABSTRACT FROM AUTHOR]

Inspired by the Arnold chaotic map, we design a new generation formula for constructing S-boxes, which effectively integrates the characteristics and advantages of chaos map and algebraic model and lays a good foundation for producing strong S-boxes. Then, using this generation formula as the core component, we propose a scheme for constructing dynamic S-boxes. The proposed scheme is driven by a chaotic map and can efficiently generate a large number of S-boxes. Taking advantage of the ergodicity of chaotic system, our scheme can ensure that the generated S-boxes have both excellent comprehensive performance and good diversity. The experimental results in this paper also confirm that the dynamic S-boxes produced by our method not only meet the requirements of designing encryption algorithms but also provide stronger security for image encryption. Moreover, our scheme also has high efficiency in generating S-boxes. Therefore, our scheme has good application potential in cryptography, such as providing high-performance S-boxes for image security and designing encryption algorithms with dynamic S-boxes. [ABSTRACT FROM AUTHOR]

The classical n-variable Kloosterman sums over finite fields are well understood by Deligne’s theorem from complex point of view and by Sperber’s theorem from p-adic point of view. In this paper, we study the complex and p-adic estimates of invertedn-variable Kloosterman sums, addressing a question of Katz (Finite Fields Appl 1(3):395–398, 1995). We shall give two complex estimates. The first one is elementary based on Gauss sums. The second estimate is deeper, depending on the cohomological results of Adolphson–Sperber, Denef–Loeser and Fu for twisted toric exponential sums. This deeper result assumes that the characteristic p does not divide n + 1. Combining with Dwork’s p-adic theory, we also determine the exact p-adic valuations for zeros and poles of the L-function associated to invertedn-variable Kloosterman sums in the case p ≡ 1 mod (n + 1). As we shall see, the invertedn-variable Kloosterman sum is more complicated than the classical n-variable Kloosterman sum in all aspects in the sense that our understanding is less complete, partly because the Hodge numbers are now mostly 2 instead of 1. [ABSTRACT FROM AUTHOR]

Let Fq be the finite field of order q = pm where p is a prime, and m is a positive integer. This work introduces FqR-linear (Θ, ΔΘ)-cyclic codes where R = Fq + uFq with u² = u, i.e., (Θ, ΔΘ)-cyclic codes over FqR. With the help of the decomposition method, we study the structural properties and determine the generator polynomials of FqR-linear (Θ, ΔΘ)-cyclic codes. Further, we define the Gray map over FqR and find the Gray images of FqR-linear (Θ, ΔΘ)-cyclic codes over Fq. Finally, with the help of our established results, we have constructed some new codes corresponding to FqR-linear (Θ, ΔΘ)-cyclic codes. [ABSTRACT FROM AUTHOR]

The Polynomial Modular Number System (PMNS) offers an alternative to the conventional binary multi-precision representation system for large integers. Its effectiveness has been demonstrated for various cryptosystems using prime field arithmetic [2,4,6], with prime sizes ranging from 256 to 736 bits. However, as the size of $ p $ increases, the relative performance of PMNS compared to standard arithmetic diminishes. Furthermore, the generation process of a PMNS has a worst-case complexity of $ {\mathcal O}(2^n) $, where $ n $ denotes the number of symbols used to represent an integer modulo $ p $ in this representation system. In this paper, we present several alternatives and improvements to the construction and implementation processes of PMNS, which are tailored to the size of $ p $. [ABSTRACT FROM AUTHOR]

In this paper, using the classification of degree 7 permutations over F q , we classify certain sparse PPs of the form P (x) = x r f (x q n - 1 q - 1 ) of F q n for n = 2 and 3. In particular, we give necessary and sufficient conditions for the polynomial f a , b (x) : = x (x 2 (q 2 + q + 1) + a x q 2 + q + 1 + b) in F q 3 [ x ] to be a permutation polynomial over F q 3 , where q > 409 is a prime power. [ABSTRACT FROM AUTHOR]

In this paper, we construct three classes of permutation quadrinomials with Niho exponents of the form f (x) = α 0 x r + α 1 x s 1 (p m - 1) + r + α 2 x s 2 (p m - 1) + r + α 3 x s 3 (p m - 1) + r ∈ F p n [ x ] , where p is an odd prime, n = 2 m is a positive even integer, and (r , s 1 , s 2 , s 3) = (1 , - 1 p k - 2 , 1 , p k - 1 p k - 2) , (1 , p k + 1 p k + 2 , 1 , 1 p k + 2) and (3, 1, 2, 3), respectively. The exponents of the first two classes are considered for the first time, and the third class covers all the permutation polynomials proposed by Gupta (Designs Codes and Cryptography 88, 1–17, 2020). [ABSTRACT FROM AUTHOR]

Let $ \mathbb{F}_q $ be the finite field of order $ q $ where $ q = p^{k} $, $ k $ is a positive integer and $ p $ is an odd prime. Let $ \mathbb{F}_q^* $ represent the nonzero elements of $ \mathbb{F}_{q} $. For $ f(x_1, \cdots, x_n)\in\mathbb{F}_q[x_1, \cdots, x_n] $, we used $ N\big(f(x_1, \cdots, x_n) = 0\big) $ to denote the number of $ \mathbb{F}_q $-rational points of the affine hypersurface $ f(x_1, \cdots, x_n) = 0 $. In 2020, Zhao et al. obtained the explicit formulae for $ N(x_1^4+x_2^4 = c) $, $ N(x_1^4+x_2^4+x_3^4 = c) $ and $ N(x_1^4+x_2^4+x_3^4+x_4^4 = c) $ over $ \mathbb{F}_q $, with $ c\in\mathbb{F}_q^* $. In this paper, by using Jacobi sums and an analog of the Hasse-Davenport theorem, we arrived at explicit formulae for $ N(a_1x_1^4+a_2x_2^4 = c) $ and $ N(b_1x_1^4+b_2x_2^4+b_3x_3^4 = c) $ with $ a_i, b_j\in \mathbb{F}_q^* (1\leq i \leq 2, 1 \leq j \leq 3) $ and $ c\in \mathbb{F}_q $. Furthermore, by using the reduction formula for Jacobi sums, the number of rational points of the quartic diagonal hypersurface $ a_1x_1^4+a_2x_2^4+\cdots+a_nx_n^4 = c $ of $ n\geq 4 $ variables with $ a_i\in\mathbb{F}_q^* $ $ (1\leq i\leq n) $, $ c\in\mathbb{F}_q $ and $ p\equiv1({\rm{mod}} \ 4) $, can also be deduced. These extended and improved earlier results.

We consider all the non-metabelian groups $G$ of order $144$ that have exponent either 36 or 72 and deduce the unit group $U(\mathbb{F}_qG)$ of semisimple group algebra $\mathbb{F}_qG$. Here, $q$ denotes the power of a prime, i.e., $q=p^r$ for $p$ prime and a positive integer $r$. Up to isomorphism, there are $6$ groups of order 144 that have exponent either 36 or 72. Additionally, we also discuss how to simply obtain the unit groups of the semisimple group algebras of those non-metabelian groups of order 144 that are a direct product of two nontrivial groups. In all, this paper covers the unit groups of semisimple group algebras of 17 non-metabelian groups.\looseness-1

Let R q (r , n) denote the r th order Reed-Muller code of length q n over F q. We consider two algebraic questions about the Reed-Muller code. Let H q (r , n) = R q (r , n) / R q (r − 1 , n). (1) When q = 2 , it is known that there is a "duality" between the actions of GL (n , F 2) on H 2 (r , n) and on H 2 (r ′ , n) , where r + r ′ = n. The result is false for a general q. However, we find that a slightly modified duality statement still holds when q is a prime or r < char F q. (2) Let F (F q n , F q) denote the F q -algebra of all functions from F q n to F q. It is known that when q is a prime, the Reed-Muller codes { 0 } = R q (− 1 , n) ⊂ R q (0 , n) ⊂ ⋯ ⊂ R q (n (q − 1) , n) = F (F q n , F q) are the only AGL (n , F q) -submodules of F (F q n , F q). In particular, H q (r , n) is an irreducible GL (n , F q) -module when q is a prime. For a general q , H q (r , n) is not necessarily irreducible. We determine all its submodules and the factors in its composition series. The factors of the composition series of H q (r , n) provide an explicit family of irreducible representations of GL (n , F q) over F q. [ABSTRACT FROM AUTHOR]

Since their introduction in 2004, Polynomial Modular Number Systems (PMNS) have become a very interesting tool for implementing cryptosystems relying on modular arithmetic in a secure and efficient way. However, while their implementation is simple, their parameterization is not trivial and relies on a suitable choice of the polynomial on which the PMNS operates. The initial proposals were based on particular binomials and trinomials. But these polynomials do not always provide systems with interesting characteristics such as small digits, fast reduction, etc.In this work, we study a larger family of polynomials that can be exploited to design a safe and efficient PMNS. To do so, we first state a complete existence theorem for PMNS which provides bounds on the size of the digits for a generic polynomial, significantly improving previous bounds. Then, we present classes of suitable polynomials which provide numerous PMNS for safe and efficient arithmetic. [ABSTRACT FROM AUTHOR]

In this paper, we establish some relations between irreducible polynomials over a finite field F q and its quadratic extension F q 2 . First we consider a relation between the numbers of irreducible polynomials of a fixed degree over F q and F q 2 , and some relations between self-reciprocal irreducible polynomials over F q and self-conjugate-reciprocal irreducible polynomials over F q 2 . We also obtain formulas for the number and the product of all self-conjugate-reciprocal irreducible monic (SCRIM) polynomials over F q 2 . [ABSTRACT FROM AUTHOR]

For each prime power q, we determine all a 휖 픽q2 for which X + Xq + X2q−1 + aXq2−q+1 permutes 픽q2. [ABSTRACT FROM AUTHOR]

Let K be a finite field of characteristic 2, and U T 2 : = U T 2 (K) be the Lie algebra of 2 × 2 upper triangular matrices over K with the multiplication x ∘ y = x y + y x = x y − y x. In this paper, we exhibit a finite basis of graded identities for the variety of Lie algebras generated by U T 2 for any grading and show that it has the Specht property. It is important to highlight that the technique used in order to solve the Specht problem is independent of the characteristic of the field and also of its cardinality. [ABSTRACT FROM AUTHOR]

Let R be a noncommutative ring with unity and $ Z(R) $ Z (R) be its centre. The commuting graph of R denoted by $ \Gamma (R) $ Γ (R) is a graph whose vertices are noncentral elements of R and two distinct vertices x and y are adjacent if and only if xy = yx. Let F be a finite field. In this paper, we show that if $ \Gamma (R)\cong \Gamma (M_3(F)) $ Γ (R) ≅ Γ (M 3 (F)) and $ Z(R) $ Z (R) is a field, then $ R\cong M_3(F) $ R ≅ M 3 (F). In particular, if $ \Gamma (R)\cong \Gamma (M_3(F_p)) $ Γ (R) ≅ Γ (M 3 (F p)) , then $ R\cong M_3(F_p) $ R ≅ M 3 (F p). [ABSTRACT FROM AUTHOR]

We study the extent to which curves over finite fields are characterized by their zeta functions and the zeta functions of certain of their covers. Suppose C and C' are curves over a finite field K, with K-rational base points P and P', and let D and D' be the pullbacks (via the Abel–Jacobi map) of the multiplication-by-2 maps on their Jacobians. We say that (C,P) and (C',P') are doubly isogenous if Jac(C) and Jac(C') are isogenous over K and Jac(D) and Jac(D') are isogenous over K. For curves of genus 2 whose automorphism groups contain the dihedral group of order eight, we show that the number of pairs of doubly isogenous curves is larger than naïve heuristics predict, and we provide an explanation for this phenomenon. [ABSTRACT FROM AUTHOR]

The nonlinearity of vectorial functions and of their restrictions to manifolds are defined as the Hamming distance to the set of affine mappings and of their restrictions to the manifold, respectively. Relations between the parameters of the nonlinearity of a vectorial function and their analogues for its coordinate functions and its restrictions to manifolds are established. An analogue of the Parseval identity for such parameters of vectorial functions is proved, which implies the upper bound (qk − 1)qn−k − qn/2−k for the nonlinearity of a mapping over a q-element field of n variables with k coordinates. Attainability conditions for this estimate are found, and a class of Boolean vectorial functions with high value of nonlinearity is constructed. Estimates characterizing the distribution of the nonlinearity of a vectorial function and of its restrictions to manifolds are obtained. [ABSTRACT FROM AUTHOR]

Let q be an odd prime power and suppose that $a,b\in \mathbb {F}_q$ are such that $ab$ and $(1{-}a)(1{-}b)$ are nonzero squares. Let $Q_{a,b} = (\mathbb {F}_q,*)$ be the quasigroup in which the operation is defined by $u*v=u+a(v{-}u)$ if $v-u$ is a square, and $u*v=u+b(v{-}u)$ if $v-u$ is a nonsquare. This quasigroup is called maximally nonassociative if it satisfies $x*(y*z) = (x*y)*z \Leftrightarrow x=y=z$. Denote by $\sigma (q)$ the number of $(a,b)$ for which $Q_{a,b}$ is maximally nonassociative. We show that there exist constants $\alpha \approx 0.029\,08$ and $\beta \approx 0.012\,59$ such that if $q\equiv 1 \bmod 4$ , then $\lim \sigma (q)/q^2 = \alpha $ , and if $q \equiv 3 \bmod 4$ , then $\lim \sigma (q)/q^2 = \beta $. [ABSTRACT FROM AUTHOR]

In Neri et al. (2022) [20] , the authors extended the family of 2-dimensional F q 2 t -linear MRD codes recently found in Longobardi et al. (2023) [13]. Also, for t ≥ 5 they determined equivalence classes of the elements in this new family and provided the exact number of inequivalent codes in it. In this article, we complete the study of the equivalence issue removing the restriction t ≥ 5. Moreover, we prove that in the case when t = 4 , the linear sets of the projective line PG (1 , q 8) ensuing from codes in the relevant family, are not equivalent to any one known so far. [ABSTRACT FROM AUTHOR]

Wedderburn and Hasse theorems have always fascinated many algebraists as there are just very few versions of their proofs and that are somehow not easy to follow because they contain other results inside. In this note, we aim to look at their proofs again but nowwith more simplified versions that include sufficient details in order to let them be understandable for most readers in the subjects of finite fields and elliptic curves. In the proof of Wedderburn’s theorem, we succeed to show how it is equivalent to define either a stabilizer or centralizer of non-central elements and that helps to consider the equation on the order of group by using interchangeably the index of its subgroup and the order of the orbit. As for Hasse’s theorem, we provide a short proof in just two paragraphs with a recall of the most important results that have been used, and then, we state three of its version with an explanation of how this all leads in the end to the need of an algorithm like the one of René Schoof in 1985. [ABSTRACT FROM AUTHOR]

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Let R be a noncommutative ring with unity and $ Z(R) $ Z (R) be its centre. The commuting graph of R denoted by $ \Gamma (R) $ Γ (R) is a graph whose vertices are noncentral elements of R and two distinct vertices x and y are adjacent if and only if xy = yx. Let F be a finite field. In this paper, we show that if $ \Gamma (R)\cong \Gamma (M_3(F)) $ Γ (R) ≅ Γ (M 3 (F)) and $ Z(R) $ Z (R) is a field, then $ R\cong M_3(F) $ R ≅ M 3 (F). In particular, if $ \Gamma (R)\cong \Gamma (M_3(F_p)) $ Γ (R) ≅ Γ (M 3 (F p)) , then $ R\cong M_3(F_p) $ R ≅ M 3 (F p). [ABSTRACT FROM AUTHOR]

In this paper, we present the construction of two Hadamard matrix forms over GF(2m) to generate 4x4 and 8x8 involutory MDS (IMDS) matrices. The first form provides a straightforward way to generate 4x4 IMDS matrices, while the second is an efficient way to generate 8x8 IMDS matrices using a hybrid (combination of search-based methods and direct construction) approach. In addition, we propose an algorithm for computing the branch number of any non-singular matrix over GF(2m) and improve its computational complexity for Hadamard matrices. Using this algorithm and the proposed Hadamard matrix form, we obtain 2kx2k lightweight involutory and non-involutory Hadamard MDS matrices with low XOR counts for k=2,3. Finally, we carry out a comparative study based on the XOR count to demonstrate that MDS matrices created using our Hadamard matrix forms have lower XOR counts than MDS matrices available in the literature as of today. [ABSTRACT FROM AUTHOR]

Let p stand for an odd prime and let η ∈ Z+ (the set of positive integers). Let Fq denote the finite field having q = pη elements and F*q = Fq\{0}. In this paper, when the determinants of exponent matrices are coprime to q - 1, we use the Smith normal form of exponent matrices to derive exact formulas for the numbers of rational points on the affine varieties over Fq defined by ... respectively, where dij, ei'j' ∈ Z+, ai, ci' ∈ F*q, i = 1,..., s + t, j = 1, ..., n, i' = 1,..., r + k + w, j' = 1,..., m, and b1, b2, l1, l2, l3 ∈ Fq. These formulas extend the theorems obtained by Q. Sun in 1997. Our results also give a partial answer to an open question posed by S.N. Hu, S.F. Hong and W. Zhao [The number of rational points of a family of hypersurfaces over finite fields, J. Number Theory 156 (2015), 135-153]. [ABSTRACT FROM AUTHOR]

This paper investigates conditions under which representability of each element from the field as the sum , where , , and are fixed natural numbers >1, implies a similar representability of each square matrix over the field . We propose a general approach to solving this problem. As an application we describe fields and commutative rings where 2 is a unit, over which each square matrix is the sum of two 4-potent matrices. [ABSTRACT FROM AUTHOR]

An improved lower bound is found for the bilinear complexity of the multiplication of arbitrary matrices over finite fields. [ABSTRACT FROM AUTHOR]

Let Fq be a finite field, where q is a power of a prime p such that p ≥ 5. Let α be a root of a monic polynomial of a minimal degree over Fq. In this paper, we will study elliptic curves over (Fq[α];+; *), where + is the usual addition and * represent a non-standard product law over Fq[α]. Using elliptic curves over this ring can result in a cryptographic method that is fast, simple and secure. [ABSTRACT FROM AUTHOR]

Assuming a widely believed hypothesis concerning the least prime in an arithmetic progression, we show that polynomials of degree less than n over a finite field Fq with q elements can be multiplied in time O(n logq log(n logq)), uniformly in q. Under the same hypothesis, we show how to multiply two n-bit integers in time O(n logn); this algorithm is somewhat simpler than the unconditional algorithm from the companion paper [22]. Our results hold in the Turing machine model with a finite number of tapes. [ABSTRACT FROM AUTHOR]

Let $ q $ be an even prime power and let $ \mathbb{F}_{q} $ be the finite field of $ q $ elements. Let $ f $ be a nonzero polynomial over $ \mathbb{F}_{q^2} $ of the form $ f = a_{1}x_{1}^{m_{1}}+\dots+a_{s}x_{s}^{m_{s}}+y_{1}y_{2}+\dots+y_{n-1}y_{n}+y_{n-2t-1}^{2}+\dots +y_{n-3}^2+y_{n-1}^{2}$ $+b_{t}y_{n-2t}^{2}+ $ $ \dots +b_{1}y_{n-2}^{2}+b_{0}y_{n}^{2} $, where $ a_{i}, b_j\in \mathbb{F}_{q^{2}}^{*}, $ $ m_i\ne 1, $ $ (m_{i}, m_{k}) = 1, $ $ i\ne k, $ $ m_{i}|(q+1), $ $ m_{i}\in \mathbb{Z}^{+}, $ $ 2|n $, $ n > 2 $, $ 0\leq t\leq \frac{n}{2}-2 $, $ {\mathrm{Tr}}_{\mathbb{F}_{q^2}/\mathbb{F}_{2}}(b_{j}) = 1 $ for $ i, k = 1, \dots, s $ and $ j = 0, 1, \dots, t $. For each $ b \in \mathbb{F}_{q^2} $, let $ N_{q^2}(f = b) $ denote the number of $ \mathbb{F}_{q^2} $-rational points on the affine hypersurface $ f = b $. In this paper, we obtain the formula of $ N_{q^2}(f = b) $ by using the Jacobi sums, Gauss sums and the results of quadratic form in finite fields.

This paper is aimed at using a lookup table method to improve the scalar multiplication performance of elliptic curve cryptography. The lookup table must be divided into two polynomials and requires two iterations of point doubling operation, for which negation operations are needed. It is well known that an inversion operation requires a lot of multiplication time. The advantage of this paper is that we are able to reduce one inverse element calculation for this problem and also improve the basic operations of finite fields through segmentation methods. If the normal basis method is used in the design of the inverse element operation, it must be converted to the normal basis through the standard basis. However, the conversion process requires a lot of matrix operations. Though the anti-element operation has good speed performance, it also increases the computational complexity. Using number theory and grouping methods will greatly improve the performance of inverse element operations. With application of the two-time point doubling operation in the hardware implementation, the developed approach reduces the computing time by 48% as compared with the conventional approach. The computational time of the scalar multiplication using the presented method is further improved by 67% over the traditional algorithm with only an area increase of 12%. Finally, the proposed lookup table-based technique can be utilized for software and hardware implementation, as the developed arithmetic operations are simple and are consistent in their execution.

In this paper, we discuss the adjacency matrices of finite undirected simple graphs over a finite prime field F p. We apply symmetric (row and column) elementary transformations to the adjacency matrix over F p in order to get a direct sum decomposition by other adjacency matrices. In this paper, we give a complete description of the direct sum decomposition of the adjacency matrix of any graph over F p for any odd prime p. Our key tool is quadratic residues of F p. [ABSTRACT FROM AUTHOR]

We determine the roots in F q 3 of the polynomial X 2 q ℓ + 1 + X + a for each positive integer ℓ and each a ∈ F q , where q is a power of 2. We introduce a new approach for this type of question, and we obtain results which are more explicit than the previous results in this area. Our results resolve an open problem and a conjecture of Zheng, Kan, Zhang, Peng, and Li. [ABSTRACT FROM AUTHOR]

Let 픽 q be the finite field of odd characteristic p with q elements ( q = p n , n ∈ ℕ ) and let 픽 q * represent the set of nonzero elements of 픽 q . By making use of the Smith normal form of exponent matrices, we obtain an explicit formula for the number of rational points on the variety defined by the following system of equations over 픽 q : { ∑ i = 1 r a i (1) ⁢ x 1 e i ⁢ 1 (1) ⁢ ⋯ ⁢ x n e i ⁢ n (1) = b 1 , ∑ j ′ = 0 t - 1 ∑ i ′ = 1 r j ′ + 1 - r j ′ a r j ′ + i ′ (2) ⁢ x 1 e r j ′ + i ′ , 1 (2) ⁢ ⋯ ⁢ x n j ′ + 1 e r j ′ + i ′ , n j ′ + 1 (2) = b 2 , where b i ∈ 픽 q ( i = 1 , 2 ), t ∈ ℕ , 0 = n 0 < n 1 < n 2 < ⋯ < n t , n k - 1 < n ≤ n k for some 1 ≤ k ≤ t , 0 = r 0 < r 1 < r 2 < ⋯ < r t , a i (1) ∈ 픽 q * for i ∈ { 1 , ... , r } , a i ′ (2) ∈ 픽 q * for i ′ ∈ { 1 , ... , r t } , and the exponent of each variable is a positive integer. This generalizes the results obtained previously by Wolfmann, Sun, Cao, and others. Our result also gives a partial answer to an open problem raised by Hu, Hong and Zhao [S. N. Hu, S. F. Hong and W. Zhao, The number of rational points of a family of hypersurfaces over finite fields, J. Number Theory 156 2015, 135–153]. [ABSTRACT FROM AUTHOR]