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Let m be an even positive integer. A Boolean bent function ƒ on F2m-1 × F2 is called a cyclic bent function if for any a ≠ b ∈ F2m-1 and ε ∈ F2, ƒ(ax1, x2)+ ƒ(bx1, x2 + ε) is always bent, where x1 ∈ F2m-1, x2 ∈ F2. Cyclic bent functions look extremely rare. This paper focuses on cyclic bent functions on F2m-1 × F2 and their applications. The first objective of this paper is to establish a link between quadratic cyclic bent functions and a special type of prequasifields, and construct a class of quadratic cyclic bent functions from the Kantor-Williams prequasifields. The second objective is to use cyclic bent functions to construct families of optimal sequences. The results of this paper show that cyclic bent functions have nice applications in several fields such as coding theory, symmetric cryptography, and CDMA communication. [ABSTRACT FROM AUTHOR]

Boolean functions, coding theory and $t$ -designs have close connections and interesting interplay. A standard approach to constructing $t$ -designs is the use of linear codes with certain regularity. The Assmus-Mattson Theorem and the automorphism groups are two ways for proving that a code has sufficient regularity for supporting $t$ -designs. However, some linear codes hold $t$ -designs, although they do not satisfy the conditions in the Assmus-Mattson Theorem and do not admit a $t$ -transitive or $t$ -homogeneous group as a subgroup of their automorphisms. The major objective of this paper is to develop a theory for explaining such codes and obtaining such new codes and hence new $t$ -designs. To this end, a general theory for punctured and shortened codes of linear codes supporting $t$ -designs is established, a generalized Assmus-Mattson theorem is developed, and a link between 2-designs and differentially $\delta $ -uniform functions and 2-designs is built. With these general results, binary codes with new parameters and explicit weight distributions are obtained, new 2-designs and Steiner system $S(2, 4, 2^{n})$ are produced in this paper. [ABSTRACT FROM AUTHOR]

Bent functions, or equivalently, Hadamard difference sets in the elementary Abelian group (${\mathrm {GF}}(2^{2m}), $ +), have been employed to construct symmetric and quasi-symmetric designs having the symmetric difference property. The main objective of this paper is to use bent vectorial functions for a construction of a two-parameter family of binary linear codes that do not satisfy the conditions of the Assmus–Mattson theorem, but nevertheless hold 2-designs. A new coding-theoretic characterization of bent vectorial functions is presented. [ABSTRACT FROM AUTHOR]

In this paper, we discover that univariate form of a Niho bent function is a sum of functions having the form of a Leander–Kholosha bent function taken with particular coefficients from \mathbb F2^{n}^{*} for every term. We know that the Niho bent functions are related to o-polynomials. The power terms in the univariate Niho bent function can be derived by working, in a first step, on each monomial of the corresponding o-polynomial separately, and in a second step, adding them to obtain the global expression. This allows, knowing the monomials in an o-polynomial, to obtain the power terms of the polynomial representing corresponding bent function. However, the coefficients are not calculated explicitly. The explicit form is given for the bent functions obtained from quadratic and cubic o-polynomials. We also calculate the algebraic degree of any bent function in the Leander–Kholosha class. [ABSTRACT FROM AUTHOR]

In this paper, we study permutation polynomials over the finite fields that have linear structures. We present some results on such a permutation which transforms a hyperplane to another hyperplane. We fully characterize the bilinear polynomial with linear structure. The most important result of this paper is to show the relation between a Maiorana–McFarland function with an affine derivative and a polynomial with a linear structure. Moreover, we highlight this result in the context of resilient functions which are based on Maiorana–McFarland construction. [ABSTRACT FROM AUTHOR]

In this paper, we study ternary monomial functions of the form f(x) = Trn(axd), where x Ε F3n and Trn :F3n → F3 is the absolute trace function. Using a lemma of Hou, Stickelberger's theorem on Gauss sums, and certain ternary weight inequalities, we show that certain ternary monomial functions arising in the 2006 IEEE TRANSACTIONS ON INFORMATION THEORY paper (vol. 52, pp. 2018-2032, 2006) are weakly regular bent, thus settling a conjecture of Helleseth and Kholosha. We also prove that the Coulter-Matthews bent functions are weakly regular. [ABSTRACT FROM AUTHOR]

This paper is devoted to the study of hyperbent functions in n variables, i.e., bent functions which are bent up to a change of primitive roots in the finite field GF(2n). Our main purpose is to obtain an explicit trace representation for some classes of hyperbent functions. We first exhibit an infinite class of monomial functions which is not hyperbent. This result indicates that Kloosterman sums on F2m cannot be zero at some points. For functions with multiple trace terms, we express their spectra by means of Dickson polynomials. We then introduce a new tool to describe these hyperbent functions. The effectiveness of this new method can be seen from the characterization of a new class of binomial hyperbent functions. [ABSTRACT FROM AUTHOR]

It has been an active research issue for many years to construct new bent functions. For k odd with \gcd (n, k)=1 and a\in \mathbb F3^{n}^{*} , the function f(x)=Tr1^{n}(ax^{(({3^{k}+1})/{2})}) is weakly regular bent over \mathbb F3^{n} , where Tr1^{n}(\cdot) is the trace function from \mathbb F3^{n} to \mathbb F3 . This is the well-known Coulter–Matthews bent function. In this paper, we determine the dual function of f(x) completely. As a consequence, we find many classes of ternary bent functions not reported in the literature previously. Such bent functions are not quadratic if k>1 and have (((1+\sqrt 5)/2)^w+1-((1-\sqrt 5)/2)^w+1)/\sqrt 5 or (((1+\sqrt 5)/2)^n-w+1-((1-\sqrt 5)/2)^n-w+1)/\sqrt 5 trace terms, where 0

In this paper, we consider the spectra of Boolean functions with respect to the action of unitary transforms obtained by taking tensor products of the Hadamard kernel, denoted by H, and the nega-Hadamard kernel, denoted by N. The set of all such transforms is denoted by \H, N\^n. A Boolean function is said to be bent4 if its spectrum with respect to at least one unitary transform in \H, N\^n is flat. We obtain a relationship between bent, semibent, and bent4 functions, which is a generalization of the relationship between bent and negabent Boolean functions proved by Parker and Pott [cf., LNCS 4893 (2007), 9–23]. As a corollary to this result, we prove that the maximum possible algebraic degree of a bent4 function on n variables is \lceil n \over 2 \rceil and, hence, solve an open problem posed by Riera and Parker [cf., IEEE-TIT 52:9 (2006), 4142–4159]. [ABSTRACT FROM PUBLISHER]

This paper consists of two main contributions. First, the Niho bent function consisting of 2^r exponents (discovered by Leander and Kholosha) is studied. The dual of the function is found and it is shown that this new bent function is not of the Niho type. Second, all known univariate representations of Niho bent functions are analyzed for their relation to the completed Maiorana–McFarland class \cal M. In particular, it is proven that two families do not belong to the completed class \cal M. The latter result gives a positive answer to an open problem whether the class H of bent functions introduced by Dillon in his thesis of 1974 differs from the completed class \cal M. [ABSTRACT FROM PUBLISHER]

In this paper we report the following computational results on partial spread functions in eight variables: (i) the numbers of equivalence classes of partial spread functions (in eight variables) of all possible orders; (ii) the total number of partial spread bent functions in eight variables; (iii) the distribution of the cardinalities of stabilizers (in GL(8,\BBF 2)) of partial spread bent functions in eight variables. The computational method is also described. [ABSTRACT FROM AUTHOR]

A constant-amplitude code is a code that reduces the peak-to-average power ratio (PAPR) in multicode code-division multiple access (MC-CDMA) systems to the favorable value 1. In this paper, quaternary constant-amplitude codes (codes over Z4) of length 2m with error-correction capabilities are studied. These codes exist for every positive integer m, while binary constant-amplitude codes cannot exist if m is odd. Every word of such a code corresponds to a function from the binary m-tuples to Z4 having the bent property, i.e., its Fourier transform has magnitudes 2m/2. Several constructions of such functions are presented, which are exploited in connection with algebraic codes over Z4 (in particular quaternary Reed-Muller, Kerdock, and Delsarte-Goethals codes) to construct families of quaternary constant-amplitude codes. Mappings from binary to quaternary constant-amplitude codes are presented as well. [ABSTRACT FROM AUTHOR]

Rotation symmetric bent functions and their generation two-rotation symmetric bent functions are two classes of cryptographically significant Boolean functions. However, few constructions have been presented in the literature, which either have restriction on integer $n$ or have algebraic degree no more than 4. In this paper, for any even integer $n\ge 4$ , three classes of bent functions are presented respectively. Most notably, the proposed $n$ -variable rotation symmetric bent functions and two-rotation symmetric bent functions can have any possible algebraic degree ranging from 2 to $n/2$ . Besides, we obtain bent idempotent functions with the maximal algebraic degree $n/2$ . [ABSTRACT FROM PUBLISHER]

For any bent function, it is very interesting to determine its dual function, because the dual function is also bent in certain cases. For k odd and \gcd (n, k)=1 , it is known that the Coulter–Matthews bent function f(x)=Tr\left(ax^\frac 3^k+12\right) is weakly regular bent over \mathbb F3^{n} , where a\in \mathbb F3^{n}^{*} , and Tr(\cdot ):\mathbb F3^{n}\rightarrow \mathbb F3 is the trace function. In this paper, we investigate the dual function of $f(x)$ , aiming to determine a universal formula. In particular, for two cases, we determine the formula explicitly: for the case of n=3t+1$ and k=2t+1$ with t\geq 2n=3t+2$ and k=2t+1$ with t\geq 2f(x)$ is regular bent. [ABSTRACT FROM PUBLISHER]

Bent functions can be classified into regular bent functions, weakly regular but not regular bent functions, and non-weakly regular bent functions. Regular and weakly regular bent functions always appear in pairs, since their duals are also bent functions. In general, this does not apply to non-weakly regular bent functions. However, the first known construction of non-weakly regular bent functions by Çeşmelioğlu et al. yields bent functions for which the dual is also bent. In this paper, the first construction of non-weakly regular bent functions for which the dual is not bent is presented. We call such functions non-dual-bent functions. Until now, only sporadic examples found via computer search were known. We then show that with the direct sum of bent functions and with the construction by Çeşmelioğlu et al., one can obtain infinitely many non-dual-bent functions once one example of a non-dual-bent function is known. [ABSTRACT FROM PUBLISHER]

The problem of constructing bent–negabent functions that do not belong to the completed Maiorana–McFarland class emerges implicitly through a series of construction methods proposed recently. These approaches manage to optimize the algebraic degree of bent–negabent functions, but all of the constructed bent–negabent functions belong to the completed Maiorana–McFarland class. In this paper, we use the indirect sum construction (proposed by Carlet in 2004) for constructing the bent–negabent functions that are not provably contained in this class, which is the first significant attempt in this direction. To achieve this, we first provide a class of bent functions with certain desirable properties that does not belong to this class and demonstrate the existence of the class members. Then, embedding these functions in the framework of the indirect sum construction, we are able to specify sufficient conditions for bent–negabent functions not being contained in the completed Maiorana–McFarland class. [ABSTRACT FROM PUBLISHER]

In this paper, we consider constructions of rotation symmetric bent functions, which are of the forms: fc(x)=\sum i=1^{m-1}ci(\sum j=0^{n-1}xjxi+j) +cm(\sum j=0^{m-1}xjxm+j) and ft(x)=\sum i=0^{n-1}(xixt+ixm+i+xixt+i) + \sum i=0^{m-1}xixm+i, where n=2m, ci \in \{0,1\} (the subscript u of xu in the previous expressions is taken as u modulo n). For each case, a necessary and sufficient condition is obtained. To the best of our knowledge, this class of cubic rotation symmetric bent functions is the first example of an infinite class of nonquadratic rotation symmetric bent functions. [ABSTRACT FROM PUBLISHER]

This paper considers rational integer values of Kloosterman sums over finite fields of characteristic p > 3. We shall prove two main results. The first one is a congruence relation satisfied by possible integer values. One consequence is that there are no Kloosterman zeroes in the case of characteristic p > 3, which generalizes recent works by Shparlinski, Moisio, and Lisoněk on this subject. This, in turn, implies that there are no Dillon type bent functions in the case p > 3, thus answering a question posed recently by Helleseth and Kholosha. Our other main result states that the Kloosterman sum obtains an integer value at a point if and only if the same sum lifted to any extension field remains an integer. [ABSTRACT FROM AUTHOR]

There are two construction methods of designs from $(n,m)$ -bent functions, known as translation and addition designs. In this article we analyze, which equivalence relation for Boolean bent functions, i.e. $(n,1)$ -bent functions, and vectorial bent functions, i.e. $(n,m)$ -bent functions with $2\le m\le n/2$ , is coarser: extended-affine equivalence or isomorphism of associated translation and addition designs. First, we observe that similar to the Boolean bent functions, extended-affine equivalence of vectorial $(n,m)$ -bent functions and isomorphism of addition designs are the same concepts for all even $n$ and $m\le n/2$. Further, we show that extended-affine inequivalent Boolean bent functions in $n$ variables, whose translation designs are isomorphic, exist for all $n\ge 6$. This implies, that isomorphism of translation designs for Boolean bent functions is a coarser equivalence relation than extended-affine equivalence. However, we do not observe the same phenomenon for vectorial bent functions in a small number of variables. We classify and enumerate all vectorial bent functions in six variables and show, that in contrast to the Boolean case, one cannot exhibit isomorphic translation designs from extended-affine inequivalent vectorial $(6,m)$ -bent functions with $m\in \{ 2,3 \}$. [ABSTRACT FROM AUTHOR]

We present necessary and sufficient conditions for a Boolean function to be a negabent function for both an even and an odd number of variables, which demonstrates the relationship between negabent functions and bent functions. By using these necessary and sufficient conditions for Boolean functions to be negabent, we obtain that the nega spectrum of a negabent function has at most four values. We determine the nega spectrum distribution of negabent functions. Further, we provide a method to construct bent-negabent functions in n variables (n even) of algebraic degree ranging from 2 to n \over 2, which implies that the maximum algebraic degree of an n-variable bent-negabent function is equal to n \over 2. Thus, we answer two open problems proposed by Parker and Pott and by Stănică [ABSTRACT FROM PUBLISHER]

We show that any Boolean function, in even dimension, equal to the sum of a Boolean function g which is constant on each element of a spread and of a Boolean function h whose restrictions to these elements are all linear, is semibent if and only if g and h are both bent. We deduce a large number of infinite classes of semibent functions in explicit bivariate (respectively, univariate) polynomial form. [ABSTRACT FROM PUBLISHER]

Charpin and Gong recently characterized a large class of hyperbent functions defined on fields of order 2^n, which include the well-known monomial functions with the Dillon exponent as a special case. We give a reformulation of the Charpin-Gong criterion in terms of the number of rational points on certain hyperelliptic curves. We present two applications of our result: The time needed to check the hyperbentness of a specific function is now polynomial in n, and hyperbent functions with subfield coefficients can be constructed. [ABSTRACT FROM AUTHOR]

The maximum-length sequences, also called m-sequences, have received a lot of attention since the late 1960s. En terms of linear-feedback shift register (LFSR) synthesis they are usually generated by certain power polynomials over a finite field and in addition are characterized by a-low cross correlation and high nonlinearity. We say that such a sequence is generated by a semi-bent function. Some new families of such function, repressented by f(x) = Σ... ciTr(x²i+), n odd and ci ∈ F2, have recently (2002) been introduced by Khoo et al. We first generalize their results to even n. We further investigate the conditions on the choice of ci for explicit definitions of new infinite families having three and four trace terms. Also, a class of nonpermutation polynomials whose composition with a quadratic function yields again a quadratic semi-bent function is specified. The treatment of semi-bent functions is then presented in a much wider framework. We show how bent and semi-bent functions are interlinked, that is, the concatenation of two suitably chosen semi-bent functions will yield a bent function and vice versa. Finally, this approach is generalized so that the construction of both bent and semi-bent functions of any degree in certain range for any n ≥ 7 is presented, n being the number of input variables. [ABSTRACT FROM AUTHOR]