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1

Right Buchberger Algorithm over Bijective Skew PBW Extensions

Fajardo William

Fundamenta Informaticae

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2021

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Vol. 184, nr 2

83--105

EN

In this paper we present a right version of the Buchberger algorithm over skew Poincaré-Birkhoff-Witt extensions (skew PBW extensions for short) defined by Gallego and Lezama [5]. This algorithm is an adaptation of the left case given in [3]. In particular, we developed a right version of the division algorithm and from this we built the right Grbner bases theory over bijective skew PBW extensions. The algorithms were implemented in the SPBWE library developed in Maple, this paper includes an application of these to the membership problem. The theory developed here is fundamental to complete the SPBWE library and thus be able to implement various homological applications that arise as result of obtaining the right Grbner bases over skew PBW extensions.

2

Simple Verification of Completeness of Two Addition Formulas on Twisted Edwards Curves

Dryło Robert, Kijko Tomasz

International Journal of Electronics and Telecommunications

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2020

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Vol. 66, No. 3

459--464

EN

Daniel Bernstein and Tanja Lange [9] proved that two given addition formulas on twisted Edwards elliptic curves ax² + y² = 1 + dxy are complete (i.e. the sum of any two points on a curve can be computed using one of these formulas). In this paper we give simple verification of completeness of these formulas using a program written in Magma, which is based on the fact that completeness means that some systems of polynomial equations have no solutions. This method may also be useful to verify completeness of additions formulas on other models of elliptic curves.

3

Determining Formulas Related to Point Compression on Alternative Models of Elliptic Curves

Dryło Robert, Kijko Tomasz, Wroński Michał

Fundamenta Informaticae

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2019

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Vol. 169, nr 4

285--294

EN

Let E be an elliptic curve given by any model over a field K. A rational function f : E → K of degree 2 such that f(P) = f(Q) ⇔ Q = ±P can be used as a point compression on E. Then there exists induced from E multiplication of values of f by integers given by [n]f(P) := f([n]P), which can be computed using the Montgomery ladder algorithm. For this algorithm one needs the generalized Montgomery formulas for differential addition and doubling that is rational functions A(X1, X2, X3) ∈ K(X1, X2, X3) and [2] ∈ K(X) such that f(P + Q) = A(f(P), f(Q), f(Q − P)) and [2]f(P) = f([2]P) for generic P,Q ∈ E. For most standard models of elliptic curves generalized Montgomery formulas are known. To use compression for scalar multiplication [n]P for P ∈ E, one can compute after compression [n]f(P), which is followed by [n + 1]f(P) in the Montgomery ladder algorithm, then one can recover [n]P on E, since there exists a rational map B such that [n]P = B(P, [n]f(P), [n + 1]f(P)) for generic P ∈ E and n ∈ Z. Such a map B is known for Weierstrass and Edwards curves, but to our knowledge it seems that it was not given for other models of elliptic curves. In this paper for an elliptic curve E and the above compression function f we give an algorithm to search for generalized Montgomery formulas, functions on K induced after compression by endomorphisms of E, and the above map B for point recovering. All these tasks require searching for solutions of similar type problems for which we describe an algorithm based on Gröbner bases. As applications we give formulas for differential addition, doubling and the above map B for Jacobi quartic, Huff curves, and twisted Hessian curves.

4

Remarks on multivariate extensions of polynomial based secret sharing schemes

Derbisz J.

Studia Bezpieczeństwa Narodowego

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2014

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R. 4, Nr 6

285--297

EN

We introduce methods that use Gröbner bases for secure secret sharing schemes. The description is based on polynomials in the ring R = K[X1,...,Xl] where identities of the participants and shares of the secret are or are related to ideals in R. Main theoretical results are related to algorithmical reconstruction of a multivariate polynomial from such shares with respect to given access structure, as a generalisation of classical threshold schemes. We apply constructive Chinese remainder theorem in R of Becker and Weispfenning. Introduced ideas ﬁnd their detailed exposition in our related works.

PL

Wprowadzamy metody wykorzystujące bazy Gröbnera do schematów podziału sekretu. Opis bazuje na wielomianach z pierścienia R = K[X1,...,Xl], gdzie tożsamości użytkowników oraz ich udziały są lub są związane z ideałami w R. Główne teoretyczne rezultaty dotyczą algorytmicznej rekonstrukcji wielomianu wielu zmiennych z takich udziałów zgodnie z zadaną (dowolną) strukturą dostępu, co stanowi uogólnienie klasycznych schematów progowych. W pracy wykorzystujemy konstruktywną wersję Chińskiego twierdzenia o resztach w pierścieniu R pochodzącą od Beckera i Weispfenninga. Wprowadzone idee znajdują swój szczegółowy opis w naszych związanych z tym tematem pracach.

5

Further results on the equivalence to Smith form of multivariate polynomial matrices

Boudellioua M. S.

Control and Cybernetics

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2013

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Vol. 42, no. 2

543--551

EN

Multivariate polynomial matrices arise from the treatment of linear systems of partial differential equations, delay-differential equations or multidimensional discrete equations. In this paper we generalize some of the results obtained for the equivalence to the Smith normal form for a class of multivariate polynomial matrices.

6

Equivalence and reduction of delay-differential systems

Boudellioua M. S.

International Journal of Applied Mathematics and Computer Science

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2007

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Vol. 17, no 1

15-22

EN

A new direct method is presented which reduces a given high-order representation of a control system with delays to a firstorder form that is encountered in the study of neutral delay-differential systems. Using the polynomial system description (PMD) setting due to Rosenbrock, it is shown that the transformation connecting the original PMD with the first-order form is Fuhrmann’s strict system equivalence. This type of system equivalence leaves the transfer function and other relevant structural properties of the original system invariant.