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Yingpu Deng

Publications and source records attributed to Yingpu Deng.

At least 19 recordsLinked to original sources
arXiv2026

Nonexistence of certain classes of generalized bent functions: Revisiting the element partition method

We obtain new nonexistence results for two classes of generalized bent functions from $\mathbb{Z}_{q}^{n}$ to $\mathbb{Z}_{q}$, called type $[n,q]$ generalized bent functions. The first class concerns the case $q=2 p_1^{e_1} p_2^{e_2}$, where $p_1$ and $p_2$ are distinct odd primes. By applying the element partition method introduced by Lv and Li to earlier results of Feng and Feng-Liu, we obtain sharper nonexistence results for several families of parameters satisfying explicit congruence and order conditions. These results extend known nonexistence theorems in cases where the prime divisors of the odd part of $q$ are self-conjugate. The second class concerns the case $q=2 \cdot 3^a \cdot 7^b$. By extending the idea of the element partition method and combining it with explicit computations in suitable cyclotomic fields and their subfields, we prove that generalized bent functions of type $[1,2\cdot 3^a\cdot 7^b]$ do not exist for all positive integers $a$ and $b$.

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arXiv2024

An Explicit Construction of Orthogonal Basis in $p$-adic Fields

In 2021, the $p$-adic signature scheme and public-key encryption cryptosystem were introduced. These schemes have good efficiency but are shown to be not secure. The attack succeeds because the extension fields used in these schemes are totally ramified. In order to avoid this attack, the extension field should have a large residue degree. In this paper, we propose a method of constructing a kind of specific orthogonal basis in $p$-adic fields with a large residue degree, which would be helpful to modify the $p$-adic signature scheme and public-key encryption cryptosystem.

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arXiv2024

On $p$-adic Minkowski's Theorems

Dual lattice is an important concept of Euclidean lattices. In this paper, we first give the right definition of the concept of the dual lattice of a $p$-adic lattice from the duality theory of locally compact abelian groups. The concrete constructions of ``basic characters'' of local fields given in Weil's famous book ``Basic Number Theory'' help us to do so. We then prove some important properties of the dual lattice of a $p$-adic lattice, which can be viewed as $p$-adic analogues of the famous Minkowski's first, second theorems for Euclidean lattices. We do this simultaneously for local fields $\mathbb{Q}_p$ (the field of $p$-adic numbers) and $\mathbb{F}_p((T))$ (the field of formal power-series of one indeterminate with coefficients in the finite field with $p$ elements).

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arXiv2023

Norm Orthogonal Bases and Invariants of $p$-adic Lattices

In 2018, the longest vector problem (LVP) and the closest vector problem (CVP) in $p$-adic lattices were introduced. These problems are closely linked to the orthogonalization process. In this paper, we first prove that every $p$-adic lattice has an orthogonal basis and give definition to the successive maxima and the escape distance, as the $p$-adic analogues of the successive minima and the covering radius in Euclidean lattices. Then, we present deterministic polynomial time algorithms to perform the orthogonalization process, solve the LVP and solve the CVP with an orthogonal basis of the whole vector space. Finally, we conclude that orthogonalization and the CVP are polynomially equivalent.

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arXiv2023

Convergence, Finiteness and Periodicity of Several New Algorithms of p-adic Continued Fractions

$p$-adic continued fractions, as an extension of the classical concept of classical continued fractions to the realm of $p$-adic numbers, offering a novel perspective on number representation and approximation. While numerous $p$-adic continued fraction expansion algorithms have been proposed by the researchers, the establishment of several excellent properties, such as the Lagrange Theorem for classic continued fractions, which indicates that every quadratic irrationals can be expanded periodically, remains elusive. In this paper, we present several new algorithms that can be viewed as refinements of the existing $p$-adic continued fraction algorithms. We give an upper bound of the length of partial quotients when expanding rational numbers, and prove that for small primes $p$, our algorithm can generate periodic continued fraction expansions for all quadratic irrationals. As confirmed through experimentation, one of our algorithms can be viewed as the best $p$-adic algorithm available to date. Furthermore, we provide an approach to establish a $p$-adic continued fraction expansion algorithm that could generate periodic expansions for all quadratic irrationals in $\mathbb{Q}_p$ for a given prime $p$.

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arXiv2023

On $p$-adic Gram-Schmidt Orthogonalization Process

In his famous book ``Basic Number Theory", Weil proved several theorems about the existence of norm-orthogonal bases in finite-dimensional vector spaces and lattices over local fields. In this paper, we transform Weil's proofs into algorithms for finding out various norm-orthogonal bases. These algorithms are closely related to the recently introduced closest vector problem (CVP) in $p$-adic lattices and they have applications in cryptography based on $p$-adic lattices.

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arXiv2023

On Periodicity of Continued fractions with Partial Quotients in Quadratic Number Fields

The properties of continued fractions whose partial quotients belong to a quadratic number field K are distinct from those of classical continued fractions. Unlike classical continued fractions, it is currently impossible to identify elements with periodic continued fraction expansions, akin to Lagrange's theorem. In this paper, we fix a real quadratic field K and take an ultimately periodic continued fraction with partial quotients in $\mathcal{O}_K$. We analyze its convergence and the growth of absolute values of $\mathcal{Q}$-pairs, and establish necessary and sufficient conditions for a real quartic irrational to have an ultimately periodic continued fraction converging to it with partial quotients in $\mathcal{O}_K$. Additionally, we analyze a specific example with $K=\mathbb{Q}(\sqrt{5})$. By the obtained results, we give a continued fraction expansion algorithm for those real quartic irrationals $\xi$ belong to a quadratic extension of $K$, whose algebraic conjugates are all real. We prove that the expansion obtained from the algorithm is ultimately periodic and convergent to the specified $\xi$.

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arXiv2022

Finding Sums of Four Squares via Complex Continued Fractions

The problem of representing a given positive integer as a sum of four squares of integers has been widely concerned for a long time, and for a given positive odd $n$ one can find a representation by doing arithmetic in a maximal order of quaternion algebra once a pair of (positive) integers $x,y$ with $x^2+y^2\equiv-1\mod n$ is given. In this paper, we introduce a new method to find a representation of odd integer $w$ given $x,y$ satisfying the above requirement. This method can avoid the complicated non-commutative structure in quaternion algebra, which is similar to the one we use to obtain a representation of a prime $p\equiv1\mod4$ as sum of two squares by doing continued fraction expansions, except that here we will expand complex number using Hurwitz algorithm.

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arXiv2022

The Endomorphism Rings of Supersingular Elliptic Curves over $\mathbb{F}_p$ and the Binary Quadratic Forms

It is well known that there is a one-to-one correspondence between supersingular $j$-invariants up to the action of $\text{Gal}(\mathbb{F}_{p^2}/\mathbb{F}_p)$ and type classes of maximal orders in $B_{p,\infty}$ by Deuring's theorem. Interestingly, we establish a one-to-one correspondence between $\mathbb{F}_p$-isomorphism classes of supersingular elliptic curves and primitive reduced binary quadratic forms with discriminant $-p$ or $-16p$. Due to this correspondence and the fact that $\mathbb{F}_p$-isogenies between elliptic curves could be represented by quadratic forms, we show that operations of these isogenies on supersingular elliptic curves over $\mathbb{F}_p$ are compatible with the composition of quadratic forms. Based on these results, we could reduce the security of CSIDH cryptosystem to computing this correspondence explicitly.

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arXiv2021

Supersingular $j$-invariants and the Class Number of $\mathbb{Q}(\sqrt{-p})$

For a prime $p>3$, let $D$ be the discriminant of an imaginary quadratic order with $|D|< \frac{4}{\sqrt{3}}\sqrt{p}$. We research the solutions of the class polynomial $H_D(X)$ mod $p$ in $\mathbb{F}_p$ if $D$ is not a quadratic residue in $\mathbb{F}_p$. We also discuss the common roots of different class polynomials in $\mathbb{F}_p$. As a result, we get a deterministic algorithm (Algorithm 3) for computing the class number of $\mathbb{Q}(\sqrt{-p})$. The time complexity of Algorithm 3 is $O(p^{3/4+ε})$.

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arXiv2020

On two problems about isogenies of elliptic curves over finite fields

Isogenies occur throughout the theory of elliptic curves. Recently, the cryptographic protocols based on isogenies are considered as candidates of quantum-resistant cryptographic protocols. Given two elliptic curves $E_1, E_2$ defined over a finite field $k$ with the same trace, there is a nonconstant isogeny $β$ from $E_2$ to $E_1$ defined over $k$. This study gives out the index of $\rm{Hom}_{\it k}(\it E_{\rm 1},E_{\rm 2})β$ as a left ideal in $\rm{End}_{\it k}(\it E_{\rm 2})$ and figures out the correspondence between isogenies and kernel ideals. In addition, some results about the non-trivial minimal degree of isogenies between the two elliptic curves are also provided.

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arXiv2019

Constructing Cycles in Isogeny Graphs of Supersingular Elliptic Curves

Loops and cycles play an important role in computing endomorphism rings of supersingular elliptic curves and related cryptosystems. For a supersingular elliptic curve $E$ defined over $\mathbb{F}_{p^2}$, if an imaginary quadratic order $O$ can be embedded in $\text{End}(E)$ and a prime $L$ splits into two principal ideals in $O$, we construct loops or cycles in the supersingular $L$-isogeny graph at the vertices which are next to $j(E)$ in the supersingular $\ell$-isogeny graph where $\ell$ is a prime different from $L$. Next, we discuss the lengths of these cycles especially for $j(E)=1728$ and $0$. Finally, we also determine an upper bound on primes $p$ for which there are unexpected $2$-cycles if $\ell$ doesn't split in $O$.

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arXiv2017

Algorithm for computing the factor ring of an ideal in Dedekind domain with finite rank

We give an algorithm for computing the factor ring of a given ideal in a Dedekind domain with finite rank, which runs in deterministic and polynomial-time. We provide two applications of the algorithm: judging whether a given ideal is prime or prime power. The main algorithm is based on basis representation of finite rings which is computed via Hermite and Smith normal forms.

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arXiv2016

On the Integral Representation of Binary Quadratic Forms and the Artin Condition

For diophantine equations of the form ax^2+bxy+cy^2+g=0 over Z whose coefficients satisfy some assumptions, we show that a condition with respect to Artin reciprocity map, which we call the Artin condition, is the only obstruction to the local-global principle for integral solutions of the equation. Some concrete examples are presented.

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arXiv2015

Nonexistence of two classes of generalized bent functions

We obtain new nonexistence results of generalized bent functions from $\{Z^n}_q$ to $\Z_q$ (called type $[n,q]$) in the case that there exist cyclotomic integers in $ \Z[ζ_{q}]$ with absolute value $q^{\frac{n}{2}}$. This result generalize the previous two scattered nonexistence results $[n,q]=[1,2\times7]$ of Pei \cite{Pei} and $[3,2\times 23^e]$ of Jiang-Deng \cite{J-D} to a generalized class. In the last section, we remark that this method can apply to the GBF from $\Z^n_2$ to $\Z_m$.

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