{"title":"The geometry of covering codes in the sum–rank metric","authors":"Matteo Bonini, Martino Borello, Eimear Byrne","doi":"10.1007/s10623-025-01628-6","DOIUrl":"https://doi.org/10.1007/s10623-025-01628-6","url":null,"abstract":"<p>We introduce the concept of a sum–rank saturating system and outline its correspondence to covering properties of a sum–rank metric code. We consider the problem of determining the shortest length of a sum–rank-<span>(rho )</span>-saturating system of a fixed dimension, which is equivalent to the covering problem in the sum–rank metric. We obtain upper and lower bounds on this quantity. We also give constructions of saturating systems arising from geometrical structures.</p>","PeriodicalId":11130,"journal":{"name":"Designs, Codes and Cryptography","volume":"74 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143805904","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Joonas Ahola, Iván Blanco-Chacón, Wilmar Bolaños, Antti Haavikko, Camilla Hollanti, Rodrigo M. Sánchez-Ledesma
{"title":"Fast multiplication and the PLWE–RLWE equivalence for an infinite family of maximal real subfields of cyclotomic fields","authors":"Joonas Ahola, Iván Blanco-Chacón, Wilmar Bolaños, Antti Haavikko, Camilla Hollanti, Rodrigo M. Sánchez-Ledesma","doi":"10.1007/s10623-025-01601-3","DOIUrl":"https://doi.org/10.1007/s10623-025-01601-3","url":null,"abstract":"<p>We prove the equivalence between the Ring Learning With Errors (RLWE) and the Polynomial Learning With Errors (PLWE) problems for the maximal totally real subfield of the <span>(2^r 3^s)</span>th cyclotomic field for <span>(r ge 3)</span> and <span>(s ge 1)</span>. Moreover, we describe a fast algorithm for computing the product of two elements in the ring of integers of these subfields. This multiplication algorithm has quasilinear complexity in the dimension of the field, as it makes use of the fast Discrete Cosine Transform (DCT). Our approach assumes that the two input polynomials are given in a basis of Chebyshev-like polynomials, in contrast to the customary power basis. To validate this assumption, we prove that the change of basis from the power basis to the Chebyshev-like basis can be computed with <span>({mathcal {O}}(n log n))</span> arithmetic operations, where <i>n</i> is the problem dimension. Finally, we provide a heuristic and theoretical comparison of the vulnerability to some attacks for the <i>p</i>th cyclotomic field versus the maximal totally real subextension of the 4<i>p</i>th cyclotomic field for a reasonable set of parameters of cryptographic size.</p>","PeriodicalId":11130,"journal":{"name":"Designs, Codes and Cryptography","volume":"74 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143797694","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Constructions of binary cyclic codes with minimum weights exceeding the square-root lower bound","authors":"Hai Liu, Chunyu Gan, Chengju Li, Xueying Shi","doi":"10.1007/s10623-025-01621-z","DOIUrl":"https://doi.org/10.1007/s10623-025-01621-z","url":null,"abstract":"<p>Cyclic codes are an interesting type of linear codes and have wide applications in communication and storage systems due to their efficient encoding and decoding algorithms. Constructing binary cyclic codes with parameters <span>([n, frac{n+1}{2}, d ge sqrt{n}])</span> is an interesting topic in coding theory, as their minimum distances have a square-root bound. Let <span>(n=2^lambda -1)</span>, where <span>(lambda )</span> has three forms: <span>(p^2, p_1p_2, 2p_2)</span> for odd primes <span>(p, p_1, p_2)</span>. In this paper, we mainly construct several classes of binary cyclic codes with parameters <span>([2^lambda -1, k ge 2^{lambda -1}, d ge sqrt{n}])</span>. Specifically, the binary cyclic codes <span>({mathcal {C}}_{(1, p^2)})</span>, <span>({mathcal {C}}_{(1, 2p_2)})</span>, <span>({mathcal {C}}_{(2, 2p_2)})</span>, and <span>({mathcal {C}}_{(1, p_1p_2)})</span> have minimum distance <span>(d ge sqrt{n})</span> though their dimensions satisfy <span>(k > frac{n+1}{2})</span>. Moreover, two classes of binary cyclic codes <span>({mathcal {C}}_{(2, p^2)})</span> and <span>({mathcal {C}}_{(2, p_1p_2)})</span> with dimension <span>(k= frac{n+1}{2})</span> and minimum distance <i>d</i> much exceeding the square-root bound are presented, which extends the results given by Sun, Li, and Ding [30]. In fact, the rate of these two classes of binary cyclic codes are around <span>(frac{1}{2})</span> and the lower bounds on their minimum distances are close to <span>(frac{n}{log _2 n})</span>. In addition, their extended codes are also investigated.</p>","PeriodicalId":11130,"journal":{"name":"Designs, Codes and Cryptography","volume":"21 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143797794","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Quantum codes and irreducible products of characters","authors":"Eric Kubischta, Ian Teixeira","doi":"10.1007/s10623-025-01599-8","DOIUrl":"https://doi.org/10.1007/s10623-025-01599-8","url":null,"abstract":"<p>In a recent paper, we defined a type of weighted unitary design called a twisted unitary 1-group and showed that such a design automatically induced error-detecting quantum codes. We also showed that twisted unitary 1-groups correspond to irreducible products of characters thereby reducing the problem of code-finding to a computation in the character theory of finite groups. Using a combination of GAP computations and results from the mathematics literature on irreducible products of characters, we identify many new non-trivial quantum codes with unusual transversal gates. Transversal gates are of significant interest to the quantum information community for their central role in fault tolerant quantum computing. Most unitary <span>(text {t})</span>-designs have never been realized as the transversal gate group of a quantum code. We, for the first time, find nontrivial quantum codes realizing nearly every finite group which is a unitary 2-design or better as the transversal gate group of some error-detecting quantum code.</p>","PeriodicalId":11130,"journal":{"name":"Designs, Codes and Cryptography","volume":"72 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143784818","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Giacomo Micheli, Vincenzo Pallozzi Lavorante, Abhi Shukul, Noah Smith
{"title":"Constructions of locally recoverable codes with large availability","authors":"Giacomo Micheli, Vincenzo Pallozzi Lavorante, Abhi Shukul, Noah Smith","doi":"10.1007/s10623-025-01624-w","DOIUrl":"https://doi.org/10.1007/s10623-025-01624-w","url":null,"abstract":"<p>Let <i>p</i> be a prime number, <i>m</i> be a positive integer, and <span>(q=p^m)</span>. For any fixed locality <i>r</i> such that <span>(pnot mid r(r+1))</span>, we construct infinite families of locally recoverable codes with availabilty of nodes lower bounded by <span>(q/r!+O(sqrt{q}))</span> and number of locality sets equal to <span>(q^2/(r+1)!+O(q^{3/2}))</span>.\u0000</p>","PeriodicalId":11130,"journal":{"name":"Designs, Codes and Cryptography","volume":"34 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143784812","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A new method for erasure decoding of convolutional codes","authors":"Julia Lieb, Raquel Pinto, Carlos Vela","doi":"10.1007/s10623-025-01623-x","DOIUrl":"https://doi.org/10.1007/s10623-025-01623-x","url":null,"abstract":"<p>In this paper, we propose a new erasure decoding algorithm for convolutional codes using the generator matrix. This implies that our decoding method also applies to catastrophic convolutional codes in opposite to the classic approach using the parity-check matrix. We compare the performance of both decoding algorithms. Moreover, we enlarge the family of optimal convolutional codes (complete-MDP) based on the generator matrix.</p>","PeriodicalId":11130,"journal":{"name":"Designs, Codes and Cryptography","volume":"17 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143766850","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Eduardo Camps-Moreno, Hiram H. López, Gretchen L. Matthews, Rodrigo San-José
{"title":"The weight hierarchy of decreasing norm-trace codes","authors":"Eduardo Camps-Moreno, Hiram H. López, Gretchen L. Matthews, Rodrigo San-José","doi":"10.1007/s10623-025-01619-7","DOIUrl":"https://doi.org/10.1007/s10623-025-01619-7","url":null,"abstract":"<p>The Generalized Hamming weights and their relative version, which generalize the minimum distance of a linear code, are relevant to numerous applications, including coding on the wire-tap channel of type II, <i>t</i>-resilient functions, bounding the cardinality of the output in list decoding algorithms, ramp secret sharing schemes, and quantum error correction. The generalized Hamming weights have been determined for some families of codes, including Cartesian codes and Hermitian one-point codes. In this paper, we determine the generalized Hamming weights of decreasing norm-trace codes, which are linear codes defined by evaluating sets of monomials that are closed under divisibility on the rational points of the extended norm-trace curve given by <span>(x^{u} = y^{q^{s - 1}} + y^{q^{s - 2}} + cdots + y)</span> over the finite field of cardinality <span>(q^s)</span>, where <i>u</i> is a positive divisor of <span>(frac{q^s - 1}{q - 1})</span>. As a particular case, we obtain the weight hierarchy of one-point norm-trace codes and recover the result of Barbero and Munuera (2001) giving the weight hierarchy of one-point Hermitian codes. We also study the relative generalized Hamming weights for these codes and use them to construct impure quantum codes with excellent parameters.</p>","PeriodicalId":11130,"journal":{"name":"Designs, Codes and Cryptography","volume":"22 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143745305","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"On the cycle structure of a class of Galois NFSRs: component sequences possessing identical periods","authors":"Xiao-juan Wang, Tian Tian, Wen-feng Qi","doi":"10.1007/s10623-025-01616-w","DOIUrl":"https://doi.org/10.1007/s10623-025-01616-w","url":null,"abstract":"<p>Nonlinear feedback shift registers (NFSRs) are widely used in the design of stream ciphers and the cycle structure of an NFSR is a fundamental problem still open. In this paper, a new configuration of Galois NFSRs, called F-Ring NFSRs, is proposed. It is shown that an <i>n</i>-bit F-Ring NFSR generates <i>n</i> sequences with the same period simultaneously, that is, sequences from all bit registers have the same period. Recall that the ring-like cascade connection proposed by Zhao et al. (Des Codes Cryptogr 86:2775–2790, 2018) also has such period property. But it is abnormal that if every component shift register is nonsingular, then the ring-like cascade connection is <i>singular</i>. F-Ring NFSRs proposed in this paper could fix this weakness. Moreover, it is proved that when an <i>n</i>-stage <i>m</i>-sequence is input to the internal state of an F-Ring NFSR by xor, the periods of its internal state are multiples of <span>(2^n-1)</span>. At last, two toy examples are given to illustrate the new configuration.</p>","PeriodicalId":11130,"journal":{"name":"Designs, Codes and Cryptography","volume":"216 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143736558","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
William D. Carey, Matthew David Kearney, Rachel Kirsch, Stefan Popescu
{"title":"Universal partial tori","authors":"William D. Carey, Matthew David Kearney, Rachel Kirsch, Stefan Popescu","doi":"10.1007/s10623-025-01609-9","DOIUrl":"https://doi.org/10.1007/s10623-025-01609-9","url":null,"abstract":"<p>A De Bruijn cycle is a cyclic sequence in which every word of length <i>n</i> over an alphabet <span>(mathcal {A})</span> appears exactly once. De Bruijn tori are a two-dimensional analogue. Motivated by recent progress on universal partial cycles and words, which shorten De Bruijn cycles using a wildcard character, we introduce universal partial tori and matrices. We find them computationally and construct infinitely many of them using one-dimensional variants of universal cycles, including a new variant called a universal partial family.</p>","PeriodicalId":11130,"journal":{"name":"Designs, Codes and Cryptography","volume":"11 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143713013","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Studying the isomorphism of NFSRs via a general framework of bijections","authors":"Jingtao Xiong, Jianghua Zhong, Dongdai Lin","doi":"10.1007/s10623-025-01622-y","DOIUrl":"https://doi.org/10.1007/s10623-025-01622-y","url":null,"abstract":"<p>Nonlinear feedback shift registers (NFSRs) are used in many recent stream ciphers as their main building blocks. Two NFSRs are said to be isomorphic if their state diagrams are isomorphic, and to be equivalent if their sets of output sequences are equal. So far, numerous work has been done on the equivalence of NFSRs with same bit number, but much less has been done on their isomorphism. Actually, the equivalence problem of NFSRs with same bit number can be transformed to their isomorphism problem. The latter can be solved if the bijection between their states and its inverse can be explicitly expressed, which are quite hard to get in general. This paper studies the isomorphism of NFSRs by building a general framework for bijections. It first gives basic bijections. It then presents a unified formula for bijections, and discloses that any bijection can be expressed as a composite of finite basic bijections, setting up a general framework for bijections. Based on the general framework, the paper discloses in theory how to obtain all Galois NFSRs that are isomorphic to a given NFSR, and then reveals the bijections between the states of the previous types of Galois NFSRs and their own equivalent Fibonacci NFSRs. Finally, it proposes a new type of Galois NFSRs that are isomorphic and further equivalent to Fibonacci NFSRs, covering and improving most previous types of Galois NFSRs known to be equivalent to Fibonacci NFSRs.\u0000</p>","PeriodicalId":11130,"journal":{"name":"Designs, Codes and Cryptography","volume":"183 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143713069","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}