The Power of Power Codes: New Classes of Easy Instances for the Linear Equivalence Problem

Fuente: arXiv
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Main Authors: Battagliola, Michele, Horlemann, Anna-Lena, Mazumder, Abhinaba, Mora, Rocco, Santini, Paolo, Schaller, Michael, Weger, Violetta
Format: Preprint
Published: 2026
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author Battagliola, Michele
Horlemann, Anna-Lena
Mazumder, Abhinaba
Mora, Rocco
Santini, Paolo
Schaller, Michael
Weger, Violetta
author_facet Battagliola, Michele
Horlemann, Anna-Lena
Mazumder, Abhinaba
Mora, Rocco
Santini, Paolo
Schaller, Michael
Weger, Violetta
contents Given two linear codes, the Linear Equivalence Problem (LEP) asks to find (if it exists) a linear isometry between them; as a special case, we have the Permutation Equivalence Problem (PEP), in which isometries must be permutations. LEP and PEP have recently gained renewed interest as the security foundations for several post-quantum schemes, including LESS. A recent paper has introduced the use of the Schur product to solve PEP, identifying many new easy-to-solve instances. In this paper, we extend this result to LEP. In particular, we generalize the approach and rely on the more general notion of power codes. Combining it with Frobenius automorphisms and Hermitian hulls, we identify many classes of easy LEP instances. To the best of our knowledge, this is the first work exploiting algebraic weaknesses for LEP. Finally we show an improved reduction to PEP whenever the coefficients of the monomial matrix are in a subgroup of the multiplicative group of the finite field.
format Preprint
id arxiv_https___arxiv_org_abs_2603_23230
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle The Power of Power Codes: New Classes of Easy Instances for the Linear Equivalence Problem
Battagliola, Michele
Horlemann, Anna-Lena
Mazumder, Abhinaba
Mora, Rocco
Santini, Paolo
Schaller, Michael
Weger, Violetta
Cryptography and Security
Information Theory
Given two linear codes, the Linear Equivalence Problem (LEP) asks to find (if it exists) a linear isometry between them; as a special case, we have the Permutation Equivalence Problem (PEP), in which isometries must be permutations. LEP and PEP have recently gained renewed interest as the security foundations for several post-quantum schemes, including LESS. A recent paper has introduced the use of the Schur product to solve PEP, identifying many new easy-to-solve instances. In this paper, we extend this result to LEP. In particular, we generalize the approach and rely on the more general notion of power codes. Combining it with Frobenius automorphisms and Hermitian hulls, we identify many classes of easy LEP instances. To the best of our knowledge, this is the first work exploiting algebraic weaknesses for LEP. Finally we show an improved reduction to PEP whenever the coefficients of the monomial matrix are in a subgroup of the multiplicative group of the finite field.
title The Power of Power Codes: New Classes of Easy Instances for the Linear Equivalence Problem
topic Cryptography and Security
Information Theory
url https://arxiv.org/abs/2603.23230