Fast Multiplication and the PLWE-RLWE Equivalence for an Infinite Family of Maximal Real Subfields of Cyclotomic Fields

Fuente: arXiv
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Autori principali: Ahola, Joonas, Blanco-Chacón, Iván, Bolaños, Wilmar, Haavikko, Antti, Hollanti, Camilla, Sánchez-Ledesma, Rodrigo Martín
Natura: Preprint
Pubblicazione: 2024
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author Ahola, Joonas
Blanco-Chacón, Iván
Bolaños, Wilmar
Haavikko, Antti
Hollanti, Camilla
Sánchez-Ledesma, Rodrigo Martín
author_facet Ahola, Joonas
Blanco-Chacón, Iván
Bolaños, Wilmar
Haavikko, Antti
Hollanti, Camilla
Sánchez-Ledesma, Rodrigo Martín
contents 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 $2^r 3^s$-th cyclotomic field for $r \geq 3$ and $s \geq 1$. 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 $\mathcal{O}(n \log n)$ arithmetic operations, where $n$ is the problem dimension. Finally, we provide a heuristic and theoretical comparison of the vulnerability to some attacks for the $p$-th cyclotomic field versus the maximal totally real subextension of the $4p$-th cyclotomic field for a reasonable set of parameters of cryptographic size.
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id arxiv_https___arxiv_org_abs_2410_00792
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Fast Multiplication and the PLWE-RLWE Equivalence for an Infinite Family of Maximal Real Subfields of Cyclotomic Fields
Ahola, Joonas
Blanco-Chacón, Iván
Bolaños, Wilmar
Haavikko, Antti
Hollanti, Camilla
Sánchez-Ledesma, Rodrigo Martín
Cryptography and Security
Number Theory
11T71 (Primary), 94A60 (Secondary)
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 $2^r 3^s$-th cyclotomic field for $r \geq 3$ and $s \geq 1$. 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 $\mathcal{O}(n \log n)$ arithmetic operations, where $n$ is the problem dimension. Finally, we provide a heuristic and theoretical comparison of the vulnerability to some attacks for the $p$-th cyclotomic field versus the maximal totally real subextension of the $4p$-th cyclotomic field for a reasonable set of parameters of cryptographic size.
title Fast Multiplication and the PLWE-RLWE Equivalence for an Infinite Family of Maximal Real Subfields of Cyclotomic Fields
topic Cryptography and Security
Number Theory
11T71 (Primary), 94A60 (Secondary)
url https://arxiv.org/abs/2410.00792