Attacks on Sparse LWE and Sparse LPN with new Sample-Time tradeoffs

Fuente: arXiv
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Main Authors: Agrawal, Shashwat, Bagchi, Amitabha, Kumar, Rajendra
Format: Preprint
Published: 2026
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author Agrawal, Shashwat
Bagchi, Amitabha
Kumar, Rajendra
author_facet Agrawal, Shashwat
Bagchi, Amitabha
Kumar, Rajendra
contents This paper extends the Kikuchi method to give algorithms for decisional $k$-sparse Learning With Errors (LWE) and $k$-sparse Learning Parity with Noise (LPN) problems for higher moduli $q$. We create a Kikuchi graph for a sparse LWE/LPN instance and use it to give two attacks for these problems. The first attack decides by computing the spectral norm of the adjacency matrix of the Kikuchi graph, which is a generalization of the attack for $q=2$ given by Wein et. al. (Journal of the ACM 2019). The second approach computes non-trivial closed walks of the graph, and then decides by computing a certain polynomial of edge labels in the walks. This is a generalization of the attack for $q=2$ given by Gupta et. al. (SODA 2026). Both the attacks yield new tradeoffs between sample complexity and time complexity of sparse LWE/LPN.
format Preprint
id arxiv_https___arxiv_org_abs_2603_27190
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Attacks on Sparse LWE and Sparse LPN with new Sample-Time tradeoffs
Agrawal, Shashwat
Bagchi, Amitabha
Kumar, Rajendra
Cryptography and Security
This paper extends the Kikuchi method to give algorithms for decisional $k$-sparse Learning With Errors (LWE) and $k$-sparse Learning Parity with Noise (LPN) problems for higher moduli $q$. We create a Kikuchi graph for a sparse LWE/LPN instance and use it to give two attacks for these problems. The first attack decides by computing the spectral norm of the adjacency matrix of the Kikuchi graph, which is a generalization of the attack for $q=2$ given by Wein et. al. (Journal of the ACM 2019). The second approach computes non-trivial closed walks of the graph, and then decides by computing a certain polynomial of edge labels in the walks. This is a generalization of the attack for $q=2$ given by Gupta et. al. (SODA 2026). Both the attacks yield new tradeoffs between sample complexity and time complexity of sparse LWE/LPN.
title Attacks on Sparse LWE and Sparse LPN with new Sample-Time tradeoffs
topic Cryptography and Security
url https://arxiv.org/abs/2603.27190