Cryptanalysis of a public key cryptosystem based on diophantine equations via weighted LLL reduction

Jintai Ding, Momonari Kudo*, Shinya Okumura, Tsuyoshi Takagi, Chengdong Tao

*Corresponding author for this work

Research output: Chapter in Book or Report/Conference proceedingConference Proceedingpeer-review

1 Citation (Scopus)

Abstract

Okumura proposed a candidate of post-quantum cryptosystem based on Diophantine equations of degree increasing type (DEC). Sizes of public keys in DEC are small, e.g., 1,200 bits for 128 bit security, and it is a strongly desired property in post-quantum erea. In this paper, we propose a polynomial time attack against DEC. We show that the one-wayness of DEC is reduced to finding special (relatively) short vectors in some lattices. The usual LLL algorithm does not work well for finding the most important target vector in our attack. The most technical point of our method is to heuristically find a special norm called a weighted norm to find the most important target vector. We call this method "weighted LLL algorithm" in this paper. Our experimental results suggest that our attack can break the one-wayness of DEC for 128 bit security with sufficiently high probability.

Original languageEnglish
Title of host publicationAdvances in Information and Computer Security - 11th International Workshop on Security, IWSEC 2016, Proceedings
EditorsKatsunari Yoshioka, Kazuto Ogawa
PublisherSpringer Verlag
Pages305-315
Number of pages11
ISBN (Print)9783319445236
DOIs
Publication statusPublished - 2016
Externally publishedYes
Event11th International Workshop on Security on Advances in Information and Computer Security, IWSEC 2016 - Tokyo, Japan
Duration: 12 Sept 201614 Sept 2016

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume9836 LNCS
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349

Conference

Conference11th International Workshop on Security on Advances in Information and Computer Security, IWSEC 2016
Country/TerritoryJapan
CityTokyo
Period12/09/1614/09/16

Keywords

  • Diophantine equation
  • Post-quantum cryptosystem
  • Weighted LLL reduction

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