New cryptanalytic results on IDEA

Eli Biham, Orr Dunkelman, Nathan Keller

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

Abstract

IDEA is a 64-bit block cipher with 128-bit keys introduced by Lai and Massey in 1991. IDEA is one of the most widely used block ciphers, due to its inclusion in several cryptographic packages, such as PGP and SSH. The cryptographic strength of IDEA relies on a combination of three incompatible group operations - XOR, addition and modular multiplication. Since its introduction in 1991, IDEA has withstood extensive cryptanalytic effort, but no attack was found on the full variant of the cipher. In this paper we present the first known non-trivial relation that involves all the three operations of IDEA. Using this relation and other techniques, we devise a linear attack on 5-round IDEA that uses 219 known plaintexts and has a time complexity of 2103 encryptions. By transforming the relation into a related-key one, a similar attack on 7.5-round IDEA can be applied with data complexity of 243.5 known plaintexts and a time complexity equivalent to 2 115.1 encryptions. Both of the attacks are by far the best known attacks on IDEA

Original languageEnglish
Title of host publicationAdvances in Cryptology - ASIACRYPT 2006 - 12th International Conference on the Theory and Application of Cryptology and Information Security, Proceedings
Pages412-427
Number of pages16
DOIs
StatePublished - 2006
Externally publishedYes
Event12th International Conference on the Theory and Application of Cryptology and Information Security, ASIACRYPT 2006 - Shanghai, China
Duration: 3 Dec 20067 Dec 2006

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume4284 LNCS
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349

Conference

Conference12th International Conference on the Theory and Application of Cryptology and Information Security, ASIACRYPT 2006
Country/TerritoryChina
CityShanghai
Period3/12/067/12/06

ASJC Scopus subject areas

  • Theoretical Computer Science
  • Computer Science (all)

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