Key recovery attacks on 3-round Even-Mansour, 8-step LED-128, and full AES2

Itai Dinur, Orr Dunkelman, Nathan Keller, Adi Shamir

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

26 Scopus citations

Abstract

The Even-Mansour (EM) encryption scheme received a lot of attention in the last couple of years due to its exceptional simplicity and tight security proofs. The original 1-round construction was naturally generalized into r-round structures with one key, two alternating keys, and completely independent keys. In this paper we describe the first key recovery attack on the one-key 3-round version of EM which is asymptotically faster than exhaustive search (in the sense that its running time is o(2n ) rather than O(2n) for an n-bit key). We then use the new cryptanalytic techniques in order to improve the best known attacks on several concrete EM-like schemes. In the case of LED-128, the best previously known attack could only be applied to 6 of its 12 steps. In this paper we develop a new attack which increases the number of attacked steps to 8, is slightly faster than the previous attack on 6 steps, and uses about a thousand times less data. Finally, we describe the first attack on the full AES2 (which uses two complete AES-128 encryptions and three independent 128-bit keys, and looks exceptionally strong) which is about 7 times faster than a standard meet-in-the-middle attack, thus violating its security claim.

Original languageEnglish
Title of host publicationAdvances in Cryptology, ASIACRYPT 2013 - 19th International Conference on the Theory and Application of Cryptology and Information Security, Proceedings
Pages337-356
Number of pages20
EditionPART 1
DOIs
StatePublished - 1 Dec 2013
Externally publishedYes
Event19th International Conference on the Theory and Application of Cryptology and Information Security, ASIACRYPT 2013 - Bengaluru, India
Duration: 1 Dec 20135 Dec 2013

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
NumberPART 1
Volume8269 LNCS
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349

Conference

Conference19th International Conference on the Theory and Application of Cryptology and Information Security, ASIACRYPT 2013
Country/TerritoryIndia
CityBengaluru
Period1/12/135/12/13

Keywords

  • AES encryption scheme
  • Cryptanalysis
  • LED encryption scheme
  • iterated Even-Mansour
  • key recovery attacks

ASJC Scopus subject areas

  • Theoretical Computer Science
  • Computer Science (all)

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