Improved linear sieving techniques with applications to step-reduced LED-64

Itai Dinur, Orr Dunkelman, Nathan Keller, Adi Shamir

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

Abstract

In this paper, we present advanced meet-in-the-middle (MITM) attacks against the lightweight block cipher LED-64, improving the best known attacks on several step-reduced variants of the cipher in both single-key and related-key models. In particular, we present a known-plaintext attack on 2-step LED-64 with complexity of 248 and a related-key attack on 3-step LED-64 with complexity of 249. In both cases, the previously known attacks have complexity of 260, i.e., only 16 times faster than exhaustive key search. While our attacks are applied to the specific scheme of LED-64, they contain several general methodological contributions: First, we present the linear key sieve technique, which allows to exploit linear dependencies between key bits to obtain filtering conditions in MITM attacks on block ciphers. While similar ideas have been previously used in the domain of hash functions, this is the first time that such a technique is applied in block cipher cryptanalysis. As a second contribution, we demonstrate for the first time that a splice-and-cut attack (which so far seemed to be an inherently chosen-plaintext technique) can be used in the knownplaintext model, with data complexity which is significantly below the code-book size. Finally, we extend the differential MITM attack on AESbased designs, and apply it independently in two stages from both sides of the cipher, while using the linear key sieve and other enhancements.

Original languageEnglish
Title of host publicationFast Software Encryption - 21st International Workshop, FSE 2014, Revised Selected Papers
EditorsCarlos Cid, Christian Rechberger
PublisherSpringer Verlag
Pages390-410
Number of pages21
ISBN (Print)9783662467053
DOIs
StatePublished - 1 Jan 2015
Externally publishedYes
Event21st International Workshop on Fast Software Encryption, FSE 2014 - London, United Kingdom
Duration: 3 Mar 20145 Mar 2014

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume8540
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349

Conference

Conference21st International Workshop on Fast Software Encryption, FSE 2014
Country/TerritoryUnited Kingdom
CityLondon
Period3/03/145/03/14

Keywords

  • AES
  • Cryptanalysis
  • Even-Mansour
  • Known plaintext splice-and-cut
  • LED
  • Meet-in-themiddle attack
  • Splice-and-cut

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