Meet-in-the-Filter and Dynamic Counting with Applications to Speck

Alex Biryukov, Luan Cardoso dos Santos, Je Sen Teh, Aleksei Udovenko*, Vesselin Velichkov

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract / Description of output

We propose a new cryptanalytic tool for differential cryptanalysis, called meet-in-the-filter (MiF). It is suitable for ciphers with a slow or incomplete diffusion layer such as the ones based on Addition-Rotation-XOR (ARX). The MiF technique uses a meet-in-the-middle matching to construct differential trails connecting the differential’s output and the ciphertext difference. The proposed trails are used in the key recovery procedure, reducing time complexity and allowing flexible time-data trade-offs. In addition, we show how to combine MiF with a dynamic counting technique for key recovery. We illustrate MiF in practice by reporting improved attacks on the ARX -based family of block ciphers Speck. We improve the time complexities of the best known attacks up to 15 rounds of Speck 32 and 20 rounds of Speck 64/128. Notably, our new attack on 11 rounds of Speck 32 has practical analysis and data complexities of 224.66 and 226.70 respectively, and was experimentally verified, recovering the master key in a matter of seconds.

Original languageEnglish
Title of host publicationApplied Cryptography and Network Security
Subtitle of host publication21st International Conference, ACNS 2023, Proceedings
EditorsMehdi Tibouchi, XiaoFeng Wang
Number of pages29
ISBN (Electronic)9783031334887
ISBN (Print)9783031334870
Publication statusPublished - 29 May 2023
Event21st International Conference on Applied Cryptography and Network Security - Kyoto, Japan
Duration: 19 Jun 202322 Jun 2023
Conference number: 21

Publication series

NameLecture Notes in Computer Science
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349


Conference21st International Conference on Applied Cryptography and Network Security
Abbreviated titleACNS 2023

Keywords / Materials (for Non-textual outputs)

  • ARX
  • Differential cryptanalysis
  • Speck
  • Symmetric-key


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