Cryptanalysis of FIDES

Itai Dinur, Jérémy Jean

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

7 Scopus citations


FIDES is a lightweight authenticated cipher, presented at CHES 2013. The cipher has two version, providing either 80-bit or 96- bit security. In this paper, we describe internal state-recovery attacks on both versions of FIDES, and show that once we recover the internal state, we can use it to immediately forge any message. Our attacks are based on a guess-and-determine algorithm, exploiting the slow diffusion of the internal linear transformation of FIDES. The attacks have time complexities of 275 and 290 for FIDES-80 and FIDES-96, respectively, use a very small amount of memory, and their most distinctive feature is their very low data complexity: the attacks require at most 24 bytes of an arbitrary plaintext and its corresponding ciphertext, in order to break the cipher with probability 1.

Original languageEnglish
Title of host publicationFast Software Encryption - 21st International Workshop, FSE 2014, Revised Selected Papers
EditorsCarlos Cid, Christian Rechberger
PublisherSpringer Verlag
Number of pages17
ISBN (Print)9783662467053
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)
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349


Conference21st International Workshop on Fast Software Encryption, FSE 2014
Country/TerritoryUnited Kingdom


  • Authenticated encryption
  • Cryptanalysis
  • Guessand-determine

ASJC Scopus subject areas

  • Theoretical Computer Science
  • General Computer Science


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