An Automatic Cryptanalysis of Transposition Ciphers Using Compression

  • Noor R. Al-Kazaz
  • Sean A. Irvine
  • William J. Teahan
Conference paper

DOI: 10.1007/978-3-319-48965-0_3

Volume 10052 of the book series Lecture Notes in Computer Science (LNCS)
Cite this paper as:
Al-Kazaz N.R., Irvine S.A., Teahan W.J. (2016) An Automatic Cryptanalysis of Transposition Ciphers Using Compression. In: Foresti S., Persiano G. (eds) Cryptology and Network Security. CANS 2016. Lecture Notes in Computer Science, vol 10052. Springer, Cham

Abstract

Automatically recognising valid decryptions as a result of ciphertext only cryptanalysis of simple ciphers is not an easy issue and still considered as a taxing problem. In this paper, we present a new universal compression-based approach to the automatic cryptanalysis of transposition ciphers. In particular, we show how a Prediction by Partial Matching (PPM) compression model, a scheme that performs well at many language modelling tasks, can be used to automatically recognise the valid decrypt with a 100 % success rate. We also show how it significantly outperforms another compression scheme, Gzip. In this paper, we propose a full mechanism for the automatic cryptanalysis of transposition ciphers which also automatically adds spaces to decrypted texts, again using a compression-based approach, in order to achieve readability.

Keywords

Cryptanalysis Transposition ciphers Plaintext recognition Compression PPM Word segmentation 

Copyright information

© Springer International Publishing AG 2016

Authors and Affiliations

  • Noor R. Al-Kazaz
    • 1
  • Sean A. Irvine
    • 1
  • William J. Teahan
    • 1
  1. 1.School of Computer ScienceBangor UniversityBangor, GwyneddUK