Cryptanalysis of the KeeLoq block cipher

Andrey Bogdanov

Paper 2007/055

Cryptanalysis of the KeeLoq block cipher

Andrey Bogdanov

Abstract

KeeLoq is a block cipher used in numerous widespread passive entry and remote keyless entry systems as well as in various component identification applications. The KeeLoq algorithm has a 64-bit key and operates on 32-bit blocks. It is based on an NLFSR with a nonlinear feedback function of 5 variables. In this paper a key recovery attack with complexity of about $2^{52}$ steps is proposed (one step is equivalent to a single KeeLoq encryption operation). In our attack we use the techniques of guess-and-determine, slide, and distinguishing attacks. Several real-world applications are vulnerable to the attack. To our best knowledge this is the first paper to describe and cryptanalyze the KeeLoq block cipher.

Metadata

Available format(s): PDF
Category: Secret-key cryptography
Publication info: Published elsewhere. Unknown where it was published
Keywords: secret-key cryptography block ciphers cryptanalysis linear cryptanalysis boolean functions authentication codes applications
Contact author(s): abogdanov @ crypto rub de
History: 2007-02-20: received
Short URL: https://ia.cr/2007/055
License: CC BY

BibTeX

@misc{cryptoeprint:2007/055,
      author = {Andrey Bogdanov},
      title = {Cryptanalysis of the {KeeLoq} block cipher},
      howpublished = {Cryptology {ePrint} Archive, Paper 2007/055},
      year = {2007},
      url = {https://eprint.iacr.org/2007/055}
}