### Abstract

Original language | English |
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Title of host publication | Tatracrypt '07 - 7th Central Europe Conference Of Cryptology |

Publisher | Slovak Academy Sciences Mathematical Institute |

Publication date | 2008 |

Pages | 167-188 |

Publication status | Published - 2008 |

Event | 7th Central European Conference on Cryptology (TATRACRYPT 2007) - Smolenice, Slovakia Duration: 22 Jun 2007 → 24 Jun 2007 http://zeus.fei.stuba.sk/Katedry/KAIVT/Tatracrypt2007/ |

### Conference

Conference | 7th Central European Conference on Cryptology (TATRACRYPT 2007) |
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Country | Slovakia |

City | Smolenice |

Period | 22/06/2007 → 24/06/2007 |

Internet address |

Series | Tatra Mountains Mathematical Publications |
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Volume | 41 |

ISSN | 1210-3195 |

### Cite this

*Tatracrypt '07 - 7th Central Europe Conference Of Cryptology*(pp. 167-188). Slovak Academy Sciences Mathematical Institute. Tatra Mountains Mathematical Publications, Vol.. 41

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*Tatracrypt '07 - 7th Central Europe Conference Of Cryptology.*Slovak Academy Sciences Mathematical Institute, Tatra Mountains Mathematical Publications, vol. 41, pp. 167-188, 7th Central European Conference on Cryptology (TATRACRYPT 2007), Smolenice, Slovakia, 22/06/2007.

**Periodic Ciphers with Small Blocks and Cryptanalysis of KeeLoq.** / Courtois, Nicolas T.; Bard, Gregory V.; Bogdanov, Andrey.

Research output: Chapter in Book/Report/Conference proceeding › Article in proceedings › Research › peer-review

TY - GEN

T1 - Periodic Ciphers with Small Blocks and Cryptanalysis of KeeLoq

AU - Courtois, Nicolas T.

AU - Bard, Gregory V.

AU - Bogdanov, Andrey

PY - 2008

Y1 - 2008

N2 - KeeLoq is a lightweight block cipher that is massively used in the automobile industry [12, 13, 31, 32]. KeeLoq has two remarkable properties: it is periodic and has a very short block size (32 bits). Many different attacks on KeeLoq have been published in recent years [8, 15, 9, 10, 5]. In this paper we study a unique way of attacking KeeLoq, in which the periodic property of KeeLoq is used in to distinguish 512 rounds of KeeLoq from a random permutation. Our attacks require the knowledge of the entire code-book and are not among the fastest attacks known on this cipher. However one of them works for 100 % of all keys, including so called "strong keys", see [15]. In general, it is important to show how many different attacks are possible on a weak cipher such as KeeLoq.

AB - KeeLoq is a lightweight block cipher that is massively used in the automobile industry [12, 13, 31, 32]. KeeLoq has two remarkable properties: it is periodic and has a very short block size (32 bits). Many different attacks on KeeLoq have been published in recent years [8, 15, 9, 10, 5]. In this paper we study a unique way of attacking KeeLoq, in which the periodic property of KeeLoq is used in to distinguish 512 rounds of KeeLoq from a random permutation. Our attacks require the knowledge of the entire code-book and are not among the fastest attacks known on this cipher. However one of them works for 100 % of all keys, including so called "strong keys", see [15]. In general, it is important to show how many different attacks are possible on a weak cipher such as KeeLoq.

M3 - Article in proceedings

T3 - Tatra Mountains Mathematical Publications

SP - 167

EP - 188

BT - Tatracrypt '07 - 7th Central Europe Conference Of Cryptology

PB - Slovak Academy Sciences Mathematical Institute

ER -