A Real-World Attack Breaking A5/1 within Hours

  • Timo Gendrullis
  • Martin Novotný
  • Andy Rupp
Conference paper

DOI: 10.1007/978-3-540-85053-3_17

Part of the Lecture Notes in Computer Science book series (LNCS, volume 5154)
Cite this paper as:
Gendrullis T., Novotný M., Rupp A. (2008) A Real-World Attack Breaking A5/1 within Hours. In: Oswald E., Rohatgi P. (eds) Cryptographic Hardware and Embedded Systems – CHES 2008. CHES 2008. Lecture Notes in Computer Science, vol 5154. Springer, Berlin, Heidelberg

Abstract

In this paper we present a real-world hardware-assisted attack on the well-known A5/1 stream cipher which is (still) used to secure GSM communication in most countries all over the world. During the last ten years A5/1 has been intensively analyzed [1,2,3,4,5,6,7]. However, most of the proposed attacks are just of theoretical interest since they lack from practicability — due to strong preconditions, high computational demands and/or huge storage requirements — or have never been fully implemented.

In contrast to these attacks, our attack which is based on the work by Keller and Seitz [8] is running on an existing special-purpose hardware device, called COPACOBANA [9]. With the knowledge of only 64 bits of keystream the machine is able to reveal the corresponding internal 64-bit state of the cipher in about 6 hours on average. We provide a detailed description of our attack architecture as well as implementation results.

Keywords

A5/1 GSM special-purpose hardware COPACOBANA 
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Copyright information

© Springer-Verlag Berlin Heidelberg 2008

Authors and Affiliations

  • Timo Gendrullis
    • 1
  • Martin Novotný
    • 1
  • Andy Rupp
    • 1
  1. 1.Horst Görtz Institute for IT-SecurityRuhr-University BochumGermany

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