CryptoDB
A Real-World Attack Breaking A5/1 within Hours
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| 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. 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 and have never been fully implemented. In contrast to these attacks, our attack which is based on the work by Keller and Seitz [KS01] is running on an existing special-purpose hardware device, called COPACOBANA. 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 7 hours on average. Besides providing a detailed description of our attack architecture as well as implementation results, we propose and analyze an optimization that leads again to an improvement of about 16% in computation time. |
BibTeX
@misc{eprint-2008-17824,
title={A Real-World Attack Breaking A5/1 within Hours},
booktitle={IACR Eprint archive},
keywords={A5/1, GSM, special-purpose hardware, COPACOBANA},
url={http://eprint.iacr.org/2008/147},
note={ arupp@crypto.rub.de 13969 received 31 Mar 2008},
author={Timo Gendrullis and Martin Novotny and Andy Rupp},
year=2008
}