Paper 2008/147
A Real-World Attack Breaking A5/1 within Hours
Timo Gendrullis, Martin Novotny, and Andy Rupp
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.
Metadata
- Available format(s)
-
PDF
- Publication info
- Published elsewhere. Unknown where it was published
- Keywords
- A51GSMspecial-purpose hardwareCOPACOBANA
- Contact author(s)
- arupp @ crypto rub de
- History
- 2008-04-01: received
- Short URL
- https://ia.cr/2008/147
- License
-
CC BY
BibTeX
@misc{cryptoeprint:2008/147,
author = {Timo Gendrullis and Martin Novotny and Andy Rupp},
title = {A Real-World Attack Breaking A5/1 within Hours},
howpublished = {Cryptology {ePrint} Archive, Paper 2008/147},
year = {2008},
url = {https://eprint.iacr.org/2008/147}
}