[HGI-News-de] HGI Seminar 24. April: "Realtime A5/1 Attacks with Precomputed Tables" by M. Novotny

[Newsletter des Horst Görtz Instituts]

Hallo,

im Rahmen des HGI-Seminars "Aktuelle Themen der IT-Sicherheit" wird  
am kommenden Donnerstag der folgende Vortrag angeboten:

Martin Novotny und Andy Rupp (Lehrstuhl für Kommunikationssicherheit, RUB):
"Realtime A5/1 Attacks with Precomputed Tables"

Termin:
Donnerstag, der 24. April um  11.00 Uhr
Raum: IC 4/161.

Alle Interessierte sind herzlich eingeladen!


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Zusammenfassung:

GSM communication is encrypted with A5/1 stream cipher. Many attack
scenarios against GSM have been proposed, however none of them was fully
implemented. The first real-world attack appears to be the smart
brute-force attack recently developed and implemented in COSY group,
Ruhr-University Bochum. When using COPACOBANA machine, the cipher can be broken in several hours.

Another approach is to use precomputed tables, denoted as time-memory
trade-off (TMTO) tables. This method allows for very fast attack, e.g.
A5/1 cipher might be broken in a couple of minutes. However,
precomputation of TMTO tables demands extensive computation power and
hence it may last from several weeks up to several thousands of years,
depending on both the cipher and the computation platform.

In our talk we will discuss variants of TMTO methods, their advantages
and drawbacks with respect to the actual cipher and with respect to
efficient hardware implementation. We will present a hardware engine
calculating TMTO tables for A5/1. The engine was designed and
implemented for COPACOBANA machine. We also will discuss the design
tricks used to gain maximum performance of the machine.

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Informationen über die nächsten geplannten Vorträge im Rahmen des
HGI-Seminars sind auch im Web zu finden:
http://www.hgi.rub.de/deutsch/lehrangebot/seminar/ss2008.html

Gruß,
Biljana Cubaleska