Cracking A5 GSM encryption (HAR 2009)

This talk titled "Cracking A5 GSM encryption" was given by Karsten at Hacking at Random (HAR) 2009.

The A5/1 algorithm is one of the ciphers used in GSM networks. It is used to encrypt both voice and signaling data.In the GSM network, A5/1 is applied both in the handset and the BTS on the corner of the network. The first phase of communication including radio resource allocation and authentication is unencrypted. Dialing and voice is encrypted. The attack on the A5/1 demoed at HAR 2009 is a reimplementation of the attack by THC, which was done in early 2008. Their approach differs slightly, as they use more common hardware to generate the tables, namely graphics cards with GPGPU capability and attempt to build a distributed infrastructure of nodes where each node donates both a small portion of diskspace for a part of the table and some kind of fast hardware for the generation of and lookup in its own table. They also took this project as a motivation to design and code a general purpose TMTO library. The attack itself is still the same and we owe THC much for their pioneering work. Also take a look at http://airprobe.org for information and software on the sniffing of GSM data. You can download the presentation here. The project page can be visited here.

Speaker Bio: Karsten is a security researcher and hardware hacker. Karsten's academic research deals with privacy protection, while his hacking projects focus on cryptographic hardware. In the past year, Karsten presented on smart-card security and embedded cryptography at 25C3, USENIX Security, BlackHat, CanSecWest, Toorcon, and the HOPE conference. Karsten is a security researcher and hardware hacker. Karsten's academic research deals with privacy protection, while his hacking projects focus on cryptographic hardware. In the past year, Karsten presented on smart-card security and embedded cryptography at 25C3, USENIX Security, BlackHat, CanSecWest, Toorcon, and the HOPE conference.

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Vivek Ramachandran is a security evangelist and has been working in computer security related fields for the past 7 years. In 2007, Vivek spoke at world renowned conferences Defcon (WEP Cloaking Exposed) and Toorcon (The Caffe Latte Attack). The discovery of the Caffe Latte Attack was covered by CBS5 news, BBC online, Network World etc news agencies.In 2006, Vivek was announced as one of winners of the Microsoft Security Shootout contest held in India among 65,000 participants. He has also been a recipient of a Team Achievement at Cisco Systems for his work on 802.1x and Port Security modules on the Catalyst 6500 switches. Currently he spends all of his time maintaining Security- Freak.Net , SecurityTube.Net and is the co-founder of Axonize. Vivek, is a Bachelor in Electronics and Communications Engineering from the prestigious Indian Institute of Technology, Guwahati.You can contact him at vivek[at]securitytube.net