Presentations slides from HAR2009 for a talk on cracking A5 GSM encryption.
You can download it from the following link: https://packetstormsecurity.com/files/download/80627/119_GSM.A51.Cracking.Nohl.pdf
Source: https://packetstormsecurity.com/files/80627/HAR-2009-Cracking-A5-GSM-Encryption.html