This open source software allows the 'cracking' of A5/1 keys used to secure GSM 2G calls and SMS.
The cracking unitity Kraken, developed by Frank A. Stevenson, is written in C++/python and targets AMD (ATI) GPUs and CPUs.
A public mailing list for announcements and discussion can be found here .
Please fill bugs and support requests through the issue tracker as they may be of little relevance to the majority of the mailing list subscribers.
The (read only) Kraken git can be fetched with
The A5/1 decryption was originally meant to be used with Airprobe (http://airprobe.org), which allows interfacing with the radio waves with
the help of gnuradio. This tutorial explains the decryption process.
Airprobe has, for most users, since been replaced by the cheaper Osmocom phones