This open source software allows the 'cracking' of A5/1 keys used to encrypt GSM 2G calls and SMS.
The cracking utility Kraken, developed by Frank A. Stevenson, is written in C++/python and runs on AMD GPUs or CPUs.
Kraken leverages rainbow tables that were computed as a community effort.
A public mailing list for announcements and discussion can be found here .
You may also file bugs and support requests through the issue tracker if they are of little relevance to the majority of the mailing list subscribers.
The (read only) Kraken git can be fetched with
git clone git://git.srlabs.de/kraken
The A5/1 decryption was originally meant to be used with Airprobe), which allows interfacing with the radio waves with
the help of gnuradio.
Airprobe has, for most users, since been replaced by the cheaper Osmocom phones