A public mailing list for announcements and discussion can be found at http://lists.reflextor.com/cgi-bin/mailman/listinfo/a51.
Bugs and support requests must be filed through the issue tracker, they are of little interest to the majority of the subscribers.
There are 2 independent programs, the first being Kraken and its associated utilities, developed by Frank A. Stevenson, which
targets AMD (ATI) GPUs and the CPU (written in C++/python). The (read only) kraken git is at git://git.srlabs.de/kraken.
The second is a device independent TMTO library, currently under development which targets ATI and NVIDIA GPUs and also the CPU (C++).
The A5/1 decryption is logistically a part of airprobe (http://airprobe.org), which allows interfacing with the radio waves with
the help of gnuradio.
Channel Coding and Modulation: http://www.azizi.ca/gsm/system/index.html
Physical and Logical Channels: http://students.ee.sun.ac.za/~gshmaritz/gsmfordummies/intro.shtml