Recent posts

GMR-1 dissection merged in Wireshark mainline

All the current patches that were pending in the sylvain/gmr branch of our osmocom Wireshark tree have now been merged into the official trunk. Thanks to the Wireshark folks for reviewing them and merging them quickly.

What's supported :

  • BCCH partial support (segment 1/2A/3A fully dissected)
  • CCCH partial support (all messages ever seen on Thuraya are supported)
  • RR partial support (all messages ever seen on Thuraya are supported)
  • MM/CC forwarded to GSM dissectors and are mostly correct

The sylvain/gmr branch will now be removed but may re-appear in the future if new dissectors are written. Basically if we have new gmr stuff pending inclusion it'll be in that branch, and if the branch doesn't exist it just means the official trunk contains everything so far.

Osmo-GMR now supports A5-GMR-1 cipher

Osmo-GMR now has support for cipher stream generation. This allows to see past the CIPHER MODE COMMAND in the examples (I will put the key along with the demo files soon).

You can see the actual code in the git : ​http://cgit.osmocom.org/cgit/osmo-gmr/commit/?id=c70e5208d5a0daa9b3ff77c28f54d97f549d90f2

The algorithm was re-implemented by the Osmo-GMR team based on the reversing work done at the University of Bochum by a team comprised of Benedikt Driessen, Ralf Hund, Carsten Willems, Christof Paar, and Thorsten Holz. The Osmo-GMR team actually contributed in the late stages of this work by providing real world captures to validate the reversed algorithm and the attacks.

Lecture on cryptoanalysis of GMR-1 and GMR-2 ciphers

On February 2nd, researchers Be­ne­dikt Dries­sen und Ralf Hund of the University of Bochum will report on their analysis of the GMR-1 and GMR-2 ciphers.

According to the ​abstract, the cipher used in GMR-1 and thus Thuraya is more or less the same than GSM's A5/2, and can be broken at similar complexity (i.e. almost none).

Video and Slides of Sylvain's 28C3 GMR talk

OsmocomGMR main author Sylvain Munaut has given a presentation about the GMR-1 standard and the OsmocomGMR software at the 2011 annual CCC conference (28C3).

It is a great introduction into the topic, and a recommended read/view for everyone wanting to experiment with our OsmocomGMR software.

The slides are available from ​http://events.ccc.de/congress/2011/Fahrplan/attachments/2027_28c3_introducing_osmocom_gmr.pdf

The video is available from ​http://mirror.fem-net.de/CCC/28C3/mp4-h264-HQ/28c3-4688-en-introducing_osmo_gmr_h264.mp4