[GSM] GSM Analyzer

As described in earlier blog posts, I coded a driver for an USB radio receiver which is comparable to USRP. So I’m able to “record” radio data and save it, or process it on-the-fly with some tools.

GSM Analyzer is a C# tool that demodulates and decodes the GMSK signal which GSM uses. Furthermore it decodes the L3 (Layer 3 Protocol) messages sent in the broadcast channel (BCCH). This means, I’m able to “tune in” into some GSM radio channel and sniff the packets which the base station (BTS) is sending. Usually thats just really public information like the provider ID, information about the network and such things. Nothing interesting.

People who know the nokia net monitor would just look up that in the phones menu…
I “just” select some radio frequency and look that up there using my tool ;)

That project is really just for fun. Some people call me crazy. No idea why they do that. Thats really not hard to decode. And it has nothing useful yet. Okay… if I’m able to decrypt the A5 crypted SDCCH/TCH traffic, that whole story really would get interesing. But thats still pure theory yet.

Maybe I will describe that stuff more in the near future. Maybe I will release the source code. Maybe I won’t :)

See the project page for some videos. (the text is the same, except for the video description)

2 Responses to “[GSM] GSM Analyzer”

  1. bonzo Says:

    You are soo crazy ;-) ( http://www.youtube.com/watch?v=LmQFH5XdC7s )

    But A5/X is still a bunch of work!
    http://www.cs.technion.ac.il/users/wwwb/cgi-bin/tr-get.cgi/2006/CS/CS-2006-07.pdf

  2. geggo Says:

    hmm but chapter 4 “An Instant Ciphertext-Only Attack on A5/2” sounds very promising.
    it just requires eight SDCCH frames to calculate back the A5 registers. looks just too simple :)

Leave a Reply

You must be logged in to post a comment.


We are using cookies on our website

Please confirm, if you accept our tracking cookies. You can also decline the tracking, so you can continue to visit our website without any data sent to third party services.