you will not get anything out of the rainbow tables with less than 64bits of keystream, if you abstain from bad ideas like doing 2^N lookups for each N bits missing.
what is the content of the other half-burst in a typical FACCH usage scenario? if you can for example come up with significantly less than 2^57 possible contents of the missing half, it might be economical to guess. Furthermore a lucky coincidence would be to have the second halfburst of the downlink and the first halfburst of the uplink (in the same time slot) being from 2 known LAPDm frames. On Tue, Jan 04, 2011 at 01:02:50PM +0100, Sylvain Munaut wrote: > Hi, > > > Has anyone given any thought how to apply the rainbow table to FACCH channels > ? > > For FACCH the burst are stolen from TCH but not en entire burst, just > half a burst (so a L2 message is split over 8 half bursts). > We know where they are (thanks to stealing bits). But we only ever > have 57 consecutive known bits ... never 64 or more ... (unless you > have two consecutive known FACCH bursts). > > > Cheers, > > Sylvain > _______________________________________________ > A51 mailing list > [email protected] > http://lists.lists.reflextor.com/cgi-bin/mailman/listinfo/a51 _______________________________________________ A51 mailing list [email protected] http://lists.lists.reflextor.com/cgi-bin/mailman/listinfo/a51
