Michael Richardson writes: > > Tero Kivinen <[email protected]> wrote: > > Michael Richardson writes: > >> > Implementations MUST use different L2 keys when using different MIC > >> > lengths, as using same key with different MIC lengths might be > >> unsafe > (i.e., using same key for both MIC-32 and MIC-64). See IEEE > >> 802.15.4 > Annex B.4.3 for more information. > >> > >> This seems like it isn't a problem. It would apply to network-wide > >> keying only. > > > It applies all keys, not only network-wide keys. > > yes, but if one uses 802.15.9, then the likelyhood of repeated keys is pretty > low, right?
No. Broadcast keys are most likely same for some time, and if you join the network before they are changed, the 15.9 will deliver you the same keys than last time. Pairwise keys generated by 15.9 are of course going to be different. > > Most common use might be someone using MIC-32 for beacons, but using > > MIC-64 for actual data or something like that. > > Yes, but why do that? > What's the benefit? Most likely saving bytes over the air. The EBs are sent quite often, and things that are there are already known by anybody who is already joined the network, thus they only care about the exact timing of the frame, not really about the content. Of course if there is changes for the network setup indicaed by EB, then it would be different, but I do not think anybody does that, as chaing any of the parameters inside the network (timing, channels used etc) would really mess up the network completely thus tearing down the network and starting over is better option. -- [email protected] _______________________________________________ 6tisch mailing list [email protected] https://www.ietf.org/mailman/listinfo/6tisch
