Do you have traces of the attach/authentication? It seems like for some reason
your MS don't like A5/3, because they are supposed to reply with Cipher Mode
Complete. So top of my head I had the thought there might be something wrong
with the initial establishment of the keys.
> 2018. márc. 6. dátummal, 10:58 időpontban Bruckner Jan (ETAS-SEC/ECT-Mu)
> <jan.bruck...@escrypt.com> írta:
> Dear list,
> I’m having trouble using the A5/3 encryption in my setup. A5/1 works
> perfectly fine [attachment a5_1.pcapng]. As soon as I switch to A5/3 and e.g.
> send an SMS, the last valid message I see in the Wireshark traces of the
> GSMTAP of osmo-bts-trx is the Ciphering Mode Command requesting A5/3. After
> that, several messages arrive at the bts, but it seems like it can’t make any
> sense of them. The MS repeatedly tries to send the SMS but never succeeds
> [attachment a5_3.pcapng]. Both MSs are connected to the same bts.
> According to the Classmarks of all MSs, A5/1 as well as A5/3 are supported.
> This is my Setup:
> - USRP N210
> - osmo-trx
> - osmo-bts-trx
> - osmo-nitb
> - osmo-pcu
> - osmo-sgsn
> - osmo-ggsn
> I’m using a Debian 9 VM and tried both the packages from osmocom-latest as
> well as osmocom-nightly.
> The MSs I’ve tested are two Nexus 6 and one Samsung Galaxy S I9000. All three
> with sysmocom nano USIMs.
> Could the decryption at the bts be incorrect? Has anyone tested/used it
> I’ll be happy to provide additional information if needed.