The only thing which I found is "CIPHERING" in file /usr/include/ISI/icpr82/pn_modem_network_isi.h

There is NET_CIPHERING_INDICATOR_OFF and NET_CIPHERING_INDICATOR_ON which are probably defines for ciphering_status field in NET_CIPHERING_IND structure.

Looks like those are defines for isi packets and if yes, isi modem could send us this information.

@jonwil, can you recheck if above structure is really not exported by some dbus (or other) api? And if not, it is possible to listen for isi packets on n900 and manually parse them (e.g. find that NET_CIPHERING_IND)?