Hello,
In GSM the BS can force the mobile TE to run the call in unencrypted mode; this feature is used, for example, to sniff GSM calls with IMSI catchers; for more details see http://en.wikipedia.org/wiki/IMSI-catcher I was investigating this a bit in the log file fsogsmd.log and have some kind of surprise and some questions: A 'grep CPRI fsogsmd.log' after a fresh reboot shows that %CPRI=1 is enabled, i.e. during a phone call the device will show if or if not encryption takes place: fsogsmd.log:2012-03-23T14:46:00.026356Z [INFO] libfsotransport <0710:3>: SRC: "%CPRI=1" -> [ "OK" ] fsogsmd.log:2012-03-23T14:46:55.872445Z [INFO] libfsotransport <0710:3>: URC: [ "%CPRI: 1,2" ] the meaning of "%CPRI: 1,2", is that: '1' is for GSM (ciphering enabled) and the '2' for GPRS (ciphering state not applicable) now I did some phone call (in/out) and always ciphering was shown and enabled: fsogsmd.log:2012-03-23T14:47:03.324784Z [INFO] libfsotransport <0710:3>: URC: [ "%CPRI: 1,2" ] fsogsmd.log:2012-03-23T14:48:33.408969Z [INFO] libfsotransport <0710:3>: URC: [ "%CPRI: 1,2" ] fsogsmd.log:2012-03-23T14:50:24.799359Z [INFO] libfsotransport <0710:3>: URC: [ "%CPRI: 1,2" ] now I let the FR suspending and waked it up again; and during the re-init of the modem it is set to "do not show encryption" on call, i.e. is is switched of with "%CPRI=0": fsogsmd.log:2012-03-23T14:52:13.633599Z [INFO] libfsotransport <0710:3>: SRC: "%CPRI=0" -> [ "OK" ] fsogsmd.log:2012-03-23T14:54:09.952246Z [INFO] libfsotransport <0710:3>: SRC: "%CPRI=0" -> [ "OK" ] Why is this? Another question is, when I try from userland to switch cipher notification on again, it seems that this chat(1) does not work: root@om-gta02:~# chat -vs < /dev/ttySAC0 > /dev/ttySAC0 '' 'AT%CPRI=1' What I'm doing wrong here with chat(1)? I'm attaching as well an older thread from the comunity list from last year; In general I think that a) SHR should switch cipher notification to on b) SHR should show during the call if the call is encrypted or not on the screen (and not only in the log files); any comments on this? Thanks matthias ----- Forwarded message from Matthias Apitz <g...@unixarea.de> ----- Date: Tue, 5 Jul 2011 07:57:24 +0200 From: Matthias Apitz <g...@unixarea.de> To: Timo Juhani Lindfors <timo.lindf...@iki.fi> Cc: List for Openmoko community discussion <commun...@lists.openmoko.org> Subject: Re: FR && non encrypted calls El día Monday, July 04, 2011 a las 09:35:24AM +0300, Timo Juhani Lindfors escribió: > Matthias Apitz <g...@unixarea.de> writes: > > Is the FR capable to show that the call runs in non encrypted mode > > because the BS forced the ME to this mode? The question is for Om2008.9 > > but as well valid for any other distribution running on the FR. > > I think the GSM part (Calypso) delivers this information in the AT%CPRI > message. With ogsmd (part of the python version of fso-frameworkd) I > have lines like > > Jul 3 11:57:43 ginger org.freesmartphone.GSM.Network.CypherStatus: enabled: > unknown > > in /var/log/syslog. > > om2008.9 does not use ogsmd afaik but gsmd. I did some tests sending down AT-cmds with the 'chat' command and watching the AT chatting in /var/log/messages: Per default it is set to off: root@om-gta02:~# chat -vs < /dev/ttySAC0 > /dev/ttySAC0 '' 'AT%CPRI?' Jul 5 07:39:50 om-gta02 local2.info chat[1556]: send (AT%CPRI?^M) Jul 5 07:39:50 om-gta02 user.notice root: AtChat : ? : "%CPRI: 0" Jul 5 07:39:50 om-gta02 user.notice root: AtChat : ? : "OK" Then I switched it on with: root@om-gta02:~# chat -vs < /dev/ttySAC0 > /dev/ttySAC0 '' 'AT%CPRI=1' which gives in the /var/log/messages: Jul 5 07:41:37 om-gta02 local2.info chat[1557]: send (AT%CPRI=1^M) Jul 5 07:41:37 om-gta02 user.notice root: AtChat : ? : "OK" then I dialed a number: Jul 5 07:43:49 om-gta02 user.notice root: AtChat : T : "ATD089xxxxxxxx;" Jul 5 07:43:51 om-gta02 user.notice root: AtChat : N : "+CSSI: 1" Jul 5 07:44:17 om-gta02 user.notice root: AtChat : F : "OK" Jul 5 07:44:17 om-gta02 user.notice root: Modem : QModemCall::dialRequestDone() Jul 5 07:44:17 om-gta02 user.notice root: AtChat : T : "AT+CLCC" Jul 5 07:44:17 om-gta02 user.notice root: AtChat : F : "%CPRI: 1,2" Jul 5 07:44:17 om-gta02 user.notice root: AtChat : F : "OK" Jul 5 07:44:17 om-gta02 user.notice root: Modem : dialing was ok, we are connected Jul 5 07:44:23 om-gta02 user.notice root: Modem : QModemCall::hangup() Jul 5 07:44:23 om-gta02 user.notice root: AtChat : T : "AT+CHLD=1" Jul 5 07:44:23 om-gta02 user.notice root: Modem : hangup groups Jul 5 07:44:23 om-gta02 user.notice root: AtChat : F : "OK" as you see, one of the result code of the TE is "%CPRI: 1,2", where the '1' is for GSM (ciphering enabled) and the '2' for GPRS (ciphering state not applicable), see also page 167 for the values in http://www.cartft.com/support_db/support_files/CTFPND-3_AT_Command_Reference.pdf with a bit of tweaking, at least this information is visible in the log files if the connection is ciphered or not. HIH matthias -- Matthias Apitz t +49-89-61308 351 - f +49-89-61308 399 - m +49-170-4527211 e <g...@unixarea.de> - w http://www.unixarea.de/ _______________________________________________ Openmoko community mailing list commun...@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community ----- End forwarded message ----- -- Matthias Apitz e <g...@unixarea.de> - w http://www.unixarea.de/ UNIX since V7 on PDP-11, UNIX on mainframe since ESER 1055 (IBM /370) UNIX on x86 since SVR4.2 UnixWare 2.1.2, FreeBSD since 2.2.5 _______________________________________________ Shr-devel mailing list Shr-devel@lists.shr-project.org http://lists.shr-project.org/mailman/listinfo/shr-devel
