[Replicant] Question regarding a freedom respecting modem

[m d]

 > ##I'm also unsure if there are more ways than the IMEI to identify
> ##devices. It's for instance possible to identify the family of WiFi
> ##chips being used just by looking at what is being transmitted. So it
> ##may be possible to still get some identifying information out of the
> ##device even if the IMEI has been changed.
> 
> Radio fingerprinting pointed above?
##Yes, I wasn't aware of any papers for GSM. Thanks for the link, I'll try
##to find the time to read it.
OK no problems. By the sound of your previous hypothesis of identifying devices by family of wifi etc... + this research paper, it might be "safe" to assume that IMEI identification of use for blacklisting of devices. Therefore even a device with a spoofed IMEI might not be able to falsify its identity. This could be quite significant for all sorts of reasons, but for Replicant itself the main concern after all would be for rebuilding the /efs partition once it becomes corrupted. This is a different plan than spoofing an IMEI in terms of mentality, at least for me =)
The other thing which I forgot to ask previously, you might not know the answer to this but, would it be possible to correlate the call logs from several sim cards to an IMEI? As in, would a service provider be able to gather all call logs from a device's IMEI if this device had been used with different sim cards?


    On Monday, 10 May 2021, 16:38:41 BST, Denis 'GNUtoo' Carikli <gnutoo at cyberdimension.org> wrote:  
 
 On Tue, 4 May 2021 12:20:16 +0000 (UTC)
m d <mdreplicantmd at yahoo.com> wrote:

> ##It's rather related to the cellular network architecture: you are
> ##connected to a given antenna / base station that knows at what
> distance ##of it you are. In addition you might move so there is a
> feature ##called handover that enables you to switch form one base
> station to the ##next one while moving. So you then have multiple
> base stations that ##knows the distance between you and them. With
> that it's trivial to get ##your position.
> 
> OK, is that distance known to the network via the RSSI?
> I think this handover feature might be somewhat related to this
> "triangulation" method, in which case what if the device remains
> static from within a building next to a window. Is it possible that
> the station could only connect to 1 base without providing distance
> information between the other ones?
I'm not an expert on that, as I lack low level knowledge on the
standards like GSM, GPRS, 3G, etc. 

If I recall well, the device sends distance measurements, but it's not
magic either as you probably cannot fake the distance too much else it
would probably stop working.

> ##I'm also unsure if there are more ways than the IMEI to identify
> ##devices. It's for instance possible to identify the family of WiFi
> ##chips being used just by looking at what is being transmitted. So it
> ##may be possible to still get some identifying information out of the
> ##device even if the IMEI has been changed.
> 
> Radio fingerprinting pointed above?
Yes, I wasn't aware of any papers for GSM. Thanks for the link, I'll try
to find the time to read it.

> One more thing, is the function to hide caller ID one of proprietary
> software? I'm unable to hide my caller ID on Replicant although the
> function was working as expected with proprietary ROMS. 

That's probably because it's not implemented yet.

There is some rough information on what is implemented and what is not
here:
https://redmine.replicant.us/projects/replicant/wiki/Libsamsung-ril

That list doesn't take into account the libsamsung-ipc part and how
things are implemented, so it's not very reliable but it still gives a
rough idea of the status.

Having a complete implementation could also enable projects like
LineageOS to reuse libsamsung-ipc and libsamsung-ril. 

This could then benefit the GNU/Linux distributions that use vendor
kernels too (or even upstream kernel once we make it work with that).

Denis.
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