3 ms·

I've long suspected that the only way to make an actually private/secure cellular phone is by bypassing 3G all-together and making it optional -- forcing the SM

I've long suspected that the only way to make an actually private/secure cellular phone is by bypassing 3G all-together and making it optional -- forcing the SMS/SIP features of the phone were actually on separate hardware that had very limited integration with the phone itself (essentially as dangerous as any external USB device would be)? Most smart phones are considered pwned-by-default due to the inclusion of the 3G/4G/whatever chip you have no control over. Of course, there's the whole issue of distributed trust by way of pre-loaded X509 certs but there are some relatively secure ways around that (keybase, meeting in person and swapping PGP keys, etc) that would move the goalpost far enough to where it might not even matter any more. Does anyone know anything that's close to this? basically a phone that only uses SDR for connectivity?

confounded 8y ago
> SMS/SIP features of the phone were actually on separate hardware... basically a phone that only uses SDR for connectivity? Not exactly what you’re after, but the Librem 5 (crowd-funded, at the head-scratching stage) aims to put the baseband processor in an optional M2 slot with killable power. On a device that runs Debian. From following progress on that project I’ve got the impression that everything to do with chips for mobile connectivity are so patent/IP-law encumbered that there’s little hope for Free Software replacements. https://puri.sm/shop/librem-5/ https://puri.sm/shop/librem-5/ However, hacking on that handset is the best chance I’m aware of for you getting the device you want (perhaps with something else in the M2 slot).
- znpy 8y ago
  > but the Librem 5 aims to put the baseband processor in an optional M2 slot with killable power. If that comes true I am definitely getting one.
- subway 8y ago
  I think only the prototypes are using M2. The production devices likely won't have a removable modem, but it will still be a separate chip with separately controllable power.
- jrcii 8y ago
  The Neo900 has a completely sandboxed baseband, and you can kill the baseband with the Dragonbox Pyra. Both are on their way.
pjc50 8y ago
> a phone that only uses SDR for connectivity? There are some hardcore GSM hackers slowly assembling the parts for this: http://git.osmocom.org/ http://git.osmocom.org/
ossguy 8y ago
If you want to use an SDR instead of a dedicated 2G/3G/LTE modem, you would still need 2G/3G/LTE baseband firmware to teach your SDR how to access the cell network (if/when you wanted that). As mentioned by "pjc50", OsmocomBB (see https://osmocom.org/projects/baseband https://osmocom.org/projects/baseband ) aims to do this for 2G, though it isn't quite ready yet. FreeCalypso (see https://www.freecalypso.org/software.html https://www.freecalypso.org/software.html ) has a working 2G firmware, but is focused on very specific hardware. Note that any free/adaptable baseband firmware for 3G/LTE is still a long way off. In the meantime, it's better to use a phone that gives you control over the cellular modem (if you still need the modem), as "confounded" suggested (with the Librem 5). Other phones similar to the Librem 5 are also specifically designed to ensure the modem is not doing anything unexpected, such as the Neo900: https://neo900.org/faq#privacy https://neo900.org/faq#privacy - "Unlike some other smartphones do, Neo900 won't share system RAM with the modem and system CPU will always have full control over the microphone signal sent to the modem. You can think of it as a USB dongle connected to the PC, with you in full control over the drivers, with a virtual LED to show any modem activity." Regardless of which of these you choose, you can already separate your phone number from your SIM card with projects like https://jmp.chat/ https://jmp.chat/ so you don't need to use a cellular modem just to send/receive SMS/MMS and calls if you happen to be around wifi already. And you get other nice features like voicemail auto-transcribed and delivered as text by default, too (see https://jmp.chat/#voicemail https://jmp.chat/#voicemail for details). So I'd start by using https://jmp.chat/ https://jmp.chat/ with your existing phone and phone number, then switch to new phones/modems as the modem separation gets better.
- yjftsjthsd-h 8y ago
  Thanks for sharing jmp.chat; this finally looks like an alternative to Google Voice, and a really good alternate at that
vincnetas 8y ago
In case of SDR you should not forget to get a license to transmit in GSM spectrum: Legalities and options The GSM spectrum is very expensive private property. You may not transmit (or even receive) in GSM bands without permission. In the UK, it is an offence under the Wireless Telegraphy Act to transmit on licensed bands without permission and furthermore intercepting GSM without a warrant is an offence under the Regulation of Investigatory Powers Act.You should apply for a licence (example from OFCOM below) before commencing GSM testing and will also need a faraday cage to suppress radiation. (For these reasons, GSM interfaces get less scrutiny than TCP/IP for example). https://www.contextis.com/blog/binary-sms-the-old-backdoor-to-your-new-thing https://www.contextis.com/blog/binary-sms-the-old-backdoor-t...

confounded 8y ago

> SMS/SIP features of the phone were actually on separate hardware... basically a phone that only uses SDR for connectivity? Not exactly what you’re after, but the Librem 5 (crowd-funded, at the head-scratching stage) aims to put the baseband processor in an optional M2 slot with killable power. On a device that runs Debian. From following progress on that project I’ve got the impression that everything to do with chips for mobile connectivity are so patent/IP-law encumbered that there’s little hope for Free Software replacements. https://puri.sm/shop/librem-5/ https://puri.sm/shop/librem-5/ However, hacking on that handset is the best chance I’m aware of for you getting the device you want (perhaps with something else in the M2 slot).

znpy 8y ago
> but the Librem 5 aims to put the baseband processor in an optional M2 slot with killable power. If that comes true I am definitely getting one.
subway 8y ago
I think only the prototypes are using M2. The production devices likely won't have a removable modem, but it will still be a separate chip with separately controllable power.
jrcii 8y ago
The Neo900 has a completely sandboxed baseband, and you can kill the baseband with the Dragonbox Pyra. Both are on their way.

pjc50 8y ago

> a phone that only uses SDR for connectivity? There are some hardcore GSM hackers slowly assembling the parts for this: http://git.osmocom.org/ http://git.osmocom.org/

ossguy 8y ago

If you want to use an SDR instead of a dedicated 2G/3G/LTE modem, you would still need 2G/3G/LTE baseband firmware to teach your SDR how to access the cell network (if/when you wanted that). As mentioned by "pjc50", OsmocomBB (see https://osmocom.org/projects/baseband https://osmocom.org/projects/baseband ) aims to do this for 2G, though it isn't quite ready yet. FreeCalypso (see https://www.freecalypso.org/software.html https://www.freecalypso.org/software.html ) has a working 2G firmware, but is focused on very specific hardware. Note that any free/adaptable baseband firmware for 3G/LTE is still a long way off. In the meantime, it's better to use a phone that gives you control over the cellular modem (if you still need the modem), as "confounded" suggested (with the Librem 5). Other phones similar to the Librem 5 are also specifically designed to ensure the modem is not doing anything unexpected, such as the Neo900: https://neo900.org/faq#privacy https://neo900.org/faq#privacy - "Unlike some other smartphones do, Neo900 won't share system RAM with the modem and system CPU will always have full control over the microphone signal sent to the modem. You can think of it as a USB dongle connected to the PC, with you in full control over the drivers, with a virtual LED to show any modem activity." Regardless of which of these you choose, you can already separate your phone number from your SIM card with projects like https://jmp.chat/ https://jmp.chat/ so you don't need to use a cellular modem just to send/receive SMS/MMS and calls if you happen to be around wifi already. And you get other nice features like voicemail auto-transcribed and delivered as text by default, too (see https://jmp.chat/#voicemail https://jmp.chat/#voicemail for details). So I'd start by using https://jmp.chat/ https://jmp.chat/ with your existing phone and phone number, then switch to new phones/modems as the modem separation gets better.

yjftsjthsd-h 8y ago
Thanks for sharing jmp.chat; this finally looks like an alternative to Google Voice, and a really good alternate at that

vincnetas 8y ago

In case of SDR you should not forget to get a license to transmit in GSM spectrum: Legalities and options The GSM spectrum is very expensive private property. You may not transmit (or even receive) in GSM bands without permission. In the UK, it is an offence under the Wireless Telegraphy Act to transmit on licensed bands without permission and furthermore intercepting GSM without a warrant is an offence under the Regulation of Investigatory Powers Act.You should apply for a licence (example from OFCOM below) before commencing GSM testing and will also need a faraday cage to suppress radiation. (For these reasons, GSM interfaces get less scrutiny than TCP/IP for example). https://www.contextis.com/blog/binary-sms-the-old-backdoor-to-your-new-thing https://www.contextis.com/blog/binary-sms-the-old-backdoor-t...