[PLUG] /not/ OK, Google

[Keith Lofstrom]

On Thu, Jul 02, 2015 at 07:59:37AM -0700, Denis Heidtmann wrote:
> Can a smart phone be turned off (other than removing the battery)?

The power switch is not direct.  Without a chip teardown and trace
of the logic (which nobody cares enough to participate in) we have
no idea what logic paths control power to the system.

This is an opportunity for a hack - two tiny pixel-sized microwatt
LEDs added to the phone, one connected physically to the phone
power supply, the other to phone transmitter power.  The smallest
LEDs I know about are 0.5 x 1 mm and draw 30 mW - does anyone make
LEDs 200 times smaller, with built-in ballast resistors?

A powered-but-not-transmitting phone could still store voice data
in the capacious memory, but this would be easy to spot.  A small
modification to the operating system to zero any "unused" memory
before data service would help protect privacy.  Thus justifying
this posting as linux related.

In the long term, though, we cannot maximize privacy without 
maximum transparency.  That includes both software AND hardware.
There are many out-of-work chip designers who would be glad to
help design open hardware smart phones, and help teardown and
validate what the chinese semiconductor fab actually makes. 
But that will involve equipment, CAD tools, and manufacturing
cost, which is dreadfully expensive.

Keith

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Keith Lofstrom          keithl at keithl.com