The downside of using a faraday cage with an activated phone: The phone
will start "screaming" looking for a tower, and you'll get much reduced
battery life. Turning phone off first and *then* putting it in the bag
saves battery and prevents any suspected "backup battery" driven chips
from getting a signal out..although if that's your threat-model, they
could just record whatever telemetry they need and send later.
i.e., if a phone is suspected to be compromised and could turn on the
core or auxiliary chips (with main or backup battery), and activate the
microphone or camera, the faraday cage bag will prevent it from sending
that data right away but it could be instructed to store that data
instead and send it back later.
Personally I think removing the battery is sufficient for most phone
models; the backup batteries are unlikely to be enough to drive the more
concerning chips and sensors for long even if they're wired up to it in
the first place.
On 03/05/15 19:45, Mirimir wrote:
On 05/03/2015 11:20 AM, Georgi Guninski wrote:
On Sat, May 02, 2015 at 06:21:16PM -0600, Mirimir wrote:
For the Faraday bag, see
<http://www.instructables.com/id/RFID-Secure-Wallet/>. It's easy to
test. Just put the phone in the bag, and call it. If it rings, there are
leaks.
I am noob at smartphones, but isn't this very close to
functionally equivalent to just physically remove the
battery from the phone?
At what distance is phone with removed battery detectable?
Well, if someone implanted "backup battery" this fails,
but the implanted battery must be sufficiently small
to not see it.
I don't know enough about smartphones to say. The effectiveness of
removing the battery may vary among devices. Snowden told people
visiting him in Hong Kong to put their phones in the refrigerator, which
is a Faraday cage. Also, using a bag is arguably less hassle than
removing the battery.
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