How are the Baltimore riots going?/Any way we can help?

Cathal Garvey cathalgarvey at
Sun May 3 12:05:22 PDT 2015

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
>>> <>. 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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