Hacker News Reader

Comment by umvi | Hacker News Reader

I guess the police will learn to put the phone in a Faraday cage as soon as it's seized

The FBI has been doing this for some years now. There was an amusing story a while back about how Verizon put a new cell on top of the building where the FBI had their special shielded room, and the signal was so strong it was able to penetrate the shielding and some phones were lost. I could only find this brief mention here: https://spectrum.ieee.org/tech-talk/telecom/wireless/when-th...

One possible countermeasure: detect the lack of any electromagnetic field paired with no vibrations at all and colder temperature, ergo the phone isn't in someone's pocket in a no reception area but very likely was put in a shielded box. Phone sensors can reveal a lot of what is happening around them.

And everytime you put the phone in a safe, it gets wiped...

If it's your safe, then the phone very likely could detect its position very near to it before being screened so it can temporarily disable the automatic wipe. That includes your bank or some relatives safe of course. As I wrote, sensors can be used to detect various conditions, including accidents. Vibration, temperature, field, orientation, position and dynamic variations of the above all can be used to extrapolate data about what is happening outside the phone. Don't take me to the letter, of course an automatic wipe of the phone should take into account a huge number of false positives before kicking in. That's a field where AI could play a role in profiling users even without accessing audio, video and other personal data.

Why would you put your phone in a safe? Are the chances of it being stolen really that high?

There are many office/lab environments where personal electronic devices cannot be present for various reasons (security, EMI, etc.). Metal safes and lock boxes are common places to store PEDs when entering those environments.

Replace the word 'safe' with 'metal gym locker' and the answers are probably obvious.

Or if you go hiking in the middle of nowhere with no signal, the phone wipes itself. Very useful thanks.

That is not what the post says, thanks.

How is it not?

"detect the lack of any electromagnetic field paired with no vibrations at all and colder temperature"

You go hiking far outside of civilization and go to sleep in a tent, there are no electromagnetic fields around you at all(that the phone can detect anyway), there are no vibrations at all, and the temperature is cold because the phone is not on your body.

Or for a slightly more realistic example - I stayed with a friend recently who lives in a house from the 12th century - walls in there are about a meter thick, in certain rooms there is absolutely zero reception from any network, wifi doesn't penetrate at all. The no vibrations and low temperature points also apply there.

What am I missing that the post apparently said?

He's suggesting some sensor checks, not giving a total framework to account for every edge case. If you were to implement something like this, you would take many cases, including edge cases, into account.

With regards to the scene from "Snowden" where he places the phones in a micro wave oven. I was surprised to find that this doesn't work - at least not with my grandma's oven.

Can they just take them offline? Or...at do they at some point need to be online for the evidence gathering?

I wonder how can they prove that she did it? Or it's your phone, you know the password and let's try to convict you? If it was programmed to be erased before the phone was taken /crime committed she is not guilty I guess.

Sell 'mobile' Faraday cages one for every squad car... Profit?

http://www.reynoldskitchens.com/aluminum-foil/

[1] + this kind of pouch. Probably could sell them for at least 100$ a piece. 'battle tested'

[1]https://i5.walmartimages.com/asr/15479a20-388b-4138-9f8c-1a1...

It would be hard to sell it for $100 if you can buy digital evidence bags for a couple bucks: https://www.arrowheadforensics.com/products/evidence-packagi...

Put a "5G-ready!" sticker on it, and you're back in business.

And people called my hats crazy...

Just use a chip packet instead?

https://www.telegraph.co.uk/news/2017/11/27/australian-sacke...

Reply on news.ycombinator.com