Klaus Zimmermann's Corner

Are smartphones becoming more Faraday Cage-resistant?

This morning, out of sheer curiosity I decided to do a quick experiment with my smartphone. For some reason, upon booting it wouldn't turn the wifi on, so I decided to "punish" the (necessary) evil machine a little bit by confining it to a makeshift Faraday Cage - a metallic box of chocolates that we got from a friend as a present.

I've seen a lot of both documentaries and tin-foil hat movies where people successfully evade surveillance of tapped devices by putting them inside metallic containers like a Microwave Oven (Citizenfour by Laura Poitras), an empty bag of chips (Enemy of the state), or even the good ol' trick of wrapping it inside a heavy wet towel (Arnie in Total Recall). When nothing of these is available, a sheet of aluminum foil wrapping the device completely is enough to isolate it.

Or is it?

Turns out that the box of chocolates failed to contain the phone. I tested it by calling it from my partner's phone, and the damn thing would still ring. What the fuck? I tested the box and certified it was made of steel of sorts (unlike brass or aluminum, it's magnetic), but was still pretty pissed that the phone beat it. Ok, phone, you asked for it. Time to take it to the next level.

I opened the microwave oven and shut the phone inside of it. Side note: this is probably one of the scariest experiences of life, even when you know that you won't accidentally turn on the oven. Yeah, that will show that evil machine. After all, this is what Snowden did, right?

... And the phone would still ring. Note that this was both via voice and through a data app like Whatsapp.

I'm running out of options here. Last resort, wrapping it in plain old tin foil. C'mon, all these action movies with spies and all can't be wrong, right? But nope, the phone would still ring. What the hell.

What eventually worked was to layer up the defenses: when I wrapped the phone in foil and put it inside the metal box, it finally stopped receiving calls. Well, that took some effort, at least significantly more than what you see or read about in movies and spy fiction where a thin layer of aluminum is enough to deter the villain's tracking devices, leaving him blind about the hero's whereabouts.

the faraday cage, a pikachu-themed metallic box of chocolates

And that gets me thinking: how the hell can a cell phone survive this sort of isolation? Is this "stubborness" part of the "I'm going to be constantly connected" agenda or the "I'm going to spy on everything about you, no matter how hard" one? I previously did this Faraday Cage experiment about four years ago with a much older phone, and that one was successfully isolated with a layer of tin. Could be that cell phone makers - with their unremovable batteries, etc - are pushing for the point where a cell phone will never ever be disabled unless strict countermeasures are taken?

I guess these are all rhetorical questions to which I think I already know the answer. But anyway, if you own any of these tracking devices I'd recommend trying this experiment. We already know that this is not technology that's fighting for your side anyway, might as well take the time to figure out how much would it take to take the damn thing down when needed.

Have you ever tried isolating your phone with some sort of RF blocker? How much effort did it take for you to isolate yours? Let me know in Mastodon!

This post is number #15 of my #100DaysToOffload project. Follow my progress through Mastodon!

Last updated on 05/04/21