Blocking people from taking pictures of me with smartphone

Question

This question might be better suited for Skeptics, but I guess that those who can really answer this might hang around here.

In the second episode of the fourth season of the french spy series The Bureau (see around 0:36 in this clip), one hacker (A) demonstrated how when someone else (B) is taking a picture of him with a smartphone, the picture is not captured and instead a message "Do not do that motherf...!" is shown.

A claims that it works thanks to an app that he has on his own smartphone, interacting with B's smartphone to prevent it from taking pictures.

My question is if this really is doable. Of course if A previously hacked B's phone then there is nothing particularly special about it, but could this be achieved so that no random person showing app can take a picture of A with their smartphone?

Answer 1

tl;dr

No, this completely falls within the realms of fiction!

The longer explanation

For something like this to work, Alice would need to find an exploit in the camera of Bob, which would then prevent Bob from taking a picture. The only ways of Alice to exploit Bob's camera is for her to send some kind of information to it.

Possible ways for her to do this would either be via what the camera "sees" or via some other channel (Bluetooth, Ad-Hoc Wi-Fi, etc.).

The first way is, to be frank, absolutely nuts. There are exploits related to images and specific image formats, but all those exploit the specifications of how image files are read, rather than the pixels on it.

As far as Bluetooth or Wi-Fi goes, this is a little bit more believable, but just barely above "Zoom and Enhance". If Alice could connect to Bob's phone via Bluetooth, there may be an exploit she could use that would disable the camera app.

However, if Bob used a dedicated camera instead of his phone, then Alice is out of luck and her picture will be taken.

How could I protect myself from having my picture taken?

There are, however, creative ways to hide yourself from cameras. After all, reality can be so much cooler than fiction if you get a bit creative.

Infrared LEDs emit infrared light. This light is not visible to our eyes, but to cameras. This difference is something that hackers can exploit.

By attaching many, high-powered infrared LEDs to your clothing in a way that they shine on your face (e.g. through LED strips on the inside of your hoodie, on your baseball cap, etc.), your face will receive much more light than the surroundings, causing your face to be extremely overexposed.

This will probably stop security cameras, since they will try to set their exposure in a way that most of the picture (i.e. your surroundings) are illuminated correctly.

Somebody taking pictures manually of you may be able to set the exposure correctly, showing your face, but making the rest of the picture very dark. With some clever image manipulation tricks, and multiple pictures taken at different exposure levels, you can be shown in your surroundings, even with such LEDs in place.

Cool, can I see how that looks like?

Here you can see a picture of glasses with just a few LEDs:

^{Attribution: Tokyo National Institute of Informatics}

The two pictures on the top are with the LEDs turned off. This is how a person would see it. The green frame shows that a camera has detected a face.

The two pictures down below show the LEDs turned on. It's much harder to detect details of the person, but it's still doable, especially if you have some reference image. The camera, in this case, failed to identify a person.

With more and/or stronger LEDs, the effect will be much stronger.

Here is also a video, showing them in action with a typical webcam. Again, with some reference, a person is still identifiable.

What about the downsides to this?

Before you go online and order a 500 pack of infrared LED strips, there are some downsides to this technique.

• A battery or some other power source is required. This may be the least of your worries, since LEDs don't draw that much power, but running around with a 9v in your pocket may become annoying.
• You don't see if it's not working. Unless you regularly take selfies of your overexposed face, you don't know if your security system has failed.
• Since you quite literally look like a shining ball of light on pictures, people reviewing security camera footage will probably start investigating why Jesus is casually walking through the mall. It does attract unwanted attention, is what I am trying to say.
• You depend on your clothing. Depending on where you go, it might not be feasible to wear clothing close to your face, such as a swimming pool. You may be able to wear a baseball cap, but then you run into the problem of a power source.

Answer 2

This is not doable.

Unless hacked, your smartphone doesn't communicate with other smartphones around it. It doesn't even know if someone is taking pictures. There's no way it could possibly block someone taking a photo of you.

In the clip you've linked, A explains that he can do "whatever he wants", like "altering the Internet connection". He's implicitly saying that he hacked her phone, that's how he got full control of it.

Answer 3

Here is a patent for technology that will tell smart phone A not to take a picture of asset B.

https://www.theatlantic.com/technology/archive/2016/07/what-if-cameras-stopped-telling-the-truth/491150/

Now if all the smart phone vendors implemented this, similar to how the consumer grade DVD player vendors all agree on DVD copying then eventually you'd get the situation where most phones don't take the image. Not perfect of course.

Answer 4

I think there might be scenarios in which this could work. Imagine a person wearing a T-shirt with a QR code. Person B tries to shoot a photo with his smartphone. The smartphone recognises the QR code which

1. automatically opens a web browser showing a webpage stating "Stop this"

   or

2. generates a buffer overflow due to buggy implementation of the QR code interpreter.

Answer 5

If A has knowledge of an unpatched vulnerability in B's phone, then it's possible that A's device could wirelessly upload an exploit to B's phone and interfere with the photo software's operation to prevent the photo being saved. If this is done passively, then A needs exploits for any phone that they could encounter. It also wouldn't work on older digital cameras that don't have wireless capability, but most people don't carry those anymore. The ability could only be available to a select few, since software and/or hardware manufacturers would patch the vulnerability if they got their hands on the exploit.

It's possible than an exploit like this exist, but it'd either be in the hands of a government agency using it for surveillance or someone who would sell it.

From the video clip, it doesn't look like there is physical interference with the camera, since you can see the target's face on the screen before the photo is taken. MechMK1 gave some good examples of physical interference methods, but there is also the case of a billionaire's yacht blocking paparazzi cameras by shooting lasers at the sensors and this purse that reacts to camera flashes with its own

Answer 6

Part of this is theoretically possible, but the scenario as described is a TV fantasy.

There is active research into detecting lenses pointed at a target, but they are aimed at sniper rifles, not cameras, e.g. this patent. There are also multiple ways to detect hidden cameras, aimed at surveillance. And, of course, there's even an app for that.

These technologies could be combined into a detector that notices when someone points a camera at you, including that from a smartphone. Leaving questions of reliability and false positives aside, it could be combined with a technology like the anti-face-detection LEDs MechMK1 mentions to form a kind of selective camera camouflage.

But how would you get the other person's smartphone to show a message, or a picture entirely different from the one they were trying to take? The first case would require you to hack their smartphone, over the air, in real time. If that were feasible, it would already happen, and for more nefarious purposes. For a spy movie, that's the kind of rocket-shooting, underwater-driving car that we accept in such movies, but it's not real. To show a completely different picture (the 2nd example in the clip) simply defies the laws of physics. You would have to project light into the camera aimed at you, but to fill the entire picture and not the tiny dot of your projector lens would require the light beams to bend in ways that light simply doesn't bend like.

Answer 7

Yes, it is doable, but it would be a voluntary feature of the camera app of the person that takes the photo. I do not think it is implemented in any common camera app, but there are implementations in many photocopiers, that prevent you from copying things with a certain dot pattern on it.

The EURion constellation is a special pattern, that can be recognized by these devices and stops people from copying banknotes. In addition to photocopiers, some software like Adobe Photoshop implements this as well.

People already experimented with printing EURion on t-shirts and other clothing. I do not think they were successful.

Other experiments involve adversarial pattern for image recognition neural networks, that prevent face detection or lead the camera not to focus on the face, when it is in auto-focus mode. Most of such patterns are rather obvious make-up, that you would not wear every day. Another technical device that uses infrared LEDs is mentioned in the post of MechMK1.

Answer 8

This is not something which anyone can attain. Previous responses explain very well why. However there are some people which may actually go very very near to that! Most modern smartphones either work using iOS (Apple) or Android (Google). If you were the CEO of Apple you cloud simply impose that the company forces a silent update to all devices (phones/tablets) so that if they detect your specific Bluetooth they will refise to take pictures! A similar thing can be obtained from the Google CEO but it would require a more tricky approach (no need for detsils: your engineers will know how to do that :-) So to sum it up to block all the phones you need the cohoperation of both Google's and Apple's CEO, then a simple app on your phone will simply trigger the protection! :-)

So.... In case (very unlikely!) these company already have embedded such "no photo" trigger and you are the first and only hacker to discover it then you could simply implement the client app to trigger this!

Answer 9

If the original question is limited to "hacking" just Person B's phone, then it's quite doable with only minor "suspension of disbelief."

First, Person A obtains B-phone's SIM id. Then Person A's phone checks the location of PhoneB, and if it's within, say, 10 meters, PhoneA checks an outgoing message (here's where some hack software would have to have been loaded) from PhoneB indicating a camera is activated. Now Person A is at least warned.

FWIW, it is completely reasonable to posit that NSA-level tools can force OTA installs onto PersonB's phone without any notifications being made. And for that matter, given another few years' worth of software development and smartphone processor capability, why not claim that such a software install includes facial recognition tools that could identify PersonA and then intercept the current camera image(s).

Answer 10

TL;DR: i disagree with most answers here, Apple and Google could probably do it.

Apple could implement it for all iPhones, i guess Google could do the same for all androids phones, for all internet-connected phones under their control with GPS enabled. (system that asks an internet server if it's ok to use the camera in that GPS position before allowing a camera app, or any app, to take control of the camera hardware.. sure one could argue that "all you have to do is to disable internet and GPS", but they could also make those mandatory to take a picture, at least for non-rooted (or in iPhone-terminology, non-jailbroken) phones)