[HN Gopher] Spy camera detection using smartphone time-of-flight...
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Spy camera detection using smartphone time-of-flight sensors
Author : Nirali_Feige
Score : 750 points
Date : 2021-11-18 16:21 UTC (1 days ago)
(HTM) web link (dl.acm.org)
(TXT) w3m dump (dl.acm.org)
| ww520 wrote:
| Does the app take pictures to find the lens? Or videos?
| frizensami wrote:
| It's analyzing the camera feed in real time, so more like a
| video.
| ww520 wrote:
| Good to know. Yes, continuous video feed is easier to spot a
| light source. Can do differential analysis.
| qwertox wrote:
| Here's a demo video [0] of the app. It is embedded in the
| author's website [1]
|
| [0] https://www.youtube.com/watch?v=AFjGQNaqmXA
|
| [1] https://sriramsami.com/research/
| HackOfAllTrades wrote:
| A stand-alone Single-Point LIDAR might be used to remove the
| high-end phone requirement. Should interface to a phone USB port
| with a simple UART/I2C-USB adapter. Search Amazon.com for
| LIDAR finds 'Lidar Range Finder Sensor Module TF-Luna, Single-
| Point Micro Ranging Module 0.2 to 8m Compatible with Pixhawk,
| Arduino and Rasppbarry Pi with UART / I2C Communication
| Interface' $25. And 'MakerFocus TFmini-s Micro Lidar Module
| 0.1-12M Lidar Range Finder Sensor Obstacle Avoidance Sensor Tiny
| Module 1000Hz Single Point UART I2C IO Compatible with Pixhawk Ar
| duino and Raspberry Pi' $39. The 2nd one is waterproof.
| HackOfAllTrades wrote:
| Also on Amazon 'Worldoor CC308+ Multi-Detector Full-Range All-
| Round Detector For Hidden Camera / IP Lens/ GMS BUG / RF Signal
| Detector Finder , CC308 + detector hidden mini camera/IP
| camera/general manager/radio frequency signal detector
| instrument' <$20.
|
| And several similar hidden camera detectors. I have no idea how
| well/badly this sort of device works.
| latexr wrote:
| The site is unusable if you have cookies disabled. It does not
| let you read the content of any page.
| frizensami wrote:
| Perhaps you could try this direct PDF link at
| https://dl.acm.org/doi/pdf/10.1145/3485730.3485941. Hopefully
| that works.
| latexr wrote:
| Same issue, but thank you for trying for an alternative. I'll
| skip this one; it may be wise be wary of a website so adamant
| about cookies that they refuse to show any content when they
| don't get them.
| anthomtb wrote:
| The acronym should be removed from the HN title. LAPD does
| nothing but sow confusion when used as the first word here.
| frizensami wrote:
| Author here, sorry, I didn't post this (but it is the paper's
| title). Hopefully it gets corrected.
| [deleted]
| errcorrectcode wrote:
| Molka is/was a problem in Korea. I wonder how it compares to
| SpyFinder Pro which seems like it's 95%+.
|
| https://www.kickstarter.com/projects/spyassociates/spyfinder...
| max47 wrote:
| that kickstarter campaign is borderline a scam. They have an
| msrp of 400$ for a Chinese gadget you can by for <10$ online.
| And no, their LEDs are not special and you can source better
| ones from digikey for less than 1$.
| djmips wrote:
| Borderline? You are being charitable.
| errcorrectcode wrote:
| It's not a "scam" if people buy it and it works. There is the
| cost to design such a thing. It's not free. The unit price
| was high. The rest are knock-offs who didn't have to pay for
| R&D.
|
| Then you can make and sell your very own one using their
| effort.
| frizensami wrote:
| Good question. We evaluated the "K18" hidden camera detector,
| and not the SpyFinder, but they use an identical principle.
| schleck8 wrote:
| While it's especially bad of a situation in South Korea, it has
| become a serious issue globally.
|
| > The same poll found that one in 10 guests (11%) had found
| hidden cameras in an Airbnb rental.
|
| https://www.forbes.com/sites/suzannerowankelleher/2020/01/27...
| errcorrectcode wrote:
| That number seems absurd and speculative to fit a FUD
| narrative.
| cf100clunk wrote:
| "Tiny hidden spy cameras concealed in sensitive locations
| including hotels and bathrooms are becoming a significant threat
| worldwide." I think motel room tenting and indoor foil-wearing
| might seem to be more justifiable, less paranoiac. Who knew?
| woeirua wrote:
| I wonder how hard it would be to engineer a material that you can
| put on top of the hidden camera lens that would greatly diffuse
| the specific frequency range of light that these ToF sensors use
| while permitting mostly visible light through? If so, it might be
| possible to defeat this approach relatively easily.
|
| Looking at what the DL filter is doing, I wonder how well this
| really generalizes. It seems that many of those examples are
| virtually indistinguishable to a human (hence the high false
| positive rate for the naked eye experiments).
| jcun4128 wrote:
| Bring a 360 degree projector, up the ante
| frizensami wrote:
| w.r.t the material, it seems to be possible, since ToF sensors
| operate in a narrow 850 nm band. However, I don't know if a
| coating can be made that also doesn't overlap with the visible
| light range since 850 nm is somewhat close to red light, or
| whether that would be cheap if so (given that the hidden
| cameras themselves are only $1 at the moment).
|
| I also have similar reservations about the DL approach in
| general. What makes me more confident is that we trained on a
| relatively small number of objects (~10) and tested on a
| totally different set of 30 objects. We're also using very
| small regions-of-interest as inputs (5x5), so there's little to
| no overfitting on the environment or objects themselves.
| hyperstar wrote:
| What are the best ways of doing this without a smartphone?
| frizensami wrote:
| The free option: use your smartphone's flashlight and try to
| spot unnaturally bright / colored reflection.
|
| If you want to spend some money and don't mind carrying an
| extra device: probably any of the "hidden camera detectors" on
| the market will be at least somewhat useful. K18, CC308+, etc.
|
| We're trying with our work to get better or at least equivalent
| results without having to use external devices.
| [deleted]
| est wrote:
| Put a very bright light source next to the spot you don't want
| to be caught in a camera. The viewer would only see a ball of
| light.
| frizensami wrote:
| I don't think this works, mainly because an extremely bright
| external source of 850 nm light looks incredibly suspicious
| through the sensor (as we expect the ToF sensor to be the
| only light source). We could add that check in explicitly.
| randomswede wrote:
| I think the bright light is intended as a countermeasure to
| the hidden camera, not as a countermeasure to finding the
| hidden camera.
|
| Basically, to keep position X unobservable through the
| hidden camera, ensure that there is an overwhelming source
| of photons between position X and the hidden camera.
|
| Since we don't know where the hidden camera is, the best we
| cam do is to assume that the immediate vicinity of the
| bright light will accomplish this.
| frizensami wrote:
| Oh, I must have misunderstand, since the root comment was
| talking about detection methods. But yes, jamming is a
| good option, and there have been papers to make areas
| "unrecordable". I don't have my citation manager on hand
| now, but I think it was an early ACM Sensys / Mobisys
| research work.
| benbojangles wrote:
| similar technology exists on ebay for under $5, you plug it into
| the phone's usb port and it emits ir led lighting and back into a
| lens
| chris_wot wrote:
| Can you supply a link to one of these devices?
| aaronax wrote:
| This reminds me in a way of the yacht with a system that detects
| cameras taking a picture of the yacht and sends a beam towards
| the camera to wash out the image.
|
| https://petapixel.com/2012/10/28/worlds-largest-private-yach...
| frizensami wrote:
| Pretty interesting idea. In fact, there are a number of
| military-related systems to spot sniper scopes (generally
| optics) with lasers, which I expect is similar to what they
| used here.
| iseanstevens wrote:
| Clever! Thanks :)
| victoraaa wrote:
| fdsd
| coretx wrote:
| Did the Rubidium price go up already ? ;-)
| jeffbee wrote:
| I'm having a hard time seeing how the obsolete and not exactly
| tiny OV2640 was crammed into that electrical plug. The integrated
| module is a 10mm cube with a 1/4" lens and to be useful it needs
| a power supply and either a storage controller or wireless
| network interface.
| frizensami wrote:
| We just used the OV2640 module itself
| (https://www.aliexpress.com/i/4000036275403.html) which is
| pretty small. While we didn't actually include a little battery
| and perhaps something like an ESP-32 to control it, I'm pretty
| sure those could fit inside the plug if hollowed out.
| SubiculumCode wrote:
| LAPD is not the Los Angeles Police Department, despite what we
| all were thinking.
| [deleted]
| micahcc wrote:
| Ok I'm not crazy
| abfan1127 wrote:
| what is it?
| throw_away wrote:
| > To answer this question, we propose LAPD (Laser- Assisted
| Photography Detection)
| [deleted]
| milleramp wrote:
| It hard to tell if these modules contained IR interference
| filters, some of the part numbers are only for sensors not
| modules. If they have interference filters I could see that there
| would be a strong IR reflection. It would be interesting to see
| the results with a absorptive filter, although I am guessing real
| spy cameras have no filter at all. Improve the sensitivity vs
| making a pretty picture.
| simonebrunozzi wrote:
| I would be curious to know what would be the best method/tool to
| detect hidden cameras in places you visit (e.g. hotels, AirBnBs).
| I looked for devices on Amazon.com and found nothing that seems
| to be really good at detection.
| [deleted]
| elric wrote:
| So, could this be used to find better hiding spots for hidden
| cameras?
| bawolff wrote:
| Security is always an arms race. Making the person hiding the
| cameras make the extra effort is worth it because some will be
| too lazy. Also some wont know and be caught which increases
| precieved risk which may tip the risk-reward scale more towards
| risk for the person hiding the camera making it less likely
| they would decide to try.
| [deleted]
| frizensami wrote:
| Yeah, that's fair. If someone really wanted to do this though,
| they could also just use existing products like this one:
| https://www.amazon.com/Worldoor-Multi-Detector-Full-Range-
| Al....
| DennisAleynikov wrote:
| absolutely, at least against this method of detection
| dclowd9901 wrote:
| Maybe, but realistically, since the sensor uses the properties
| of a camera lens to detect the camera itself, I would have to
| bet there is little that could actually be done to obscure the
| hidden camera and also still get a usable image from it. This
| is a pretty brilliant detection method.
| nybble41 wrote:
| It might be easier to design the room to create false
| positives and undermine trust in the detectors. Assuming you
| have that kind of influence, anyway. That's not an option if
| you're just trying to plant a camera in an existing room.
|
| I assume minimizing the aperture would be a fairly reliable
| way to avoid detection. A pinhole camera would be hard to
| find by any optical technique, though the video quality would
| suffer. Perhaps one could project through a pinhole onto a
| screen and record the projection, so the sensor is angled
| away from the room?
| frizensami wrote:
| That's an interesting idea: trying to create so many false
| positives that the user gives up. We're already removing
| around 100+ false positives per frame at the moment in
| difficult cases, so perhaps it's possible to overwhelm the
| filters with very maliciously designed environments.
|
| I think the easier way would be to hide the cameras in much
| harder-to-reach places so that it's inconvenient for the
| user to get their smartphone near. This might reduce the
| kind of videos that can be taken, but maybe an attacker
| will find that a reasonable tradeoff.
| djmips wrote:
| Probably the very smart spy camera can detect off axis
| TOF artificial light and close a shutter over the lens.
| Assuming your app integrates over the scanning motion,
| the camera won't be detected while it's shutter is
| closed. After the illumination is completed the spy
| camera can re-open it's shutter.
|
| The spy camera could also something like your system to
| detect the phone camera and take defensive measures.
| frizensami wrote:
| Yes, perhaps. At the very least, adding a variable
| shutter and extra logic will drive up the price of the
| camera, which will be some consolation.
| loonster wrote:
| A honeycomb lens filter (commonly used in military rifle
| optics) would greatly reduce the angle that the camera
| can be detected.
| chii wrote:
| what about fiber-optics to direct light from a pin-hole?
| would the entrance of the fiber-optics cable be
| detectable this way?
| raldi wrote:
| "Specifically, the hidden camera [...] reflects the incoming
| laser pulses at a higher intensity than its surroundings due to
| an effect called lens-sensor retro-reflection. This occurs when
| almost all light energy impacting an object is reflected directly
| back to the source"
| [deleted]
| polishdude20 wrote:
| Given this, can you just hold up a flashlight right next to
| your head and look around the room for bright spots?
| frizensami wrote:
| This is actually one of the recommended methods if you have
| no other options. It's not particularly good otherwise
| because of the limited visibility cone of the hidden camera
| reflections. From experience, the flashlight often tends to
| occlude the reflections you want to see, or the user isn't in
| the right place to see the reflections (near the flashlight).
| gpt5 wrote:
| That's exactly how detection tools work today.
|
| Here is a random one:
|
| https://www.lexuma.com/products/lexuma-xscan-portable-
| hidden...
| xipho wrote:
| Likely. Headlamps are well known tools for collecting spiders
| at night, when positioned just right they will reflect off
| the spider's eyes as you move your head around. It's an
| amazing thing to see spiders _everywhere_.
| BLKNSLVR wrote:
| Can vouch for this having heard the theory and tried the
| "torch at eye-level" method and been able to zero-in on
| small spiders from a distance of about 5m.
|
| It's quite amazingly effective, especially the first time,
| when you're not really convinced.
| brokenmachine wrote:
| Thanks for giving me nightmares.
| lapetitejort wrote:
| For peace of mind that sounds like the _worst_ tool to use.
| Eelongate wrote:
| Just try to remember the spiders protect you from _the
| other bugs._
| hungryforcodes wrote:
| No thanks. I'll take my army of friendly neighborhood
| geckos instead.
| lotsofpulp wrote:
| Same with house centipedes!
| samstave wrote:
| hOUSE rIVER mONSTERS?
|
| Anyone????
|
| House Atredies?
|
| I sense the Emperor behind it.
| mensetmanusman wrote:
| Started looking for hidden cameras, ended cowering in
| fear from the thousands of eyes in the closet.
| krapp wrote:
| The ones smart enough to remain unseen are the ones you
| should worry about.
| pasker wrote:
| I remember we were spotting alligators at the Amazon river
| with flashlight and their eyes reflections :-)
| gorgoiler wrote:
| It is _the_ standard way of detecting concealed lenses.
|
| Random google result:
|
| https://www.pimall.com/nais/startfinder.html
| joelkesler wrote:
| That was actually pretty interesting. Here is a video of
| the device in use:
| https://www.youtube.com/watch?v=1x3aDW8ghaY
|
| I am not sure if it is worth the price, but it's cheaper
| than a top of the line smartphone with a time-of-flight
| sensor
| frizensami wrote:
| Agreed, and a very valid point that these off the shelf
| detectors are pretty cheap compared to ToF smartphones.
| There are a number of unfavourable things about the
| detectors though:
|
| - No automated detection, so lots of human subjectiveness
| on whether a bright spot should be investigated
|
| - Background lighting can be an issue, so the view
| through the detector can be filled with bright
| reflections
|
| - When I tried this for longer than 30 seconds, there's
| really some eye strain involved
|
| The idea is that the smartphone has more than this one
| purpose, and the detection system can improve with
| software updates, whereas you get what you see with the
| detector and nothing more.
| rtkwe wrote:
| The light returns pretty directly to the source which is why
| most devices designed to use that detection method have the
| illuminators around an eyepiece so there's less distance
| between the illuminators and your eye.
| micahcc wrote:
| It took me a full minute to realize this wasn't the Los Angeles
| Police Department's R&D division
| [deleted]
| aaron695 wrote:
| It's interesting with these wrap head lamps, which have 40
| COB(Chip on Board) LEDs, is you see spiders everywhere at night.
| And other large animal eyes with a Tapetum lucidum look
| 'strange', not like normal led reflections.
|
| It's a bit unnerving/cool that you'll see 10 pairs of eyes
| looking back from the lawn you might have just been lying on.
|
| https://www.amazon.com/Headlight-Rechargeable-210%C2%B0Illum...
|
| I'd be looking at something like that, at least as a first run
| over the room. But perhaps to augment. It allows you to see
| spider eyes at 5+ meters.
| chris_wot wrote:
| What I would like to know is - how do you detect who is using an
| IR blaster?
| djmips wrote:
| My old smart phone would easily show IR light. I suppose newer
| models might have IR filters.
| samstave wrote:
| If there was literally ANY metric I would want in a HUD; 'How
| many cameras are viewing me now, and where are they' has got to
| be the top of the list...
| emptyparadise wrote:
| Put all their fields of view on a minimap.
| jcun4128 wrote:
| > system that leverages the time-of-flight (ToF) sensor on
| commodity smartphones
|
| I think only the high end iPhones/iPad have these type of cameras
| right now right?
|
| I'd also be curious about the exact angle you have to hit to get
| a reflection
|
| Probably wouldn't work but bright flash in a room?
| frizensami wrote:
| Great question about the angle actually. There's previous work
| by an applied physics group [1] that shows the detectable
| field-of-view from the camera is about 20 degrees. Our
| experiments also confirm that.
|
| We also think using the smartphone flashlight (if that's what
| you mean) is the best way forward. That's already very helpful
| (and recommended) for humans to find hidden cameras, and it
| should be a useful extra modality for our work too.
|
| [1] https://ieeexplore.ieee.org/document/8790792
| jcun4128 wrote:
| You don't have to answer but, I'm assuming by the phone's API
| you can steer the beam/have an exact precision known of the
| minimum angle you can sample? That's pretty cool tech to work
| with.
| frizensami wrote:
| Unfortunately we can't steer the ToF beam, so the user has
| to move the phone around to multiple positions (a 2D grid
| of positions, basically). The app provides pretty clear
| guidance on where to move the phone to cover all possible
| spots, though.
| semi-extrinsic wrote:
| My Huawei P30 Pro from 2019 has a ToF sensor, so I don't think
| it's very uncommon?
| jcun4128 wrote:
| Yeah I guess my phone is not in that tier... it looks to be
| marked up 2x from GSMArena's prices... but $150 vs. $350
| pricing. Also the Moto G Stylus (my phone) is from 2020
| frizensami wrote:
| Yep, there are a pretty decent number of smartphones with it,
| and I think the trend is moving in the right direction
| (iPhone 12 Pro had it and Apple included it in the iPhone 13
| Pro too).
| z3t4 wrote:
| If the spy camera has infrared leds then you can detect those by
| removing the infrared filter from a camera, can be done on some
| smartphone cameras programmatically I think.
| Scoundreller wrote:
| In a dark room, you can point an old-style remote control at an
| iPhone camera and see button presses light up the IR
| transmitter.
|
| I do this to test their batteries :)
|
| But older Cell-phones (flip phones) with CMOS sensors used to
| be really good at this as they wouldn't filter much IR in order
| to work better in low-light conditions.
| SubiculumCode wrote:
| I was really hoping that they had an app I could install, as they
| implemented LAPD on Android.
| frizensami wrote:
| Hey! Author of the work here. We just finished presenting this
| at a conference yesterday, so we're working on open-sourcing
| the code now with some feedback from the community. It's got
| some warts because of API limitations (no way to automatically
| align color and ToF cameras, so we're manually doing that).
| SubiculumCode wrote:
| Cool work. It would be great for scanning hotel rooms.
| frizensami wrote:
| Thank you!
| rbanffy wrote:
| You'll still need the laser emitter. Here I would hope the
| emitter can be operated in a high-power small-target mode to
| also obliterate the detected cameras. Extra points if it can do
| so autonomously - I leave it over the bed, go out for dinner,
| and come back to a room without any cameras.
| [deleted]
| elwell wrote:
| The expansion/collapsing of the header on that page seems to get
| in the way when scrolling up.
| super_tycoon wrote:
| Played around with this idea using the ToF sensor on my galaxy
| note 10+ and an app called 'ToF Viewer'[1]
|
| https://imgur.com/a/XcEMxcZ
|
| Camera array of a thinkpad T480 with windows hello (ir camera)
| and a hazard light/strobe (sourced... locally)
|
| [1]
| https://play.google.com/store/apps/details?id=com.lvonasek.t...
| frizensami wrote:
| Funnily enough this is exactly how we started the project, just
| with a different Thinkpad model.
|
| Separately, Lubos, the creator of ToF Viewer, is very helpful
| to the ToF community and constantly answers any questions about
| APIs or sample code. I'd recommend talking to him if anyone
| wants to get started with ToF-based applications.
| jaywalk wrote:
| You have to go to the second page of the full PDF to even see
| what LAPD stands for, which is Laser-Assisted Photography
| Detection. They need to be more mindful of this, especially when
| they made up the acronym themselves.
| intrasight wrote:
| Cool tech. Too bad about the paper title. One should never use
| a novel acronym in an academic title IMHO.
| w0mbat wrote:
| LAPD is worse than novel, it is already used in another
| context where it is very well known.
|
| Most people will already know this, but LAPD = Los Angeles
| Police Department, often featured in TV shows, films and the
| news.
| ska wrote:
| > Most people will already know this, but LAPD
|
| s/most people/most americans/
|
| plus some non americans of course, but it's not a global
| association by any means.
| elzbardico wrote:
| The authors are from Singapore. The association is not that
| direct for non-americans. Actually, I only noticed it after
| several people mentioned it here.
| PeterHolzwarth wrote:
| 95.75 percent of the planet is not American, if you are
| partially referring to the acronym of the police department.
| haswell wrote:
| Regardless of this, it's generally good form to define an
| acronym the first time it's used, even if there was no
| duplication/overlap.
|
| With that said, while you're correct:
|
| - A significant portion of tech advancement is US-centric, so
| I understand the instinct to ask for clarification
|
| - I'd argue that the LAPD is relatively well-known world-
| wide, much like the RCMP, or RAF, or other very famous
| organizations
| Majestic121 wrote:
| I don't think you should argue this : No idea what RCMP
| stands for without a google search. I got RAF from the
| context (I assume you mean Royal Air Force ?), but without
| context I would map it to other things. And I have no
| assumption about the meaning of LAPD
| Jolter wrote:
| Well, you just got me to Google "rcmp". That's just one
| data point of course, and I was indeed aware of their
| informal name from popular culture.
| [deleted]
| [deleted]
| ngneer wrote:
| Could someone please help explain the threat? Are people being
| blackmailed with footage obtained of them? Is this occurring en
| masse?
| quantified wrote:
| No more threat than my installing a couple in your living room,
| dining room and kitchen. Carry on...
| ngneer wrote:
| That is not the best analogy, because I assume less risk at
| home than elsewhere. My question was about the threat, and
| since adversaries are not installing cameras in people's home
| your comment does not answer my question.
| Enginerrrd wrote:
| Ever stay in an airbnb?
| ngneer wrote:
| Of course, frequently. I must still be missing something. I
| have had zero extortion requests. My footage might be
| captured for private consumption by some perv, but where is
| the harm to me?
| mensetmanusman wrote:
| Extortion is generally geared towards women. Violence
| towards women like this is a general negative
| externality/tax on society because everyone interacts with
| women.
| ngneer wrote:
| I am inclined to agree, and you are correct if you assume
| that I am male. But I would prefer to see the data.
| Without it, the first sentence of the abstract is
| unsubstantiated. "Tiny hidden spy cameras concealed in
| sensitive locations including hotels and bathrooms are
| becoming a significant threat worldwide." The paper cites
| no evidence for "significant threat worldwide". Academic
| fancy?
| trickstra wrote:
| Would you argue that voyeurism should stop being a crime
| then?
| ngneer wrote:
| That is a good question, and thanks for helping me to
| test the limits of my argument. I would say that
| voyeurism, like all crime, can be expected to follow a
| spatiotemporal probability cloud. Society does not accept
| folks peering into your home and as an individual you
| have recourse. I think it is fuzzier as soon as you step
| out into public. I would definitely consider an airbnb or
| most other spaces that are outside my control to be
| public spaces. But the question of voyeurism is sort of
| distinct from my main question, which is how big is the
| risk? Do we have data on how many people are hurt by this
| issue?
| dexwiz wrote:
| Issues are with AirBNB and shady landlords. Sometimes people
| being pervs, but also just extortion. You can create an AirBNB
| listing wither hyper restrictive rules, spy on your tenants,
| and then charge them fines after the fact.
| ngneer wrote:
| I see. Makes sense. Are such airbnb experiences common,
| though? Given other controls such as reviews, are they
| expected to be long lived? I could maybe see the harm caused
| to a few individuals, which is deplorable, but once a single
| extortion event happens the expectancy of income is reduced.
| dexwiz wrote:
| Anecdotal, but my partner recently went to a lake house for
| an engagement party. The lake house is a touristy location,
| and obviously meant to be a vacation home. However, the
| renters would only list the property as a "meditation
| retreat." Meaning no alcohol, no noise, no day guests, no
| fun. They had beach chairs in an unlocked area, and after
| the weekend sent a $900 bill to the guests. Apparently even
| though the chairs were freely accessible, using them
| constituted rental, so they charged $50 per chair per day.
| How else did they the host know they used the chairs that
| many times if they were not spying on them somehow? I
| imagine if they actually did anything, that bill would have
| been higher.
| terryf wrote:
| Wonder if some rules and ... oh, regulations? would
| create a situation where the renter would not have to
| worry about issues like this. Perhaps similar to rules
| and regulations that ... hotels have?
| fortran77 wrote:
| I was working on a project like this and we relied on the fact
| that the IR filter on most cameras was a retro reflector. Remove
| the IR filter and the camera will be harder to find. I think the
| technique here also depends on the IR filter's characteristics.
| frizensami wrote:
| That's a good point. I'm not sure how the removal of the IR
| filter will affect this work. I mentioned some prior work from
| the physics side [1] in another comment that explores the
| reflection characteristics in more detail. I don't think they
| explored the IR filter contribution as well, so this could be
| an interesting direction.
|
| [1] https://ieeexplore.ieee.org/document/8790792
| fortran77 wrote:
| We were trying to detect audience members filming at live
| events and in movie theatres, esp. premieres and film
| festivals (and this was some time ago, when studios, etc,
| cared more about this). It worked pretty well, even in the
| early 2000s. I suspect you could do much better today with
| some "AI" behind it.
| sturgl wrote:
| IR cut filters used in smartphone-style cameras are typically
| reflective.
|
| Installing an absorptive IR cut filter on top of the lens
| would decrease the amount of reflected light, and might
| hinder your approach. Those are pretty cheap to buy, so you
| could try it out pretty easily.
| fortran77 wrote:
| The key is they're _retroreflective_.
|
| From this paper:
|
| > Specifically, the hiddencamera embedded in the object
| reflects the incoming laser pulses at a higher intensity
| than its surroundings due to an effect called lens-sensor
| retro-reflection. This occurs when almost all light energy
| impacting an object is reflected directly back to the
| source (see Section 2.2). These unexpectedly high-intensity
| reflections from hidden cameras cause certain regions of
| the ToF sensor to be "saturated" and appear as black
| pixels. LAPD processes these saturated areas to
| automatically identify the hidden camera and its location
| and displays it on the user's smartphone screen.
| mnw21cam wrote:
| The filter/sensor itself doesn't need to be
| retroreflective. The fact that it's sitting at the focus
| of a lens makes it retroreflective.
| sturgl wrote:
| Nevertheless, if you block all the ~850nm IR light from
| reaching the lens, then there cannot be any retro
| reflection at this wavelength, meaning the ToF cannot see
| anything.
| frizensami wrote:
| Yes, I agree. I believe military-grade optics detection
| systems use multiple wavelengths, and some even use short
| bursts of visible light, making it harder to block.
| ridaj wrote:
| Can you overwhelm this detector by hiding the camera in another
| reflective material (eg wrinkled metal or shards of glass wall
| decor)
| djmips wrote:
| Yes.
| frizensami wrote:
| I'm not sure that it's a conclusive yes here. We have a
| procedure to remove the effects of background reflection
| saturation by constantly analysing the maximum reflection
| size. So if there's a large reflection in the scene, we walk
| the user back til we have all reflections at the same size or
| smaller than the the larger expected hidden camera
| reflection. This works fairly well.
|
| However, if the camera reflection is always within a larger
| reflection for all possible distances and angles, then I
| doubt this will work.
| injidup wrote:
| I know a woman who discovered a hidden camera in the female
| toilet at work disguised as some kind of utility hook on the
| door. Cheap to buy on amazon!! The SD card inside had pictures of
| the company owner's desk but not an actual picture of him. The
| police declined to prosecute because of lack of evidence.
| xanaxagoras wrote:
| Gross.
| stronglikedan wrote:
| > The police declined to prosecute because of lack of evidence.
|
| Thank goodness! Imagine being convicted of a crime because some
| perv took some pictures of your personal stuff in an attempt to
| frame you.
| spoonjim wrote:
| Prosecute and convict are different. You should at least pull
| his credit card transactions and see if he recently bought
| it.
| jjcon wrote:
| That would still be circumstantial wouldn't it?
| mywittyname wrote:
| Lots of evidence is circumstantial.
|
| Contrary to popular believe, circumstantial evidence is
| not bad evidence. In isolation, it might not be enough to
| convict, but when used in conjunction with other
| evidence, it can create a damning case.
|
| 1. The camera contained pictures of owners desk.
|
| 2. That model camera was purchased on amazon by the
| owner.
|
| 3. The serial number of the camera indicates that it was
| sold on amazon and produced around the time of purchase
| by the owner.
|
| 4. The camera was found in a place the person had
| reasonable, unrestricted access to.
|
| 5. owner was found in possession of pictures that look to
| have been taken by the device, in the position where the
| device was originally discovered.
|
| * I'm not asserting these facts are true, just stating
| them for the sake of example.
|
| In isolation, each of these pieces of evidence don't
| prove much, but in totality, it is highly unlikely that
| all of those things would happen to an innocent person.
| Jury's don't need to be 100% certain to convict, they
| need a preponderance of evidence.
|
| I can see why a prosecutor wouldn't pursue this case
| against a rich person though. The police are unlikely to
| do a good job at collecting evidence, a good lawyer will
| get enough of it thrown out, victims probably won't want
| to testify anyway, and being a business owner, this
| person might have clout with local politicians who will
| make trouble.
| GekkePrutser wrote:
| Sounds like that scene from Austin powers :) where he
| keeps saying the pump isn't his.
|
| But you're right that's pretty damning.
| HWR_14 wrote:
| I mean, if you showed him buying the same model from
| Amazon and it had pictures from him testing it in his
| office, that's probably enough to convict.
| rtkwe wrote:
| Individual pieces of evidence are often circumstantial,
| taken together they're enough to prove something.
| moron4hire wrote:
| Most evidence is. "Circumstantial" doesn't automatically
| make the evidence useless.
| IIAOPSW wrote:
| Yes, which is insufficient for a conviction but
| reasonable suspicion to get a warrant.
| IshKebab wrote:
| Enough circumstantial evidence is perfectly sufficient
| for conviction.
| dzhiurgis wrote:
| Add fingerprints and DNA from SD card, logs on PC...
| [deleted]
| mike-cardwell wrote:
| To be fair to the owner, that would be a good way of setting up
| somebody else to take the fall if the camera was discovered.
| frizensami wrote:
| Hey! Sriram here, author of this work. I'd be glad to answer any
| questions. There's also a short talk I gave about this here
| (https://www.youtube.com/watch?v=t4Txdhlji4k) if that's helpful!
| djmips wrote:
| Would your system work against flat cams?
| https://youtu.be/BdgwO_i5p54
| megablast wrote:
| Does it work against something that doesn't exist yet??
| genewitch wrote:
| Lensless cameras have been around for a long time, the
| chips and masks that are completely flat is a new idea, I
| guess.
|
| Single pixel cameras are lensless, for instance.
| pishpash wrote:
| At some point if you are light-emitting you're going to be
| captured. May need to turn yourself into a blackbody, i.e.
| hide under sheets.
| frizensami wrote:
| Thats very interesting, first time hearing of it. Not sure,
| really depends on what kind of reflection it generates when
| light hits it, and because of the unique design I'm not sure
| what that will be.
| deegles wrote:
| What are the properties of the cameras that don't get detected?
| Wouldn't bad actors just use the same app to check if their
| cameras are detectable at installation time?
| frizensami wrote:
| So far the biggest issue is if the camera is angled oddly
| away from the user (basically, outside the 20 degree
| observable FoV). Another issue would be if they manage to
| install a larger camera that returns larger reflections
| (which we filter out).
|
| Regarding using the app to check, I guess that applies for
| the existing handheld detectors as well. It's definitely
| something that intelligent attackers can try to plan for, but
| we havent tested the adversarial robustness of the system
| right now. That would be a very interesting direction for us
| as well.
| frizensami wrote:
| But at least for the larger camera case, we can just
| increase one of the filtering thresholds for reflection
| size, which is already doable on the UI
| starwind wrote:
| Do you have any plans release this as an app I could install on
| my phone?
| frizensami wrote:
| Yes, we do! There are a couple of user-facing annoyances at
| the moment, one of which I mentioned in another comment
| (hacks to align the color and ToF images). Hopefully these
| API limitations are removed soon, or we find better
| workarounds.
| david_allison wrote:
| Would you consider open sourcing the app as-is?
|
| You've got a community of people who're willing to spend
| time polishing.
| frizensami wrote:
| It's definitely something I'm considering. The only hard
| blocker now is a hashmap that checks for our test phones'
| unique ID and applies a fixed transform to align both
| cameras. Right now, any other phones will cause an
| immediate crash. Minimally I think we need to disable
| this and maybe include a small UI to let users put in the
| alignment parameters (just a scale + offset).
| frizensami wrote:
| Also I appreciate the interest, thank you. I'm heading
| back from the conference over the next few days, so I
| should be more free to take a look at it soon.
| david_allison wrote:
| Feel free to shoot me an email (in profile) if you'd like
| this UI done. No need for anything else other than the
| source code.
|
| It'd be a massive benefit to society to make this widely
| available.
| jmnicolas wrote:
| If you do release it, is it possible to not depend on
| Google services please? I am almost a year in my degoogled
| life!
| colordrops wrote:
| Is there a support group or discord for degooglers? I did
| it a month or so ago and am still dealing with the
| ramifications. Most recently I used App Warden to disable
| all the spyware libs (including Google's) shipped with
| WeChat. They detected this, and banned my 10 year old
| account with all my friends and relatives. Been
| struggling for two days trying to get it reactivated, cuz
| it will be extremely difficult to travel back to China
| without it. I am not blind to the irony of keeping
| Tencent on my phone as I remove Google.
|
| What would be really helpful is a database of apps,
| similar to the WINE project, maintaining how well they
| work on a de-googled phone, with a table, columns being
| "no root", "rooted", "with microg", etc, and a WINE style
| rating of how well it works and what problems you'll run
| in to.
|
| You would know which banking services, etc don't work
| well or at all and could choose your establishments with
| foresight.
| T4iga wrote:
| There is a GitHub repo[1] with a very limited list last
| time I checked. That the best I could fined in my
| degoogled time. The Techlore Youtube-Channel-Community
| (yes, I realise the irony) also seems like a reasonably
| healthy place to start. There is also a bunch of telegram
| groups with NoGoolag[2] at the center. I would not
| recommend for the 70:30 mix of conspiracy and tech
| support but they are at least technically very
| knowledgeabl, and sometimes helpful, even considering
| their almost 'religious' technical beliefs.
|
| [1] https://github.com/techlore/plexus
|
| [2]https://t.me/NoGoolag
| jmnicolas wrote:
| Sorry I'm not aware of anything like this. I went "all
| in" : I just installed GrapheneOS on my phone, Linux on
| my desktop and stopped using anything Google related
| (except YouTube that I watch in a dedicated browser).
| Abishek_Muthian wrote:
| Off-topic
|
| What were your biggest reliance on Google services you
| found in this 1 year and how did you overcome it?
| frizensami wrote:
| Interesting question. Mainly as mentioned above we needed
| Google Play Services for AR. Nothing else stands out at a
| high level.
|
| However there is a clear bottleneck with the Google AR
| team for features that the community really wants. While
| it's understandable, perhaps the open source libraries
| aren't the priority or there's short staffing, there are
| issues like this one - https://github.com/google-
| ar/arcore-android-sdk/issues/153 - that have been open
| since Jan 2018. This one asks that we can use the
| smartphone flashlight simultaneously with ARCore, but
| there's no visibility on how close we are at the moment.
| This feature would have likely improved our work's
| performance greatly, but even in general, many other AR
| developers are asking for it.
|
| Re: overcoming it, there's not much we can do in this
| case. We just didn't implement the feature.
| Abishek_Muthian wrote:
| I apologize Sriram I actually I meant to ask that to the
| user jmnicolas who asked you to for de-googled
| application; Yet you provided valuable information.
|
| Long standing issues/feature requests are typical of
| Google's Android ecosystem, Regardless I eagerly await
| for your release. I think ToF based spy-camera detection
| could make a great addition to the women safety apps in
| India.
| frizensami wrote:
| Ah, I see. Thank you!
| frizensami wrote:
| I would love to, but I'm not sure how yet without a major
| re-write. The augmented reality code we completely rely
| on is part of Google Play Services for AR. I definitely
| do understand the benefit of degoogling, so maybe it can
| be a community effort once I opensource it.
| robotresearcher wrote:
| > Google Play Services for AR.
|
| Google's branding is awful.
| lrem wrote:
| Google Play Music All Access -> YouTube Red
|
| Man, we're so bad at naming, that we keep joking about
| it... And trying to satire that with internal codenames
| (the ones engineers give without adult supervision)...
| And somehow those often seem better than the external
| names :(
| bradknowles wrote:
| So does this mean the app will not be available on
| iPhone?
| frizensami wrote:
| It could also possibly work on iOS, but there's a catch
| we have not yet explored. We're relying on something
| called the "confidence" score in the ToF camera API,
| which has 8 possible values (3 bits) in Android, but from
| what I last saw, has only 3 possible values total in iOS.
| It's not clear how this lack of info exposed by the APi
| will affect accuracy.
|
| This is something we'd have to separately test, and
| ultimately make a wholly different app for if it's
| feasible on iOS.
| seaman1921 wrote:
| Please don't make the functionality worse just to please
| the de-googled hacker=news crowd.
| colordrops wrote:
| There's no reason it has to be worse. It's good
| development practice to design your system to loosely
| couple with dependencies you have no control over. Worst
| case you could have two versions, and the one that
| supports google services works better for whatever
| imagined reason.
| raylad wrote:
| iOS too?
| Iolaum wrote:
| Awesome, if there's a waiting list or a website that we can
| join or follow to be notified of a release please share.
| frizensami wrote:
| Sadly no project-specific page yet, but I'll definitely
| update on my page at https://sriramsami.com/research/ (I
| think there's an RSS feed?) when it's active.
| specto wrote:
| https://sriramsami.com/feed.xml
| iamwil wrote:
| It's easy to set up a mailing list. Just sign up for
| mailchimp, or any one of the many newsletter products
| like substack or tinyletters, just to collect the email
| addresses. Not many people regularly read RSS anymore,
| sadly.
| iamwil wrote:
| Where do we sign up to be notified when this is released?
| Mikejames wrote:
| +1
| datameta wrote:
| same here
| 123pie123 wrote:
| I do like this
|
| what technology advancement would be needed to increase the
| detection rate and reduce the false positives?
| frizensami wrote:
| Right, a few things would be very useful:
|
| - Increasing the resolution of ToF cameras (right now images
| are around 320 x 240) --> reflections from hidden cameras can
| then be more detailed, whereas now it's only 1 or 2 pixels
| each.
|
| - Increasing the bit-depth of ToF images - right now every
| pixel is only 3 bits (8 colors). It's very hard to
| differentiate bright hidden camera reflections from
| everything else, so we had to do a lot of work for that.
|
| - API improvements in conjunction with augmented reality
| libraries, e.g., a) allowing Android devs to enable the
| flashlight when AR apps are running b) more raw access to the
| ToF sensor if possible
| debt wrote:
| 320 x 240, is this the resolution of the depth data
| provided by the LiDAR sensor?
| frizensami wrote:
| Yep, exactly.
| floatboth wrote:
| Hm, if "ToF sensors" _are_ LiDARs.. why does only Apple
| market them as LiDAR? Why are all the "3D scanning" apps
| only for Apple's "Pro" devices? How come no one knows
| that some Android devices can do the same things? I
| didn't know until this thread!
| raxxorrax wrote:
| I assume one is active while the other is not. With two
| cameras you have the option of stereoscopic analysis
| where you have to match pixels of two cameras looking on
| the scene from a different angle. That uses significant
| cpu-time though, difficult for real time applications.
| Results vary because the matching isn't trivial and the
| difference in angle in smartphone cameras is very low.
|
| If you have a projector, you can do more. I believe Apple
| uses a flash, which has a low resolution, but is perhaps
| less cpu-intensive and less error prone, although it has
| a lower resolution. That would be a real Lidar, which is
| an active measurement. Of course combining that with
| sensible stereoscopy nets better results.
| salicideblock wrote:
| All ToF systems are active.
|
| ToF stands for "time of flight". It works exactly by
| measuring how long the signal takes to go from camera to
| object and back [1]
|
| Stereoscopic cameras are another type of 3R camera, they
| are not ToF and they are not active.
|
| Each has pros and cons.
|
| [1] https://en.m.wikipedia.org/wiki/Time-of-flight_camera
| dr_kiszonka wrote:
| My understanding is that not all ToF sensors are LiDARs.
| There are also different types of LiDARs, e.g., some of
| them scan the environment and others just emit a single
| beam in the same one direction. I think iPhone Pro has
| the scanning one, but I haven't read much about it.
| frizensami wrote:
| There's a lot of marketing involved in this naming, with
| Samsung calling it DepthVision and Apple calling it
| LIDAR. There may be a difference here, however. My
| understanding is that Apple LIDAR is doing what we call
| "direct" ToF, where the round trip travel time of laser
| pulses is actually measured (this can be in nanoseconds).
| This lines up with what self driving car (and other
| expensive) LIDARs do.
|
| Most other ToF sensors use "indirect" ToF, where they
| measure the phase difference between incoming and
| outgoing signals to derive distance.
|
| However, it gets murky as cheap 2D LIDARs on say, robot
| vacuum cleaners, use geometric techniques to find
| distance (basically return angle of a reflection). I
| explored this in a previous work.
|
| TLDR: I would recommend not taking any naming at face
| value and reading the actual datasheet or more commonly,
| technical marketing materials, since few ToF
| manufacturers that I see have a public datasheet.
| pnw wrote:
| Samsung started marketing their ISOCELL Vizion 33D camera
| in 2020 with 640 x 480 resolution. So it's likely we'll
| see better ToF resolution announced in some phones in the
| next year or two.
|
| Great project btw!
| frizensami wrote:
| Thank you! Actually, my understanding when I started this
| project was that I would get a 640 x 480 image (IMX516
| sensor). However, I could only get a 320 x 240 image from
| the sensor through the Android API, so that was a bit of
| an oddity.
| datameta wrote:
| The results are even more impressive with that
| considered!
| frizensami wrote:
| Thank you! Hoping for higher resolutions soon.
| 5faulker wrote:
| The next project would be creating another device to detect
| these spy camera detectors
| stinos wrote:
| A hidden camera which detects ToF sensors
| filoeleven wrote:
| Ah yes, like the radar detector wars!
|
| > many early "stealth" radar detectors were equipped with a
| radar-detector-detector-detector circuit, which shuts down
| the main radar receiver when the detector-detector's signal
| is sensed, thus preventing detection by such equipment.
|
| https://en.m.wikipedia.org/wiki/Radar_detector#Radar_detecto.
| ..
| pishpash wrote:
| Well if the hidden camera can be shut down by turning on a
| hidden camera detector, then the hidden camera detector
| becomes a hidden camera jammer! All the better.
| 14 wrote:
| I was wondering if cameras started using anti-reflective glass
| would this prevent detection? Some of the glass I've looked up
| say they reflect less than 1% of light. How sensitive is your
| app could it detect 1% reflections? Thanks
| nomel wrote:
| It's lens + sensor stackup reflection. Camera sensors are
| much more reflective than a lens.
| 14 wrote:
| So would something like anti reflective glass for light
| coming into the camera then another layer of like tint that
| will stop light from reflecting back out if the camera? Ya
| I know that doesn't exist but That is because they were not
| trying to do undetected as hard before. Just thinking of
| counter surveillance techniques.
| PaulDavisThe1st wrote:
| > Just thinking of counter surveillance techniques.
|
| Counter-counter surveillance techniques, IIUC.
| frizensami wrote:
| Yep, the combination is highly reflective. I cited another
| work (by a physics research group) in a comment that
| modelled and tested this effect comprehensively.
| 14 wrote:
| Would you speculate if anti reflective glass on the
| outside of the camera and a layer of one way tint on the
| inside that would allow light through but prevent it from
| reflective back out? I'm just thinking what we will
| expect in the future to sell the "undetectable spy
| camera".
| frizensami wrote:
| That's a great question. I'm not totally sure if this is
| possible. If it was, I think one-way mirrors would use
| this technology. For now, it seems like they only work
| because they only let 50% of the light through + there's
| a brightness differential between both sides. Perhaps
| someone more informed about this could chime in.
| mnw21cam wrote:
| Yeah, there's no magic material that can violate the
| second law of thermodynamics, because it's the second law
| of thermodynamics. One-way mirrors are just partial
| mirrors with less light on one side than the other.
| user-the-name wrote:
| There's no such thing as a "one way tint".
|
| https://en.wikipedia.org/wiki/One-
| way_mirror#Principle_of_op...
| nomel wrote:
| This is a simple implementation of a one way mirror.
|
| Metamaterials have a chance at at:
| https://www.nist.gov/news-events/news/2014/07/new-nist-
| metam...
| pishpash wrote:
| Then they'd have a signature of reflecting less than
| surrounding. In the long long run, probably more robust
| to detect the entropy generated by computation in a
| physical area (i.e. heat) and not the optics.
| frizensami wrote:
| Agreed. I expect however that any easily available
| thermal sensing, especially on smartphones (see FLIR,
| etc), could be easily defeated with a strong adversary
| doing good thermal management.
|
| As you say though, extra heat is a physical guarantee, so
| maybe a smarter technique exists to separate signal from
| noise in the thermal domain that I don't know of yet.
| ticklemyelmo wrote:
| Could this be applied to longer-range applications? Concert /
| theater cameras, camera / binocular observers, counter-sniper
| detection?
| frizensami wrote:
| While the broader technique should work for those
| applications, the platform (smartphone ToF sensors) probably
| won't. Smartphone ToF sensors have a pretty limited range. We
| were only able to detect cameras within 1 metre of the
| smartphone because we're really using the hardware for
| something it's not intended for.
|
| For the applications you suggest, there are some existing
| military-looking devices out there that use multiple lasers
| to find sniper scopes, for example. My basic searching shows
| at least https://www.ldsystems.us/product/sniper-optics-
| detector/#, though I'm sure there's more.
| mensetmanusman wrote:
| Great work!
|
| Do you have a link to where you can buy these types of time of
| flight lasers/sensors? Curious about the additional hardware
| cost versus sensitivity.
| frizensami wrote:
| Thank you!
|
| While this work operates on ToF sensors that are already
| present in smartphones (e.g., Samsung S20+/Ultra), a
| Microsoft/Azure Kinect should also be a valid option because
| it has a depth camera as well. It has a higher resolution and
| bit-depth as well.
|
| We initially intended to compare against the Kinect, but it
| doesn't fit the use case (something that you can have on you
| at all times). However, it could be a cheap choice for a
| different kind of deployment (automated hidden camera
| detection with robots, perhaps?)
| tootie wrote:
| So I had no idea phones have ToF sensors these days. Do
| most phones have them or only the high-priced flagships?
| What are the actual intended uses for them?
| frizensami wrote:
| High priced flagships have them but there are also a few
| midrange phones like the Huawei P30 Pro that have them
| too. The trend seems pretty positive towards more ToF
| sensors in phones, especially because Apple has had them
| for two iPhone Pros in a row now.
|
| They're basically for augmented reality applications
| because they sense depth. Placing objects at the right
| size and scale in the augmented view is much easier and
| more accurate with the ToF sensors, for instance.
| genewitch wrote:
| Any phone that has sub 200ms focus times has to have some
| sort of TOF sensor, right? The Asus Zenfone 2/3 laser,
| the Huawei monochrome sensor on the honor series, the
| portrait and/or macro sensors on the Xiaomi mi note 10,
| whatever the original Zenfone had, and so on.
|
| Not all of them are lasers, which might be important.
| archon810 wrote:
| Do you know if the Pixel 6 series supports ToF?
| frizensami wrote:
| I don't think so. There's "laser-assisted autofocus"
| which might be slang for an actual ToF sensor, but
| sometimes that's just a single laser pulse (I.e., no 2D
| image that we need).
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