Not sure how many people are aware that the newer Alexa devices have "presence detection" that uses ultrasound so they can detect when people are nearby. [0]
Heck, even Ecobee remote temperature sensors can do this.
Reminds me of the story about how the Google Nest smoke detector had a microphone in it. [1]
0 - https://www.amazon.com/b?node=23435461011&tag=googhydr-20&hv...
1- https://www.reddit.com/r/privacy/comments/asmusq/google_says...
> The method takes advantage of normal network communication between connected devices and the router. These devices regularly send feedback signals within the network, known as beamforming feedback information (BFI), which are transmitted without encryption and can be read by anyone within range.
> By collecting this data, images of people can be generated from multiple perspectives, allowing individuals to be identified. Once the machine learning model has been trained, the identification process takes only a few seconds.
> In a study with 197 participants, the team could infer the identity of persons with almost 100% accuracy – independently of the perspective or their gait.
So what's the resolution of these images, and what's visible/invisible to them? Does it pick up your clothes? Your flesh? Or mosty your bones?
Android devices already know exactly where they are even with GPS disabled, because they sniff the nearby WIFI networks and then ask Google where they are. QED Google knows already, all combined is mass metadata surveillance already provided to those that tap into it.
Any sub-meter precision or presence detection does not really matter, if these companies have all your other questions, queries, messages, calendars, browse history, app usage, and streaming behaviour as well.
Various cheating to get their conclusions (from the paper):
> To allow for an unobstructed gait recording, participants were instructed not to wear any baggy clothes, skirts, dresses or heeled shoes.
> Due to technical unreliabiltities, not all recordings resulted in usable data. For our experiments, we use 170 and 161 participants for CSI and BFI, respectively. [out of 197]
I wish they had explained what the technical unreliabilities were.
Having worked with ML-based sensing for years, what stands out here isn't the accuracy (near 100%), it's the simplicity. No specialized hardware, no cameras, no cooperation from the target needed. Just passive observation of unencrypted beamforming feedback that every modern router already broadcasts.
The window to embed privacy protections into the IEEE 802.11bf standard is closing. Once this is ratified without safeguards, retrofitting privacy will be much harder.
WiFi Could Become an Invisible Mass Surveillance System
Highly unlikely and would be a waste of effort and resources. In the real world we are already well surveilled by cameras, microphones, satellites, cell phones, televisions, modern vehicles with a large number of cameras, web enabled doorbell cameras, refrigerators, AirTags, robot vacuum cleaners that map our home and monitor us, anything bluetooth enabled and that is even before actual spy devices like laser microphones that can turn most windows into a giant microphone.
All of these methods are far more attainable without trying to recreate microwave imaging that has been used by the feds for ages and the feds use a handheld device vs. this complex lab setup and this is even before we talk about advanced high resolution milspec FLIR which some companies have managed to get into serious trouble for selling to sanctioned countries for ITAR violations.
You can do it to yourself[1], I am using Tommy for presence detection in Home Assistant, works great (my house is small, so two ESP32s works fine, I am sure having 3-4 would let it see my cat breathing).
This "could become" sounds exactly like when you look at a cool robotics project, and when you ask the researcher what it could be used for, they say "it could be used for search & rescue after a natural disaster".
The truth is that it's cool research that currently has zero use-case. But a) journalists would not write about that and b) researchers may try to use examples to explain what their research does. Probably researchers are tempted to find a cool use-case of course, because it's better for them if journalists write about their research.
This sounds like cool research that is not remotely close to becoming an invisible mass surveillance system.
Right... tbh it's a bit like Flock or Ring. Yes sure it's potentially bad (probably is already but leaving some room for doubt).
Yet, it's pointless when people VOLUNTEER they private information to corporate actors who happily give EVERYTHING to the highest bidder or, when they have to, for free to governments who ask.
So... sure, be worried of that, be worried of networks of cameras but and more if you ALREADY give everything away, don't be worried, just embrace it! I'm not even being sarcastic here.
This reminds me of cold war era espionage. There is a documented case where a listening device was hidden in a KGB room where sensitive typing was happening, such as code / decode. The CIA/MI6 were able to decipher by hearing the key stokes and assigning an alphabetic value to them. Crazy smart. So, I guess it works along the same general principals?
Funny how mass surveillance concerns are popping up here and there these days. That boat sailed 20 years ago.
WiFi Sensing is part of Wi-Fi 7 and present in most recent laptops and smartphones. Local NPU machine learning can be combined with WiFI radar. Malware can attack phone and radio basebands and exploit this capability. It can uniquely fingerprint human biometrics, measure breathing rate, record keystrokes and more. Thousands of academic papers have been published in the last 15 years on "device free wireless sensing", before the capability was ratified by IEEE as 802.11bf. It's being rolled out commercially. Mitigations include drywall or insulation with a layer of RF shielding.
"Xfinity using WiFi signals in your house to detect motion", 500 comments, https://news.ycombinator.com/item?id=44426726#44427986
"Wi-fi signal tracks heartbeat without wearables", 80 comments, https://news.ycombinator.com/item?id=45488908
2022 laptop demo of respiration sensing, https://www.intel.com/content/www/us/en/research/respiration... | https://community.intel.com/t5/Blogs/Tech-Innovation/Client/...
2025 biometric signature, https://www.theregister.com/2025/07/22/whofi_wifi_identifier...
> Researchers.. developed.. a biometric identifier for people based on the way the human body interferes with Wi-Fi signal propagation.. CSI in the context of Wi-Fi devices refers to information about the amplitude and phase of electromagnetic transmissions.. interact with the human body in a way that results in person-specific distortions.. processed by a deep neural network, the result is a unique data signature.. [for] signal-based Re-ID systems
"Could Become" ?
https://hueblog.com/2025/09/23/step-by-step-guide-setting-up...
https://hueblog.com/2025/12/01/next-step-for-hue-motionaware...
I was really impressed that a ESP32 Antenna Array Can essentially make a WiFi camera - it uses both time and phase differences to localize based on MAC addresses (which are sent plaintext) https://www.youtube.com/watch?v=sXwDrcd1t-E
There are much better invisible mass surveillance devices like the one you carry around in your pocket every day.
In a dynamically changing environment (from the perspective of Wi-Fi signal), this will be difficult but not impossible with modern applications of ML algorithms. We worked on this technique back in 2016-18 at the University of Toronto WIRLab; take a look at the results video from back then. I think the person is somewhat identifiable. https://www.youtube.com/watch?v=lTOUBUhC0Cg
This reminds me of those side channel attacks in crypto. Maybe it works, but any adversary most certainly has easier ways of surveilling you, like hidden cameras with facial recognition.
Caveat: Indoors. However, since indoors is typically a private space, the degree of surveillance depends on the owner of the space. Civilians can only compel government agencies to make sure that government buildings do not enable tracking. We won't be able to stop Walmart, they can always play the security card which trumps privacy every time.
Thanks to this disaster of a website that prompts my browser to accept notifications, and autoplays a video ad that hijacked my audio output and shifted the content I was listening to over to the internal computer speaker.
WiFi is already part of invisible mass surveillance systems, though not in the way described in the article. It's part of how cell phones fix location, based on nearby wifi endpoints, which is then sent to google, apple, every app, every advertiser, etc.
Could? It has, long time ago:
The first iPad did not have GPS module. It has location system, though. It worked by listening to WiFi and knowing the location of the routers. The list of them updated over the air.
Could this be countered by wearing wire-mesh patch clothing, perhaps in randomized stylish arrangements?
Correct me if I'm wrong but assuming they didn't already know your identity, wearing a mask for instance would prevent profiling you based on your radio wave constructed facial features.
You'd have been mocked as a tinfoil hat wearer for saying this more than 18 months ago
You're carrying a mass surveillance system in your pants pocket
That makes sense. Wi-Fi uses radio waves, part of the light spectrum. Like our eyes or cameras can watch and record, Wi-Fi can also be used for this purpose.
> In a study with 197 participants, the team could infer the identity of persons with almost 100% accuracy
That a super impressive! I wonder how that would be at scale, with a few millions people. I’m don’t think that would remain as accurate
Reminds me of the xfinity in-home wifi motion detection, discussed here: https://news.ycombinator.com/item?id=44426726
Cameras just use light waves and are already a mass surveillance system.
I don't see how this is categorically any different from hidden networked cameras. Perhaps that's the real issue we should be focusing on in terms of privacy and mass surveillance.
You lost me at "these are formed using radio signals rather than light"
How good is ethernet over electrical sockets these days. I had one about 15 years ago maybe, but it wasn't that good.
Has tech changed. I'd use it over my wifi setup if its was fast.
So, should I start walking around with a jammer or something?
related (2022): DensePose From WiFi https://arxiv.org/abs/2301.00250
I'm skeptical; this seems like a pretty crappy way to do surveillance. Cameras give you much more information.
And you could surveil them as well, and then shoot them a directed EMP to fry their circuits.
I remember reading about this in a Cory Doctorow novel decades ago, Eastern Standard Tribe, I think.
Scary title, 3 month late into the party… really we don’t deserve better articles with non-dramatic content, much faster?
hah. Could.
At university over a decade ago, we were looking at using Bluetooth/WiFi signals to create live room maps for military applications.
Since then, the tech has only got better.
Cool spooky concept, but seems like this could be easily foiled by shoving some aluminum foil into one's pockets or wearing thermal clothing in the winter. Or moving furniture around.
My cheapo Amazon desk is steel framed, and the monitors have all sorts of metal and signals running through them. I know it impacts wifi because my wifi-connected printer gets crappy signal on one side and decent signal on the other. Good luck getting a positive ID via wifi when I'm sitting at it.
Likewise I don't see how this survives in the real world for a mass surveillance application. Any "signature" will be in constant flux as environments change, in terms of everything from crowds to weather. I'll need to see a demo outside of a controlled environment before I start trying to obfuscate my signature or remodel my house to run Ethernet everywhere.
interesting that Intel AX210 with 4x2 antenna on 6GHz allows Channel State Information (CSI) collection
Perhaps we should ask be using aluminium foil hat now
Xfinity does it or at least say they do.
Could? Is mate. Is.
LOL @ "Could"
Nothing says "out of touch with reality" like 'murcan media.
If you have a phone in your hand the wifi isn't what's surveiling you. At least with wifi routers it's much easier to control what software is running on the device relative to an iOS or android device.
As someone in the RF world, there are way more concerning emerging threats that are much harder to mitigate.
802.11bf WLAN Sensing Task Group
https://www.ieee802.org/11/Reports/tgbf_update.htm
Task Group bf is expected to develop an amendment that defines modifications to the IEEE 802.11 medium access control layer (MAC) and to the Directional Multi Gigabit (DMG) and enhanced DMG (EDMG) PHYs to enhance Wireless Local Area Network (WLAN) sensing (SENS) operation in license-exempt frequency bands between 1 GHz and 7.125 GHz and above 45 GHz.
---
- Stations to inform other stations of their WLAN sensing capabilities
- Request and setup transmissions that enable WLAN sensing measurements to be performed
- Exchange of WLAN sensing feedback and information
Who cares, we have nothing to hide.
"As radio waves move through a space and interact with people, they create distinctive patterns that can be captured and analyzed. These patterns are comparable to images produced by cameras, but they are formed using radio signals rather than light. "
The concept sounds not unlike like the multispectral imaging produced by Geordi's visor in TNG.
Seems conceptually possible, but likely too much computing power and observing time (to build up and learn each individual's pattern in that part of the RF band), at least in current times.
I'm sure it could be developed to work in the field, but what is the use case where it pays off to make the silly-money investment to make it happen? Especially so when it's far easier to simply notice pings and get better data when approximately everyone always carries their mobile phone.
reminder - there's tech out there that is capable of reading your thoughts. remotely. look up radiomyography
Beamforming information is utilized for creating this surveillance. There are also a lack of configurations in common routers to turn off BFI. The BFI information is available to any WiFi snooping and can easily be used to detect presence. You just need to read the BFI data (its plaintext) and if it changes, you can track wherever the smartphone the beam is now pointing towards. Detecting exactly who is another feature but in general, WiFi technologies are insecure and easily available as surveillance devices.
This reads like proper science fiction tech!
I’m not understanding this. You still have to deploy a piece of hardware to read the Wi-Fi waves. Why wouldn’t you just deploy some other piece of hardware that’s better at surveilling the surroundings? Also, if the Wi-Fi device is in the area are not busy now your camera is off that doesn’t seem good. Also, I imagine you have to tune it for every environment, geometry that doesn’t sound easy. And then after all that work, I move my Wi-Fi router 4 inches to the left.
I’m not understanding this. You still have to deploy a piece of hardware to read the Wi-Fi waves. Why wouldn’t you just deploy some other piece of hardware that’s better at surveilling the surroundings? Also, if the Wi-Fi device is in the area are not busy now your camera is off that doesn’t seem good. Also, I imagine you have to tune it for every environment, geometry that doesn’t sound easy.
I’m not understanding this. You still have to deploy a piece of hardware to read the Wi-Fi waves. Why wouldn’t you just deploy some other piece of hardware that’s better at surveilling the surroundings? Also, if the Wi-Fi device is in the area are not busy now your camera is off that doesn’t seem good
I’m not understanding this. You still have to deploy a piece of hardware to read the Wi-Fi waves. Why wouldn’t you just deploy some other piece of hardware that’s better at surveilling the surroundings?
There is no could. This is a turnkey function for any modern managed wifi system right now.
Can we make WiFi 2 that doesn’t let people do this?
“Could become”
Already is and widely used for exactly what the article worries about
Not surprised, related: https://news.ycombinator.com/item?id=46920315
This is a VERY controlled environment - and they used 20 passes of each person walking with direct knowledge of each person to train for identity. They did no tests with multiple people walking at the same time, or with any other external moving distortion effects (doors opening, etc) . This is very far from actual 'identification' of people in real public settings - and no doubt the cell phone everyone is carrying with them offers many orders of magnitude better opportunity. In a real crowded environment this would be nearly worthless.
The devices that reported BFI information were also stationary, and there were no extra devices transmitting information that would be conflicting.
A single camera would be much more effective.