This is a preliminary paper, which we intend to update as our understanding of this issue evolves.
Picture if you will a scenario in which some person is moving in her or his home. For some reason, WiFi is present in the home. It may be because the person or one of her or his housemates wishes to use the WiFi, it may be a neighbor's WiFi, or perhaps it is some sort of city-wide WiFi. Outside is another person whom we shall call the adversary. The adversary, equipped with a smartphone, moves around the home taking signal strength readings to determine the locations of the WiFi emitting devices. Once the smartphone is equipped with that data, the smartphone is then able to track the person inside her or his home by observing how the WiFi signals interact with the body of the person moving within the home. The adversary's purpose? Perhaps the adversary is a current or former intimate partner of the person inside the home and wishes to stalk her or him. Perhaps the adversary is a robber or a kidnapper, seeking data to determine the best time to strike. Perhaps the adversary simply takes too much interest in other people's business.
While we are unaware of any examples of this technology being used for criminal or other questionable activities by low-budget individuals with smartphones, the technology does exist, and it is likely only a matter of time before low-budget criminals and other disreputable people do begin performing such reconnaissance. An article submitted by Yanzi Zhu et al in 2018, but last updated in January 2020, describes such a form of reconnaissance that can be performed using a smartphone to detect and track people inside a building where WiFi is present.[[1],[2],[3]] It was tested on 11 offices and apartments, with the consent of the owners of these spaces. The researchers explain that radiofrequency signals interact with our bodies in a variety of ways, such as reflecting off of us, sending information about our location, movement, and physiological properties through the air, even if we are not using or carrying any wireless devices.
Since the attack is passive, that is, relying on existing ambient WiFi signals, it is covert in so far as no additional signals are being added. Since it requires only a minimally equipped WiFi receiver and some software to make the necessary calculations, a smartphone will do, making it likely that at some point in the future, low budget snoops will be performing this sort of reconnaissance. The attack does require some walking around in order to measure signal strengths and get an idea of where WiFi devices are located. That data having been collected, human motion interacts with radiofrequency signals traveling multiple paths between WiFi devices and the snoop, changing those signals and thus allowing for tracking of people inside the building by the snoop, who may be outside the building. The more WiFi devices that are present, the more accurate the reconnaissance. The writers emphasize that, given more advanced equipment than was used in their experiment, the snoop would be able to obtain even more information. Encryption is useless in preventing this form of reconnaissance.
What is spyware? According to a 2005 Federal Trade Commission Spyware Workshop,
“It is difficult to define spyware with precision. The working definition proposed for purposes of the workshop was software that aids in gathering information about a person or organization without their knowledge and which may send such information to another entity without the consumer’s consent, or asserts control over a computer without the consumer’s knowledge. Panelists and commenters agreed that this was a useful starting point for defining spyware.”[[4]]
When we usually think of spyware, sometimes called stalkerware or spouseware, we think of covert software programs that log keystrokes, record screen activity, track GPS locations, take over webcams or microphones, etc., installed on our devices without our consent.[[5],[6],[7],[8]] However, these are not the only kinds of software that meet the Federal Trade Commission's working definition. A person doesn't even have to have an electronic device to have information gathered about them, without their knowledge, and for software to assist in this information gathering. Software related to hidden cameras and hidden microphones could also aid in “gathering information about a person or organization without their knowledge.”[[9],[10],[11]] Indeed, if we took out the requirement that there has to be software, a simple mechanical telescope could serve as spyware for some peeping Tom.[[12]]
While definitions of spyware may vary, it is our opinion that gathering information about someone by means of the wireless signals that interact with that person's body, without their knowledge, should count as using spyware. Even if we preferred to keep the definition of spyware more narrow, this sort of wireless based surveillance clearly has a lot of privacy-invading potential that is in some ways comparable to more traditional types of spyware.
Of particular concern is that violent criminals such as human traffickers have often been ahead, technologically speaking, of those law enforcement agencies who seek to crack down on violent crimes such as human trafficking.[[13]] As early as 2018, the Guardian reported that the Internet of Things was already opening up new frontiers in domestic abuse.[[14]] And, in so far as corrupt law enforcement in some parts of the world may be in league with the violent criminals, heaven help us all.[[15]] While location data does have legitimate uses, such as alerting emergencies services to the locations of people in need of assistance, history shows us that all too often, private data often falls in the hands of violent criminals and others with malicious or questionable intent.
What makes the mere presence of WiFi signals a potential tool for stalkers and other adversaries to track people is a sort of technology called passive bistatic radar or, in some cases, passive multistatic radar. Radar (radio detection and ranging), in general, as explained by Willian Melvin and James Scheer, "involves the transmission of an electromagnetic wave to a potential object of interest, scattering of the wave by the object, receipt of the scattered energy at the receive site, and signal processing applied to the received signal to generate the desired information product."[[16]]
Bistatic radars are those in which the transmitter and receiver are at separate locations. Multistatic radar is similar, but includes more than two antennas, again at separate locations. Bistatic and multistatic radars differ from monostatic radar, where the transmitter and the receiver share the same location. Passive bistatic radar is a sort of bistatic radar when the transmitting source is a broadcast, communications, or radionavigation signal, and the receiver, at a separate location, does not transmit any signals of its own. In passive bistatic radar, the transmitter typically does not cooperate with the receiver. Other terms sometimes used include passive coherent location (PCL), piggy-back radar, passive covert radar, parasitic radar, opportunistic radar, and broadcast radar. [[17]]
Illuminator of opportunity, sometimes called simply illuminators, is a term used to describe the non-cooperating transmitting antennas used by passive radar. Potential illuminators of opportunity include analog radio such as FM, digital television such as DVB-T, digital radio DAB (Digital Audio Broadcasting), various kinds of cellular signals, WiFi (including IEEE 802.11a, IEEE 802.11g, and IEEE 802.11n), etc. The performance of the passive radar can vary significantly depending on the illuminator or illuminators of opportunity used. For example, FM-based passive radar has relatively low accuracy but high detection range, whereas WiFi-based passive radar has relatively high accuracy but short detection range. DAB-based passive radar has medium accuracy and medium detection range, and DVB-T-based passive radar has high accuracy and medium detection range.[[18]]
Because illuminators of opportunity were not designed for target detection, passive radar is likely to have suboptimal performance, from the perspective of those who wish to use it, relative to active radar. However, not needing its own transmitter does make passive radar much cheaper than active radar. Since signal transmissions can allow active radars to be more easily located, passive radars are more covert. Additionally, as the electromagnetic spectrum becomes more congested with more and more telecommunications signals, the ability of passive radar to take advantage of these existing signals rather than take up its own frequency bands is desirable from the perspective of not wishing to further add to the electromagnetic congestion. Since illuminators of opportunity are not under the control of radar designers, a lot of the progress made in making passive radar more effective over the years has been in the area of signal processing, and the signal processing is likely to become even more effective as the years pass.[[19]]
Illuminators of opportunity can be natural rather than artificial. Apparently, every object above absolute zero emits millimeter waves carrying information about itself, and passive millimeter waves imaging systems are able to scan people's bodies using these natural millimeter waves.[[20]] Passive sensors on weather satellites are able to detect faint signals, between23.6 and 24 GHz, emitted by atmospheric water vapor, significantly reducing forecast error, though this capability is threatened by the coming of 5G.[[21]]
An article published in 2003 discusses a passive radar system called Celldar which could “track aircraft, monitor traffic congestion and spot speeding motorists without tipping them off that they are being watched.”[[22]] This cellphone-based radar was considered an improvement over a previous passive radar technology, Lockheed Martin's Silent Sentry, which took advantage of radio and television signals, because the increased number of cell phone towers as compared to radio and television towers means Celldar has more illuminators of opportunity to work with. The author of the article was unclear whether Celldar could be used to track individual people, pointing out that sources disagreed on that point. However, an article published in 2006, and another article published in 2015, confirm that passive radar based on cellular signals can indeed track a running person, at least at close range.[[23],[24]]
It is likely that over time as cellular signals include a greater range of frequencies, cellular towers and masts are more densely placed, and signal processing becomes more advanced, it will become increasingly possible to track people by means of cellular signals, and it is probably only a matter of time before criminals and other creepy adversaries begin to use this technology.
The 5G currently being rolled out in many places throughout the world is expected to include a variety of frequency bands, including millimeter waves.[[25]] That is interesting, because millimeter waves have been used by full body scanners, both active and passive, for years.[[26]] In 2010, a Gizmodo investigation uncovered, by FOIA request, 100 full body images which were improperly, and maybe illegally, stored from a Generation 2 millimeter wave scanner at a Florida Federal courthouse.[[27]] Apparently, about 35,000 such images were saved. Since passive millimeter wave scanners relying on a person's natural millimeter wave emissions already exist,[[28],[29]] it is highly probable that in the future, we will also see passive body-scanning radars which make use of the millimeter wave portion of 5G, and we might also see peeping toms making use of such radars.
In 2010, Tyler Ralsont et al demonstrated through the wall sensing using a rather large phased array active radar system.[[30]]
In 2012, Kevin Chetty et al demonstrated the ability to detect a moving person through walls using passive WiFi radar. The illuminator of opportunity was a D-Link router which conformed to the IEEE 802.11g standard. During the experiments, two laptops were wirelessly connected via the router, and one of these transferred a 1 GB file to the other. The experiments were conducted at an equipment storage building. For comparison purposes, the researchers positioned one receiving antenna where it would be obstructed by a wall, and another where it would be unobstructed.[[31],[32]]
In 2014, Guanhua Wang et al demonstrated the ability to essentially lipread using bistatic WiFi radar by detecting and analyzing the WiFi reflections from mouth movements. Since the researchers utilized beamforming to focus signals on the user's mouth, it does not seem to be strictly passive in the sense of using a non-cooperating transmitter, but it is possible that future research may lead to way to lipread using WiFi without beamforming. The work should be considered preliminary, since as of 2014 the researchers only got it to work with a pre-defined vocabulary, but it does provide proof of concept that mouth movements interact with WiFi signals in such a way that it would be possible for passive radar to detect. Within the pre-defined vocabulary, the researchers achieved a 91% detection accuracy for a single person speaking up to six words, and a 74% detection accuracy when up to three people spoke at the same time. As of 2014, WiHear required the speaker to avoid other movements while speaking, but it is possible more advanced signal processing may provide a workaround for this issue in the future.[[33]]
In 2015, Kamran Ali et al demonstrated keystroke recognition using bistatic WiFi radar. Since the experiment was performed under rather controlled conditions, the methodology would likely need to be further developed before it could be used in a less controlled environment as a truly passive WiFi radar. However, under the conditions tested, the researchers achieved a 97.5% detection rate for keystrokes, a 96.4% accuracy at classifying single keys, and a 93.5% accuracy at recognizing keystrokes in a continuously typed sentence. The methodology used relies on the idea that while typing keys, human hands and fingers move in unique ways that interact with WiFi signals, and can be observed by measuring Channel State Information (CSI) values. According to the researchers, “CSI values quantify the aggregate effect of wireless phenomena such as fading, multi-paths, and Doppler shift on the wireless signals in a given environment.” The illuminator used by the researchers was a TP-Link TLWR1043ND WiFi router operating in 802.11n mode at 2.4 GHz, and the receiver was a Lenovo X200 laptop with an Intel Link 5300 WiFi NIC. The signal processing required significant noise reduction, that is, removal of unwanted data in order to isolate the data associated with the keystrokes. This has significant implications for adversaries who may wish to learn passwords or other private information typed into computers.[[34],[35],[36]]
Image source: https://www.youtube.com/watch?v=Pgvp_2hPRng [[37]]
In 2016, but with an article published in 2018, Dina Katabi et al demonstrated EQ-radio, which appears to be an active radar system capable of detecting human emotions by observing the changes in the wireless signal caused by heartbeats, nearly as accurately as an ECG monitor. The EQ-radio system look for four basic emotions, joy, pleasure, sadness, and anger. Once EQ-radio has had time to learn about an individual subject, it can detect that person's emotions with 87% accuracy, as compared to 88.2% for an ECG-based system. For an unfamiliar person, EQ-radio can detect the person's emotions with 72.3% accuracy.[[38],[39]] If an abusive adversary managed to use something similar to EQ-radio to covertly monitor a person's emotions, it could have significant implications in a domestic violence situation where the abusive adversary wishes to control or criticize his or her partner's emotions, such as those who make comments like, “No one likes you because you are so negative."[[40]]
Also in 2016, two articles described the ability to identify individual people using WiFi-based passive radar. In one, the transmitter was a TP-Link TLWR1043ND WIFI router with two antennas, operating in 802.11n AP mode at 2.4GHz, and the receiver was a Lenovo X200 laptop with Intel Link 5300 WIFI NIC, which had 3 antennas. In the other, a Netgear R7000 WiFi access point was used as the transmitter, and a HP 8530p laptop equipped with an Intel WiFi link 5300 802.11n chipset was used as the receiver. [[41],[42]]
In 2017, Chitra R. Karanam and Yasamin Mosto demonstrated the ability to create a 3D image of an area with two unmanned aerial drones using cooperative bistatic WiFi radar.[[43],[44]]
As we mentioned earlier, in an article published in 2018, last updated in January 2020, Yanzi Zhu et al demonstrated a version of passive WiFi radar, able to detect people inside a building, that could be performed using only a smartphone, and tested it in 11 real-world offices and apartments.[[45],[46],[47]]
In 2018, Saandeep Depatia and Yasamin Mostofi demonstrated the ability to count crowds through walls using bistatic WiFi radar, without requiring the people to carry any devices. At five different campus locations, including three classrooms, a conference room, and a hallway, they conducted a total of 44 experiments. They placed a D-Link WBR-1310 WiFi router using 802.11g outside the rooms, and took RSSI (Received Signal Strength Indicator) measurements from the other side of the rooms, also outside of said rooms. For the experiments, they instructed people to walk around, so what they did might not work for more stationary crowds. Under the conditions tested, their counts were accurate to within 2 people.[[48],[49]]
A brief history of passive radar
As early as 1924, Appleton and Barnett used a bistatic radar system, taking advantage of radio stations in the UK to confirm the existence and take measurements of the Heaviside layer of the ionosphere, both with and without the cooperation of said radio stations.[[50]] In 1935, the Daventry experiment succeeded in using ambient radiation from a nearby BBC station to detect a Heyford bomber about 8 miles away.[[51]]
Radar and in particular passive radar is likely to raise questions related to the Fourth Amendment of the United States constitution.[[52]] Even in situations where courts may decide the Fourth Amendment does not apply, other potentially relevant laws include the Stored Communications Act (SCA), the Computer Fraud and Abuse Act (CFAA), and the Electronic Communications Privacy Act (ECPA).[[53]]
A legal precedent worth reviewing is Kyllo v. United States, 533 U.S. 27 (2001).[[54]]
On August 6th, 2018, the Seattle City Council passed an ordinance requiring that, “Smart meter data is only used for legitimate purposes such as utility service, grid management, or energy efficiency programs” and that, “The dissemination of smart meter data is restricted to those purposes.”[[55]] The nature of how wireless signals interact with people's bodies makes it impossible for any smart meters using wireless signals to be in compliance with these laws. (Note that we aren't lawyers and this is not a professional legal opinion.) When wireless signals interact with people's bodies, the wireless signals disseminate private data about us through the air. Depending on the precise nature of the wireless signals (frequency, etc), these wireless signals may transmit this data through walls, and the data may include information about our movements, our identities, what we are saying, what we are typing, our breathing, and even our emotions. Whatever data is present is available to anyone nearby with the proper equipment (which is often very cheap) and signal processing software. As commercially available receiving equipment becomes more advanced, and as signal processing techniques continue to become more advanced, these issues are likely to become more pressing, particularly if the signal processing software becomes commercially available. This threatens not only the privacy of the household for which the smart meter is intended to measure electric usage for, but also the privacy of any neighboring households within range of those wireless signals, which is especially likely to be an issue in apartment buildings.
Criminals and other adversaries are already using spyware and other surveillance tools for a variety of purposes, including domestic abuse, contemporary slavery, and robbery.
For example, in a module on “Technology facilitating trafficking in persons”, the United Nations mentions that human traffickers (that is, contemporary slavers) already make use of location data and other information they find on social media for the purpose of targeting and grooming potential victims, who might then be kidnapped, lured with promises or threats, or otherwise taken into contemporary slavery.[[56]] One of the types of information transmitted by wireless signals and able to be picked up with radar technology is location information. Now, it is a different sort of location information than what is transmitted over social media. However, there are at least a couple ways a human trafficker might make use of radar location information in addition to the sort of location information human traffickers are already able to obtain over social media. Once a human trafficker has already obtained the general location of the potential victim down to the household level, the human trafficker might travel to that location and then use passive radar to track the potential victim inside that home, looking for an opportunity to catch the potential victim alone. Alternatively, if the human trafficker is able to install remotely controlled spyware on devices in or near the potential victim's home, those devices could be used to gather location information and other data about the potential victim with the use of active or passive radar technology.
The module on “Technology facilitating trafficking in persons” released by the United Nations also mentions that human traffickers are able to use technology to remotely control enslaved persons, sometimes to the point of avoiding face to face contact, or to attempt to regain control after the person has escaped.[[57]] Currently used methods include examining the enslaved person's phone records, accessing the enslaved person's phone applications through the cloud, and installing spyware on the enslaved person's phone or other devices. Again, radar and in particular passive radar offers human traffickers additional options for remote surveillance, on top of those options already in use. If human traffickers become sophisticated enough to use passive radar technology to continue tracking an escaped person, even if that person ditches his or her cellphone, this could pose a particularly serious threat.
Spyware and other surveillance technology is already being used in domestic violence. In a 2014 NPR survey of 70 domestic violence shelters in the United States, 85% of domestic violence shelters surveyed said they were working with survivors whose abusers tracked them using GPS technology. 75% domestic violence shelters surveyed said they were working with survivors whose abusers had eavesdropped on their conversations remotely, using spyware.[[58]] Again, radar and in particular passive radar technology offers domestic abusers additional surveillance tools, ones that could potentially work, at least at short range from receiving antennas (antennas which could be remotely controlled) to track people even people who decide not to use cell phones or other wireless devices.
Monica Rueda at the San Jose Police Department in California has confirmed to Wired that some burglars are using Bluetooth scanners to locate electronics they wish to steal, which helps provide a possible explanation to a number of car break-in thefts where only electronics were stolen.[[59]] A Bluetooth scanner is of course a much simpler form of surveillance technology than passive radar, but the point is that surveillance technology which becomes commercially available – and passive radar has the potential to become commercially available very soon – is likely to fall into use by burglars and other criminals. However, in terms of defensibility, passive radar is a much more serious issue than Bluetooth scanners. To protect your laptop against a Bluetooth scanner, you would turn off your Bluetooth before leaving your laptop unattended. To protect yourself from passive radar, it is not sufficient to turn off your own wireless signals. You must also somehow persuade those around you to turn off their wireless signals as well.
In 2018, Citizen Lab reported with “high confidence” that the cellphone of Omar Abdulaziz, a Saudi dissident residing in Canada, was targeted and spied upon with the use of Pegasus spyware, sold by NSO Group.[[60]] The Guardian reports that, “After the alleged hack, several members of Abdulaziz’s family and friends were arrested in Saudi.” Recently, the Royal Canadian Mounted Police warned Abdulaziz about serious threats to his life.[[61]] Passive radar offers an additional mechanism of surveillance that repressive governments could potentially use.
Between 1367 and 1417, intense persecution of Jewish people in Spain forced most of them to convert to Christianity. On September 27, 1480, the king and queen of Spain, Ferdinand and Isabella, issued an order to establish tribunals to judge cases of so-called “heretical depravity”, and in particular, to search out and punish converts from Judaism to Christianity believed to be continuing to practice Judaism in secret. These tribunals would come to be known as the Spanish Inquisition.[[62]]
The Gay Sunshine reported in 1972 that the Atascadero State Hospital in California had performed over 4,000 lobotomies on prison inmates, many as alleged curatives for homosexuality.[[63]] That there are people in this world who take such obscene interest in how other people love each other, that they would cut out parts of those other people’s brains, illustrates the importance of privacy to our freedom of thought and emotion.
The very idea of some modern person, taking a similar sort of obscene interest in other people’s thoughts and feelings as a Spanish Inquisitor or of one of the doctors who used to lobotomize gay people, but armed with active or passive radar technology that can potentially read people’s lips or sense their emotions remotely, is truly terrifying. And torture is not something humanity has outgrown. As Daniel P. Mannix points out, “In North Africa, paratroopers tortured Algerian rebels using the devices developed by the Spanish Inquisition plus electricity.”[[64]]
Since we should assume that the presence of wireless signals will continue to pose as ever-greater privacy risk as receiving equipment and signal processing become more advanced, we need to reconsider consent issues regarding exposure to wireless signals, bearing in mind that these can negatively affect the privacy even of individuals who are not themselves using any wireless devices. We should take steps now to transition our society as much as is possible to a wired communications architecture, with special consideration to places where privacy is especially important, such as homes, schools, medical facilities, domestic violence shelters, shelters for survivors of modern slavery, and so on.
We should build an extensive network of public telephones, such as payphones, or, even better, the free to use equivalent of payphones.[[65]] Ideally, payphone systems should be updated to include text messaging and internet access, by wired means, in order to better conform with cultural expectations that text messaging and internet access be available. 21st century payphones could potentially include outdoor ethernet jacks for people to plug in VOIP phones and laptops. VOIP phones should also be updated to include text messaging and other features people expect from smartphones. We should begin crowd-funding campaigns to set up more publicly available free to use or low cost computer labs, utilizing wired internet connections, especially at libraries, at or near shelters for victims of domestic violence and modern slavery, at or near homeless shelters and encampments, and in low income communities, with additional ethernet connections available for people who bring their own laptops and VOIP phones. We should also design wired landline phones that are fully text messaging capable.[[66]] People should be instructed on how to set up wired home networks, using ethernet switches and other wired technology, in order to protect their families and neighbors from unwanted surveillance. Smart meters using wireless communications should be phased out as rapidly as possible.
To the extent that fully transitioning to a wired communications architecture may not be fully possible, because many people will be reluctant to give up wireless technology, in spite of the risks to themselves and those around them, those working to fight against violent crime such as domestic violence, modern slavery, kidnapping, and robbery, should to be aware of how radar and in particular passive radar technologies may soon come into use by violent criminals, and attempt to develop countermeasures. We should also strive to develop quantum entanglement technology to a level suitable for commercial communications as rapidly as possible.[[67]]
[1] Zhu, Yanzi, Zhujun Xiao, Yuxin Chen, Zhijing Li, Max Liu, Ben Y. Zhao, and Haitao Zheng. “Et Tu Alexa? When Commodity WiFi Devices Turn into Adversarial Motion Sensors,” January 11, 2020. https://doi.org/10.14722/ndss.2020.23053.
[2] “Using Wi-Fi to ‘See’ behind Closed Doors Is Easier than Anyone Thought: With Nothing but a Smartphone and Some Clever Computation, Researchers Can Exploit Ambient Signals to Track Individuals in Their Own Homes.” MIT Technology Review, November 2, 2018. https://www.technologyreview.com/2018/11/02/239959/using-wi-fi-to-see-behind-closed-doors-is-easier-than-anyone-thought/.
[3] “NDSS 2020 Et Tu Alexa? When Commodity WiFi Devices Turn into Adversarial Motion Sensors.” Youtube. NDSS Symposium, April 6, 2020. https://www.youtube.com/watch?v=6O1fUx9O-j0.
[4] Majoras, Deborah Platt, Orson Swindle, Thomas B. Leary, Pamela Jones Harbour, and Jon Leibowitz. “Monitoring Software on Your PC: Spyware, Adware, and Other Software.” Federal Trade Commission, 2005. https://www.ftc.gov/sites/default/files/documents/reports/spyware-workshop-monitoring-software-your-personal-computer-spyware-adware-and-other-software-report/050307spywarerpt.pdf.
[5] “Beware of Keyloggers: Digital Stalking Is Stalking.” The Sydney Morning Herald, February 22, 2013. https://www.smh.com.au/technology/beware-of-keyloggers-digital-stalking-is-stalking-20130218-2enxw.html.
[6] Tidy, Joe. “Stalkerware: The Software That Spies on Your Partner.” BBC News, October 25, 2019. https://www.theguardian.com/uk-news/2018/feb/13/stalkers-using-bugging-devices-and-spyware-to-monitor-victims.
[7] “Secretly Stalked: Your Ex Could Be Watching Everything You Do on Your Phone.” 13 WTHR, November 2019. https://www.wthr.com/article/secretly-stalked-your-ex-could-be-watching-everything-you-do-your-phone.
[8] “Trafficking in Persons & Smuggling of Migrants Module 14 Key Issues: Technology Facilitating Trafficking in Persons.” UNODC, May 2019. https://www.unodc.org/e4j/en/tip-and-som/module-14/key-issues/technology-facilitating-trafficking-in-persons.html.
[9] “Exposing the Secrets of High-Tech Peeping Toms.” NBC2, October 31, 2016. https://www.nbc-2.com/story/33533825/exposing-the-secrets-of-high-tech-peeping-toms.
[10] Hutchinson, Derick, and Kevin Dietz. “Defenders: Ypsilanti Man Secretly Tapes Relative, Boyfriend during Sex Acts: Michael Pickerel Pleads Guilty to Financial Crimes.” Click On Detroit, June 12, 2019. https://www.clickondetroit.com/news/2019/06/12/defenders-ypsilanti-man-secretly-tapes-relative-boyfriend-during-sex-acts/.
[11] “Man Charged for Filming Roommate and Boyfriend with Hidden Camera.” News 10. December 16, 2019. https://ktvl.com/news/local/man-charged-for-filming-roommate-and-boyfriend-with-hidden-camera.
[12] Kennedy, Rob. “Peeping Tom Used Telescope to Repeatedly Spy on Students Getting Undressed.” Chronicle Live, July 14, 2017. https://www.chroniclelive.co.uk/news/north-east-news/peeping-tom-telescope-students-undressed-13328980.
[13] Lazareva, Inna. “Meet the Virtual Vigilantes Who Bust Human Traffickers from Their Laptops.” Reuters, June 19, 2018. https://www.reuters.com/article/us-global-trafficking-technology-hackers/meet-the-virtual-vigilantes-who-bust-human-traffickers-from-their-laptops-idUSKBN1JG00F. “But the years of lobbying that preceded the crackdown showed how authorities with limited digital expertise struggle to stop criminals who use technology at every stage of their business, from recruiting via social media to tracking victims via webcam.”
[14] Naughton, John. “The Internet of Things Has Opened up a New Frontier of Domestic Abuse.” The Guardian, July 1, 2018. https://www.theguardian.com/commentisfree/2018/jul/01/smart-home-devices-internet-of-things-domestic-abuse.
[15] Bales, Kevin. Disposable People: New Slavery in the Global Economy. Berkeley, CA: University of California Press, 2012. 5, 28-29, 31, 36, 54, 59, 63-64, 66-68, 168
[16] Melvin, William L, and James A Scheer. “Radar Applications.” In Principles of Modern Radar: Vol. III: Radar Applications, 1. Edison, NJ: SciTech Publishing, 2014.
[17] Griffiths, Hugh, and Chris Baker. “Passive Bistatic Radar.” In Principles of Modern Radar: Vol. III: Radar Applications, 499–541. Edison, NJ: SciTech Publishing, 2014.
[18] Malanowski, Mateusz. “Illuminators of Opportunity.” In Signal Processing for Passive Bistatic Radar, 48–78. Norwood, MA: Artech House, 2019.
[19] Malanowski, Mateusz. “Introduction.” In Signal Processing for Passive Bistatic Radar, 1–8. Norwood, MA: Artech House, 2019.
[20] Meng, Yang, Anyong Qing, Chuan Lin, Jiefeng Zang, Yizhe Zhao, and Cheng Zhang. “Passive Millimeter Wave Imaging System Based on Helical Scanning.” Scientific Reports 8, no. 7852 (May 18, 2018). https://doi.org/10.1038/s41598-018-25637-9.
[21] Werner, Debra. “Weather Experts Call for Further Dialogue to Limit 5G Impact on Weather Forecasting.” SpaceNews, January 14, 2020. https://spacenews.com/passive-microwave-5g-ams-2020/.
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[23] Lu, Yilong, Danny Tan, and Hongbo Sun. “An Experimental GSM Based Passive Radar.” 2006 Asia-Pacific Microwave Conference, December 2006. https://doi.org/10.1109/apmc.2006.4429719,
[24] Abdullah, Rsa Raja, Asem A. Salah, A. Ismail, F. Hashim, N.h. Abdul Aziz, and N. E. Abdul Rashid. “Ground Moving Target Detection Using LTE-Based Passive Radar.” 2015 International Conference on Radar, Antenna, Microwave, Electronics and Telecommunications (ICRAMET), October 2015. https://doi.org/10.1109/icramet.2015.7380777.
[25] Horwitz, Jeremy. “The Definitive Guide to 5G Low, Mid, and High Band Speeds.” VentureBeat, December 10, 2019. https://venturebeat.com/2019/12/10/the-definitive-guide-to-5g-low-mid-and-high-band-speeds/.
[26] Saffold, J. "MMW Radar Characteristics and Applications." In Principles of Modern Radar: Radar Applications, 3:87–116. Edison, NJ: SciTech Publishing, 2014.
[27] Johnson, Joel. “One Hundred Naked Citizens: One Hundred Leaked Body Scans.” Gizmodo, November 16, 2010. https://gizmodo.com/one-hundred-naked-citizens-one-hundred-leaked-body-sca-5690749.
[28] Meng, Yang, Anyong Qing, Chuan Lin, Jiefeng Zang, Yizhe Zhao, and Cheng Zhang. “Passive Millimeter Wave Imaging System Based on Helical Scanning.” Scientific Reports 8, no. 7852 (May 18, 2018). https://doi.org/10.1038/s41598-018-25637-9.
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[50] Walker, Gabrielle. “Chapter 6: Mirror in the Sky.” In An Ocean of Air: Why the Wind Blows and Other Mysteries of the Atmosphere. Orlando: Harcourt, 2007.
[51] Oikonomou, Dimitrios, Panagiotis Nomikos, George Limnaios, and Konstantinos C Zikidis. “Passive Radars and Their Use in the Modern Battlefield.” Journal of Computations & Modelling 9, no. 2 (April 2019): 37–61. https://www.researchgate.net/publication/332119662_Passive_Radars_and_their_use_in_the_Modern_Battlefield.
[52] “Fourth Amendment of the US Constitution -- Search and Seizure.” Justia Law. https://law.justia.com/constitution/us/amendment-04/.
[53] Murrill, Brandon J., Edward C. Liu, and Richard M. Thompson II. “Smart Meter Data: Privacy and Cybersecurity.” Federation of American Scientists (FAS). Congressional Research Service, February 3, 2012. https://fas.org/sgp/crs/misc/R42338.pdf.
[54] “Kyllo v. United States, 533 U.S. 27 (2001).” Justia Law. https://supreme.justia.com/cases/federal/us/533/27/.
[55] “Seattle City Council Adopts Nation's Strongest Law to Protect Utility Customer Personal Data.” ACLU of Washington, August 6, 2018. https://www.aclu-wa.org/news/seattle-city-council-adopts-nation’s-strongest-law-protect-utility-customer-personal-data.
[56] “Trafficking in Persons & Smuggling of Migrants Module 14 Key Issues: Technology Facilitating Trafficking in Persons.” UNODC, May 2019. https://www.unodc.org/e4j/en/tip-and-som/module-14/key-issues/technology-facilitating-trafficking-in-persons.html.
[57] Ibid.
[58] Shahani, Aarti. “Smartphones Are Used To Stalk, Control Domestic Abuse Victims.” NPR, September 15, 2014. https://www.npr.org/sections/alltechconsidered/2014/09/15/346149979/smartphones-are-used-to-stalk-control-domestic-abuse-victims.
[59] Newman, Lily Hay. “Burglars Really Do Use Bluetooth Scanners to Find Laptops and Phones: Bluetooth Scanners Are Readily Available and Easy to Use—Which Means That Smash-and-Grab Car Break-in Might Not Have Been Pure Chance.” Wired, November 18, 2019. https://www.wired.com/story/bluetooth-scanner-car-thefts/.
[60] Marczak, Bill, John Scott-Railton, Adam Senft, Bahr Abdul Razzak, and Ron Deibert. “The Kingdom Came to Canada: How Saudi-Linked Digital Espionage Reached Canadian Soil.” Citizen Lab, October 1, 2018. https://citizenlab.ca/2018/10/the-kingdom-came-to-canada-how-saudi-linked-digital-espionage-reached-canadian-soil/.
[61] Kirchgaessner, Stephanie. “Exclusive: Saudi dissident warned by Canadian police he is a target: Omar Abdulaziz, who was close to murdered journalist Jamal Khashoggi, told of threat posed by Saudi Arabia.” The Guardian, June 21, 2020. https://www.theguardian.com/world/2020/jun/21/exclusive-saudi-dissident-warned-by-canadian-police-he-is-a-target.
[62] Netanyahu, Benzion. “The Jewish Question.” In The Origins of the Inquisition in Fifteenth Century Spain. Second edition. New York: New York Review of Books, 2001.
[63] Ordover, Nancy. American Eugenics: Race, Queer Anatomy, and the Science of Nationalism. Minneapolis: University of Minnesota Press, 2003. 114.
[64] Mannix, Daniel P. The History of Torture. Lake Oswego, Oregon: eNet Press, 2014. 14.
[65] DeVito, Lee. “Detroit Has a New Old-School Payphone That's Free to Use.” Detroit Metro Times, November 19, 2019. https://www.metrotimes.com/news-hits/archives/2019/11/19/detroit-has-a-new-old-school-payphone-thats-free-to-use.
[66] For a currently available, though suboptimal, solution, see:
“How To Text Enable Your Landline Number? Step By Step Guide.” Text My Main Number, 2019. https://textmymainnumber.com/how-to-text-enable-your-landline-number-step-by-step-guide/.
[67] Burrows, Leah. “Toward an Unhackable Quantum Internet: Researchers Demonstrate the Missing Link for a Quantum Internet.” The Harvard Gazette, April 14, 2020. https://news.harvard.edu/gazette/story/2020/04/researchers-demonstrate-the-missing-link-for-a-quantum-internet/.