What is the “proof of location” and why it matters
An introduction to the Proof of Location
Back in 1997, Adam Back invented hashcash, a CPU cost-function to be deployed as a denial-of-service counter measure. A couple of years after, Markus Jakobsson and Ari Juels, coined the term “proof of work” (PoW) to describe this mechanism. POWs are protocols in which a prover demonstrates to a verifier that she/he has performed a certain amount of computational work in a specified interval of time. As you probably know, POW is the basis of many popular cryptocurrencies and smart contract systems. Others use the “proof of stake” (PoS), which is another consensus mechanism and, as you can imagine, other systems exist as well; and in their large majority assist in the verification that the information being added to a ledger is valid.
So far so good. Let’s add location in the mix!
How location fits in here?
The boom of the smartphone market and the incorporation of Global Navigation Satellite System (GNSS) devices in them, brought to the public Location-Based Services (LBS). We all use them when we want to see our location on a map App, discover nearby restaurants, avoid traffic, order transportation means (e.g. taxi, uber etc.) or check in how much time our bus will arrive. Almost 3 billion mobile applications currently in use, rely on positioning information [GSA says so].
Usually, we don’t question the accuracy nor validity of an LBS-powered app, because we are perfectly used to obtain our location inside relative accuracy levels and in the large majority of times, without any particular problem. For the use cases mentioned above, that’s not a big issue.
But what about use cases, where location needs to be trustworthy and verifiable? How can you trust, as a developer or user or service provider, an app which requires GNSS input streams from a device which you cannot verify, in particular when this is proven to be spoof-able?
Check the example of spoofing Pokemon Go to get a better score https://drfone.wondershare.com/virtual-location/pokemon-go-spoofing-android.html
Or this example on the validity of geosocial utility traces, which proves that a large portion of visited Foursquare locations is missing from checkins, and most check in events are either forged or superfluous events.
Or a better one on spoofing ship AIS (Automatic Identification System) signal https://www.gpsworld.com/chinese-gps-spoofing-circles-could-hide-iran-oil-shipments/
Or see how UBER drivers were faking their location for taking quicker ride requests https://www.imyfone.com/change-location/fake-gps-on-uber/
Or spoofing the GPS of Tesla Model 3 (a dangerous one!) https://www.regulus.com/blog/tesla-model-3-spoofed-off-the-highway-regulus-researches-hack-navigation-system-causing-car-to-steer-off-road/
In an LBS-powered world, many important transactions will rely on location. And proving verifiable location is becoming a necessity, because TRUST will be utterly important. As we saw above, self-reported location claims, using GPS or Galileo (or any other GNSS positioning) have a certain risk.
What is required is a Proof-of-Location (PoL), in other words a digital certificate (issued by some kind of system) which should be able to verify the reported physical location of a device, while at the same time, ensure user’s privacy. Currently there are various proposed solutions to this problem. Some of them use a centralized infrastructure (e.g. Wi-Fi, mobile phone providers etc.) and others propose decentralized solutions (e.g. using blockchain approaches). This article won’t go deep into these solutions (anyway I don’t clearly get many of them, to be honest!).
Some quite clever computer scientists and engineers have put effort to research and patent solutions. Below I finish this article with some quick links to relevant examples. Have a look on the links and feel free to comment.
- I enjoyed reading this conference article by Javali et al. (2016) titled: “I Am Alice, I Was in Wonderland: Secure Location Proof Generation and Verification Protocol”
- Amoretti et al. (2018) propose a blockchain-based solution to the problem and they include a very short overview of other solutions.
- Zhu et al. (2013) came up with a system they called APPLAUS (A Privacy-Preserving LocAtion proof Updating System) in which colocated Bluetooth enabled mobile devices mutually generate location proofs and send updates to a location proof server.
In the blockchain-related PoL start-up ecosystem you can have a look on the following:
- FOAM — https://foam.space/ A blockchain-based and community-owned (and operated) location network
- XYO — https://xyo.network/
- Platin.io — https://medium.com/@platin_io which seems to be a dead project now, but was around for some time.
There are also some patents that I found online:
- GuardTime was granted a patent on blockchain-supported device location verification with digital signatures.
- Nokia has a relevant patent on positioning information verification https://patents.google.com/patent/WO2018220262A1/en
Come back for more and have a look on my easy reads on drones and smart location encoding systems.
