Proof of Location for smart contracts

location pointers GPS

The need to verify location is common to trigger a smart contract. Multiple blockchain solutions are popping up to provide a ‘Proof of Location’ oracle for smart contracts, which don’t rely on GPS.

What’s an oracle?
Blockchains are unable to access data outside of their network. Sometimes smart contracts need external information to function, whether that’s an exchange rate or a proof of location. Oracles are the way smart contracts access this third-party information.

Position-dependent applications include supply chain, parametric insurance, KYC/AML verification, or even consumer transactions. In the latter case, an online store might need to prove that an item has arrived at your doorstep so that the smart contract can automatically trigger a payment from your wallet.

Why not rely on GPS?

Businesses may be happy to rely on GPS, even though it’s not bulletproof. In 2016 Boeing applied for a patent for an ‘On-board backup and anti-spoofing GPS system.’

The patent highlighted some of the problems with GPS. “Examples of why GPS signals may not be available include intentional interference, unintentional interference, natural occurrences, and lack of coverage.”

“Examples of intentional interference include jamming and spoofing where jamming includes the deliberate drowning out of legitimate GPS signals, used for positioning, navigation, and timing, and frequency alignment, using higher power signals to cause loss of GPS satellite lock and to prevent reacquisition and spoofing includes the deliberate emitting of legitimate-appearing false GPS signals to shift the computed GPS position or GPS time of a target’s GPS receiver.” Next time you fly, try to forget this article!

Hacking mobile apps is an even easier way to interfere. Other GPS limitations include the heavy use of battery power which makes it a challenge for light-weight IoT applications, not to mention the difficulty of using it indoors. And blockchain people are not keen on the fact that GPS is centralized.

The blockchain solutions

Several startups are addressing the problem by creating decentralized Proof of Location blockchains which reward users for participating by paying with cryptocurrency. Each has a slightly different approach, and some use hardware solutions. Most of them aim to provide greater privacy for users compared to current smartphone apps.


Foam‘s technical team has quite a bit of blockchain experience so may be able to move faster than others. However, theirs is a hardware-based solution which could take a little time to roll out. Much like Bitcoin and Ethereum have miners, Foam nodes provide geo triangulations combined with a verified timestamp.

The startup plans to use Low Power Wide Area Network (LPWAN) devices. These offer the low power and longer battery life of Bluetooth with the range of cellular and also use the unlicensed radio spectrum.


XYO popped up this year, but have the advantage of leveraging their existing hardware. Sister company XY Findables has sold more than 100,000 gadgets which track your keys, bags, and other belongings.

They plan to roll out a firmware upgrade to enable all the owners of these gadgets to become nodes or ‘sentinels’ which are used for ‘Proof of Origin’.


Platin doesn’t use any specialized hardware other than smartphones. It uses ‘Sensor Fusion’ to combine GPS, Bluetooth, accelerometers, WiFi and cellular-network observations. They acknowledge that this is still spoofable, though there are plans to address on-device manipulations.

They also intend to have a reputation score which will involve time-based behaviors. If there are anomalies in the location (e.g., traveling from London to New York in 2 hours), this will damage your rating.

The project is still at an early stage and plans to use the Xain blockchain but integrate with Ethereum. Xain, in turn, is an Ethereum variant.

While many businesses may decide to rely on GPS for now, there are several new options on the horizon.

Other links: Research paper

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