Enabling the Dissemination of High-Value IoT Data Through Decentralized Auctions on the Blockchain

Overview

This RESTful API, written in Express, models an IoT device according to the Mozilla Web of Things API. It automatically starts an Auction contract, provides endpoints for the highest bidder to retrieve the device data using the API Key won in the auction, and also automatically collects funds from the highest bid in the contract after the auction ends.

Instructions

To install dependencies: npm i

Either install the Ganache GUI and change port number to 8545 or run in terminal ganache-cli -b 3

To start IoT API backend: npm start, which creates an instance of the AuctionFactory, which we use to keep track of all created auctions, and starts one Auction. After that, running npm run testAll would create 5 more auctions using the same AuctionFactory.

To view the auctions on the frontend: copy the AuctionFactory address generated in terminal and replace it in Details.js at line 216.

Running migration: 2_deploy_contracts.js
  Deploying AuctionFactory...
  ... 0x782fd6a0e54f7c3934261f94e6bdcbb257a6ad2adf9f63d923c23ca4fb1492ab
  AuctionFactory: 0xd62ba15ba2ec4e589b569c6f04eabe61c99c7008

async refreshAuctions() {
    let factoryInstance = await AuctionFactory.at(
      "0xd62ba15ba2ec4e589b569c6f04eabe61c99c7008"
    );
    ...
}

Files

/contracts

This folder contains AuctionFactory.sol which creates a smart contract for creating new auction smart contracts for the IoT devices, and it stores all the active auctions.

The file dataAuction.sol creates a smart contract for managing auctions, allowing for:

1. Bidding.
2. Getting an API key after transaction is locked.
3. Confirming the validity of the data provided by an API key by comparing hashes.
4. Allow refunding of bids lower than highest bid.
5. Withdrawing rewards after auction is completed.

/migrations

This folder contains the scripts which deploy the AuctionFactory to the Ethereum blockchain when running npm start (npm start runs the command truffle migrate --reset --compile-all)

index.js

This file contains the functionality of the RESTful API. On start, the createAuction function is automatically called. This creates an Auction contract, assuming the ethereum address of the IoT device to be the first geth address and setting the auction length to 100 seconds. It also generates a random API key and hashes the first 256 bytes of the data file, both of which are put into the Auction contract. This allows the highest bidder to retrieve the data from this API and verify the validity of the data after the end of the auction, respectively.

The createAuction function also calls the getLocation function, which populates the location field of the metadata with the current location of the simulated "IoT device," using IP address lookup.

The withdrawFunds function, also called on start, automatically attempts to withdraw the funds, paid by the highest bidder, from the Auction contract at set time intervals. It will only be successful after the end of the auction bidding period and after the highest bidder has verified the data (handled automatically by our frontend).

Finally, we have two functions for the API endpoints:

app.get("/things/pi/properties/temperature", (req, res) => {...

app.get("/things/pi/properties/humidity", (req, res) => {...

These endpoints allow the highest bidder to retrieve the pertinent simulated device's data (for the purposes of the MVP, we have included some sample data), using the API key they received from the Auction as authentication in the x-access-token header.

sampleMetadata.json

This file contains example metadata for a few kinds of devices. This metadata is put into the Auction contract so that bidders can see to what kind of device a particular auction pertains. On the frontend, we are able to provide filtering on all available auctions using the fields in the metadata, including location.

temperature.json and humidity.json

These files contains sample data that one might expect to receive from a Nest thermostat or humidity sensor, respectively.