The following dapp seeks to be a proof-of-concept for on-chain Covid-19 certificate verification and submission. The project is based on the Proof-of-Existence exercise discussed in the bootcamp.
At this moment in time, many countries provide their citizens with a proof of their vaccination in either physical, i.e. as a hard document or in software form, which in its most simplest form can be done by encoding the patient's vaccine information into a QR-Code, allowing for easy verification.
This project shows a very elementary way of making use of the later form, i.e. software, to save and verify Covid-19 certificates on-chain.
IMPORTANT: Since this is not a production ready dapp, I had to think of a way to disallow the submission of any sort of random QR-Code, which can be malicious in certain cases. So to make sure that only certain QR-Codes are submitted, the decoded string contained within the QR-code starts with the prefix "COVPASS:" followed by the name of the certificate holder, e.g. "COVPASS: John Doe". To generate such QR-Codes with manually defined text, use a website like this. This provides a slight sense of authenticity to this experimental project.
You can find some sample QR-codes in the sample-qrcodes folder for testing.
Ropsten: 0xaf7854C86aB9F533F05E6396927B5dff9703bDdD
Make sure to use Meta-Mask on Ropsten!
- app: contains all the files for the front end.
- contracts: contains all the solidity code
- migrations: contains the .sol files for migrating the contracts to chain.
- node_modules: contains node-modules, which are ignored from the commits
- tests - contains the smart contract unit tests
It is recommended to use VS-Code for testing this project.
Make sure to install the Live Server Plugin by Ritwick Dey to be able to run the website locally. Once installed, open the "app.html" file in VS-Code and then on the bottom right side of the window click on "go live". This should open up the page in your default browser.
Note: Node version 16.13.0 LTS was used while testing and building this project.
In a new terminal window, navigate to the project root and install the projects dependencies along with truffle, web3 and ganache-cli.
npm install
npm install -g ganache-cli
npm install -g truffle
npm install web3
Make sure to have these lines of code in the truffle-config.js file:
development: {
host: "127.0.0.1",
port: 7545,
network_id: "*",
}
If you wish to change the deployment options above, then you are welcome to do that.
For ease of use, we are going to use ganache UI. Download it from here.
Run ganache UI, select "New Workspace" and then in the workspace tab, click on add project and select thetruffle-config.js in the root directory of the project. Go to the Server tab and then make sure the host name is set to: 127.0.0.1 - lo and port number to 7545, or as set in the truffle-config.js file. Also make sure to add a local network with the above configuration in metamask installed to your browser to test the app later.
Now we have set up Ganache and are listeing to the changes and deployment made on the local testnet.
Being in the root project directory, deploy the contracts:
truffle migrate --network development --reset
Once deployed, copy the contract address for the CovVrfy contract. The contract address in the app.js file in the "app" folder should be replaced with the copied contract address. The variable named contractAddress for the contract address is located inside the Documents.prototype.init function.
We will now deploy the contract on Ropsten, but you can decide which network to deploy it to. Install the following packages:
npm install @truffle/hdwallet-provider
npm install dotenv
Create a .env file in the root folder and paste your infura endpoint and your mnemonic like this:
MNEMONIC="this is not a mnemonic :)"
INFURA_URL="the url"
Deploy it to Ropsten by running this in the root folder of the project:
truffle migrate --network ropsten
Similar to deploying on a local network, replace the contract address in the app.js file with the newly deployed contract's address (see above).
Run Gnache-CLI or Gnache UI as explained above in 'deploying the smart contract' section. Once the local testnet is running, open the terminal in the root folder of the project and run truffle test
The QR-Scanner library was implemented by mebjas and the code can be found in his repository.
0x3420fde3a09aAD23307c539255c9B848Ea00D008
- Provide a more user friendly way to automatically promt the user to change the network on metamask.
- Some further UI improvements
- Modifiy the smart contract to avoid saving any random string to the state array, which for now is only done by the front end code.