Jonas BouryTransforming The ETHglobal the event NFC wristbands into Smart wallet accounts
At Citizen Wallet, our mission is clear: we're dedicated to leveraging Web 3.0 technology to empower communities worldwide to launch their currencies. However, within the expansive realm of Web 3.0, a crucial element remains absent—a robust payment infrastructure facilitating the seamless integration of Web 3.0 tokens into our daily transactions. While our Citizen Wallet application ensures mobile-to-mobile transactions are as smooth as possible, there is still a gap when it comes to low-tech solutions.
Thus, we eagerly participated in the ETHGlobal London hackathon, driven by our ambition to develop an innovative solution that facilitates effortless low-tech token transactions. Time to show what we can do as the Citizen Wallet team.
About ETHGlobal London
ETHGlobal London is a hackathon event organized by ETHGlobal in London.
It is a vibrant gathering of individuals passionate about blockchain technology and its potential to revolutionize various aspects of our society and economy. It's a place where ideas are born, collaborations are formed, and the future of decentralized technology is shaped. It is an event for builders so the main focus of the program is a coding competition where teams have 36 hours to build something innovative and cool from scratch.
Our project: NFC wallet
We arrived with the idea to build something that can enable crypto transactions with NFC cards. Lo and behold, at the conference we noticed that all participants received an NFC wristband to get access to the event location and to be able to connect with people by tapping the wristband with their phone.
A cool feature for networking. But what if this wristband could become more than an access token and shareable business card … what if these bad boys could become crypto wallets?
Transforming NFC Cards into Smart Wallets
Our first task was to develop an application capable of reading NFC tags and converting them into wallets. Leveraging the account abstraction contract, we created smart wallets derived from the NFC tag's serial number. These smart wallets were linked with a payment master, covering transaction costs instead of requiring individual gas ownership.
Upon wallet creation, the application generated a QR code of the public address, Making it easy to deposit assets to that account. This can be stablecoins like USDC or self-generated tokens that represent a finite resource like food, drinks, meeting rooms, or print credits.
The web application was linked with a blockchain indexer that keeps track of the wallet balance and synced the data in real time. That way the wallet balance data was instantly updated when a transaction was executed.
NFC scanner application
Let’s make it personal
To give it a cool spin and make the wallets more personal we figured out a way to capture the information on the participant’s ETHGlobal-profile. The wallet that was created automatically was linked with the profile information of the participant. So our demo also led to surprising faces when people saw their profile pictures pop up on our phones.
Payment Terminals/POS Integration
For NFC wallet interaction, we developed a straightforward Point of Sale (POS) mobile application. Users could select items for purchase, such as coffee, and complete transactions by tapping their NFC against the POS device. Each POS device possessed a unique private key, with whitelisting required for device addresses to execute withdrawal functions, ensuring security.
Payment flow with POS application
For detailed technical insights, see our GitHub repository: https://github.com/citizenwallet/ethglobal-london-app
We opted for Base's Layer 2 blockchain infrastructure for its swift and economical transactions. With recent Ethereum updates, transaction costs on Base have plummeted below 1 cent, making it ideal for microtransactions like purchasing a coffee.
The use cases
In practise there are definitely a lot of use cases for this tech. It can basically be used at any event as a convenient cashless payment method. It becomes even more powerful by issuing wallets with several tokens instead of only 1 currency. A co-working place for example could issue tokens for printing, coffee, meeting rooms, ….
That way you can easily manage available resources within your event / community.
in short: it is a simple tool that any common can use to share common’s finite resources. (like earth… )
Our result
Following 36 hours of dedicated effort, we were honored to be selected as finalists, receiving €3500 in prize money—a valuable resource as we continue to expand the capabilities of Citizen Wallet. You can find a video of our presentation below.
In conclusion, our experience at ETHGlobal London was immensely gratifying, and we eagerly anticipate further development and integration of our project within the Citizen Wallet ecosystem. It's inspiring to witness the collaborative efforts shaping an inclusive and open financial system —a system that serves the common good rather than being beholden to private interests.
Want to learn more or are you interested in using this tech at your event? Feel free to reach out.