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  OffChain

OffChain - Offline CBDC Payments

OffChain is a device that not only makes offline CBDC payments as easy as card payments in almost any environment, but also provides answers to critical mass adoption questions. Flexibility, key management and recovery, privacy, security and usability, just to name a few.

Inspiration

Driven by the belief that CBDCs can change people's lives for the better - although there is still a long way to go - OffChain aims to enhance and accelerate this process by sharing some possible answers to specific obstacles along the way.

What it does

Essentially, it is a device that allows offline transactions on the XRPL to be brought online at a later date. But it does much more than prevent the "Double Spending Problem". It makes blockchain technology usable without even realizing you're using a blockchain. All issues related to self-custody are taken care of for the user, but without handing them over to a central authority.

• Flexibility - What is that "device" that works in every environment?
  • It can be a smart card (credit card), an RFID key, or even look like a coin.
  • It can be powered by almost anything from a smartphone to a POS terminal (directly or via NFC).
  • Communication can take place via Bluetooth, WiFi, NFC or directly.
• ESG
  • Carbon credits can also be stored on the device.
• Usability
  • It's just like using a credit/debit card. Neither the merchant nor the consumer will notice that they are using a blockchain.
• Key Management - The user only needs to enter a PIN code to make a payment.
  • The PIN can be recovered in case of loss as it is also known to the issuer (financial institution).
  • Money is not lost on a lost device.
  • Nobody, not even the issuer, can access the funds without having access to the device AND knowing the PIN.
• Privacy
  • Users can change their device/address regularly or even own several of them and cannot be publicly traced.
  • The issuer can provide authorities with personal data (KYC) of the device owner if required.
• Security
  • It is as secure as any major credit/debit card as it works very similarly.

To better understand how it works, just watch the video to see it in action.

How we built it

It is based on FreeRTOS and uses the XRPL as the underlying payment technology. FreeRTOS is a real-time operating system owned and managed by Amazon to provide a secure OS for AWS IoT devices, smart cards, and more. The combination of some unique XRPL features like tickets and sequences and the atomic transaction capability that FreeRTOS offers enables CBDC payments that are as simple as card payments.

Challenges we ran into

Developing a working prototype wasn't very difficult, but as testing in the wild showed, solving connectivity problems isn't all that easy. If a chip card moves too far away from its power source (card terminal), it switches itself off immediately. Figuring out which changes already made need to be undone and how to do that was quite a challenge.

Accomplishments that we're proud of

OffChain offers practical answers to some of the most important questions when it comes to CBDC adoption. And true to the motto "ideas trigger ideas", hopefully more developers/issuers will soon be looking in this direction.

What we learned

1. OffChain was only intended to make offline CBDC payments safe and easy. But as more problems were solved, more emerged in other areas. Issuing a CBDC is definitely a lot more complex than initially thought.
2. CBDCs offer a variety of new business opportunities. In fact, during OffChain's development, at least 10 of them were accidentally developed.

What's next for OffChain - Offline CBDC Payments

The current and most important task is to bring it into a completely fail-safe state. Various "Secure Elements" (crypto chips) are then tested for security and resource consumption. And finally, step by step, it will be made ready for production.

Built With

• angular.js
• esp32
• freertos
• smartcard
• xrpl
• xrpl.js