Offline Payments

Offline payments ensure economic resiliency by enabling transactions to occur even in environments with no or unreliable internet or service connectivity. From rural merchants in remote areas to urban customers impacted by network or service disruptions, the ability to perform offline transactions is rapidly becoming an essential feature of modern financial ecosystems.

Survivability in the Face of Failure:

Despite their growing importance, current offline payment systems face several challenges:

Double spending is an inevitable security risk of offline payments.

Particularly evident in solutions requiring hardware-based secure elements for wallets and terminals, as no efficient ecosystem exists for large-scale application deployment and upgrades.

The widespread reliance on Fund, Pay, Defund, and Reconcile (FPDR) models introduces adjunct layers that require separate reconciliation frameworks, complicating adoption.

Recognizing these limitations, Crunchfish has engineered a modular offline payment system combining interoperability, security, and scalability into a streamlined architecture that may be integrated with any type of underlying payment scheme.

Offline Payments in an Online World

The Reserve, Pay, and Settle approach optimizes offline payments by leveraging existing rails for online settlement rather than relying on separate reconciliation layers. The modularity of this unique approach of offline payments combines the interoperability of EMVCo card payments with the programmable flexibility of Ethereum smart contracts, delivering a comprehensive framework for secure offline transactions.

The Reserve, Pay, and Settle approach optimizes offline payments by leveraging existing rails rather than relying on separate reconciliation layers:

Pre-authorizing funds ensures trust without immediate backend connectivity.

Enable secure offline transactions validated by terminals.

Offline transactions are reconciled through online settlement structures, preventing fraud and enhancing efficiency.

Offline Payment Demos

Proximity Offline Payments

Using QR

Using QR and Bluetooth

Using QR and ultrasound

Using NFC and Bluetooth

Consecutive offline payment

Using QR and Face ID

Remote Offline Payments

Using telecom

Crunchfish enables applications to operate across various communications protocols using its patent-pending Trusted Application Protocol (TAP). This provides the survivability in the face of failure required of digital payments as a public good, instead of relying on a happy-flow approach, where digital payments only work when everything works. Client / Server applications can be trusted offline and transport its messages via any communication protocol in proximity and remotely, not just TCP/IP, using Crunchfish’s patent-pending Trusted Application Protocol (TAP).

The TAP protocol is transport-layer agnostic and relies on secure client / server communications from secure endpoints. With an isolated runtime executing environment, implemented preferably within a virtual secure element, having a private key generated and operating from within the virtual operating system, it is possible to enable secure end to end communications between clients or between a client and the server without any trust gaps, on long-distance or short-distance channels, by means of PKI and cryptographic signatures. This enables not only secure offline payments communications but also improved client authentication security for online payments.

In the paper “The design philosophy of the DARPA Internet Protocols” published in 1988 by David D. Clark from Massachusetts Institute of Technology outlines that the internet fundamentally is “a packet switched communication facility in which a number of distinguishable networks are connected together using packet communications processors called gateways which implement a store and forwarding algorithm”.

Crunchfish Digital Cash is inspired by the design philosophies that was developed by the Defense Advanced Research Projects Agency (DARPA) in the 1970s and became the internet as we know it today. It is an incredible robust protocol based on packet switching. This is how Crunchfish Digital Cash works for payments. He also outlines seven secondary design goals for TCP/IP, for which Crunchfish Digital Cash has an equivalent and patent-pending Trusted Application Protocol (TAP). Crunchfish Digital Cash is based on the same design principles and may deliver for digital payments what the internet has done for digital communications.

Any public good in the society like the internet, electricity or telecom must be carefully designed to continue working despite temporary outages of the service. It is hard to understand why digital payments, certainly also a public good, is not as robust as other public goods. Digital payments service must be as robust, inclusive and private as cash payment.