Offline CBDC Settlement SDK

The biggest challenge in deploying a true Central Bank Digital Currency (CBDC) is enabling secure offline payments without double-spend risks. Most digital payment systems require internet connectivity, but real financial inclusion demands transactions that work fully offline. To solve this, we built the Offline CBDC Settlement SDK — a plug-and-play framework for secure NFC-based offline payments that bridges hardware-level communication with cloud settlement. How It Works 1. Hardware Handshake Using React Native and ISO-DEP smart card emulation, devices exchange payment data through custom NFC APDU commands instead of internet-based protocols. 2. Cryptographic Validation Transactions are signed using TweetNaCl Ed25519 cryptography and verified locally before funds are accepted. Verified transactions are securely stored in SQLite, reducing double-spend vulnerabilities. 3. Cloud Settlement When connectivity returns, offline ledgers sync with a Node.js/Express server, where transactions are audited against a Supabase PostgreSQL vault before final settlement. Accelerated by IBM Bob IBM Bob helped us: Audit and secure our APIs and cryptographic implementation. Harden backend infrastructure against replay and injection attacks. Generate secure Docker-based DevOps infrastructure. Build CI/CD pipelines with GitHub Actions for automated deployment. By combining NFC hardware communication, cryptographic security, and IBM Bob’s enterprise AI tooling, the Offline CBDC Settlement SDK provides a scalable blueprint for real-world offline digital currencies.