Money that works even when the internet doesn't.
A peer-to-peer payment protocol designed to remain secure against future cryptographic threats, enabling instant offline transactions via QR, NFC, BLE, or SMS.
Trust Layer
Why offline money is safe. We use Hybrid PQXDH key exchange and cryptographic vouchers to secure transactions.
Threat Model & Prevention
- Double Spending Strict nonce limits on generated vouchers ensure they cannot be reused when devices sync.
- Replay Attacks AES-256-GCM encryption paired with ECDSA signatures safely reject any intercepted vouchers.
Quantum-Resistant PKI
Celeris utilizes a hybrid key encapsulation mechanism combining ECDH with Kyber/ML-KEM-768 for connection establishment, ensuring that tomorrow's supercomputers can't decrypt today's financial transactions.
Offline Deferred Settlement
Payments are guaranteed locally and completely settled digitally. As soon as connectivity returns, vouchers reconcile directly via standard UPI or IMPS banking rails.
How It Works
The Anatomy of an
Offline Payment
How Celeris bridges the gap between disconnected devices and the global financial grid.
What happens if...
We built Celeris for the messy reality of physical infrastructure. We expect failures, and the protocol handles them gracefully.
Receiver never comes online?
The payment voucher has an encoded expiry time (TTL). If the receiver fails to relay the voucher to the network before it expires, the transaction is negated locally, and the sender's balance is safely restored. No money is lost.
SMS fails or is delayed?
The app queues the transmission and retries automatically. If SMS fails completely, the voucher remains stored locally on both devices. The moment either device detects Wi-Fi or cellular data, it completes the background sync via HTTP.
User sends twice offline?
The protocol securely strictly limits offline spending to a pre-authorized limit. The system refuses to sign offline vouchers exceeding this limit without a brief online balance refresh beforehand.
Partial settlement?
Settlement is strictly atomic. A transaction is either 100% verified and settled on the banking ledger, or it fails entirely. If a bank API times out during the final stage, the server holds the verified receipt and auto-retries via UPI or IMPS until success.
Where this actually matters
This isn't theoretical infrastructure. Celeris is designed for the moments when UPI fails and cards are useless.
The No-Network Village Shop
A merchant in a remote rural area with zero data coverage can accept payments all day. Customers generate vouchers, tap via NFC, and the merchant's app queues the encrypted receipts. Later, the app auto-syncs the entire batch when they head to town.
The Metro Tunnel Split
You're underground where mobile internet is non-existent. You need to split a cab fare instantly. Instead of waiting, you scan a QR code offline. The transaction is instantly mathematically bound, and the app handles the rest asynchronously.
Disaster Resilience
During natural disasters, cell towers go down and ATMs empty out. While regular digital payments fail, Celeris's protocol ensures critical transactions — buying emergency supplies or water — can still happen offline, keeping local economies moving.
System Dynamics
Constraints designed for security and predictability in real-world environments.
- Offline Transactions Strict Pre-Authorized Limit
- Settlement Execution Deferred Asynchronous
- P2P Latency (BLE / NFC) Instant Verification
- SMS Fallback Integration Automated Queuing
- Network Resilience Self-Healing Sync
The Positioning
Bridging the physical reliability of cash with the digital ease of modern fintech.
| Feature | Celeris | UPI | Cash | Cards |
|---|---|---|---|---|
| Offline Capability | ||||
| Instant Verification | ||||
| Digital Settlement Layer | ||||
| Double-Spend Proof | ||||
| Post-Quantum PKI | - |