Skip to content
Biswajit Rath

← Work

UPI Offline Mesh

Offline payments system

A secure offline UPI mesh network with encrypted payments, duplicate-proof settlement, and low-latency processing.

Year
2026
Status
In progress
Built with
Spring Boot, Apache Kafka, AWS, RSA-OAEP, AES-256-GCM
Diagram: two peers exchange an AES-256-GCM encrypted payment offline, then settle through a Kafka ledger and UPI bank rails once they reconnect.

The problem

UPI assumes a connection. Plenty of places where people need to pay don't have a reliable one.

What I built

A mesh network that carries UPI payments without internet access, keeps every payment encrypted in transit, and settles each one exactly once, even when the same payment reaches the server along more than one path.

Why it's shaped this way

Payment payloads are encrypted with AES-256-GCM, and the keys that protect them are wrapped with RSA-OAEP, so devices relaying a payment can pass it on without being able to read it. Settlement runs through Apache Kafka.

What was hard

Outcome