project / 2025-26
Privacy systems / full-stack build
ZK Guardian
A privacy-first healthcare prototype exploring zero-knowledge consent verification for FHIR workflows without exposing patient identity on-chain.
- built with TypeScript / React Native / Expo / Node.js / Express / Circom / Solidity / Polygon Amoy / FHIR R4
- source View source ↗
notes on the build
Challenge
ZK Guardian starts with a sharp question: how do you prove a clinician had valid consent to access data without publicly revealing who accessed what?
That is a better product question than a generic blockchain prompt because it forces the privacy boundary to stay explicit from the start.
Approach
The project combines several layers:
- a mobile app for consent and audit visibility
- a Node/Express gateway for orchestration
- Circom circuits for proof generation
- Solidity contracts for on-chain audit records
- FHIR examples to keep the healthcare side grounded
The important decision is that the chain only sees hashes and proofs. The system is built around verifiability, not exposure.
Why it stands out
What makes ZK Guardian interesting is that the cryptography is attached to a real boundary with real stakes: healthcare access, auditability, consent, and emergency flows.
Why it matters to me
It sits at an intersection I keep returning to: serious user needs, strong privacy constraints, and architecture that has to be precise to mean anything.
what mattered
- Zero-knowledge audit flow built around consent verification rather than identity disclosure.
- Mobile, gateway, contracts, circuits, and FHIR examples kept in one coherent repository.
- Explicit privacy boundary: no PII or PHI stored on-chain.
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