Our main website
picture of our extension and website where we want to verify

🛡 HumanProof

Inspiration

The internet is entering an era where distinguishing humans from AI is becoming increasingly difficult. Traditional CAPTCHA systems were designed for a very different internet, and modern AI systems are rapidly weakening many existing human-verification methods.

At the same time, many identity verification systems require users to sacrifice privacy by uploading personal documents, biometrics, or sensitive information to centralized platforms.

We wanted to explore a different approach: Can we verify humanity without exposing identity?

That question inspired HumanProof.

What it does

HumanProof is a privacy-preserving proof-of-humanity system built on Midnight Network.

Instead of solving CAPTCHA puzzles repeatedly, users verify once locally through a browser extension. The extension then generates anonymous cryptographic proofs proving the user is human without exposing personal identity, biometrics, or sensitive data.

Our system generates replay-resistant nullifiers tied to:

the user,
the domain,
and the current date.

These proofs are submitted to a Midnight smart contract for uniqueness verification, allowing websites to confirm humanity while keeping user information private.

How we built it

HumanProof consists of four major components:

🔹 Browser Extension

Acts as a local identity wallet that:

stores verification locally,
generates anonymous proofs,
communicates with websites.

🔹 Demo Website

A simple verification portal that interacts with the extension and demonstrates the user flow compared to traditional CAPTCHA systems.

🔹 Bridge Server

A local Node.js server that connects the browser extension to Midnight infrastructure.

🔹 Midnight Smart Contract

Handles replay-resistant nullifier verification and prevents duplicate proof usage without revealing identity information.

We used:

Midnight Network
Compact smart contracts
JavaScript
Node.js
Docker
Browser Extension APIs

Challenges we ran into

One of our biggest challenges was that most of our team had little to no previous experience with:

Midnight,
blockchain development,
Web3 systems,
or privacy-preserving smart contracts.

Understanding how the local Midnight infrastructure, proof server, bridge server, smart contracts, and browser extension architecture worked together required a steep learning curve.

We also spent significant time improving the communication flow between the website, extension, and local verification server while ensuring the overall demo experience remained smooth and understandable.

Another challenge was balancing technical depth with simplicity. Since this was a hackathon prototype, we wanted the system to feel realistic while still being demo-friendly and approachable.

Accomplishments that we're proud of

Building a complete end-to-end verification flow using Midnight
Successfully integrating a browser extension with local cryptographic proof generation
Implementing replay-resistant verification logic
Creating a privacy-first architecture where no personal information is stored on-chain
Learning an entirely new ecosystem and shipping a working prototype during the hackathon

What we learned

This hackathon completely changed how we think about digital identity and privacy.

Before the event, many of us associated blockchain mainly with cryptocurrency or financial systems. Working with Midnight introduced us to a different perspective: using privacy-preserving infrastructure to build trust systems without exposing sensitive data.

We also learned how browser extensions, local verification systems, and smart contracts can work together to create decentralized identity experiences.

Most importantly, we learned that privacy-focused applications can still provide strong usability and meaningful real-world functionality.