🛡️ zkBadge – Private Achievement Verifier

A decentralized zero-knowledge DApp built with Midnight’s Compact language that allows users to prove they hold valid certifications or identity attributes—without revealing any sensitive information.

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🚀 Overview

zkBadge enables anyone to register and prove ownership of a digital certificate (like a degree, license, or ID clearance) privately using ZK proofs. Admins verify the legitimacy of certificate hashes off-chain. Verified users can then access gated features without exposing personal data.

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🔐 Key Features

• ✅ Private ZK Certificate Registration
• ✅ Off-chain Verification with On-chain Status Tracking
• ✅ Access Gated Features Based on Verification
• ✅ Connects with Lace Wallet
• ✅ Built using Midnight’s Compact smart contract language
• ✅ Frontend built with React + TailwindCSS

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🧠 Use Case Examples

• Prove you're certified in a field (e.g., KYC, license, diploma) without sharing personal info.
• Access gated DAOs, jobs, or services privately.
• Integrate with Discord, Web3 platforms, or real-world events requiring private access control.

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🏗️ Architecture

🧾 Smart Contract (Compact)

• register(): Register a certificate hash with ZK proof
• verify_certificates(): Admin approves known/legit certificate hashes
• check_verification(): Anyone can check if a user is verified
• access_private_feature(): Grants verified users access to protected resources

See contracts/zkBadge.compact

🌐 Frontend (React)

• Connect Lace Wallet
• Disclose private certificate as a ZK proof
• Submit proof to smart contract
• View verification status
• Access private content

See frontend/

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🛠️ How to Run Locally

🧩 Prerequisites

• Lace Wallet
• Midnight CLI or devnet tools
• Node.js ≥ v18
• Yarn

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Run the code

# run proof server
docker run -p 6300:6300 midnightnetwork/proof-server -- 'midnight-proof-server --network testnet'

node -v
yarn install

cd packages/contracts
npx turbo run build

cd ../api
npx turbo run build

# To run the cli DApp instance
cd .. && cd packages/cli
npx turbo run build
# You can either run the cli DApp testnet mode or in undeployed mode
yarn testnet-remote # For testnet-mode
yarn standalone # For undeployed mode

cd ../frontend
npx turbo run build
yarn build

Testing

npm install -g vitest
cd packages/contracts
npx turbo run build
yarn test

Note: Make sure packages/frontend is correct; adjust if your frontend folder uses a different name.

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🧪 Sample Test Scenario

1. User holds a certificate issued by a trusted authority

2. They generate a ZK proof using the witness function

3. Contract checks that:

   • Certificate is valid
   • Not expired
   • Owned by the prover

4. Admin verifies hash off-chain and calls verify_certificates()

5. User gains access to access_private_feature()

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🧰 Tech Stack

Layer	Tech
Smart Contract	Midnight Compact Language
ZK Proofs	Disclose / Witness functions
Wallet	Lace Wallet
Frontend	React + TailwindCSS + Vite
Chain	Midnight Testnet

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🥇 Hackathon Submission

• Team: DavyKing
• Status: ✅ Complete
• License: MIT

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🤝 Future Improvements

• Fully automate issuer verification via oracle or cross-contract call
• Integrate Discord bot for real-time badge gating
• Add NFT-based badges for off-chain identity portability

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⚠️ Troubleshooting (Optional)

• Node version: Use Node ≥ v18 for compatibility with Vite and Midnight tools
• Vite + WASM top-level await: If your build fails due to WASM, add vite-plugin-wasm and ensure ESM imports
• Turbo caching: Run npx turbo clean if cached builds cause stale outputs