Latens allows users to privately prove Bitcoin balance ownership or threshold conditions without revealing their address or exact balance on-chain

• Privacy-First: Prove you own ≥X BTC without revealing your address or exact balance
• Zero-Knowledge: Uses ZK proofs verified on Starknet
• Bitcoin Native: Works with real Bitcoin blockchain data
• Trustless: Cryptographically verifiable proofs
• Modern UI: Glassmorphism design with live protocol statistics

┌─────────────────┐
│  Bitcoin Chain  │
└────────┬────────┘
         │
         ▼
┌─────────────────┐      ┌──────────────┐
│  Indexer        │─────▶│ Merkle Tree  │
│  (Backend)      │      │  Builder     │
└─────────────────┘      └──────┬───────┘
                                │
                                ▼
                         ┌──────────────┐
                         │ ZK Circuit   │
                         │ (Cairo)      │
                         └──────┬───────┘
                                │
         ┌──────────────────────┴──────────────────────┐
         ▼                                             ▼
┌─────────────────┐                          ┌─────────────────┐
│  Frontend       │                          │  Starknet       │
│  (Next.js)      │─────────────────────────▶│  Contracts      │
└─────────────────┘      Submit Proof        └─────────────────┘

latens/
├── backend/              # Python backend service
│   ├── src/
│   │   ├── indexer/     # Bitcoin data fetching
│   │   ├── crypto/      # Merkle tree & Poseidon hash
│   │   ├── circuit/     # Cairo circuit & proof generation
│   │   ├── api/         # FastAPI server
│   │   └── models/      # Database models
│   ├── tests/
│   └── requirements.txt
├── contracts/           # Cairo smart contracts
│   ├── src/
│   │   ├── state_root_registry.cairo
│   │   └── proof_verifier.cairo
│   ├── tests/
│   └── Scarb.toml
├── frontend/            # Next.js frontend
│   ├── src/
│   │   ├── app/
│   │   ├── components/
│   │   └── lib/
│   └── package.json
└── docs/                # Documentation
    ├── prd.md
    └── flow.md

Run the full stack (Frontend + Backend + DB) with one command:

docker-compose up --build

• Frontend: http://localhost:3000
• Backend API: http://localhost:8000/docs

• Python 3.10+
• Node.js 18+
• Scarb (for contracts)
• Starknet wallet (Argent/Braavos)

cd backend
python -m venv venv
# Windows: venv\Scripts\activate | Mac/Linux: source venv/bin/activate
pip install -r requirements.txt
uvicorn src.api.main:app --reload

cd frontend
npm install
npm run dev

cd contracts
scarb build
# Deploy to Testnet (requires .env vars)
python scripts/deploy.py

cd backend
python -m src.scripts.generate_snapshot --block-height 800000

cd backend
uvicorn src.api.main:app --reload

Open browser to http://localhost:3000/demo

1. Enter Bitcoin Address: Input your BTC address locally
2. Generate Proof: Client-side commitment + backend proof generation
3. Connect Wallet: Connect Starknet wallet (Argent/Braavos)
4. Submit Proof: Verify on-chain without revealing address
5. View Result: See verification status

• ✅ Exact balance remains private
• ✅ Salt prevents correlation attacks
• ✅ Only threshold satisfaction is proven
• ✅ Bitcoin address never appears on-chain

# Backend tests
cd backend
pytest tests/ -v

# Contract tests
cd contracts
scarb test

# Frontend tests
cd frontend
npm test

• PRD - Product Requirements Document
• Flow - Detailed User Flow Specification
• Implementation Plan - Technical Implementation Guide

• Backend: Python, FastAPI, SQLAlchemy
• ZK Circuits: Cairo
• Smart Contracts: Cairo on Starknet
• Frontend: Next.js, TypeScript, TailwindCSS
• Cryptography: Poseidon hash, Merkle trees

1. Private Balance Verification: Prove ownership without revealing amount
2. Threshold Gating: Access DAOs/services with ≥X BTC requirement
3. Anonymous Reputation: Build cross-chain reputation from Bitcoin holdings
4. Compliance Proofs: Prove non-interaction with blacklisted addresses

MIT

This is a hackathon project. Contributions welcome!

• Starknet Docs
• Blockstream API
• Cairo Book