SatVault

Inspiration

Bitcoin holders have limited options to generate yield without sacrificing security. We saw an opportunity to leverage Starknet's zero-knowledge technology to bring advanced DeFi capabilities to Bitcoin in a trustless manner. By combining Bitcoin's value with Starknet's scalability and adding gamification elements, we wanted to make Bitcoin staking not just profitable, but genuinely engaging and fun.

What it does

SatVault is a comprehensive Bitcoin staking platform on Starknet featuring:

Flexible Staking: Stake Bitcoin for 30-365 days with dynamic APY rewards Gamification Engine: Earn XP, unlock achievements, and climb the leaderboard Privacy Layer: Optional zero-knowledge stakes with encrypted amounts and proof verification Cross-Chain Bridge: Multi-chain payment routing between Bitcoin, Starknet, and Ethereum Real-time Management: Claim rewards anytime, manage multiple stakes, track performance

How we built it

We built SatVault using:

Smart Contracts (Cairo): Four interconnected contracts - BitcoinStakingVault, GameEngine, PrivacyLayer, and PaymentRouter deployed on Starknet Sepolia Frontend (Next.js 15 + TypeScript): Modern React app with Tailwind CSS, Zustand for state management, and starknet.js for blockchain interactions Wallet Integration: Seamless connection with Argent X and Braavos using get-starknet Token System: Mock BTC ERC-20 token for proof-of-concept staking mechanics

The architecture uses basis points for precise calculations, u256 for Bitcoin amounts, and modular design allowing independent contract upgrades.

Challenges we ran into

Bitcoin Bridge: Built a mock ERC-20 (mBTC) as proof-of-concept while designing for future real BTC bridge integration ZK Proofs: Implemented simplified zero-knowledge proofs demonstrating the concept, planning production-grade libraries for mainnet Wallet Compatibility: Handled differences between Starknet wallets with comprehensive error handling and user-friendly messages Cairo Math: Carefully managed u64 timestamps and u256 amounts to prevent overflow in reward calculations using basis points Gas Optimization: Minimized storage operations and used efficient data structures for lower transaction costs

Accomplishments that we're proud of

Full-Stack DeFi Platform: Complete end-to-end application from Cairo smart contracts to production-ready UI Four Integrated Contracts: Successfully deployed multiple complex contracts working seamlessly together Engaging Gamification: Created a fun achievement system with 10+ badges and competitive leaderboard Privacy Innovation: Implemented working ZK commitment schemes showcasing Starknet's privacy capabilities

What we learned

Cairo Development: Mastered Cairo 2.8.2 syntax, storage patterns, and optimization techniques for Starknet Zero-Knowledge Cryptography: Understood commitment schemes, proof generation, and the importance of proper ZK libraries DeFi Mechanics: Implemented time-locked staking, APY calculations, and reward distribution from first principles Web3 UX: Learned that clear transaction feedback and gamification significantly increase user engagement Modular Architecture: Building contracts independently before integration greatly simplified debugging and testing

What's next for SatVault

Short-term:

Integrate real Bitcoin bridge (tBTC, iBTC) with Lightning Network support Launch NFT achievement badges and seasonal competitions Deploy production-grade ZK privacy features Release native mobile apps for iOS and Android

Medium-term:

Implement liquid staking tokens (stBTC) tradeable on DEXes Launch governance DAO with VAULT tokens Add auto-compounding and yield optimization strategies Build analytics dashboard with portfolio tracking

Long-term:

Expand to multi-asset staking (ETH, SOL, etc.) Develop institutional features and whitelabel solutions Create stake derivatives and insurance protocols Deploy on Starknet L3 for ultra-low fees

Vision: Make SatVault the leading platform for bringing Bitcoin's $1T+ market cap into programmable, private, and engaging decentralized finance on Starknet.

Built With

• cairo
• nextjs
• typescript