DeviceBound Wallet

Inspiration

The inspiration for DeviceBound Wallet came from the constant trade-off between security and usability in traditional crypto wallets.
Seed phrases are insecure and cumbersome — users often lose access or get phished. We wanted to build a wallet that feels as natural as Face ID, yet as secure as a hardware wallet.

Our goal: No seed phrases, no extensions, no downloads — just your device.

What it does

DeviceBound Wallet is a smart wallet that replaces private key storage with WebAuthn / Passkeys.
Instead of managing keys manually, users authenticate using their built-in device biometrics (Touch ID, Face ID, Windows Hello, etc.), while a smart contract enforces ownership and transaction validation on-chain.

Key capabilities:

🆕 Create wallet using WebAuthn (Passkey)
🔁 Recover wallet using Passkey + contract address
💸 Send transactions signed with device hardware
🧱 Deploys smart contract wallet automatically
📱 Installable as a PWA with offline readiness

How we built it

Frontend: Built with React 18 + TypeScript + Vite, providing a lightweight and fast DApp experience.
Blockchain: Smart contract written in Solidity (v0.8.24) and deployed to Sepolia and BSC Testnet.
WebAuthn Integration: Used native browser APIs to create and authenticate credentials.
- Extracted public keys from COSE / CBOR format.
- Converted ASN.1 signatures to ECDSA (r, s) format.
- Mapped public key hash to on-chain wallet identity.
Contract Interaction: Managed via ethers.js v6.
PWA: Enabled offline support with vite-plugin-pwa and Workbox.

Challenges we ran into

⚙️ Handling ASN.1 → ECDSA signature conversion for Passkeys.
🧩 Maintaining cross-browser WebAuthn compatibility (Chrome, Safari, Edge).
🔐 Validating Passkey signatures on-chain using Solidity’s ecrecover.
🧠 Designing a multi-device registration system capped at 3 devices.
🧰 Building a secure and recoverable flow without ever exposing private keys.

Accomplishments we’re proud of

🔑 Fully functional device-bound wallet — no seed phrases needed.
📱 Seamless biometric signing for blockchain transactions.
🧠 Robust architecture combining WebAuthn + Smart Contracts.
🌍 Multi-chain support (Ethereum Sepolia, BSC Testnet).
⚡ Built and deployed as a Progressive Web App (PWA).

What we learned

We learned how to bridge the gap between Web2 authentication standards and Web3 identity models.
WebAuthn’s public-key credentials can be safely extended to on-chain logic, enabling hardware-level non-custodial wallets.