Tyler Vanderhoeven demonstrates Zafeguard, a stateful policy signer service for Stellar smart wallets that enables sub-accounts to spend from a parent account under customizable spending limits, showcasing composable authentication and account abstraction on Soroban.
Tyler Vanderhoeven presents a demo of Zafeguard, a service built on his Stellar Smart Wallet account abstraction protocol proposal. The system combines ED25519 signers, SECP256R1 passkey WebAuthn signers, and policy signers (smart contracts that authenticate) to enable flexible wallet functionality. Zafeguard allows creation of child accounts that can spend from a parent account under defined parameters, such as spending limits per time interval. The demo shows creating a passkey-based smart wallet, attaching an ED25519 signer with a stateful policy that permits spending 100 lumens every 10 ledgers, and updating those parameters. Key advantages include using a single wallet standard across all services while enabling custom functionality through policies, avoiding asset fragmentation across multiple bespoke wallets. The policy contract itself is less than 150 lines of code, demonstrating the power of Soroban's composable auth and check auth functions for building sophisticated wallet infrastructure.
