Digital Bridge, a project recognized at the Unitize Hackathon, uses Chainlink's External Adapter to connect a two-factor authentication (2FA) API to a Chainlink oracle for decentralized verification of 2FA PIN validity. This integration allows smart contracts on the Ethereum blockchain to interact with off-chain APIs, enhancing on-chain security workflows. The implementation involves a Chainlink node that detects transactions containing a customer ID and hashed one-time password, queries an off-chain server to verify the 2FA code, and returns a Boolean value on-chain to authorize user actions if validated. The project showcases Chainlink's capability to facilitate secure, tamper-proof digital agreements by bridging blockchain and external systems, with potential applications in securing DeFi funds and KYC verification. The technical setup includes developing an External Adapter, configuring a Digital Bridge Chainlink oracle node, and writing smart contracts to utilize the adapter for verifying 2FA PINs, ensuring a robust defense against man-in-the-middle attacks. The demo setup provides a framework for developers to explore integrating 2FA services with smart contracts, emphasizing the importance of using hashed data on-chain to maintain security.