Digital Habits: Phone-Free 2FA 作者： Ulrik Lyngs

Use your computer browser for 2FA so you don't need to reach for your phone every time you log in to e.g. your Microsoft account.

Digital Habits: Phone-Free 2FA runs in your browser's sidebar, so your codes stay visible next to the page you're logging into — no hunting through pinned tabs or toolbar popups.

Phone-Free 2FA is developed by computer scientists at the University of Oxford (Dr Ulrik Lyngs) and the University of Maastricht (Dr Konrad Kollnig, Henry Tari), as part of Centre for Digital Habits (digitalhabits.org).

⚙ How it works
Two-factor authentication (2FA) makes digital life much more secure — a hacker can't get in with your password alone. Phone-Free 2FA is an authenticator that uses the most common method: time-based one-time passwords (TOTP). You add a 2FA secret key from any service that supports TOTP (e.g. a university Microsoft account). Phone-Free 2FA encrypts it locally and generates a fresh 6-digit login code every 30 seconds.

All data is stored locally in encrypted form in the browser using the extension storage API. Nothing is sent over the network. The code is fully open-source — you can find it at https://github.com/ulyngs/redd-phone-free-2fa

Secret keys are encrypted with AES-256-GCM, using a master passphrase that is key-derived via PBKDF2 with 600,000 iterations. The extension auto-locks after configurable inactivity (or immediately when you close the sidebar) and clears copied codes from the clipboard after 30 seconds. Failed unlock attempts trigger progressive lockout to deter guessing.

🖐 Biometric unlock
Biometric unlock is not currently available on Firefox — the browser does not allow the WebAuthn Credentials API from extension pages. Use your master passphrase to unlock. Biometric unlock (Touch ID on macOS; passkey providers such as Google Password Manager on Windows) is available on Chrome and Edge.

📦 Backup and migration
Users can export password-protected backups or view their secret keys to transfer accounts to a different authenticator.

🔐 Strong-by-default passphrase
Master passphrases must be at least 12 characters, and new passphrases are checked locally against common-password lists, keyboard patterns (qwerty, 12345…), and repeating patterns so that weak choices are caught at setup time rather than later.