The cross-platform feature is enabled via the FIDO standard, which employs public-key cryptography principles to provide passwordless login and multi-factor authentication in a variety of settings. When a user’s phone is unlocked, it can store a unique FIDO-compliant passkey and share it with a website for authentication. Passkeys may also be simply synchronized to a new device from cloud backup in the event that a phone is misplaced, according to Google’s website.
