Google has extended its Advanced Protection Program for account security to the iPhone platform. The program uses security keys, which make use of public-key cryptography to verify a user s identity and URL of the login page. This scheme protects against the brute-forcing of accounts, the use of stolen credentials to illicitly access accounts, schemes that bypass traditional 2FA have appeared in the wild, making secure keys more attractive to high-risk users. It has also made the program simpler to sign up to for Android users.
Source: https://threatpost.com/google-account-security-keys-iphone/151957/