Information on the use of Cryptnox FIDO2 security keys on Android
FIDO2 vs U2F Security Keys via NFC on Android
U2F (Universal 2nd Factor) and FIDO2 are open security standards for strong, phishing-resistant authentication using physical security keys (like a YubiKey).
U2F is the older standard, used only as a second factor (after entering a password)
FIDO2 is the newer standard that enables both second factor and passwordless logins, using what’s called a resident key (stored on the device).
Both are supported by major platforms like Google, Microsoft, and Apple — but with varying levels of support depending on the device, browser, and method of connection (USB, NFC, Bluetooth).
The Corrected Key Facts about NFC security keys on Android
Android supports both U2F and FIDO2 over NFC, but with limitations depending on the key type and the browser or app in use.
U2F via NFC works reliably as a second factor, e.g., when logging into your Google account, if the security key was registered via Android.
FIDO2 over NFC support in Chrome on Androidis limited or buggy — especially for resident keys (passwordless login).
Security keys used via NFC are typically only used as a second factor on Android (you still need to enter a password).
To enable passwordless login or resident key support with the same physical key, it’s recommended to register the key on a desktop (e.g., Windows, macOS), but without guarantee that it will work event as 2FA only via Android.
You can register the same key twice — once on Android (for 2FA via NFC) and once on a desktop (for FIDO2/resident keys).
Compatibility Table: External Security Keys via NFC
