You don’t have to store them with Google. Passkeys are supported in both iOS and Android natively. Within the last few months both Bitwarden and 1Password support storing passkeys as well.
It does not. The fingerprint always only unlocks the device's HSM ("secure enclave" in Apple speak).
Between your devices enrolled in the ecosystem, private keys are synced securely (AFAIK, they make it so that an existing device’s HSM encrypts keys using the pubkey of the new one’s HSM); for signing up using your device on someone else's computer there's a process that combines QR codes with Bluetooth communication.
I kind of don't like to store my fingerprints with Google. Even FBI collects them when you are indicted.
What about allowing us to log in to services via asymmetric keys?
You don’t have to store them with Google. Passkeys are supported in both iOS and Android natively. Within the last few months both Bitwarden and 1Password support storing passkeys as well.
It is just an asymmetric key. Phones try to store them securely but you could use an app to just generate them and store your key wherever.
Note that you pretty much can't store them with Google or Apple; smartphone biometric sensors operate the on-device HSM, not something remote.
So, how does it work when you are accessing account from a different device? How the other device knows your fingerprint?
It does not. The fingerprint always only unlocks the device's HSM ("secure enclave" in Apple speak).
Between your devices enrolled in the ecosystem, private keys are synced securely (AFAIK, they make it so that an existing device’s HSM encrypts keys using the pubkey of the new one’s HSM); for signing up using your device on someone else's computer there's a process that combines QR codes with Bluetooth communication.
Eh. The feds already have my fingerprints due to a background check…