How to implement Passkeys

I'll echo what Tim has stated, when searching for materials you'll have better luck searching for WebAuthn rather than Passkeys.

The architecture diagram on this page may help you conceptualize what you might need. While the nomenclature is geared to AWS, rather than Google/Firebase, the main idea stays the same (especially because it's centered around a serverless architecture)

This github issue indicates that Firebase auth doesn't support WebAuthn MFA out of the box. So if you want to support Passkeys entirely out of Firebase you'll need to either create a custom auth flow, or explore integrating with another Identity Provider.

If you're not looking to developing something custom, I'd recommend finding an identity prover that supports WebAuthn out of the box. Otherwise, I've got some additional developer guidance here.

Beyond an identity provider, if you are looking for a custom build you need to ensure:

1. That you build flows on your client application to support WebAuthn
2. You have databases to store WebAuthn credentials
3. Database for authentication requests, and registration requests (for challenge validation).

There are services to help you implement passkeys. They wrap passkeys to make it simpler to integrate even with something like firebase.

I recommend reading about Passkeys at https://passkeys.com they have great documentation there as well.

Second, you should check out apple docs:

https://developer.apple.com/documentation/authenticationservices/public-private_key_authentication/supporting_passkeys

Here’s a tutorial found on Youtube that helped me integrate it into my site : https://youtu.be/5A7ZP-Pex3k

Developer resources are currently being built and will be available this fall. For the time being, any resources about supporting WebAuthn with discoverable credentials can be used. "passkey" is just the end user name for discoverable WebAuthn credentials and is not specific to Apple.

I'd recommend looking at SimpleWebAuthn: https://simplewebauthn.dev/