The browser prompts you to tap the Yubikey, and the Yubikey will use the information received in step 1 to re-create the same key pair created when you registered your Yubikey.The server remembers you had registered a Yubikey, so it generates a new challenge to send back along with the AppID and nonce created when you first registered your Yubikey.The nonce and public key are sent back to the server to be stored so they can be used later when the user wants to authenticate.Your Yubikey will generate a nonce and hash it together with the AppID and the secret key to create a private and public key.When the Yubikey receives this information, you'll be prompted by the browser to tap the Yubikey to confirm the request.

When you plug in your Yubikey and signal that you want to register a security key, the server you want to authenticate with sends a challenge and an AppID to the Yubikey.First, you must authenticate using another method, like your email and password.With your Yubikey, you must first register it into your account to authenticate later. Yubikeys use U2F (Universal 2nd Factor), an open standard for two-factor authentication based on public-key cryptography. It's a form of Multi-Factor Authentication. In other words, 2FA is the process requiring a user to verify their identity in two unique ways before they are granted access to a system. Instead of using a code, you can use a device such as your Yubikey. In our case, 2FA adds another layer of security by requiring you to provide something you have, for example, a code from an authenticator app or SMS on your phone. Usually, when logging in to any service, you must enter something you know, such as your login credentials, email, and password. Yubikeys are a type of security key manufactured by Yubico. A Yubikey is a hardware authentication device that makes two-factor authentication easier by plugging it into your laptop and tapping it.