Fido2 Definition

KZero Staff
Jul 27, 2023

What is FIDO2?

FIDO2 (Fast Identity Online2) is a global authentication standard based on public key cryptography that was developed by the FIDO Alliance in partnership with the World Wide Web Consortium (W3C). It is an update to the original FIDO standard.

The goal of the FIDO standards is to enhance authentication security by implementing passwordless authentication. Passwordless authentication systems use public key cryptography to authenticate a user’s identity rather than using password-based authentication methods that are generally insecure and vulnerable to phishing attacks.

How Does FIDO2 Work?

FIDO2 is an authentication process designed to replace passwords with passkeys. These passkeys use public key cryptography to authenticate a user’s identity. A user’s private key will be stored on a device, and, after the user has unlocked the key, will be used to authenticate their identity.

The FIDO2 standard includes two main standards:

  • WebAuthn: WebAuthn is a standard developed by W3C to allow passwordless web authentication. It links a web application into the FIDO2 authentication process.
  • Client to Authenticator Protocol (CTAP): CTAP operates at the other end of the protocol, linking an external authenticator to the browser. This allows someone to use a smartcard, USB security token, mobile device, or similar tool to authenticate their identity.

The FIDO2 Process

FIDO2 authenticates users’ identities via a multi-stage process. The three main steps include:

  • Registration: When a user creates an account, they register their external authenticator or biometric data with a website. A private key for the website is stored on the user’s device, while the corresponding public key is sent to the FIDO2 server.
  • Authentication: When the user attempts to log into the service, the server will send a challenge to the client. The client will use the associated private key to digitally sign this challenge and send the result to the server.
  • Verification: The server has the user’s public key on file. This public key can be used to verify the digital signature and validate the user’s identity.

Benefits of FIDO2 Authentication

FIDO2 is experiencing growing adoption because it provided benefits to both user and the services that they are authenticating to. Some of the main advantages of FIDO2 include:

  • Improved Security: FIDO2 eliminates password-based authentication in favor of passwordless authentication using public key cryptography. This eliminates the risk of weak or reused passwords or authentication material being exposed via phishing attacks.
  • Better User Experience: Eliminating passwords means that users no longer need to recall and enter passwords for each of their accounts. This makes the authentication experience faster and easier for users.
  • Interoperability: FIDO is an open standard that defines interfaces for linking websites and external authenticators into the process. This makes it easy for anyone to implement and use FIDO2 across any platform.


FIDO2 is an authentication standard developed by the FIDO Alliance and W3C to enhance authentication security via passwordless authentication. By replacing passwords with authentication based on public key cryptography, FIDO2 eliminates the security risks of passwords and enhances the user experience via an open, interoperable authentication protocol.

KZero Staff

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