What is FIDO2?

FIDO2 is the latest specification of the non-commercial FIDO Alliance (Fast Identity Online), which was created with the aim of developing open and license-free standards for secure, worldwide authentication on the World Wide Web. First came FIDO Universal Second Factor (FIDO U2F), then FIDO Universal Authentication Framework (FIDO UAF), meaning that FIDO2 is the third standard to emerge from the alliance’s work.

At its core, FIDO2 consists of the Client to Authenticator Protocol (CTAP) and the W3C standard WebAuthn, which together enable authentication where users identify themselves with cryptographic authenticators (such as biometrics or PINs) or external authenticators (such as AirID FIDO keys, wearables or mobile devices) to a trusted WebAuthn remote peer (also known as a FIDO2 server) that typically belongs to a website or web app.

Why do you need security specifications like FIDO2?

FIDO2 provides the option of using two-factor authentication, in which the usual username password login is supplemented by an encryption with FIDO2 keys as well as an additional FIDO2 security key token (hardware), or a completely password-free authentication.

What both variants have in common is that they eliminate the standard user login with user name and password, which isn’t considered the most secure, as well as simple two-factor authentications (email, mobile app, SMS): This prevents cyber criminals using typical attack patterns such as man-in-the-middle attacks and phishing from succeeding and taking over the user’s account. Even if the log-in data is compromised, the FIDO2 login will only work with the respective hardware token or private key, which is also bound to a dedicated hardware.

The fact that FIDO2 is an open standard makes it easier for software and hardware developers to implement the standard in their own products so they are able to offer users this very secure login method.

How does FIDO2 work?

The main goal of FIDO Alliance is to increasingly eliminate passwords on the web. In order to achieve this, the secure communication path between the client (browser) and the respective web services is first set up or registered in order to be permanently available for later logins. In this process, FIDO2 keys are generated and verified, which provide the basic encryption for the logon procedure. The procedure is as follows:

1. The user registers with an online service and generates a new key pair on the device used - consisting of a private key and a public FIDO2 key.
2. While the private key is stored on the device and is only known on the client side, the public key is registered in the web service’s key database.
3. Subsequent authentications are now only possible by verification with a private key, which must always be unlocked by a user action. There are various options such as entering a PIN, pressing a button, voice input, or inserting separate two-factor hardware (FIDO2 token). Some operating systems such as Windows 10 and Android can now also act as security tokens themselves.

What are the requirements to use FIDO2 authentication?

The FIDO2 specification defines all components that are required for the modern authentication procedure.

First and foremost is the repeatedly mentioned W3C standard WebAuthn, which allows online services to enable FIDO authentication via a standard Web API (written in JavaScript) that is also implemented in various browsers and operating systems. Applications that already support the standard declared in March 2019 include Windows, Android, and iOS (version 13 or higher) as well as the following browsers: Google Chrome, Mozilla Firefox, Microsoft Edge, and Apple Safari (version 13 or higher).

The second critical component is the Client to Authenticator Protocol (CTAP). This protocol enables the various FIDO2 security keys like the AirID FIDO Security Keys to interact with the browsers and also to act as authenticators. Both the browser used, and the desired hardware token must therefore be able to communicate via CTAP in order to use this security feature (including password-free login).

Advantages of FIDO2 over password authentication

This introduction has briefly explained why password-free or two-factor authenticated login procedures such as FIDO2 are the future. Compared to the traditional password log-in, they offer a much smaller attack surface for cyber criminals. With the right tools, it’s not difficult for criminals to work out passwords, while they would need the hardware security token to gain unauthorized access to a FIDO2-protected user account. In addition, you can use one FIDO2 security key for different web services instead of creating and remembering different passwords.

The advantages of FIDO2 authentication at a glance:

Sources & References

• FIDO Alliance -  https://fidoalliance.org  
• FIDO Alliance Specifications - https://fidoalliance.org/specifications/download/
• World Wide Web Consortium -  https://www.w3.org/
• FIDO2 - https://fidoalliance.org/fido2/
• The CTAP Standard - https://fidoalliance.org/specs/fido-v2.1-rd-20201208/fido-client-to-authenticator-protocol-v2.1-rd-20201208.html
• What is Web Authentication - https://fidoalliance.org/fido2/fido2-web-authentication-webauthn/
• The WebAuthn Standard - https://w3c.github.io/webauthn/
• Mozilla WebAuthn - https://developer.mozilla.org/en-US/docs/Web/API/Web_Authentication_API
• Microsoft All about FIDO2 - https://techcommunity.microsoft.com/t5/identity-standards-blog/all-about-fido2-ctap2-and-webauthn/ba-p/288910