Passkey: how does it work ?

March 3, 2025

A world without passwords?

Imagine a world where you never have to remember or type a password again—no more frustrating resets, no more password policies to update, and no more security breaches due to weak credentials. 

Tech giants like Apple, Google, and Microsoft are making this vision a reality with passkeys, a new authentication method designed to replace traditional passwords with a more secure and seamless experience.

Apple recently introduced passkey authentication for iCloud, allowing users to sign in using biometric verification or a trusted device via iCloud Keychain’s. (try by yourself on: https://www.icloud.com/)

But this isn’t just an Apple innovation—it’s part of a larger movement towards a passwordless future, with WebAuthn (Web Authentication API) playing a key role. And the good news? If you’re using Keycloak, you already have native support for passkeys through WebAuthn.

What is a Passkey? The evolution of authentication

To appreciate the shift towards passkeys, it’s important to understand how authentication has evolved. Traditionally, authentication relies on three primary factors:

  • Something You Know – A password, PIN, or secret answer.
  • Something You Have – A security key, smartphone, or authentication token.
  • Something You Are – Biometric data like fingerprints, facial recognition, or iris scans.

Most login methods use one or a combination of these factors. However, passwords—being the most common method—come with significant risks, including phishing, credential leaks, and brute-force attacks. Multi-factor authentication (MFA) improves security, but it often adds friction for users.

How do passkeys work?

Passkeys simplify authentication by combining something you have (your trusted device) and something you are (biometrics). Instead of remembering a password, users authenticate with their fingerprint, face scan, or device PIN. Behind the scenes, passkeys use public-key cryptography, ensuring that credentials cannot be stolen, intercepted, or phished.

The Advantages of Passkeys

Passkeys provide a range of benefits compared to traditional authentication methods:

  • Phishing Resistance (Something You Know) – This method is removed with Passkey and all their disagreement such as : phishing, usage of the same password, remove the password rules, etc.
  • Seamless Authentication (Something You Are & Something You Have) – Users authenticate instantly using biometrics or their device, eliminating the need to remember or enter passwords.

And more because this method enhanced Security – Passkeys use cryptographic key pairs, meaning no passwords are stored or transmitted, reducing the risk of credential leaks and brute-force attacks.

Passkey vs. Passkey WebAuthn

Passkeys can be implemented in different ways, and WebAuthn plays a crucial role in web-based authentication.

Passkey in General

Passkeys, as a concept, replace passwords with cryptographic credentials stored on a user’s trusted device.

For example, when logging into a mobile banking app, users authenticate with Face ID or a fingerprint, and the app verifies their identity without requiring a password.

Passkey WebAuthn

WebAuthn enables passkeys for web applications, allowing users to log into websites securely. A typical login process looks like this:

  1. The user navigates to a web service and selects “Sign in with Passkey.”
  2. The browser prompts for biometric verification directly for the devise or via external device like a phone or a security key.
  3. The user is authenticated without entering a password.

For organizations using Keycloak, WebAuthN provides built-in support for passkeys, making it easier to implement secure passwordless authentication in enterprise applications.

Challenges and Considerations of Passkeys

While passkeys offer a promising alternative to passwords, there are challenges to consider:

• Device Dependency and Recovery Issues : Passkeys are typically stored on a specific device. If the device is lost or replaced, users need a backup mechanism, such as cloud synchronization or a secondary authentication method.

• Cross-Platform and Compatibility Limitations :  Although major tech companies support passkeys, some applications, browsers, or legacy systems may not yet be compatible, leading to usability challenges.

• Implementation Complexity for Organizations : Organizations must update their authentication infrastructure, educate users, and provide fallback methods to ensure a smooth transition to passkeys.

• User Adoption and Behavioural Shifts : Many users are familiar with passwords and may resist switching to passkeys. Education and gradual adoption strategies can help ease the transition.

Conclusion: Embracing the passwordless future

Passkeys represent a major leap forward in authentication security and usability. By eliminating passwords, they reduce phishing risks, enhance user experience, and provide a more robust security model.

With Keycloak’s native WebAuthn support, organizations can easily integrate passkeys into their authentication flows, paving the way for a secure, frictionless future. While challenges remain, the shift towards passkeys is inevitable—and now is the time to start preparing.

Are you ready to implement passkey authentication? Explore our official Cloud-IAM documentation to learn how to get setup Passkey on Keycloak.

Written by
Last update :
David MACE
March 3, 2025

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