In the world of digital security, the terms ‘password’ and ‘passkey’ are often discussed, but they represent fundamentally different approaches to authentication. While passwords have been the standard for decades, passkeys, built on the FIDO Alliance’s standards, offer a different method for verifying a user’s identity that addresses many of the inherent weaknesses of traditional passwords.

A password is a form of shared secret. The user creates a string of characters, and the service they are accessing stores a representation of that secret, typically a cryptographic hash. During login, the user provides their password, and the service checks if it matches the stored version. This model is vulnerable to server-side data breaches, where large lists of these secrets can be stolen, and to phishing attacks, where users are tricked into revealing their password to a malicious actor.

The Architecture of Traditional Passwords

The security of a password system relies entirely on keeping the secret confidential. However, its nature as a piece of information that is known, typed, and transmitted makes it a frequent target. Attackers use techniques like credential stuffing, where stolen passwords from one breach are tried on other services, and social engineering to deceive users. The responsibility for creating and remembering strong, unique passwords falls on the user, leading to common issues like password reuse and the use of weak, easily guessable credentials.

How Passkeys Revolutionize Authentication

A passkey eliminates the concept of a shared secret. Instead, it uses a cryptographic key pair: a private key that is securely stored on a user’s device (like a phone or computer) and a public key that is registered with the website or application. The private key never leaves the device. When a user logs in, the service sends a unique challenge. The user’s device uses its biometric scanner (fingerprint, face ID) or a device PIN to authorize the use of the private key to ‘sign’ this challenge. This signature is then sent back to the service, which verifies it using the public key. Because the private key is never transmitted and is tied to a specific website, passkeys are resistant to phishing attacks and server-side data breaches that leak user credentials.