Passkeys replace a reusable secret with a key pair
A password is a secret a person must remember and send to a service, usually through a sign-in page. That creates several weak points: people reuse passwords, attackers can trick them into entering one on a fake site, and stolen password databases can expose credentials.
A passkey works differently. When it is created, the device generates two linked cryptographic keys. The service keeps the public key; the private key stays on the user’s device or in a secure system that synchronizes passkeys across devices. To sign in, the service sends a fresh challenge, and the device proves it has the private key—often after the user unlocks it with a fingerprint, face scan, or device PIN. The biometric check unlocks the device; it is not sent to the website as a password.
The sign-in is tied to the real site
The key is associated with the service’s legitimate web address. A look-alike phishing page cannot simply collect the passkey the way it can collect a typed password: the device will not use the credential for the wrong site. And because the service stores a public key rather than a reusable login secret, a stolen database is less useful for impersonating users.
These properties make passkeys attractive to companies: they can reduce account takeovers and the costs of password resets, while making sign-in quicker for users. The same mechanism can also replace one-time codes that attackers sometimes intercept or trick people into sharing.
Recovery remains the hard part
A passkey is convenient only if people can reach it when they switch or lose devices. Device ecosystems can synchronize passkeys, and services may offer other recovery methods—but those fallback routes still need protection. A weak recovery process can become the easiest way into an account, even when the main sign-in is strong. So the shift is not just about removing password boxes; it is about making the entire path back into an account as secure as the passkey itself.
