Generically, passkeys refer to various schemes for storing authenticating information in hardware, a concept that has existed for more than a decade. What's different now is that Microsoft, Apple, Google, and a consortium of other companies have unified around a single passkey standard shepherded by the FIDO Alliance. Not only are passkeys easier for most people to use than passwords; they are also completely resistant to credential phishing, credential stuffing, and similar account takeover attacks.
On Monday, PayPal said US-based users would soon have the option of logging in using FIDO-based passkeys, joining Kayak, eBay, Best Buy, CardPointers, and WordPress as online services that will offer the password alternative. In recent months, Microsoft, Apple, and Google have all updated their operating systems and apps to enable passkeys. Passkey support is still spotty. Passkeys stored on iOS or macOS will work on Windows, for instance, but the reverse isn't yet available. In the coming months, all of that should be ironed out, though.
Passkeys work almost identically to the FIDO authenticators that allow us to use our phones, laptops, computers, and Yubico or Feitian security keys for multi-factor authentication. Just like the FIDO authenticators stored on these MFA devices, passkeys are invisible and integrate with Face ID, Windows Hello, or other biometric readers offered by device makers. There's no way to retrieve the cryptographic secrets stored in the authenticators short of physically dismantling the device or subjecting it to a jailbreak or rooting attack. Even if an adversary was able to extract the cryptographic secret, they still would have to supply the fingerprint, facial scan, or -- in the absence of biometric capabilities -- the PIN that's associated with the token. What's more, hardware tokens use FIDO's Cross-Device Authentication flow, or CTAP, which relies on Bluetooth Low Energy to verify the authenticating device is in close physical proximity to the device trying to log in.
"Users no longer need to enroll each device for each service, which has long been the case for FIDO (and for any public key cryptography)," said Andrew Shikiar, FIDO's executive director and chief marketing officer. "By enabling the private key to be securely synced across an OS cloud, the user needs to only enroll once for a service, and then is essentially pre-enrolled for that service on all of their other devices. This brings better usability for the end-user and -- very significantly -- allows the service provider to start retiring passwords as a means of account recovery and re-enrollment."
In other words: "Passkeys just trade WebAuthn cryptographic keys with the website directly," says Ars Review Editor Ron Amadeo. "There's no need for a human to tell a password manager to generate, store, and recall a secret -- that will all happen automatically, with way better secrets than what the old text box supported, and with uniqueness enforced."
If you're eager to give passkeys a try, you can use this demo site created by security company Hanko.