How Do Passkeys Work?
Passkeys Explained
Passwords are bad. Passwords with 2FA are better. Passkeys are the best.
We’ve written several articles about Passkeys, but many people still don’t understand how they work or why they’re safer than passwords. Today, we’re going to try to explain how Passkeys work and why they are so much safer than Passwords.
Passwords are a disaster waiting to happen. You have to change them constantly; they demand bizarre combinations of characters, and the second you forget one, they lock you out of your life. Additionally, they can be easily stolen through phishing scams and data breaches.
Passkeys are the total opposite. They are highly competent security guards who recognize you and, once you verify it’s really you, unlock the website without requiring any additional action beyond showing your face, tapping your fingerprint, or entering your device PIN.
The Magic of Passkeys
A Passkey is not a secret word you type. It’s a Secret Digital Handshake that lives on your device (computer, tablet, smartphone).
When you create a passkey, your device generates two special, mathematical keys:
The Master Key (Your Secret)
This stays locked safely inside your device (in the Secure Enclave, which is tech-speak for “tiny, impenetrable fortress”). This key never leaves your phone or computer, not even for a millisecond.
The Guest Key (The Website’s Secret)
This is the key you give to the website (like Google, Netflix, or Facebook, etc.). It’s a completely useless key on its own, but it’s designed to perfectly match the Master Key on your device.
The Passwordless Login Process – The Digital High-Five
When you want to log in, this is what happens:
You tap the “Sign In” button.
The Website sends a very fast, secure message to your device that says: “Hey, prove you’re the boss of this account!”
Your Device says, “Whoa, a secure challenge! I need the Master Key, but first, the owner has to authorize me!”
Then you show your face, tap your fingerprint, or enter your device PIN. This is just you telling your device, “Yes, it’s me. Go ahead, use the Master Key.”
Your Device then uses the Master Key to sign the secure message and sends the signature back.
The Website checks the signature with the Guest Key it has on file. If it matches, it says: “Perfect match! Come on in! No passwords, no drama.”
The bottom line is… Passkeys don’t ask you what you know (a password); they confirm what you have (your secure device) and who you are (your face, fingerprint, device PIN).
The Best Part About Passkeys: Hackers Can’t Steal What Isn’t There
Phishing sites? What me worry?
If a scammer builds a fake login page, your device will immediately say, “Wait a minute, this URL doesn’t match the Guest Key I have. I’m not going to even try to sign in.” The scammer gets absolutely nothing.
Huge Data Breaches? No worries!
If a huge company gets hacked, all the bad guys steal is the useless Guest Key that the website stored. Since the real Master Key is still safely locked inside your phone, your account is safe. The hacker has a lock with no matching door.
It’s the simplest and strongest security upgrade in decades, and all you have to do is use your face, fingerprint, or device PIN to prove it’s you.. It’s super easy and super secure.
We hope this helps you better understand Passkeys, how they work, and why they’re so much easier and safer than passwords.
Hi TC and Darcy! I depend on you so much. thanks for always being there for me and all who need you!! You are the best and the only ones I really trust. I must have missed something… I understand what passkeys are, but how do you set them up for different accounts? I prefer to use fingerprint or face recognition, however, when one of my institutions set one up it was a pin. I wasn’t given the choice of the others. I now have noticed a couple other accounts just seem to have morphed and use the same without a separate set up?? Can you please help me understand this, and if there is anything I can do to change or update the one I do seem to have. Thanks much!
When the website (the Relying Party) requests a passkey from your device, it only sends a command that says, “I need User Verification.” It is entirely up to your device and operating system (OS) to decide which method to offer.
OR
If you are using an older computer, a security key (like a YubiKey), or a virtual machine, the device may simply not have a reliable, built-in biometric sensor or the necessary Secure Enclave hardware. In this case, the PIN is the mandatory fallback to provide User Verification.
There are other more geeky reasons but those are the main reasons some sites ask for a PIN rather than biometrics (fingerprint/face scan).
Thank you for the information. I use several different computers and my cell phone but they have different signins,
Do I need to use the same pass key on all of them.
The short answer is yes, you can use a passkey across multiple devices, but how it works depends on two main things:
Synced Passkeys (The most common way): These are stored securely in a password or credential manager, like iCloud Keychain, Google Password Manager, or third-party managers (e.g., 1Password, Bitwarden). The passkey is encrypted and synced across all devices where you are signed into that manager. This makes the experience seamless—you create the passkey once, and it’s available everywhere.
Cross-Device Authentication (Hybrid Transport): If you want to sign in on a device that doesn’t have the passkey stored (e.g., logging into a Windows PC using a passkey on your iPhone), you can often use a QR code generated on the target device. You scan this code with your phone (the device that holds the passkey), and after verifying your identity (fingerprint, face ID, or PIN) on the phone, you are securely logged into the other device.
So, whether you use cloud syncing or a QR code scan, passkeys are designed to work across your devices.