Circle ID CTAP2 Shim

About

What it does
Circle ID CTAP2 Shim lets you sign in to Microsoft Entra ID (Azure AD) using your phone instead of a physical security key. When a website asks for a   security key, a QR code appears on your screen. Scan it with the Circle ID app on your phone, approve the request, and you're in. No passwords, no USB   keys, no Bluetooth pairing.                                                                                                                          

Why install it
Physical security keys are easy to lose, expensive to replace, and impossible to use when you've left them at home. This extension turns the phone already in your pocket into a FIDO2 security key that works from any computer — your desk, a shared workstation, a hotel business center, or a virtual machine. It works across networks, so your phone doesn't need to be on the same Wi-Fi as your computer.

How it works
  1. Go to a Microsoft Entra login page and choose "Security key."
  2. A QR code appears on screen with a 60-second timer.
  3. Scan it with the Circle ID app.
  4. Approve on your phone — login completes automatically.

If the timer runs out before you scan, hit Refresh to get a new QR code without restarting the login.

What you need
  - Circle ID app installed on your Android or iOS device
  - A Microsoft Entra ID account with security key sign-in enabled
  - Your organization's IT admin has set up Circle CTAP2 licensing
  - Chrome 108 or later

For IT administrators
The extension can be force-installed via Google Admin Console or Group Policy. Member enrollment is self-service — users scan a setup QR from the admin console with their Circle ID app. No manual credential provisioning required. Password changes don't affect the FIDO2 credential, so there's no re-enrollment after rotation.

Privacy
No browsing history, form data, or personal information is collected. The only data exchanged with Circle ID servers is the standard WebAuthn ceremony data needed to complete each login, and it's deleted as soon as the session ends.