How is UV handled in mailcow?¶
The UV flag (as in "user verification") enforces WebAuthn to verify the user before it allows access to the key (think of a PIN). We don't enforce but prefer UV to allow logins via iOS and NFC (YubiKey).
Login and key processing¶
mailcow uses client-side key processing. We ask the authenticator (i.e. YubiKey) to save the registration in its memory.
A user does not need to enter a username. The available credentials - if any - will be shown to the user when selecting the "key login" via mailcow UI login.
When calling the login process, the authenticator is not given any credential IDs. This will force it to lookup credentials in its own memory.
Who can use WebAuthn to login to mailcow?¶
As of today, only administrators and domain administrators are able to setup WebAuthn/FIDO2.
Please use a desktop computer to register your key with your mailcow account.
The process was tested using a YubiKey with Chrome on Windows. When registering a new, empty key, you will be prompted for a PIN for the new YubiKey. Once set and confirmed, the credentials are stored on the key. Using it with iOS works flawless now.
iOS seems not to be able to set a PIN on the device on first use, so please use a desktop computer for this step.