Target: mobile apps.
Precondition: Unlock with PIN is enabled, and my vault is logged in.
Current behavior: I invoke Bitwarden’s Auto-fill to fill credentials in some app. BW prompts me to enter my master password. My PIN is not accepted.
Proposed behavior: I invoke Bitwarden’s Auto-fill to fill credentials in some app. BW prompts me to enter my PIN. My PIN is accepted.
Convenience: I’ve configured Unlock with PIN, so I’ve accepted the security/convenience trade-off that comes with that. I want this setting to apply to everything I do with the app (while it’s logged in), which includes Auto-fill.
Security 1: I want Auto-fill using PIN instead of using biometrics because my phone unlocks with biometrics. Given that my phone unlock with biometrics, I don’t want a critical app – Bitwarden – to unlock in the same way. This is defense in depth.
Security 2: If the app I’m trying to Auto-fill into is malicious, it could (I assume) bring up a fake Bitwarden master password prompt dialog to capture my master password. Capturing my master password is much worse than capturing my PIN, and I will never enter my master password into a dialog that might be controlled by another app. So currently I can’t use the Auto-fill feature, and I instead need to go to the Bitwarden app to copy the credential’s password whenever I would otherwise use Auto-fill.
Security 3: There are some apps whose creators have blocked pasting into the password field. For those apps, using Bitwarden’s Auto-Fill – which seems to bypass the block – is the only reasonable way to get my complex password into the password field. But see the previous bullet: I’m not willing to enter my master password while another app is active.