Windows Hello and a PIN code for login, is it safe?

Microsoft's Windows login authentication feature called Windows Hello lets you sign in with a PIN code (or biometrics like a eye-image from a camera) instead of a traditional password. At first glance, using a four or six digit PIN may seem less secure than a good ten letter password, but in practice it is often safer.

Let's take a look into this briefly. Here are reasons why the PIN code might be better:

• The PIN never leaves the device, it is tied to the hardware (using the TPM chip).
• The PIN cannot be used remotely; even if stolen, the PIN is less useful to attackers.
• Brute-force protection is present, as the TPM chip enforces lockouts.
• There is multi-factor support, for example, the PIN can be combined with biometrics.

A Windows Hello PIN is not meant to replace a long domain password. Instead, it protects local sign-in and unlock scenarios. The underlying keys live in the TPM, and your PIN is only one factor in unlocking them.

So yes, from this perspective, a PIN for everyday login and unlock use cases is considered safe. It's often safer than traditional password use, as users tend to have not-so-great passwords anyway.