Android Marshmallow introduced an API which allows using fingerprints for authentication:
https://developer.android.com/about/versions/marshmallow/android-6.0.html#fingerprint-authentication

I'm not sure that we have discussed whether this is a feature we would want to enable in our app but I think it is worth considering.

The use case I am thinking of is someone who wants to require authentication before connecting to hosts in CRD, but doesn't want to enter a PIN each time.

We could require PIN entry once and allow a 'secure with fingerprint' option for subsequent connections.