biometrics

Ask the person to prove they own the device.

[dependencies]
biometrics = "*"

Use cpc pm add . biometrics to write the platform-specific dependency closure.

import "biometrics/biometrics" as bio;

fn answered(o: bio::Outcome, ctx: *u8) {
    if o == bio::Outcome::Ok { unlock(); }
}

let _o: bio::Outcome = bio::authenticate("Unlock your notes", answered);

Not a permission, and not authentication

Not a permission — a permission is asked once and remembered; this is asked every time and answered by a finger. There is nothing to grant in Settings, which is why it is not in permissions.

Not authentication. A pass means "the person holding this device is its owner", never "this user is who they claim to be to your server". Anything needing the second wants a token — keep it in securestore and gate it behind this, rather than replacing it with this.

Four ways of failing, and they are different sentences

Coverage

• tutorial · guide · ref

Tests

cd vendor/biometrics && cpc test

A finger cannot be asserted.