This is a virtual HAL implementation that is backed by system properties instead of actual hardware. It's intended for testing and UI development on debuggable builds to allow devices to masquerade as alternative device types and for emulators.
This HAL can be used on emulators, like cuttlefish, or on real devices. Add the following to your device's .mk file to include it:
PRODUCT_PACKAGES_DEBUG += android.hardware.biometrics.fingerprint-service.example
The virtual HAL will be ignored if a real HAL is also installed on the target device. Set the biometric_virtual_enabled settings and reboot the device to switch to the virtual HAL. Unset it and reboot again to switch back.
First, set the type of sensor the device should use, enable the virtual extensions in the framework, and reboot.
$ adb root $ adb shell settings put secure biometric_virtual_enabled 1 $ adb shell setprop persist.vendor.fingerprint.virtual.type rear $ adb reboot
Next, setup enrollments on the device. This can either be done through the UI, or via adb directly.
To set enrollment directly without the UI:
$ adb root $ adb shell locksettings set-pin 0000 $ adb shell setprop persist.vendor.fingerprint.virtual.enrollments 1 $ adb shell cmd fingerprint sync
Set pin
$ adb shell locksettings set-pin 0000
Tee up the results of the enrollment before starting the process:
$ adb shell setprop vendor.fingerprint.virtual.next_enrollment 1:100,100,100:true
Navigate to Settings -> Security -> Fingerprint Unlock and follow the prompts.
Verify the enrollments in the UI:
$ adb shell getprop persist.vendor.fingerprint.virtual.enrollments
To authenticate successfully set the enrolled id that should succeed. Unset it or change the value to make authenticate operations fail:
$ adb shell setprop vendor.fingerprint.virtual.enrollment_hit 1
To view all the properties of the HAL (see fingerprint.sysprop file for the API):
$ adb shell getprop | grep vendor.fingerprint.virtual