How to write a robust fingerprint device driver for Android M...

[JeanPierrePoulin]

Hello Android developers!

Our company is attempting to integrate our biometric fingerprint sensor into the Android fingerprint API recently introduced with Android Marshmallow.

Documentation and code samples have thus far done a great job of explaining how to code Java user applications to leverage the fingerprint API, but little has been found on how to properly write a C fingerprint hardware driver that can be consumed by the above-mentioned app-layer fingerprint API in Java.

Studying the fingerprint API codebase, I see that that lowest visible level of the fingerprint API (implemented by modules/libhardware/fingerprint/fingerprint.c) appears a viable place to insert the low-level code we need to interface with our hardware. Some questions remain however...

Q1: We want to implement a secure device driver compatible from Android's trusted-computing architecture. Is code we add to fingerprint.c running in the trusted zone? (i.e. unhackable)

Q2: Given the secure nature of a fingerprint driver, does our company need to develop a relationship with Google for us to obtain the resources we need to write a secure/unhackable fingerprint driver?

Q3: Does a reference hardware driver or documentation exist to guide fingerprint hardware manufacturers write better drivers?

Thank you very much for your advice!

Jean-Pierre

 

[belodion]

Welcome to the forums.

This might get a better response in our Android Developers forum. I'll mention it to the Moderators. They will decide.

 

[JeanPierrePoulin]

Thank you for the recommendation. Any hint to write a secure fingerprint driver would be greatly appreciated!

 

[hallux]

You might consider reaching out to Google for suggestions. If you're wanting to build hardware and its associated software to interface with their OS and fingerprint API, it would be in their interest to see that it works well.

Related to your question 2, if you want the resources to do this, it would only make sense you would need to develop a relationship with Google. If you didn't need to have a relationship with Google in order to gather those resources, how secure could it REALLY be?

 

[JeanPierrePoulin]

Hi hallux, thanks for taking the time.

Indeed given the nature of fingerprint drivers needing to be totally secure it is reasonable that some undocumented procedure would have to be followed in order for the driver to fully run in the trusted space appropriate for the driver. Like the documentation mentions about SPI is a good example... needing SPI communication to be handled by SELinux appears to be a challenge we don't know how to resolve yet.

Do you have a recommended way to approach the right people at Google to assist with this fingerprint driver effort?

Thank you very much!