Question about Google fido 2.0 webauthn libs.

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Bob Xin

Aug 16, 2021, 6:13:47 AM8/16/21
to FIDO Dev (fido-dev)
Question about Google fido 2.0 webauthn libs.

We want to know what kind of authentication method is used for user authentication. 
For example, on Google Pixel device user can use two ways; fingerprint or pin code. 

We checked Google Play Service API documents, about UVM extension found in Google play-service-fido library, but I don't know how to use it. Not sure if it is used correctly.

When register process enabled UVM extension, reference with W3C WebAuthn official documents.

Will get the results from here ?? I'm not sure about it. UvmEntries entities are always null.

How do we know which authentication method users used with Google GMS fido 2.0 lib ??

John Bradley

Aug 16, 2021, 10:43:32 AM8/16/21
to Bob Xin, FIDO Dev (fido-dev)
Someone from the Android team may be best to answer this.

From my recollection, that UVM was added to Android a while ago due to customer requests.  

The problem is that the underlying API the authenticator is using was updated and the authenticator no longer knows if it was a pin, fingerprint or other biometric that unlocked the key material. 

I think that is why on a current version of Android you are not getting that information back.  

Google has never been a proponent of UVM to my knowledge. I personally would not count on using it going forward.

John B.  
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Arshad Noor

Aug 16, 2021, 12:23:00 PM8/16/21

You could try the StrongKey Android Client Library (SACL) available here and here, that supports FIDO2 and UVM. There is a sample demonstration app that shows how the SACL works.

The only consideration is that the SACL is designed to work with the open-source, FIDO Certified FIDO2 server (available in the same repos mentioned above). But, like all open-source, both can be modified within the constraints of the license to do what is needed if you're willing to make the effort.

Hope that helps.

Arshad Noor

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