Question: I need to implement authentication in a php app but using fingerprint as part of credentials.

So, sincerely I'm kind of lost here.

1) Do I need a product (reader) with javascript SDK? I've seen some using ActiveX but obviously this will work just for IE. I would like a cross-browser solution here. 

2) On server side, I suppose I'll natively call some C/C++/Java libs from my php code. Is it right?

As you can see, any paper/orientation you could give me would be appreciated.

Answer: 
we made a small app using c# to handle fingerprint scanning and converted the output to binary file.
theoretically it shd be compared with wats available on the server and returns a result which determines if the user gets authenticated or not.

another method is to use a windows app that works with the fingerprint hardware and posses a simple web browser.

once the user gets authenticated it will call a url with and arg that only the coder knows.
You cannot do this using PHP - it's a scripting language.

However, you can use .NET technologies like C# or VB for hardware porting.

My idea:

1. Handle authentication using .NET technologies.
2. Pass the authentication result to PHP using ASP like embedding result in XML/JSON

I don't know how much success rate you will get from this solution, but it's worth a try.