Using "Local" Voice Biometrics
Assuming you've reached the point where you're committed to developing a mobile app that incorporates voice biometrics, another key consideration is whether the voice biometric functionality resides on the phone (i.e., is "local") or is on a server somehere (i.e., is "remote").
It's a complex consideration, with no 100% correct answer. And, there are of course advantages and disadvantages to each approach. So, we'll first explore the local approach.
Always Available. You will ALWAYS be able to use voice biometric functionality if it is located on the smartphone; the same is not true for remote processing should network access become temporarily unavailable.
No Latency. If the voice biometrics functionality is local, there will be no latency related to device distance from the remote server, busy network traffic, etc.
Distributed Enterprise Credentials. Those with enterprise-wide authentication needs may favor the use of distributed credentials. That is, there is less risk from NOT having all voiceprints residing in one centralized repository.
Isolated Individual Credential. Related to the above point, some feel that security credentials should never be transmitted. And, security credentials should never be shared or made available across multiple websites or applications.
There are other advantages too, but these are perhaps the most important. Further below we'll consider the case for "remote" deployments of voice biometrics. As you might imagine, advantages of one approach are sometimes viewed as disadvantages of the other (and vice versa).
These last two points made above, about centralized vs. de-centralized credentials and the transmission of credentials, are critically important to many companies in many industries.
Approximately 8 years ago, the FIDO Alliance was formed to address these very concerns. It is beyond the scope of this article to explain everything about the FIDO Alliance, but interested readers are strongly encouraged to visit their site. It is a very good organization, with worthwhile objectives and standards.
As you can imagine, the use of on-device voice biometric processing requires either an installable SDK from a voice biometric vendor, or on-device (chip-based) capabilities which are exposed by the mobile phone manufacturer via their preferred development APIs. And, development will generally be more complex.
Mac Computer. To start with, you'll need a Mac computer running the latest version of OS X.
Objective C. Most iPhone apps are developed in Objective C, using Xcode.
Any Computer. Android offers a more flexibility for the development environment (Eclipse is recommended).
Java. Java is the native language for Android. Download Android SDK "bundle" from Google.