Case Study: Secure VOIP Telephony Application

October 06, 2015 474 Views
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VOIP Android App Development Case Study: Secure Voice

Secure Voice is the third mobile app in the bundle, and it perfectly complements the preceding Secure Chat and Secure Email. It's designed for those who demand security of voice conversations. It uses ZRTP, which is the most advanced cryptographic key-agreement protocol that is not reliant on servers. However, for the end user it's not an ounce more complicated than any mobile dialer.

The Client brought the idea of taking an open-source library called Liblinphone and development of an Android app upon it. The suggestion sounded easy but led to a couple of obstacles. The library was actually a box of whatnot, which is a common case with many examples of open-source software created by many people in a disjointed way. That was the main, and possibly the only problem. We had to fix bugs in the library and verify this solution before forming the final vision of the future product.

As for other tasks, we had to integrate it with the entire Secure ecosystem for seamless interaction. Custom app design was made from scratch. We took the library and a) removed everything unnecessary, b) removed everything that would be able to compromise security, for example, several unprotected codecs. Here's what we got in the end.

Case Study: Secure Voice App DesignCase Study: Secure Voice App DesignCase Study: Secure Voice App Design


• Login with a Secure Apps account.
• Encrypted phone and video calls over 2G, 3G, 4G, Wi-Fi, or cellular network.
• ZRTP enables encrypted peer-to-peer phone connection and verification of contacts.
• Upon picking up a call a session-specific cryptographic key agreement is initiated. Session keys are destroyed at the end of each call, so the communication remains private between participants at all times, and protected from any intruder.
• A couple of other goodies: a proprietary compression technology brings the highest voice quality; a bitrate algorithm adapts to available network bandwidth and thus provides smooth phone call experience.
• Viewing and editing contacts from the call log.
• Bluetooth compatibility.
• Secure Voice is available via subscription that enables an account to manage a bundle of Secure mobile apps: Secure Chat, Secure Email, and Secure Voice.

UI Design for Android App Secure VoiceUI Design for Android App Secure VoiceUI Design for Android App Secure Voice

Applied technologies

• Java for Android
• Liblinphone
• ZRTP (Z Real-time Transfer Protocol)
• OkHttp
• NewRelic

Supported platforms: Android 4.0 and later. The app was tested on numerous devices, including Nexus 4, 5, and 7; Asus TF101 tablet; Samsung S-Series (3, 4, and 5), and LG G3.

Results and achievements

Being a vast improvement on Liblinphone, this Android app was the easiest of the three to implement. Picking the best, removing everything else, and optimizing the outcome for easy use. We may add here material design that looks gorgeously on Android devices even with such a visually simple app. The process was not plagued with any problems, and we made it onto the market in time. What's interesting is that on Google Play it's also the most downloaded of the three.

An advanced admin panel with a clean intuitive UI is under development, merely for the Client's convenience of managing users and setting up the server; we are also maintaining this beautiful product. Soon there will be more case studies about the products we create, so stay updated with our blog and feel free to contact us with any questions.

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