In today's world, smart phones allow users to install various third party applications from different online application market stores. Given numerous applications and developers across the world, each application cannot be trusted to behave as it declares to behave. Android, an open source platform provides a wide variety of applications for installation from Android application store (Android Market) and attracts developers worldwide. Some of the developers might be of malicious intent developing applications which may access personal information from smart phones and misuse it for various purposes. Unfortunately, while installing an application on smart phone, users know only about details declared by the developer, but not about hidden intentions of the developer. The developer can steal personal information from phone, track users, send data to third party servers etc.

In TrustGuru, we bridge the gap between information available to the users and actual intent of the application to be installed on their phone. TrustGuru is an online system which, when given an application, provides a trust rating to user. Given an application input to TrustGuru, it predicts application to be either in Red (Application is not safe), Yellow (User's decision to install or not) or Green (Go ahead, application is safe to install). TrustGuru could predict the rating of an application correctly 78.4% time. To evaluate TrustGuru we conducted a user study and found that, user perception of trust depends on functionality and usability of application, but on security and privacy of that application, which strengthens the intention to use TrustGuru for smart phone. TrustGuru could impact user's decision for downloading application for more than one third of times.