iScreen: A Pure Software-based Screen Privacy Protection System for Mobile Devices

With the explosive popularity of mobile devices, people tend to use them in different areas of daily life including shopping online, searching information, social networking and etc.. In spite of great convenience, the wide-use of mobile devices also brings about serious risk of privacy leakage through screen peeking. Even though various methods have been proposed to address this problem, they have different types of shortcomings such as additional hardware cost, not applicable to long texts and etc.. To alleviate screen peeking in a smarter way, we propose a pure software-based screen privacy protection system named iScreen for commercial mobile devices, which can effectively reduce peeper's readability but without affecting a valid user's. The key idea of iScreen is to make use of the differences of viewing angles and distances between the valid user and shoulder surfer, and accordingly adjust the font size, color scheme and screen brightness. By this means, iScreen can obviously sacrifice the shoulder surfer's readability with little degradation of the user's. We build a prototype on Android smartphones and conduct real-world experiments to evaluate its performance.