People use mobile devices ubiquitously for computing, communication, storage, web browsing, and more. As a result, the information accessed and stored within mobile devices, such as financial and health information, text messages, and emails, can often be sensitive. Despite this, people frequently use their mobile devices in public areas, becoming susceptible to a simple yet effective attack, shoulder surfing. Shoulder surfing occurs when a person near a mobile user peeks at the user's mobile device, potentially acquiring passcodes, PINs, browsing behavior, or other personal information. We propose Eye-Shield, a solution to prevent shoulder surfers from accessing or stealing sensitive on-screen information. Eye-Shield is designed to protect all types of on-screen information in real time, without any serious impediment to users' interactions with their mobile devices. Eye-Shield generates images that appear readable at close distances, but appear blurry or pixelated at farther distances and wider angles. It is capable of protecting on-screen information from shoulder surfers, operating in real time, and being minimally intrusive to the intended users. Eye-Shield protects images and text from shoulder surfers by reducing recognition rates to 24.24% and 15.91%. Our implementations of Eye-Shield, with frame rates of 24 FPS for Android and 43 FPS for iOS, effectively work on screen resolutions as high as 1440x3088. Eye-Shield also incurs acceptable memory usage, CPU utilization, and energy overhead. Finally, our MTurk and in-person user studies indicate that Eye-Shield protects on-screen information without a large usability cost for privacy-conscious users.

翻译：人们在日常计算、通信、存储、网页浏览等活动中普遍使用移动设备。因此，移动设备中访问和存储的信息（如财务与健康信息、短信及电子邮件）往往具有敏感性。然而，用户常在公共区域使用移动设备，这使得他们容易遭受一种简单但有效的攻击——肩窥。肩窥指靠近移动设备用户的人偷窥其设备屏幕，可能获取密码、个人识别码（PIN）、浏览行为或其他个人信息。我们提出Eye-Shield方案，旨在防止肩窥者获取或窃取屏幕上的敏感信息。Eye-Shield设计为实时保护所有类型的屏幕信息，且不会严重妨碍用户与移动设备的交互。该方案生成的图像在近距离下可辨读，而在较远距离和较广视角下呈现模糊或像素化效果。Eye-Shield能够实时防御肩窥者对屏幕信息的窥探，同时对目标用户造成最小干扰。通过将肩窥者对图像和文本的识别率分别降低至24.24%和15.91%，Eye-Shield实现了对屏幕内容的有效保护。我们的Android版（帧率24 FPS）和iOS版（帧率43 FPS）实现可稳定运行于高达1440×3088像素的屏幕分辨率。此外，Eye-Shield的内存占用、CPU利用率和能耗开销均在可接受范围内。最后，基于MTurk和现场用户的研究表明：Eye-Shield在保护屏幕信息的同时，并不会对注重隐私的用户造成显著可用性损失。