Novel Physical Protection of Personal Mobile Assets

智能手机和其他移动设备的物理安全设计可以追溯到12年前推出的第一批智能手机，当时它们的目的只不过是一个具有通话功能和更好用的用户界面的音乐播放器。在那个时候，只需要一个PIN码（现在更普遍地称为“密码”）就足够播放音乐和打电话了。如今，智能手机和其他移动设备的用途远不止于此。越来越多的经验证据表明，移动设备的物理安全和隐私已经不够好了。智能手机应用程序的灵敏度各不相同，但解锁设备仍然是启动大多数应用程序的必要和充分条件。这种全有或全无的解锁功能一方面会导致访问低敏感性应用程序（如天气、维基百科、IMDB等公共信息检索应用程序）不必要的高开销，另一方面又会导致访问高敏感性应用程序（如金融、约会、医疗、消息传递）的安全性不足。智能手机和其他移动设备通常与他人共享，但访问控制机制只支持单用户模式，在这种模式下，解锁手机的人都可以访问其应用程序、数据和服务。社交圈内人窥探移动设备已经成为一个不容忽视的现实威胁。然而，密码（很容易被社会内部人士窃取）仍然是主要的身份验证机制，知道密码不仅足以解锁设备，还足以更改设备上的任何设置。现在是重新思考移动设备（尤其是智能手机）物理安全的最佳时机。我建议探索提高移动设备物理安全和隐私的设计空间。我提议的未来五年的研究计划包括系统设计以及隐私和安全的人类和社会方面的调查。与我的研究小组的研究生以及我的行业和学术合作者一起，我将探索和评估支持安全可用的设备共享的替代设计，在不同程度敏感的应用程序和服务的背景下优化可用性和安全性，并解决社会内幕的威胁。

The design of physical security for smartphones and other mobile devices dates back to the first smartphones introduced more than 12 years ago, when they were intended to be little more than music players with calling capabilities and a more usable user interface. At that time, just a PIN (now known more generally as "passcode") was good enough to play music and make phone calls. Smartphones and other mobile devices are used these days for much more than that. A growing body of empirical evidence suggests that the physical security and privacy of mobile devices is not good enough any more. Smartphone apps have widely varying levels of sensitivity, yet unlocking the device is still necessary and sufficient for launching most of the apps. This all-or-nothing role of unlocking results in unnecessarily high overhead for accessing low-sensitivity apps (e.g., public information retrieval apps, such as weather, Wikipedia, IMDB) on the one hand, and insufficient security of high-sensitivity apps (e.g., financial, dating, medical, messaging) on the other hand. Smartphones and other mobile devices are commonly shared with others, yet the access control mechanisms support only single-user model, in which whoever unlocks the phone has access to its apps, data, and services. Snooping on mobile device by social insiders has been established as a real threat, which cannot be ignored. Yet, passcode (easily shoulder-surfed by social insiders) remains the primary authentication mechanism, knowledge of which is sufficient not only to unlock the device but also to change any settings on it. It's prime time to rethink physical security for mobile devices, particularly smartphones. I propose to explore the design space for improving physical security and privacy of mobile devices. My proposed research program for the next five years comprises investigation in systems design as well as human and social aspects of privacy and security. Together with the graduate students from my research group as well as my industry and academic collaborators, I will explore and evaluate alternative designs that support secure and usable device sharing, optimize usability and security in the context of apps and services of varying degrees of sensitivity, and address the threat of social insider.