Protecting Privacy with Smartphones

许多人在日常生活中都随身携带智能手机。这些智能手机配备了各种传感器，如GPS或音频，并可以访问大量数据，如一个人的照片、日历或联系人。一个人可能会与其他人分享其中的一些数据。有时这种分享是意料之外的，结果是侵犯了个人隐私。想象一下，爱丽丝已经将她的智能手机配置为与家人分享她的位置。然而，有一天，爱丽丝改变了她的日常生活，走进一家商店为她的配偶买生日礼物。爱丽丝忘记了她正在和家人分享她的位置，惊喜被破坏了，爱丽丝的隐私被侵犯了。或者，假设Bob允许他的同事访问他的位置，并期望他们只有在有正当需要时才会检索这些信息，比如有一个临时会议。然而，有一天Bob注意到他的一个同事无缘无故地不断访问他的位置。结果，鲍勃感到被跟踪，他的隐私被侵犯了。

Many people carry a smartphone with them throughout their daily lives. These smartphones are equipped with various sensors, such as GPS or audio, and have access to a lot of data, such as a person's photos, calendar, or contacts. A person may share some of this data with other people. Sometimes this sharing is not expected, resulting in a violation of the person's privacy. Imagine Alice has configured her smartphone to share her location with her family members. However, one day Alice changes her routine and enters a store to buy a birthday present for her spouse. Alice forgets that she is sharing her location with her family, the surprise is spoiled and Alice's privacy is violated. Alternatively, imagine Bob gives his co-workers access to his location with the expectation that they will retrieve this information only if there is a valid need, like having an impromptu meeting. However one day Bob notices that his location is continuously being accessed by one of his co-workers for no valid reason. As a consequence, Bob feels stalked and his privacy violated. It would have been possible for a person's smartphone to avoid the privacy violations in both scenarios by sensing the person's context and detecting unusual events, such as the user being at a new location or an authorized user sending an unusual number of queries. The argument made in this proposal is that today's smartphones have sufficient context information about their owner in order to build a common behaviour model for the owner and to use this model to detect uncommon behaviour that could potentially result in privacy violations. In more detail, I will develop privacy-enhancing technologies that allow a smartphone to protect its owner by detecting two kinds of potential privacy violations: First, violations occurring as a consequence of the owner using an information-sharing app, where the violation is triggered by the owner making a change to her daily routine or by changes to the usual context of the smartphone and its owner. Second, violations occurring as a consequence of the owner using an information-sharing app, where an authorized user of the app accesses information in unintended ways, such as issuing overly frequent requests for the information or asking for the information at unusual times (e.g., at night). Furthermore, I will develop privacy-enhancing technologies that allow a smartphone to protect its owner by not only detecting, but also avoiding potential privacy violations. The objective is to have a smartphone avoid the privacy violation in an automated and intelligent way that limits the involvement of the smartphone owner, prevents sensitive information from being shared, but still makes possible the sharing of information useful to the person asking for this information. For example, a smartphone could automatically replace sensitive information (e.g., Alice's current location) with less sensitive, but still useful information (e.g., Alice's estimated time-of-arrival at Carol's location). Smartphones and their ability to run user-installed apps have caused a lot of concern when it comes to the privacy of mobile users. The long-term goal of the proposed research is to demonstrate that today's smartphones (and future mobile devices, such as Google Glass) have enough context information available to them in order to pro-actively protect the privacy of mobile users. The proposed research will make important contributions to research in privacy-enhancing technologies for mobile platforms. These technologies will encourage more people to use smartphones and smartphone apps. This will benefit the entire smartphone ecosystem (including app developers, smartphone providers, and network operators) and therefore the economy at large.