With so much of our lives digital, online, and not entirely under our control, we risk losing access to our communications, reputation, and data. Recent years have brought a rash of high-profile account compromises, but account hijacking is not limited to high-profile accounts. In this paper, we report results of a survey about people's experiences with and attitudes toward account hijacking. The problem is widespread; 30% of our 294 participants had an email or social networking account accessed by an unauthorized party. Five themes emerged from our results: (1) compromised accounts are often valuable to victims, (2) attackers are mostly unknown, but sometimes known, to victims, (3) users acknowledge some responsibility for keeping their accounts secure, (4) users' understanding of important security measures is incomplete, and (5) harm from account hijacking is concrete and emotional. We discuss implications for designing security mechanisms to improve chances for user adoption.

End-users have become accustomed to the ease with which online systems allow them to exchange messages, pictures, and other files with colleagues, friends, and family. This con- venience, however, sometimes comes at the expense of hav- ing their data be viewed by a number of unauthorized par- ties, such as hackers, advertisement companies, other users, or governmental agencies. A number of systems have been proposed to protect data shared online; yet these solutions typically just shift trust to another third party server, are platform specific (e.g., work for Facebook only), or fail to hide that confidential communication is taking place. In this paper, we present a novel system that enables users to exchange data over any web-based sharing platform, while both keeping the communicated data confidential and hiding from a casual observer that an exchange of confidential data is taking place. We provide a proof-of-concept implementa- tion of our system in the form of a publicly available Fire- fox plugin, and demonstrate the viability of our approach through a performance evaluation.

Authenticating spontaneous interactions between devices and users is challenging for several reasons: the wireless (and therefore invisible) nature of device communication, the heterogeneous nature of devices, and lack of appropriate user interfaces in mobile devices, and the requirement for unobtrusive user interaction. The most promising approach that has been proposed in literature involves the exploitation of the so-called auxiliary channels for authentication to bridge the gap between usability and security. This concept has spawned the independent development of various authentication methods and research prototypes, that, unfortunately, remain hard to compare and interchange and are rarely available to potential application developers. We present a novel, unified cryptographic authentication protocol framework (UACAP) to unify these approaches on using auxiliary channels and analyze its security properties. This protocol and a selection of auxiliary channels aimed at authentication of mobile devices has been implemented and released in an open-source ubiquitous authentication toolkit (OpenUAT). We also present an initial user study evaluating four of these channels.

Several studies ranked security and privacy to be major areas of concern and impediments of cloud adoption for companies, but none have looked into end-users' attitudes and practices. Not much is known about consumers' privacy beliefs and expectations for cloud storage, such as web-mail, document and photo sharing platforms, or about users' awareness of contractual terms and conditions. We conducted 36 in-depth interviews in Switzerland and India (two countries with different privacy perceptions and expectations); and followed up with an online survey with 402 participants in both countries. We study users' privacy attitudes and beliefs regarding their use of cloud storage systems. Our results show that privacy requirements for consumer cloud storage differ from those of companies. Users are less concerned about some issues, such as guaranteed deletion of data, country of storage and storage outsourcing, but are uncertain about using cloud storage. Our results further show that end-users consider the Internet intrinsically insecure and prefer local storage for sensitive data over cloud storage. However, users desire better security and are ready to pay for services that provide strong privacy guarantees. Participants had misconceptions about the rights and guarantees their cloud storage providers offers. For example, users believed that their provider is liable in case of data loss, does not have the right to view and modify user data, and cannot disable user accounts. Finally, our results show that cultural differences greatly influence user attitudes and beliefs, such as their willingness to store sensitive data in the cloud and their acceptance that law enforcement agencies monitor user accounts. We believe that these observations can help in improving users privacy in cloud storage systems.

As digital content becomes more prevalent in the home, non-technical users are increasingly interested in sharing that content with others and accessing it from multiple devices. Not much is known about how these users think about controlling access to this data. To better understand this, we conducted semi-structured, in-situ interviews with 33 users in 15 households. We found that users create ad-hoc access-control mechanisms that do not always work; that their ideal policies are complex and multi-dimensional; that a priori policy specification is often insufficient; and that people's mental models of access control and security are often misaligned with current systems. We detail these findings and present a set of associated guidelines for designing usable access-control systems for the home environment.

Recent years have seen a proliferation of secure device pairing methods that try to improve both the usability and security of today's de-facto standard -- PIN-based authentication. Evaluating such improvements is difficult. Most comparative laboratory studies have so far mainly focused on completeness, trying to find the single best method among the dozens of proposed approaches -- one that is both rated the most usable by test subjects, and which provides the most robust security guarantees. This search for the "best" pairing method, however, fails to take into account the variety of situations in which such pairing protocols may be used in real life. The comparative study reported here, therefore, explicitly situates pairing tasks in a number of more realistic situations. Our results indicate that people do not always use the easiest or most popular method -- they instead prefer different methods in different situations, based on the sensitivity of data involved, their time constraints, and the social conventions appropriate for a particular place and setting. Our study also provides qualitative data on factors influencing the perceived security of a particular method, the users' mental models surrounding security of a method, and their security needs.

The growth of the applications and services market for mobile devices is currently slowed down by the lack of a flexible and reliable security infrastructure. The development and adoption of a new generation of mobile applications depends on the end user's ability to finely manage system security and control application's behavior. The virtual execution environment for mobile software and services should support the security needs of users and applications. This paper proposes an extension to the security architecture of the java virtual machine for mobile systems, to support fine-grained policy specification and run-time enforcement. Access control decisions are based on system state, application and system history data, as well as request specific parameters. The prototype implementation is running on desktops, as emulator, and on mobile devices, proving the high level of flexibility and security, with excellent performance provided by the extended architecture.