Quantitative Information Flow and Applications to Differential Privacy

International audienceSecure information flow is the problem of ensuring that the information made publicly available by a computational system does not leak information that should be kept secret. Since it is practically impossible to avoid leakage entirely, in recent years there has been a growing interest in considering the quantitative aspects of information flow, in order to measure and compare the amount of leakage. Information theory is widely regarded as a natural framework to provide firm foundations to quantitative information flow. In this notes we review the two main information-theoretic approaches that have been investigated: the one based on Shannon entropy, and the one based on Rényi min-entropy. Furthermore, we discuss some applications in the area of privacy. In particular, we consider statistical databases and the recently-proposed notion of differential privacy. Using the information-theoretic view, we discuss the bound that differential privacy induces on leakage, and the trade-off between utility and privac

The relationship between strategies of self-protection and self-improvement in the management of self-knowledge

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Privacy, trust, and self-disclosure online

Despite increased concern about the privacy threat posed by new technology and the Internet, there is relatively little evidence that people's privacy concerns translate to privacy-enhancing behaviors while online. In Study 1, measures of privacy concern are collected, followed 6 weeks later by a request for intrusive personal information alongside measures of trust in the requestor and perceived privacy related to the specific request (n = 759). Participants' dispositional privacy concerns, as well as their level of trust in the requestor and perceived privacy during the interaction, predicted whether they acceded to the request for personal information, although the impact of perceived privacy was mediated by trust. In Study 2, privacy and trust were experimentally manipulated and disclosure measured (n = 180). The results indicated that privacy and trust at a situational level interact such that high trust compensates for low privacy, and vice versa. Implications for understanding the links between privacy attitudes, trust, design, and actual behavior are discussed

Measuring self-disclosure online: Blurring and non-response to sensitive items in Web-based surveys

People are increasingly required to disclose personal information to computer- and Internet-based systems in order to register, identify themselves or simply for the system to work as designed. In the present paper, we outline two different methods to easily measure people’s behavioral self-disclosure to web-based forms. The first, the use of an ‘I prefer not to say’ option to sensitive questions is shown to be responsive to the manipulation of level of privacy concern by increasing the salience of privacy issues, and to experimental manipulations of privacy. The second, blurring or increased ambiguity was used primarily by males in response to an income question in a high privacy condition. Implications for the study of self-disclosure in human–computer interactio

Privacy and self-disclosure online

In this paper we present early results from a study which provides a detailed examination of the interaction between people's willingness to disclose personal information online and their privacy concerns and behaviors. An online survey was administered to participants in two parts using an Internet based surveying system. Part 1 of the survey measured participants' privacy concerns and behaviors. Part 2 measured participants' willingness to provide information using behavioral and dispositional measures of self-disclosure. Structural equation modeling identified two different types of privacy processes contributing to disclosure: a state process (trust and perceived privacy) and a trait process (privacy attitudes and behaviors), which were found to act independently on self disclosure. The results provide a valuable insight into people's privacy concerns and the disclosure of personal information to web sites