Bitcoin is an online communication protocol that facilitates virtual currency including electronic payments. Since its inception in 2009 by an anonymous group of developers, Bitcoin has served tens of millions of transactions with total dollar value in the billions. Users have been drawn to...

Audit mechanisms are essential for privacy protection in permissive access control regimes, such as in hospitals where denying legitimate access requests can adversely affect patient care. Recognizing this need, we develop a principled approach to audits. Our first contribution is a...

“One Click Fraud” is an online confidence scam that has been plaguing an increasing number of Japanese Internet users, in spite of new laws and the mobilization of police task forces. In this scam, the victim clicks on a link presented to them, only to be informed that they just entered a...

Physical cash is vulnerable to rising threats, such as large-scale, government-mandated forgeries, that digital cash may protect against more effectively. We study mechanisms to combine physical cash with digital cash to remove their respective shortcomings and obtain their combined advantages....

Much of the data researchers usually collect about users’ privacy and security behavior comes from short-term studies and focuses on specific, narrow activities. We present a design architecture for the Security Behavior Observatory (SBO), a client-server infrastructure designed to collect a...

Previous research has suggested that people use the private browsing mode of their web browsers to conduct privacy-sensitive activities online, but have misconceptions about how it works and are likely to overestimate the protections it provides. To better understand how private browsing is used...