In the last several years, micro-blogging Online Social Networks (OSNs), such as Twitter, have taken the world by storm, now boasting over 100 million subscribers. As an unparalleled stage for an enormous audience, they offer fast and reliable centralized diffusion of pithy tweets to great multitudes of information-hungry and always-connected followers. At the same time, this information gathering and dissemination paradigm prompts some important privacy concerns pertaining to relationships between tweeters and followers and interests of the latter. In this paper, we assess the loss of privacy in today's Twitter-like OSNs and describe an architecture and a trial implementation of a privacy-preserving service called Hummingbird. It is essentially a variation of Twitter that protects tweet contents, hashtags and follower interests from the (potentially) prying eyes of the centralized server. We argue that, although inherently limited by Twitter's mission of scalable information-sharing, this degree of privacy is valuable. We demonstrate, via a working prototype, that its additional costs are tolerably low. We also sketch out some viable enhancements that might offer even better privacy in the long term.
De Cristofaro, E.; Soriente, C.; Tsudik, G.; Williams, A. Hummingbird: Privacy at the time of Twitter. 33th IEEE Symposium on Security and Privacy; 2012 May 20-23; San Francisco, CA.