Why Johnny Can’t Blow the Whistle: Identifying and Reducing Usability Issues in Anonymity Systems Greg Norcie Jim Blythe Kelly Caine L Jean Camp Indiana University Information Sciences Institute Clemson University Indiana University
[email protected] [email protected] [email protected] [email protected] Abstract—Tor is one of the most widely used anonymity Tor uses onion routing [24] to prevent third parties from networks in the world. The anonymity provided to any individual observing or transparently interjecting themselves into a user’s Tor user is a function of the total number of Tor users. Adoption web activity. The term “onion routing” refers to Tor’s layered of anonymity tools, including Tor, can be hindered by a lack of usability. Therefore, enhancing Tor’s usability and making it encryption, analogous to the layers in an onion, which prevents easier for more people to use Tor successfully increases security third parties (including Tor nodes) from observing the content for all Tor users. To enhance Tor usability we begin by identifying of packets in transit. Tor also prevents the linkage of the source stop-points which may act as barriers to using the Tor Browser and destination of any packet in the Tor network. Of course, Bundle (TBB). We suggest changes based on our analysis of there are attacks that threaten privacy even when using Tor, these stop-points. To follow through, in our second study we test whether the changes we recommended to the Tor Project are including subversion via control of malicious nodes and timing effective in increasing usability, and find a significant decrease attacks.