People use Tor for a wide variety of reasons: to research diseases, protect themselves from domestic abuse, prevent companies from profiling them or circumvent countrywide censorship, just to name a few. If expert users and developers had tools to detect suspicious behavior, they could root out problems, improving reliability – and trustworthiness – for everyone. It relies on a large group of volunteers, some of whom are anonymous, which can raise questions about trusting the system. One of the most popular cryptographic tools – with two million daily users – is Tor, a network for browsing the Internet anonymously. But without technical knowledge and experience, users can’t know the difference between good and bad tools until it’s too late. However, bad cryptography can open gaping security holes, a fate that has befallen many popular systems. They all rely on cryptography, a delicate craft that when done properly enables secure communication despite snoopers’ efforts.

People want to protect information: hard drives from oppressive governments, physical location from stalkers, browsing history from overly curious corporations or phone conversations from nosy neighbors. There are more than 865 encryption tools in use worldwide, all addressing different aspects of a common problem.

Real tor web browser