The FBI's takedown of a billion-dollar black market website that allowed users to sell and purchase illegal items has shined a spotlight on the "dark Web," which masks users' online identities while providing a shield for everyone from hackers to journalists and the police.
Ross William Ulbricht, 29, was arrested Tuesday and charged with a battery of conspiracy crimes allegedly committed through his Silk Road website, which has been called the "Amazon of illegal drugs" or the "eBay of illicit substances." It was described by the FBI as "the most sophisticated and extensive criminal marketplace on the Internet."
The Silk Road used software called TOR, or The Onion Router -- named for its many layers, a free software program that shields users from surveillance by bouncing communications around a distributed network of relays, which are run by volunteers all around the world. Users are able to visit websites via this "dark Web" service without anyone knowing, while the software masks their physical locations.
"People use TOR for a variety of uses," Digital Citizens Alliance Fellow Garth Bruen told ABCNews.com. "People use it to preserve privacy -- activists, under threat, in Syria, in China."
There are also 'legit uses," he said. "It's also used by law enforcement because they don't want to be tracked by criminals."
Though TOR was originally sponsored by the U.S. Naval Research Laboratory, it is now developed by the Tor Project. Bruen said it caught on pretty quickly in the last three years. Silk Road is the most well-known use for it, he said.
Since its inception approximately two-and-a-half years ago, Silk Road's illicit sales revenue totaled 9.5 million Bitcoins, and commissions totaled over 600,000 Bitcoins, mostly through the sale of drugs and illegal goods. Bitcoins are Internet crypto currency, transferred through computers without the backing of banks. The sales are the equivalent of $1.2 billion, according to the FBI.
Ulbricht's arrest has been perceived mostly as a result of his own alleged sloppiness in his alleged criminal dealings, which the FBI said included placing a hit on a user who was seeking to expose Silk Road's merchants.
But Ulbricht's arrest and the shuttering of Silk Road still raises questions about the security of TOR and the ability of those seeking absolute privacy on the web to conduct business in the shadows of the Internet.
TOR and other alternate domain name systems do not completely mask users. They do create a long route between the user and the destination, and makes it much more difficult for anyone to trace where users are.
Bruen said that aside from TOR, there are hundreds of other alternate domain name systems on the Internet. Some of these systems can be accessed via TOR, while some have their own software and others are very small private channels.
TOR has become far and away the most popular anonymity network -- within 5 minutes, anyone can download it and buy illegal goods on the Silk Road site.
What's important for those choosing to remain in the shadows online is that nothing, including TOR, is absolutely anonymous. Those seeking to conduct illegal business online can, and in many cases will, be traced.
"What people have to remember is there's a limit to secrecy and anonymity if running on a public network. It's a public resource that lots of people have their hands on," he said. "As long as data exists somewhere, it's traceable."