The arrest last week of 26-year-old Ross Ulbricht brought to light a little-known world of secret websites dealing in drugs, guns and counterfeit documents that until now have been largely hidden from authorities.
The Silk Road, an online contraband marketplace operated by Ulbricht, was shut down last week. Another, called Atlantis, voluntarily shut down in late September. Both websites used a software called TOR, or The Onion Router, in order to conceal their IP addresses, the numbers that work like street addresses to allow computers, mobile phones and laptops to find them, explained Nicolas Christin, assistant professor of electrical and computer engineering at Carnegie Mellon University.
Both The Silk Road and Atlantis are just two of many websites that belong to what is known as the "deep web" or "dark web" of sites that conceal IP address from search engines and cannot be linked to by other Internet pages or blogs.
Christin said TOR's encryption software allowed people to buy and sell drugs online (mostly marijuana according to his research), as well as trade pornography and even buy and sell illegal weapons. But TOR has also helped civil society groups in places like Egypt, Syria and Libya to avoid government eavesdropping, journalists to pass information and law enforcement agencies to receive secure anonymous tips electronically. Family members can also use TOR to share photos or other information privately. Christin compared the software to using old-fashioned couriers to carry messengers in between people who want to remain anonymous.