The Wall Street Journal reports: Law enforcement authorities across Europe and the U.S. shut dozens of illegal websites and arrested some operators, employing new and as yet unknown techniques to unmask those using an anonymity network.

Authorities said on Friday they made the arrests by piercing the anonymity offered by Tor, a network that relies on encryption tools and 1,000s of servers to mask online activities. Tor, which is partly funded by the U.S. government, is used by dissidents in authoritarian countries such as Iran, China and Saudi Arabia to access the Internet, but people operating and visiting websites that sell contraband also use it to conceal their identities.

Internet security experts said it was unlikely authorities had cracked Tor’s sophisticated encryption protocols. “If that were the case, the implications would be huge,” said an official with Welund Horizon, a London firm that provides intelligence on cybercrime to law-enforcement agencies and large corporations.

That law enforcement was able to locate Tor users is “a game changer,” said Ulf Bergstrom, a spokesman for Eurojust, the European Union’s legal coordination agency. “You’re not anonymous anymore when you’re using Tor.” [Continue reading…]