Secret surfing

日期:2017-12-11 04:31:01 作者:麻樯章 阅读:

By Mark Ward NO MATTER how much you know about the Internet, it knows more about you. Every time you visit a website, you leave a record showing you were there and what pages you viewed. If you are a frequent visitor to a site, its operator will be able to build up a profile of the way you use it. Many surfers object to being tracked in this way, especially if the information being garnered is used commercially. So Michael Reiter and Avi Rubin of AT&T Labs in Florham Park, New Jersey, have found a way to give Internet surfers more privacy by making them a mere face in a crowd. People using their software, called Crowds, become anonymous members of a pool of surfers. When a member of the pool clicks on a link or types in a Web address, the request for data does not go directly to the desired site. Instead, it is sent along a randomly determined route through the crowd. The chances are that it will turn up at the website with another member’s Internet address, spoiling attempts at profiling individual users. The downside of mixing up addresses is that a surfer could get into trouble for apparently visiting websites, such as sex sites, that were actually visited by another crowd member. To become part of a crowd, users download a program called a “jondo” after John Doe, the name sometimes given to unidentified corpses in the US. The jondo effectively acts as a “proxy” server, taking the request for information and randomly picking a member of the crowd whose address will be used to pass on the request. After a few hops around the members’ computers, the request reaches the desired website, which sends data back down the path that has just been established. The request looks to the destination website as though it has come from some random member of the crowd, says Reiter. Passing requests from machine to machine slows down surfing slightly, so Reiter says crowd membership is currently limited to those with at least a 64 kilobit per second ISDN link to the Internet. Reiter says there has been a steady level of interest in the Crowds program. AT&T’s crowd has 900 members, not all of whom work for the company. The larger the crowd, the greater the anonymity of each member and the lower the delay on any surfing trip. Even when not surfing, crowd members often keep their links to the Internet live, giving the program as big a choice of addresses as possible. Crowds does not give perfect privacy, Reiter admits, but he claims it has advantages over other “anonymiser” services that funnel requests via central servers. It allows people to legitimately claim that it was not them that initiated a request to a prohibited website, for example, even if their machine originated that request. As an added safeguard, Crowds routinely strips out cookies, the small packets of data generated by many websites and stored on a visitor’s computer. Reiter says this can put a few websites off limits because some allow access only to surfers with valid cookies. He adds that Crowds protects privacy best when Java and Javascript are turned off,