IT may be easy to forget that there are people who want to remain anonymous on the Web while the online world is full of those who happily post pictures of themselves and their navels for all to see. But interest in software that allows people to send e-mail messages that cannot be traced to their source or to maintain anonymous blogs has quietly increased over the last few years, say experts who monitor Internet security and privacy.
"People in the world are more interested in anonymity now than they were in the 1990's," when the popularity of the Internet first surged, said Chris Palmer, technology manager at the Electronic Frontier Foundation, a nonprofit group in San Francisco dedicated to protecting issues like free speech on the Web.
Increasingly, consumers appear to be downloading free anonymity software like Tor, which makes it harder to trace visits to Web sites, online posts, instant messages and other communication forms back to their authors. Sales are also up at companies like Anonymizer.com, which among other things sells software that protects anonymity.
"I get the feeling it's going up," said Roger Dingledine, Tor's project leader. "But one of the features I've been adding recently," he said, enhances anonymity protection by making it harder to count downloads of the software. Still, the number of servers forming layers in the Tor network has risen to 300 from 50 in the last year, Mr. Dingledine added.
A few reasons exist for the surge, which is hard to measure - it is nearly impossible to track how many people have made themselves invisible online. People who want to continue to swap music via the Internet but fear lawsuits brought by the recording industry want to hide their identity. Some people wish to describe personal experiences that could land them in jail. And some Web authors share their thoughts about repressive regimes and face government reprisal if they are caught.
"The more equipment is acquired and produced by a repressive regime, the more important anonymity is," said Julien Pain, who heads the Internet freedom desk for Reporters Without Borders, an advocacy group that supports press freedom. The group has produced a guide, www.rsf.org/rubrique.php3?id_rubrique=542, for bloggers trying to protect their identities.
"We realized that bloggers were being arrested everywhere in the world," Mr. Pain said. One blogger in Nepal, for example, may risk arrest with every time he comments on the country's monarchy, he said.
"The problem is, you have on one side states with a lot of money," he said. "On the other side, you have small businesses" and nongovernmental organizations. Law enforcement or other government agencies have tremendous legal and technological resources to discover the identities and locations of people communicating online, though consumer software can make the task more difficult.
Despite the increased interest in anonymity, software companies have moved away from marketing products that protect identities, said Chris Jay Hoofnagle, senior counsel and director of the Electronic Privacy Information Center's office in San Francisco, a public research group that focuses on privacy and free speech issues.
"When I came into this field, it was on the heels of the failure of a number of companies that tried very hard to create privacy enhancing technologies," Mr. Hoofnagle said.
Now, though, people are more concerned about defenses that block unwanted e-mail messages and hackers seeking to steal bank accounts, credit card numbers or whole identities, said Alex Fowler, co-head of the national privacy practice at PricewaterhouseCoopers.
"The visibility and awareness of these issues goes much deeper into the general public than it did even five or six years ago," Mr. Fowler said.
Despite increased interest in anonymity and security, some providers of online anonymity protection have not been able to turn their products into successful businesses. People who want to communicate anonymously may not want anyone to know that they have obtained software to do so, and some of the available software is free, including the Java Anonymous Proxy (anon.inf.tu-dresden.de/index_en.html).
Tor, first financed by the United States Department of Defense, received support from the Electronic Frontier Foundation for a year, but the money has run out, and Mr. Dingledine is working on the project unpaid and is looking for sponsors.
Tor uses "onion routing," in which layers of servers separate computer users from the Web sites they visit to hide a user's location. The software is easily installed and operates in the background, simply adding icons in Windows.
To make sure it is working, users can visit a site like www.showmyip.com and verify that their Internet Protocol address has changed. If it has, the software is working. The software may slow browsing, because Web pages must be transmitted through various servers around the world to get to your computer.
Software bundled with Tor, called Privoxy, prevents your computer from automatically sending certain personal information to Web sites. It does not block sites from finding existing cookies on the computer, so those sites will still know you are you (but not where you are because of Tor), but it does delete new cookies after rebooting.
Some companies that focused several years ago on anonymity now focus on security, and rather than trying to sell sophisticated software to consumers, they sell to Internet service providers like Verizon and EarthLink, who in turn can promise customers protection from spam and hacker attacks.
"Privacy is a concern, it just isn't mass market," said Hamnett Hill, president and chief executive of Radialpoint, a Montreal company that provides security services for Internet customers of BellSouth, Adelphia and other companies. "One of the big enlightenments that we had at a certain point is that people don't want to buy security software. They want peace of mind."
Radialpoint used to offer software to protect identity. The idea was not enough to carry the business, which is why the company no longer focuses on such products. Of course, there still are businesses that sell software that provides anonymity protection. For example, there is Anonymizer.com and GhostSurf, which is sold by Tenebril (www.tenebril.com). And some companies sell services to protect privacy in a way that is only tangentially related to the Internet. PrivateTel, for example, offers to provide temporary phone numbers for people who, say, post personal ads.
"The need to have a conversation and to complete the actual telephone call and remain anonymous is what is the driving force," said Dan Kaluzny, the company's chief executive.
More people who use the Internet know that if they disclose any personal information online, they may receive a flood of unwanted marketing calls and e-mail messages as a result, he said.