Chinese Internet censors take more than a week to identify and block access to sites that allow Internet users to circumvent their controls, according to a top executive at Anonymizer.

"We’ve been surprised how long it takes the Chinese to block these sites," said Lance Cottrell, Anonymizer’s president and chief scientist. "It generally takes them in excess of one week."

That’s good news for Anonymizer, which recently introduced its Operation: Anti-Censorship software that allows Chinese Internet users to access blocked sites. For now, the free software is available only in English, but a Chinese version is expected to be ready in about one month, Cottrell said. "We didn’t want to delay the launch," he said.

Users can download the software by registering their e-mail address at the Operation: Anti-Censorship website. The site remained accessible from a residential Internet connection in Beijing on Tuesday afternoon, local time.

Internet censorship is a fact of life in China, where the government routinely blocks access to certain websites, including those deemed politically unacceptable. Chinese officials rarely comment on these efforts, but have in the past defended them as being in line with international norms.

Cottrell declined to go into detail about how Operation: Anti-Censorship works, but said the software basically creates an encrypted SSL connection between a user and an authenticated server that allows the user to access blocked sites. As Chinese censors shut down access to these servers, Anonymizer will move them to new IP addresses and send the updated addresses to users via e-mail updates, he said.

Because Chinese officials take about a week to block access to a server, these IP addresses need to be updated on a weekly basis. But Anonymizer is prepared to move more quickly, if required.

Operation: Anti-Censorship is designed to handle updates "on a daily basis," Cottrell said. If Chinese censors develop the ability to block sites more quickly than that, Anonymizer has a few additional tricks up its sleeve. The company has developed ways to make its servers more difficult to identify and block, and these technologies will be introduced if the need arises, he said.

This isn’t the first time that Anonymizer has looked for ways to beat Chinese censors. A couple of years ago, the company was hired by the Voice of America (VoA) to develop software to help Chinese users access blocked sites. Anonymizer is now working with the VoA on a similar project for Internet users in Iran.

What makes Operation: Anti-Censorship different from these projects is that the effort is not government-funded, Cottrell said.