If you’re a Chinese web surfer using Skype you may notice that when you chat about certain things the person responding may not respond correctly. The reason? Not surprisingly China is filtering Skype user’s messages.

The Financial Times reported that Skype chief executive Niklas Zennstrom, confirmed that Tom Online censored messages containing references to the Dalai Lama, the banned Falun Gong spiritual group and other sensitive topics.

As more instant message programs are developed and used around the world, how will China keep up with them all? It must be a staggering amount of work keeping users from uttering phrases you don’t want them to say and keeping them from reading things you don’t want them to read. Moreover there could be new IM packages released weekly or even more often. Imagine the database required to keep track of it all.

In the end if there is one problem the Chinese government may not be able to contend with it is censoring the Internet as you can only play cat and mouse for so long. On the Internet it is more like cat and mice as there are just so many ways to communicate – blogs, e-mail, websites, VoIP, encrypted VoIP, encrypted IM, etc.

How could the government for example filter communications that are encrypted? What if a group of people knew a password that changed daily allowing them to unencrypt secret messages?

I just visited to Hushmail, one of the first websites devoted to sending encrypted e-mail. I first wrote about the company in the mid-late nineties. I was surprised to see a link on their homepage to an NPR radio show that promotes Hushmail as not a way to avoid the prying eyes of the Chinese authorities but the Bush administration.

I naturally assumed Hushmail was outlawed in China so I contacted the company to confirm my suspicions. Ben Cutler who works for the parent company Hush Communications said, “We are not aware that we have been outlawed in China, we do have some users there who are able to use our service there.”

I really can’t be more surprised by this news. Is it possible the Chinese government hasn’t decided there was a threat posed by Hushmail? Perhaps they haven’t found the site yet? Representatives of the Chinese government were likely not to respond to requests so I didn’t bother sending one.

So while this Skype news is not unexpected, I wonder how the Chinese government will be able to win this cat and mice game. It just seems impossible to police the Internet indefinitely and sooner or later the monitoring operation of the Chinese government will get so costly that it is bound to affect the entire country’s productivity and competitiveness.

Perhaps however I am overstating the control China plays in the lives of the average Chinese Internet surfer. According to Forbes, Craig Mundie, senior vice president and chief technical officer for Microsoft, suggested that hyperbole had crept into the debate over state controls over access to the Internet in China.

“There are literally hundreds of millions of Chinese people who have access to the Internet. The government here tends to control very selectively access to certain pieces of information. That’s their prerogative,” he said.

This is an opposing viewpoint infrequently shared by American companies but perhaps not unexpected as Microsoft and the Chinese government forge a tighter relationship with one another. It probably isn’t good to make negative comments about China the same week the country’s president makes a historic visit to your Redmond headquarters.

Still the extent of the filtering may be difficult for anyone outside the Chinese web filtering department to ascertain.

In the mean time it is safe to say that those in China using such high-profile programs as Skype are likely to be monitored much more closely than those using less well-known products. Perhaps for those companies looking for VoIP or IM market share, being filtered by China is a sign you have become a significant player in the market. One day, news about Chinese filtering could even move the financial markets.

For now the average Chinese web surfer looking to send communications that may not be officially sanctioned may have to turn to tier two or three IM companies who are looking to become the next Skype and subsequently the next target of Chinese censors.