Late last month, China quietly ordered PC manufacturers to bundle Internet access control software with all computers sold in the country. The software, which appears to be Windows-only, looks to provide a mix of features, including whitelists, blacklists, and on-the-fly content-based filtering. But the key feature that appeals to the government may be the fact that it allows blacklists to be updated remotely.

The government has already worked with the developers of the software, called "Green Dam-Youth Escort," previously. Jinhui Computer System Engineering Co, which developed it, apparently worked out the basic features of the filtering when assisting the Chinese military in securing the distribution of internal documents, according to The Wall Street Journal, which broke the story over the weekend.

Rebecca MacKinnon, who is an Open Society Fellow and worked previously at the University of Hong Kong, has translated some of Jinhui's press materials, which indicate that the Chinese government has worked with Jinhui to make Green Dam available as a free download, and assisted in getting it installed in schools. Jinhui had apparently already arranged to have the software bundled by a number of manufacturers.

There seems to be some confusion about the exact capabilities of Green Dam, as The Journal reported that one of Jinhui's founders indicated that the software relies on a database of blocked sites that allows it to be updated remotely. Reuters, however, talked with the same person, who indicated that it can perform semantic and image-based evaluation of incoming content—as such, the founder claimed that it's impossible for the software to be used for general censorship purposes. Still the two capabilities aren't mutually exclusive, and it would certainly be possible to tune Green Dam's semantic engine in a way that enabled it to filter out politics in addition to porn.

In any case, Green Dam will have to have been fairly well integrated into the host operating system in order to function well, which presents manufacturers with a whole host of potential problems. Manufacturers tend to bundle a lot of software with their machines, which raises the possibility of conflicts between Green Dam and other software on the machine. The auto-updating of the blacklist is also mentioned as another potential security risk, and certainly raises the prospect that computer makers will have to support software with behavior that changes over time. Although the government seems to have given manufacturers little time to adjust to the mandatory policy—it's set to take effect July 1—for now, it appears that they're being given the option of simply shipping disks in the box, rather than installing and enabling Green Dam.

Although China clearly exerts great control over the political content that reaches its citizens, the government appears to be extremely squeamish about is citizens' interest in porn. As such, it's tempting to take this policy announcement at face value: an attempt at social, rather than political control. Still, if the software does have the ability to perform remote updates of a blacklist, it will mean that the Chinese government has given itself the option of having the capacity to filter political content, available at the flick of a server-side switch.