Freedom to Tinker takes another look at the Sony rootkit software (XCP) and finds something interesting inside.

For weeks, the blogosphere has been abuzz with tales of intrigue about Sony’s XCP copy protection system. Among the strangest revelations was that XCP itself infringes on the copyrights to several open source software projects. In one case, Sam Hocevar found conclusive evidence that part of XCP’s code was copied from a program called DRMS, which he co-authored with DVD Jon and released under the terms of the GPL open source license. What made this finding particularly curious is that the purpose of DRMS is to break the copy protection on songs sold in Apple’s iTunes Music Store. Why would XCP rip off code intended to defeat another vendor’s DRM?

The answer is that XCP utilizes the DRMS code not to remove Apple DRM but to add it. I’ve discovered that XCP uses code from DRMS as part of a hidden XCP feature that provides iTunes and iPod compatibility.