Trussed Computing for Office

Microsoft has decided that Office's ability to make documents unreadable unless you're running the same version is a feature, not a bug, and now require you to conenct to a server as well.

A user's computer must be able to access the Windows Server 2003 running RMS on first opening a document to authenticate the rights and decrypt the document. Otherwise, the document cannot be opened. In the future, Microsoft plans to offer an "offline" rights authentication mechanism, but not with this version of RMS.

Other issues affecting the portability of rights associated with documents could cause other problems. Nash claimed that RMS is "platform agnostic"--meaning it will work with any operating system--in that "Windows Rights Management supports industry standards." But for people to be able to access RMS-protected documents on, say, Mac OS X or Linux, the operating systems must use XrML (Extensible Rights Markup Language) in the same way Microsoft does. In that case, "there is the opportunity for interoperability of document interchange," Nash said. Otherwise, the document could not be opened on the non-Windows operating system.

The same restriction in one sense applies to other Windows users. "If you shared the document with another Windows user and that Windows user hadn't installed (RMS), that other Windows user couldn't open the document as well," Nash said.

This is exactly what James Grimmelman explains in detail won't work, and why.