Effective DRM technologies work by allowing distributors of electronic content to control viewing access to the content - whether printed matter, music, or images - with some form of customized encryption. Individual "keys" for viewing or listening to the content are provided to an end user who has purchased rights, which generally include limitations on copying, printing, and redistribution.

When a prospective owner of digital rights downloads a content file, DRM software checks the user's identity, contacts a financial clearinghouse to arrange payment, decrypts the file, and assigns a key - such as a password - for future access. The publisher of the content can configure access in numerous ways. For example, a document might be viewable but not printable, or may only be used for a limited time. (Peruse the "Digital Content for eCommerce" white paper for a discussion of various distribution scenarios and their business implications.)

On the back end, things get even more complex. Once access rights and mechanisms have been assigned to a user, distributors must ensure that everyone in the creation, production, and distribution process gets paid fairly for use of the content. End-to-end software solutions, such as the MetaTrust Utility from InterTrust, track payments all the way from the online credit-card transaction to the royalty checks being deposited in the author or artist's account

The hardware advantage
Most DRM experts agree that the best rights systems combine software and hardware access mechanisms. By tying access rights directly to computer CPUs, hard drives, or other storage media, publishers can control not only who is reading the information but also on what device. This level of protection is important for highly sensitive documents such legal documents or proprietary market research, where illegal copying and sharing could result in substantial damages.

Adobe is already partnering with Iomega to offer a media-based solution that prevents the unauthorized distribution of PDF documents stored on Iomega's popular Zip and Jaz removable disks.

"Suppose I purchase a file over the Web, copy it to my Zip disk, and a colleague copies and tries to open that file on their machine," says Trent Thomas, technology business development director at Iomega. "They get sent to the seller's Web site right away so they can purchase the document legitimately.

"When copyrighted or sensitive content is bound to a disk, I can loan, destroy, give, or lock the disk up, but when I copy the content to a hard drive or any other media - it just won't play."

InterTrust, with its experience in tying MP3 access rights to music-playing devices such as the RioPort, is developing hardware-based protection of published content. Future generations of PCs may include "copyright chips" - such as the EMBASSY chip developed by Wave Systems - that would provide hacker-proof protection for digital content.