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Vol.32 No.3 August 1998

Digital Copy Protection and SIGGRAPH Public Policy WWW Pages

Bob Ellis

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This column covers a policy issue I haven’t discussed before: digital copy protection. I also have an update on plans for SIGGRAPH’s Public Policy Web pages and a procedural item.

Digital Copy Protection

I’ve recently become aware of digital copy protection as an issue with impact on non-commercial digital recording. It was mentioned several times by attendees (there wasn’t anything on the program) at the Computers, Freedom & Privacy 98 (CFP98) Conference (reviewed in my last column). It was also brought to my attention by member Myles Losch. I thought it might be an issue of interest to SIGGRAPH members. One comment made by a CFP attendee suggested that Digital Audio Tape (DAT) devices have not been good sellers because the copy protection mechanisms limit their potential usefulness.

Myles provided me with two useful references. The first discusses digital video standards to control intellectual property on Digital Video/Versatile Disc (DVD’s) and IEEE 1394 FireWire broadband links. Please see the DVD FAQ (this discussion refers to the April 7, 1998 version that will probably have been revised when you read this). Myles says to note especially items 1.10 and 1.11, plus 2.10 on Divx triple-DES cryptography and to also note items 1.12 and 3.6 on related audio work.

The second reference is, a Web site run by the Home Recording Rights Coalition (HRRC). The HRRC provides information about legislation that addresses copy protection on recording devices. The HRRC was founded in 1981 at the time of actions relating to the legality of using a VCR to “time shift” broadcast television programs. It is frequently updated so I won’t refer to specific items.

The advent of digital recording devices such as DAT and DVD has caused the owners of recorded intellectual property such as motion pictures and music to renew their concerns about unauthorized copying. Many of you may remember the similar issue raised when analog audio tape recorders and VCRs first became available. Digital recording devices are an even greater problem for them because of the ability to make perfect copies, without the loss in quality when making analog copies.

Typically, technical mechanisms are developed in industry standards committees to prevent copying and then legislation is proposed which would make it a crime to provide mechanisms to circumvent copying, rather than the actual act of copying. The problem comes when an authorized copy is to be made (for example, of material whose intellectual property rights are owned by the person making the copies or copies made under fair use). If you make copies for a living, then you have an incentive to go through the hoops to effect the copy protection.

But if you are simply making a copy of your home movies, or results illustrating your computer graphics research, it might not be so easy. While many rights-owners do not seek to prevent this type of copying, it is not their first priority.

All of this is complicated by aspects of international treaties. Treaties in effect and proposed at the World Intellectual Property Organization may be much stricter in their interpretation of unauthorized copying than we are used to under current U.S. law which has strong protections for fair use copying.

Note particularly, that some proposed legislation in the U.S. would prohibit the sale, manufacturing or use of any device that can be used to defeat copy protection. Current laws are directed at the actual act of unauthorized copying. The situation is particularly interesting when software mechanisms are involved because of the current Bernstein cryptography export case that has been successful making software protected speech under the First Amendment. Due to the rapidly changing situation, it’s really not feasible to go into the legislative process in any greater detail here. I urge you to look at the references (particularly the HRRC site) and their links for the latest information.

USACM has been involved in this mostly as it relates to their stands on intellectual property and implementation of the international intellectual property treaties.

The DVD FAQ site has excellent descriptions of DVD technology in general. Section 1.11 describes four forms of copy protection used by DVD. Any or all of the schemes may be present on any particular DVD media.

The Analog Copy Protection System by Macrovision adds colorburst signals and pulses in the vertical blanking signal to prevent copying using composite video and s-video outputs. The copy generation management system (CGMS) embeds information in outgoing video signals to prevent making first- and/or second-generation digital copies (as with DAT, but giving more control to the rights-owner). The content scrambling system (CSS) and Digital copy protection system (CPS) both use encryption to prevent unauthorized copying.

Section 1.10 describes “regional codes” which can be used by content originators to control which parts of the world a DVD may be played. This means that a DVD purchased in one country might not be playable in another, a particularly vexing problem given the potential of international electronic commerce.

Section 2.10 presents a description of Divx proposed by Circuit City. Divx would permit the purchase of a DVD at a cost just above a one time rental and then play it once (perhaps with a time limit). Additional plays might require payment of additional fees. To effect the payment of additional fees and authorizations, a telephone connection to the player would be required.

Like the legal situation, the technical situation is constantly changing, although not so rapidly. Still, it’s not reasonable to go into greater detail here. I again urge you to check the reference for current information.

Bob Ellis is Chair of SIGGRAPH's Public Policy Committee. When last gainfully employed (1993), he was Sun Microsystem's representative on the Computer Systems Policy Project's (CSPP) Technology Committee and also co-managed Sun's external research program. Before that Ellis held computer graphics software development and management positions with Sun, GE-Calma, Atari, Boeing and Washington University (St. Louis).

Bob Ellis

The copyright of articles and images printed remains with the author unless otherwise indicated.

SIGGRAPH Public Policy Web Pages

Our Web presence is finally getting some attention thanks to volunteers Laurie Reinhart and David Nelson. It had been more than a year since any changes had been made. The first changes have been minor: we’ve cleaned up the format and links, reorganized the structure a bit and added a PDF version of the white paper for downloading.

Our list of possible things to do includes: adding some more background on SIGGRAPH’s public policy activities, including information on some of our other projects, providing information about our committee meetings, past and future, perhaps including these columns although we might just link to the on-line issues of Computer Graphics, presenting trip reports and perhaps reactivating the idea of a user survey.


This is the fourth of these Computer Graphics columns and is the final one in this first year, although as I write this only the first two are in your hands (the delay seems strange to someone who communicates primarily by electronic means!). To date, I’ve had very little feedback on whether you find these useful, comments on the material or suggestions for topics. I’m not too surprised because we’re all so busy. Also, I’m running a bit low on ideas; I’m not on empty yet, but some suggestions would be helpful. Of course if you suggest a topic I don’t know much about, I may ask you for information, or even to write a few words yourself. You can reach me at the email address below.