CD-DA (audio CD) copy protection - two recent perspectives

[vitualis]

The first article was published at "The Register" here: http://www.theregister.co.uk/content/54/27960.html

BMG is willing to make a mockery of existing standards to achieve their aims.

The second article was published on the online version of "New Scientist" (originally from the Print Edition) here: http://www.newscientist.com/news/news.jsp?id=ns99993020

Why the methods employed above may be futile.

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'No more music CDs without copy protection,' claims BMG unit
By John Lettice
Posted: 06/11/2002 at 11:28 GMT


Faced with adverse publicity to copy protection on CDs, a year ago Bertelsmann Music Group bravely gave in and promised to replace a clutch of Natalie Imbruglia CDs which were protected by Midbar's Cactus Data Shield. But a year is a long time, BMG is at it again, this time apparently set on applying copy protection to all its music products.

Not, of course, that this should be surprising. The music companies are absolutely intent on copy-proofing their products, and although they'll maybe retreat a little when irate consumers pelt them with ordure, they'll be right back just as soon as the heat dies down. And here's how this process is working in BMG's case.

A few weeks ago reader Simon Barber accidentally bought a copy of Paradise Lost's Symbol of Life with Cactus Data Shield on it. The CD was marked with the Compact Disc logo (although Philips, custodian of this standard, has objected to its use on copy-protected CDs) and also had a small print 'health warning' claiming the CD conformed to the Red Book standard and was playable on standard home CD players.

Being a troublemaker Simon didn't try to get his money back from the retailer but attacked BMG directly. BMG's first line of defence on copy protection is here, where you'll find explanations, self justifications and a mail form for all European territories. The UK version (and indeed the French – that'll annoy them) says “BMG too sees itself obliged to protect future releases by implementing a copy control system” and “BMG will be using copy control technology for digital media as has been used for a long time with comparable media such as computer software, video games and DVDs.”

This is a clear commitment to 100 per cent copy protection, and once implemented will no doubt ease the workload of the various 'corrupt CD' identification sites considerably. Ah, but what if you have a problem playing the CD? “If you can't play the BMG product on your player please contact your dealer or the responsible person at BMG under (email address of the responsible person).”

We're sure it makes more sense in German. If you fill in the form and send it off to who knows where, this is what you get from the BMG Kopierschutz Team (typos left in):

“we are sorry you have troubles with our copy protection technology. The copy protection reacts on the special new technology that is build in in burners. Unfortunately htis technics was built in many new CD players, even if they can't copy a cd.
“The copy protection yet does not recognize wheather that burner technics is build in a cd player or in a burner. That's why the cd playern might not play a copy protected CD. Since burner technics are also built in car radios, this may be the reason, why you can't listen to a copyprotected cd in your car.
“As far as we were adviced, our copy protection is according to the Red Book Standart as well as all labelling on the cd.
“A standart home CD player is one that has no burner technics built in. Our Cds play on all Cd players without burner technics.
“There will be no cd manufactured without copyprotection any more.”

Kind of makes you wish you hadn't asked, doesn't it? Our intrepid investigator, for the record, had asked about the use of the Compact Disc logo, and for information about where he could obtain “a disc that actually adheres to the Red Book standard.” Picking apart the response, it would seem that the boys in Kopierschutz hold that there's no labelling problem, that it's all the fault of the dummies who build the audio units, that the CD is fully Red Book compliant, and that you can't get one without copy protection. Indeed, in that last sentence they're claiming you won't be able to get anything without copy protection.

This is not strictly true – yet. We're told the US version of Symbol of Life will be out, without protection, in a couple of weeks, so the correct answer Kopierschutz neglected to give is, take the dodgy one back to the shop then buy the US version.

But you can understand their difficulties. If BMG is seen as experimenting on Europeans while leaving truculent Americans for another day, it might be subject to a certain amount of adverse publicity, and sales of the local market products might just collapse.

Cactus Data Shield producer Midbar, incidentally, announced this week that it was merging with Macrovision, which also said it was acquiring the copy protection assets of TTR Technologies, which developed SafeAudio. So there's a trend towards consolidation in the protection racket. If you've read the BMG information page on copy protection, you'll have noted that the company is evaluating schemes with Sonopress. Sonopress publishes a handy comparison of these technologies here. Sonopress is a division of Bertelsmann Arvato AG.


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Copy protection on CDs is 'worthless'
19:00 06 November 02
Exclusive from New Scientist Print Edition

The technology built into some CDs to stop people copying them is futile, according to a computer scientist who has put today's antipiracy systems under the microscope. He believes the continual software and hardware upgrades issued by the makers of computer CD drives and audio CD players render copy protection systems pointless in the long run.

John Halderman, a computer scientist from Princeton University in New Jersey, plans to show delegates at a digital copyright conference in Washington DC next week that the idea of CD copy-prevention is "fundamentally misguided".

In 2001, Princeton University scientists debunked the technology the music industry planned to use to inaudibly watermark sound. Halderman is now doing a similar job on copy prevention systems.

Halderman looked at three widely available copy-protected CDs. He found that the three different copy protection formats they used all had one thing in common: they all index the contents of music discs using a system meant only for recording CDs on a computer's CD drive.


Table of contents

A conventional music CD has an electronic table of contents at the beginning of each disc. But a PC-recorded CD has several tables, with a new one written every time a new recording session adds something to the disc. Each of these tables points back to the previous one.

Personal computer CD drives read the last, most recent table first and work back through the series of indices - but audio CD players read only the first table.

A CD containing a copy-prevention system indexes the music correctly in the first table but then adds dummy tables containing deliberate errors. So CD players that read only the first table will play the music normally. But PC CD drives - which people use for copying - look at the last table, see garbage, get confused and play or record nothing.

Unfortunately, some audio CD players and in-car players use PC CD drives, and will not legitimately play a protected CD you have paid for. Nor can people play music CDs on their PCs.


"Simple modifications"

But all these measures can be sidestepped, says Halderman, thanks to the computer industry's habit of continual upgrading and bug fixing. Makers of CD players and CD-ROM drives only need to make "relatively simple modifications" to their software and supposedly protected CDs can be played with ease. So playback and recording equipment is becoming resistant to copy-prevention techniques.

"Software upgrades can be delivered easily using the internet," says Halderman, "and this will permanently undermine the usefulness of audio CD copy prevention." To ban upgrades, he argues, would lead to "buggy software and poor hardware."

The record industry could lose a fortune if people stop buying CDs and make their own copies. Halderman reckons he has a solution for them. "Reduce the cost of new CDs; if discs cost only a few dollars each, buying them might be preferable to spending the time and effort to make copies or find them online."


Barry Fox

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Regards.

[easydvd]

Let's assume for just a second that this REALLY is unbeatable copy protection. At some point the data HAS to come into plain text. That's the fundamental flaw in copy protection schemes. You can't copy protect ALL the way through the data stream. Even if it were possible....you can't encrypt the output sound. My line in gives me OUTSTANDING audio when I cap from TV, I suppose it would be the same from a CD. The only thing I see this changing if it were widespread is the rip time of the disc. You may actually have to let it play and cap the audio :P :P