How does digital copyright protection work?

September 29, 2005 10:31 AM

I recently purchased an album by downloading it from a website. The license agreement said that I can burn it up to 10 times, and put it on up to 3 mobile devices. Both of those are fine by me - I only have one iPod, and I don't really need 10 CD copies of it. It did get me to thinking, though...

Is this just something I'm agreeing to and promising not to do, or is there some technology that will actually prevent it? How does an mp3 "know" how many times it's been burned or transfered to another device?

Also, if I attempt to burn it to disc, and the disc fails, does this count as one of my ten? What if I make a mix disc and only use some of the tracks?

Again, this is all intellectual curiosity.

posted by robhuddles to Media & Arts (14 answers total)

If it's a real mp3, there is definitely no DRM (Digital Rights Management) to control its use.

If it's something else, though (there are lots of audio formats), such as wmv or m4a, there may well be DRM to prevent its being used in certain ways.

In order to properly answer the question, you should probably tell us which website you got it from.
posted by Marquis at 10:36 AM on September 29, 2005

search around for the term DRM.

IMO DRM bites monky butt. I refuse to buy music with it.
posted by edgeways at 10:38 AM on September 29, 2005

here is another, decent conversation on the issue
posted by edgeways at 10:41 AM on September 29, 2005

I'll pop a related question in here:

Why do we even need to figure out the file formats/decryption schemes to get around DRM. Can't a program just take the end output (the music) and re-create that. Something like Audio Hijack for example on a Mac to create a new clean soundfile from a DRM'ed file.

Are there loss issues? Or is the drawback that you'd actually have to "play" these files to do this.?
posted by vacapinta at 10:52 AM on September 29, 2005

vacapinta: yes there is loss in quality for the digital -> audio conversion and "playing" the files all to convert would be irritating one time cost for any significantly sized library.
posted by mmascolino at 11:12 AM on September 29, 2005

vacapinta, the best way to do it, though it'd be fragile, would be to intercept the raw bites as they're decrypted but before they're decompressed. So you'd have an unencrypted AAC file that was otherwise identical to the encrypted AAC file (as an example).

The problem is that even minor changes to the software could make your interecept fail.
posted by substrate at 11:27 AM on September 29, 2005

To original questioner, Google DRM and come back later when you've read some more. :) There is probably some software which attempts to enforce those 10-copy, 3 mobile device restrictions...

To Vacapinta: DRM researchers are working on stopping that. Next-generation DRM will have "Trusted" (by the DRM people, not by you) devices that chain together. So your soundcard will have to be "Trusted" in order for music to be played on it, your monitor will have to be "Trusted" in order for an e-book to be displayed on it, etc. The idea is to stop you from grabbing the unencrypted audio/video/whatever at any point in the chain.

Right now, no DRM scheme is truly secure. They all have holes, and if you work hard enough, you can bypass them. When your entire computer is working together to stop you from doing that, however, it will become much, much harder for you. When bypassing DRM requires you to, say, solder a mod-chip into your PC that you had to smuggle into your country illegally, the barrier will be high enough that almost no one will be able to do it.
posted by jellicle at 12:27 PM on September 29, 2005

You buy an MP3 or compatible format digital song. You can install it on like 3 devices or something- depends on who you get it from. Do you have to OWN the devices yourself? If not stipulated... why not set up a service allowing people to auction off the extra installs on their mp3s to other people. So, I buy a song, it is on my home PC... technically I can put it on 3 devices, so I auction off the other two installs for cheap. I do this enough as an end user and I can make money back on the music I buy. As a service provider you shave pennies off of eah auction. would require research... but you but an MP4 or whatever from itunes for $.99. you auction two installs for .33 cents. you recoup some of your money. probably won't work because people mostly steal music. a thought tho...
posted by pissfactory at 1:07 PM on September 29, 2005

Although there is some loss in quality with this scheme, you can burn a CD of the music and then rip that CD to an unprotected format. It's digital end-to-end, but because of the different psycho-acoustic models that the different encoding formats use, you will be losing some data. There's software (for the Mac, at least) that essentially automates this process--it takes a DRMd AAC file, converts it to AIFF, and converts it back to a DRM-less AAC file. Even this might be subject to some quality loss if the actual algorithms that Apple used to rip the original AAC file are different from those you get with your Mac, but at this point, we're probably quibbling over small differences in quality.

One of the fun facts about DRM is that, although you've bought the tracks under the conditions that you can "burn 10 CDs, copy to 3 devices," the vendor can change those terms after the sale. Apple has done this once already with iTunes, making the terms of use more restrictive.

Jellicle--I agree with everything you say, although one of the major unintended consequence of the end-to-end DRM will be A) increasing inconvenience for consumers, B) greater value in cracking the DRM and distributing the DRM-less content, and C) more users who will seek out cracked, DRM-less content. I suppose TPTB could add in "features" to block the playback of DRM-less content, but that seems like it might be going a little too far.
posted by adamrice at 1:34 PM on September 29, 2005

And thats the big thing that these companies seem to be missing.

The copies mostly come from one source, and once you have an mp3 file all the "trusted" computers wont help stop its spread.

So only one person in the whole internet needs to bypass the DRM then everyone can have a copy.
And no matter how much they spend I dont think thats going to happen.
posted by Iax at 1:45 PM on September 29, 2005

adamrice writes "I suppose TPTB could add in 'features' to block the playback of DRM-less content, but that seems like it might be going a little too far."

SCMS was this kind of mis feature and was one of the reasons consumer DAT never took off.
posted by Mitheral at 2:36 PM on September 29, 2005

You buy an MP3 or compatible format digital song. You can install it on like 3 devices or something- depends on who you get it from. Do you have to OWN the devices yourself?

If we're talking about iTunes, it's your whole account that gets registered. A group of five people could share all the songs purchased by an account, but you wouldn't be able to do it on a song-by-song basis.

In answer to the original question, it's just done by counting. There's no magic. When iTunes burns a song or copies to an iPod, it updates the count. There's very little stopping someone hacking iTunes so that it burns things without updating the count, or just editing the count yourself.
posted by cillit bang at 3:28 PM on September 29, 2005

When bypassing DRM requires you to, say, solder a mod-chip into your PC that you had to smuggle into your country illegally, the barrier will be high enough that almost no one will be able to do it.

You know, it doesn't matter that everything on my computer is legally acquired... this scares the heck out of me.
posted by musicinmybrain at 5:42 PM on September 29, 2005

For those of you referencing Apple's AAC DRM and possible work-arounds - This is a very interesting site:

http://www.hymn-project.org/

FWIW, I purchase songs from iTunes, and use this app to ensure that I will be able to exercise my fair use rights under US copyright law.

I, too, have only one iPod. But it's silly to me to imagine that iPods will alwaysalwaysalways dominate the portable player market, be the best available solution, etc. Stripping DRM off of this music helps to ensure that I will have the option to choose some other AAC-capable player at a later date if I so wish.
posted by ZakDaddy at 12:19 AM on October 1, 2005