hi there,

I always wondered how DRM works. I mean, how do they know how often I burned a song or how many times I listened to it. How can they restrict me from copying it to another machine? Why wouldn't it play there. I already know, that you have to buy the keys for a song, but why couldn't they be copied to another machine too?

I simply don't believe that someting like this could be possiple. I could always transcode the song to another format like mp3 - apart from the fact that transcoding would reduce the quality...but aren't there lossless formats that allow DRM as well - or you might just store it as lossless which wouldn't make the quality worse...but that's not my question.

I'm not planing anything illegal, I'm just trying to understand why people are moaning about it...I mean many more than the people who complain about copy protected CD's - which puts in most cases even more restrictions to the customer...with most DRM protected files I'm at least allowed to burn it or to copy it to my portable player...I guess that's because there are easy work arounds for copy protected CD's...however, I don't see why this wouldn't be possible for DRM protected files too, or what makes it so complicated. But to have an answer to this question I need to know how DRM works Maybe someone can help.

thanks

The Fallacy of DRM
What Does DRM Really Mean?

sounds good I'll have a look at this...

I read through all the stuff and used google as well, but I still haven't found the answers to me questions

DRM is not a "means" but an "end". I reckon you're wanting to know more about the "means". MS have one of the most comprehensive DRM schemes in use so their architecture may be of help. Try this link and this link.

This collection of video tutorials is nice.

imagine this: you download a WMA song (or get it from a friend on a CDR or via email). you go to play it, but you need Windows Media Player 9. you download it and amazingly you have rights to install it. so you do and you go to play it. now it can go one of two ways, WMP9 connects to the server (granted you have internet access) and sees the song is free to play and it plays the song (and might only play once, or as many times as you want for the next 5, 10, 15, 30, etc days). or, it connects to server sees you DON'T have the right to play it and it asks for your credit card.

have fun! you've had your first DRM experience!

edit: reread your post so i guess you know SOME stuff about audio and computers .. i guess i could add that imagine that in some freak move, microsoft removed all ability to play mp3s from windows. and that the government was given the power to get rid of all mp3 software players. and that .. well, i could go on for a while. imagine a total "system reset" .. everything you take for granted today is gone and you have a system clean of anything microsoft and the government doesn't like and you have to use the latest and greatest 100% DRM controlled machine. this could become a complete nightmare unless consumers retain some rights...

DRM is security through obcurity. This means that the only thing that makes DRM work is trust in the user, since the user is "free" to break or reverse engineer the encryption. This has been done on both common DRM schemes; Apple's and Microsoft's. However, in most countries, decrypting a file with the sole purpose of copying it is illegal.

Not true (AFAIK) for MS with WMRM9 (See below)

I have been doing some research on the subject. My understanding for the time being is the following, for the most well known DRM scheme (Apple's Fairplay & MS/WMRM=Windows Media Rights Manager)

Case 1 : You have the song but not the the license.
I don't know of any hack in both cases. There used to be one (even two) for WMRM V7 but no longer valid with WMRM V9

Case 2 : You have the song and the license

2.1 Apple's DRM (songs bought on iTunes) can be read (eg with Foobar using the FAAC decoder), there is also a program than can convert mp4 to m4p (or the opposite ... don't remember)

2.2 WMRM. No possibility. The only workaround I know are :
- RealPlayer 10 (Real claim thay are abble to play both Apple's and MS encrypted songs, provided you have the license, by calling the apprporiate subroutines
- Nullsoft (Winamp) has announced a WMRM compatible WMA codec (See Winamp FAQs)

For both players it will not break the DRM but at least enable to use another player than WMP.

So the only solution comes with : Burn to CD / Re-rip / Encoide (to mp3 for instance), provided that your license enables you to burn a CD (it is only allowed a limited number of times in most DRM schemes).

Let me know if I miss something. I'm planning to launch an online music service and more generally speaking would be very interested for any solution that would enable protected WMA to be played on iPods (after conversion, despite the potential quality loss I am aware of).

Thanks a lot for that link! It was very useful.

So, correct if I'm wrong, but technically someone could send me a DRM protected song + the key he bought and I could listen to this song for free, right? Also, let's say the license holder is only allowed to burn a certain song 3 times, someone could just backup his purchased keys and restore them any time this person wants to burn this song another 3 times...whenever the license holder burns or listens to a song, some information of the key are changed, so that it will know how often the license holder burned or listened to a song, depending on the license structure. In addition, some hacker could write a program that burns the song to a CD without having the key updated; it could just pretend playing the file, but rather stores it somewhere and burns it from there.
Is that correct?

Some licenses allow you to copy your songs to your portable player. However, once the license holder has it on his portable player couldn't he just copy it from there over and over again?

If all this is true, the only advantage I see is that someone actually needs a key in order to play the file. However, in that case the person who bought they key could probably be traced back so anonymous file sharing could be prevented. I guess something like a serial number for programs.

This is untrue AFAIK. Licenses are individualized for a particular computer so tranferring the song + the license on another computer will not help.

we are getting closer to my question So why wouldn't that be possiple? Is the generated key based on my hardware/software? If so, what happens if I buy a new PC? I read on the Microsoft site, that it is possiple to back up / restore your keys. So it can't depend on that. Also, what about resting the keys, so that someone could get around the limitations; for instance only being able to burn the song 3 times etc.

btw.: if the license holder is allowed to burn all his songs to an Audio-CD, he could just mass copy it from there, right? So why do some songs have a restriction that only allows this 3 times? Doesn't make any sense to me...it rather frustartes the license holder, if burning failed 3 times in a row...

DRM does not mean encryption. The security part of a DRM scheme could be achieved by encryption, but also by other means.

Yes it is .... If you buy a new PC you have to request a new license or maybe the backup / restore will do .. but I guess only a limited number of times.

(....A Microsoft fraud detection service helps ensure that the customer's backup/restore system is not abused by digital media pirates ...)

so are you actually saying, that it would be quite easy for an hacker to listen to a song without having the key?

well, the question is how I do that. This would also mean, if I buy a song from a company that goes down the drain I would never be able to listen to these music again...



I saw that too, however I'm not sure how they wanna achive that...my guess is that the provided site was rather for making people jump intro the boad of DRM. Basically they say, that's secure but at the same time that users will not loose their keys... I don't think that's possiple...

I am just saying that a drm solution is not necessary encryption-based.

so if it is not encrypted where would be the protection?

By not giving you all the needed pieces for decoding, as an example.

well, but then I would have connect to the internet everytime I listen to the song, right?

That is a possibility.

I see Gabriel, you are very chaty today
Anyway, I'm still not sure how it works and you hardly find any information regarding this oon the web I mean, before I go into all that iTunes stuff I wanna know about + I find it pretty interesting too...since many people are complaining