The Non-Geeks Guide to Consumer DRM: Why Your New TV Might Not Work With Tomorrow’s DVD player
There’s a lot going on in the world of Digital Rights Management (DRM) these days and I realized not everyone understands exactly what DRM is, how it works, and what the implications are. This has popped up a few times recently among friends and family as (being the alpha geek) I’ve been asked to explain why certain music or movie files don’t work on various players. Before digging into some of the security issues around DRM I thought it would be good to post a (relatively) brief overview. I’ll be honest – as objective as I try to be, the title of this post alone should indicate that I have some serious concerns with the current direction of consumer DRM. While one of the better parts of having a personal blog is being able to throw objectivity off a very tall bridge to a very messy landing, tossing all objectivity to the wind often seriously undermines core arguments. Thus I’ll try and keep this a relatively (but not perfectly) impartial overview of the technology. In future posts I’ll dig into the security issues of DRM and make specific recommendations on security requirements for any consumer DRM system. If you’ve ever wondered why you can’t just copy a DVD, why a song you downloaded from iTunes only plays on an iPod, why a song downloaded from Napster won’t play on an iPod, or why you can print some .pdf files but not others… keep reading. If you wonder why it’s so hard to get HDTV on a TiVo or computer… keep reading. If you want to know what that new expensive HDMI cable for your XBox 360 or flat panel really is… keep reading. (and if you know all this stuff you might want to skip this post and wait for the big DRM security analysis in the coming weeks) DRM Defined Digital Rights Management (DRM) is a collection of technologies used to control the use of digital media like music, movies, television, and text. DRM decides and controls who is allowed to read or play a file, copy it, print it, email it, download it to a portable player, burn it to CD, and so on. We broadly divide the market into two halves- the consumer world, and the enterprise world (businesses). While some of the technologies overlap, this is pretty much a hard split and the use and implications of enterprise DRM are very different than consumer DRM. I’m going to simplify a bit here, but DRM essentially works by encrypting a file and tagging it with rules on how that file is allowed to be used (the rules are also protected). Whatever reads that file must be able to both decrypt it and understand (and be able to enforce) those rules. A DRM system has two technical goals: Control/protect content by restricting what software and devices can read it. Control/protect content by restricting what that software/device (and thus the user) can do with it. On the user side, this leads to two major implications: Users are restricted in how they can use content (copying, saving, etc.). Content (and thus users) are locked into using specific players/readers. Thus content publishers and technology companies use DRM as a tool to protect their content (mostly from copying, but there are other implications), and to force you to use their devices. There’s also no single standard technology for DRM, creating a bit of confusion among us consumers. Consumer DRM is actually really hard, since we’re talking about an environment where the user can hack away at both the protected content and the players (devices and software) privately, which tends to give them an advantage over time. Rather than boring you with all sorts of technical jargon I’ll explain a little bit of how this works by comparing two kinds of shiny plastic disks- CDs and DVDs. Compact Discs- Living a Life of Freedom CDs were one of the first (maybe the first, we skipped that in my college history classes) formats for digital distribution. Before music CDs all music distributed to consumers was analog, and one of the characteristics of analog is it tends to degrade over time, and as we make copies, noise sneaks into the signal. CDs changed all that by distributing music in digital form. Not that anyone was playing these things on computers in the 80s, but CDs barged into our lives with the promise of crystal-pure digital music- no scratchy records or stretchy tape. Back then all most of us knew was “it’s digital”, and beyond that we really didn’t think about it. Until CD drives started turning up in computers, that is. Most anyone who has ripped a CD into iTunes now knows that a CD is really just a collection of bits. CDs are totally unprotected unless the music label adds some sort of DRM (which rarely works, since it’s not part of the Compact Disk Digital Audio standard, and our players don’t understand it). As soon as we started putting CD drives in computers we were able to pull perfect copies off CDs onto our computers. Once CD writers and discs became cheap enough we could make perfect copies of these commercial CDs. Then we learned about file compression (to squeeze those big music files into something easier to store and trade) and combined that with the Internet and broadband and all of a sudden anyone, anywhere, could trade nearly-perfect digital music with anyone else in the world without a cent going to the music labels (or artists). They really didn’t like this. It really pissed them off. Their response? Sue the hell out of everyone and write some laws. You see, there’s a huge disparity in perception between content companies and consumers when we buy those CDs. Historically we think of it as “buying music”. We paid money, we own the CD, thus don’t we own the music? Not really- the copyright holder always owns the music, we’re just allowed to use it.
