I figured the room might be a bit too generalist to want to hear 40-50 minutes of crypto flaws, and so I was thinking about wrapping the crypto stuff up in a talk that made a technical case in favor of DRM.
If people tell me real-world crypto is going to keep people in their seats, though, I'm totally down for that; it's a much easier talk.
The room will indeed be quite general. You'll have anything from some (though probably few) 1st year students all the way to some (few again) professionals and masters/phd students. Most will be in between, skewing heavily to last/before last year CS/SOEN majors.
I don't feel very comfortable giving advice about the direction of your talk; I can only speak for myself. If you have questions I highly recommend you ask the director of presentations. That said, personally I think the case in favor of DRM could be quite interesting since I've never heard a technical person argue in that direction. (At least not while doing more than simply assuming the token devil's advocate role.) If you make a good case you'll definitely get lots of questions/objections after!
* That the current state of the industry in crypto development is so weak and poorly understood that many of the statements people make about DRM are rooted not in theory but in observations about incompetant cryptosystems, and that when implemented well, DRM crypto actually has a good track record (cryptocard satellite TV, Blu-Ray). I was hoping to use this thesis as a coat rack for a bunch of practical advice about crypto in general.
* That the security goal of DRM is not about absolute platform integrity, but about meeting the commercial objectives of content providers, and that when you relax constraints from "absolutely protecting media" to "making sure titles are difficult to pirate during their new-release window to maximize profit", you get opportunities for interesting approaches to security, like renewability.
* That taken together, these two ideas suggest that DRM is actually a really interesting CS problem, and --- leaving politics out of it --- even if you believe it's destined to fail, it's worthy of study.
If people tell me real-world crypto is going to keep people in their seats, though, I'm totally down for that; it's a much easier talk.