HDCP master key allegedly posted

by m0nastic • 16 years ago

196 90 16 years ago

m0nastic4• 16 years ago

For those curious as to what this entails, the Wikipedia article: http://en.wikipedia.org/wiki/Hdcp#Cryptanalysis Does a pretty good job explaining.

For those not quite that curious, if you've ever tried to watch a Blu-Ray movie on your computer, and gotten an error about it being restricted from playing back on your display; there's a good chance that is because of HDCP.

If this is true (and there isn't really a good reason to believe that it isn't), this is pretty bad news for the content industry.

oomkiller• 16 years ago

...And pretty good news for everyone else!

teej• 16 years ago

Are you kidding? This is -awesome-.

My single worst experience with iTunes was when I took the dive and spent that extra dollar to rent an HD movie. Just to find out a $5 movie on my $500 Mac Mini won't play on my $1,000 TV.

I haven't made a -single- Apple purchase since then. That's how badly HDCP pissed me off.

nimai• 16 years ago

You're joking, right? The only people HDCP has been affecting have been legitimate customers. Pirates have had HD video for years.

barrkel• 16 years ago

<sarcasm>You don't understand. HDCP is great for consumers. It's what lets them view fantastic content from the creative industry. Without HDCP, that content wouldn't be available to consumers.</sarcasm>

It was this angle of attack, or one very similar to it, that I remember reading from an nVidia (or it might have been ATI) powerpoint deck a few years back.

m0nastic4• 16 years ago

Yeah, I didn't mean for my comment to make it sound like I'm supporting the content industry. Rereading it makes it sound like I think this is a bad thing. It was meant more as rubbing salt in the wound.

ra2• 16 years ago

Particularly bad news for Sony

seldo• 16 years ago

Blu-Ray on Windows is the single most user-hostile computing experience I've ever had. I stopped buying/renting blu-ray movies because I didn't feel like rebooting 3 times every time I wanted to play a disc, with the software treating me like a criminal the whole time.

thehodge• 16 years ago

I bought my first Blue-Ray the other day and the experience was terrible, I put the disk in and nothing happened.. I tried to play it in windows media center, no ball.. not in VLC.. there was no player included on the disk.

I had to download a 300meg trial of PowerDVD just to play a film I'd already paid for (I also had to update my graphics card for some reason, the computer had been playing HD content for months without needing that).

That will be the last Blue-Ray disk I buy..

viraptor2• 16 years ago

> That will be the last Blue-Ray disk I buy..

I wouldn't be so sure. This is exactly the experience I got in the first year of DVDs being available. (although the player was a bit lighter ;) ) After some time we got proper software for Windows and after that, there was DeCSS.

Just give it time. If there is useful content on Blue-Ray, people will use it and the experience will improve.

flannell2• 16 years ago

I guess Microsoft is still reeling about losing the HD format war to Sony! tbh, I think everyone knows that video streaming is the future and not physical disks. I give the format two years.

illumin83• 16 years ago

The experience on Blu-Ray is terrible. I have to sit through as much as 20 minutes of unskippable commercials before I get to the menu screen. They even show you commercials about how great movies are on Blu-Ray - even though they should know you already are a customer because you're watching a Blu-Ray. Not only that, some of the commercials are streamed over the Internet, which means they use your bandwidth without asking permission to download an unskippable commercial.

The experience is getting a bit ridiculous, and I personally hope someone writes a DeCSS for Blu-Ray so that we can uncripple this format.

Btw, I don't actually buy any Blu-Ray disks, I just have my Netflix account enabled for Blu-Ray and watch most movies in that format since it looks better on my HDTV.

sofuture2• 16 years ago

Stop buying movies period -- because if not Blu-Ray, it will be another technology aimed at treating you like a criminal.

cagey• 16 years ago

Or because there are incredibly few new movies worth watching?

Osiris• 16 years ago

Blu-Ray on standalone Blu-Ray players is the single most user-hostile entertainment experience I've had.

My Samsung BD-P1590 has had new fewer than 4 firmware updates, the last of which actually caused the player to crash on most of the Blu-Ray movies I try to watch. I rent from Netflix and I have literally had to rip the movie and stream it to my XBMC box in order to watch the movie because it wouldn't play on my Blu-Ray player.

Secondly, I've had to completely disable BD-Live because when the disc has those lame downloadable previews, it takes several minutes of just sitting at a spinning wheel or lame icon with nothing (apparently) happening. If I'm lucky the preview will download and play, but 90% of the time, the player just stays like that forever and the only button that works on the remote is Power.

Lastly, the unskippable previews really piss me off. I know that DVD had this as well, but it's seriously annoying that it takes 5+ minutes just to get to the menu to watch a movie. Many times I do sit and watch the previews while popcorn is popping or the wife isn't ready to watch yet, but when I want to skip them, I really should be able to.

So, despite the fact that I try to watch movie the authorized way, most of the time I find it easier to rip/stream the movie from a BD-ROM with XMBC than to actually use my Blu-Ray player.

I really feel bad for the non-techies that have to deal with all this mess without being able to find sneaky workarounds to get it to work properly.

emordnilap• 16 years ago

> Lastly, the unskippable previews really piss me off.

I have a samsung blue ray player too. I usuallly push stop, and then hit the "title menu" (or disc menu? I forget) to skip the unskippable stuff.

grk• 16 years ago

I've never had any problems playing a Blu-Ray disc on my PS3.

ra2• 16 years ago

And so the DRM Cold War continues.

audidude• 16 years ago

For some reason I don't think that will make such a good t-shirt this time around.

daychilde• 16 years ago

Maybe it'd work better for folks like me who shop at big&tall stores... We have the perfect body for this t-shirt. Finally, all my McDonald's days are about to pay off!

flannell2• 16 years ago

I've had nothing but trouble with HDCP. I've used HDMI matrix switches to transport a video signal around the house. 40% of the time I get the HD snowstorm so have to reboot the TV to attempt a second handshake. This gives a low Wife Approval Factor. I believe they should stop torturing the paying punters, like me, and just be happy with the majority who pay and not the minority that don't. Also, before someone mentions the x billion lost per year, I doubt maybe the 100,000 that downloaded 'The Bounter Hunter' would of seriously bought it.

reduxredacted8• 16 years ago

Also, before someone mentions the x billion lost per year

It's bizarre. Imagine a job where my customer complains about how ineffective my product is yet continues to shovel money at me. Wait, even worse, my product makes their customers miserable and yet they still shovel money at me. It sort of sounds like the business model of a crack dealer.

joeyo• 16 years ago

Or a monopolist.

andybak• 16 years ago

Don't they have a contingency for this? I thought they could update the DRM code in devices with a new key or some such thing.

nash• 16 years ago

I believe the update of keys relies on the secrecy of the master key, which is never released in a device.

Hence the master key pretty much kills it all.

dfox2• 16 years ago

HDCP key exchange is very weird cryptosystem. Usually you generate some essentially random private key and trivially derive public key from it. In HDCP, it works other way around: central authority has ability to convert (random) public keys to private keys using some secret information (purpotedly this matrix). Motivation of this design is twofold: (a) actual hardware implementation is simple and (b) this central authority can impose varios policies about who gets private keys. On the other hand both these points make this cryptosystem very weak.

Therefore, this matrix may not even be leaked, but somebody might reconstruct it from relatively small number (I don't remember exact required number, but i recollect that it is at most thousands) of keypairs recovered from devices in circulation.

By the way similar mode of deployment was once recommended for RSA (having shared modulus whose factorization is known to central authority), but it is long known to be insecure (for RSA). I don't know of any non-HDCP related analysis of public key cryptography based on similar approach as HDCP (vector summing or matrix multiplication, depending on viewpoint), which probably means that it is very well known to be insecure.

Edit: and for the key update: you would have to update all deployed keys simultaneously, which is probably impossible. Moreover HDCP does not even specify any kind of infrastructure to accomplish this.

Maakuth2• 16 years ago

Yes, "allegedly". This is definitely good news if it's the real thing. I wonder how long does it take to confirm it's authenticity.

yock2• 16 years ago

I can't believe people are willing to assign any credibility to an anonymous dump of hex to pastebin.

mechanical_fish• 16 years ago

That's the wonderful thing about math. You can verify its correctness without reference to anybody's reputation or personal opinion. Indeed, that's pretty much the definition of math.

yock2• 16 years ago

Of course you can verify if it's valid, but that's remarkably short of what's being claimed here. Lots of folks here are talking as if this is the end of HDTV DRM. I'm simply advocating that someone with the means actually test it before we start singing "Ding Dong The Witch is Dead."

reduxredacted8• 16 years ago

Catch-22.

Credibility is less because it was posted anonymously as a dump of hex to paste-bin, therefore eliminating any authority that would come if this person was a well-known security researcher. If the author had credibility and wanted to use his/her reputation to make the post more credible, he'd have the pleasure of a herd of lawyers and law enforcement at his door, assuming that he lives in a country with anti-circumvention laws. So his only choice is to keep it to himself or post anonymously, taking away any credibility that comes with authority in a subject.

Regardless, someone will test this soon enough and determine if this non-credible post is credible or just a creative bunch of social engineering. That it's garnered this much attention this quickly (take a look at your major social news sites ... and tech blogs) should scare industry insiders. The mere HOPE that some random posting on pastebin would topple HDCP and bring a possible end to device interoperability would get this much attention truly highlights what a dismal mess HDCP is. If it's The Real Thing(tm), we'll know when the master key is used to generate a random device key and 80% of the time the signal is decrypted properly without having to turn both devices off and back on.

And if it is true, I hope our friend that posted it took some pretty serious precautions to protect his own anonymity.

bcl• 16 years ago

Has anyone verified that this actually works?

wmf2• 16 years ago

Time to light up the Bunnie signal.

js4all2• 16 years ago

The comments so far are just about HDCP, Blu-Ray and playback difficulties.

The paste however contains the key matrix used to encrypt and decrypt the digital video signal. If this is valid, every transmission between a HDCP-secured playback device and the display can be decrypted, thus rendering every other encryption method, used in the playback chain, useless, including AACS and BD+.

This is serious, because the keys for AACS can be revoked, if compromised. HDCP keys however can't be revoked.

bdonlan• 16 years ago

HDCP keys can be revoked. It just won't do any good - this matrix lets you create _new_ keys, just as valid as all pre-existing ones.

nitrogen3• 16 years ago

It doesn't completely render BD+ useless, as BD+ can be used to watermark the video signal according to the player model (and hypothetically other variables, like location, IP address, or player serial number). So, to avoid identification, pirates would need to crack BD+, or combine the output from multiple players to obscure the watermarking.

Another problem with cracking the transport instead of the storage medium, is that to rip from HDMI you have to play the movie at normal speed, while ripping straight from disc can be done much faster.

js4all2• 16 years ago

I agree with the second point.

Regarding on-the-fly watermarking, I see the hypothetical use, but current watermarking algorithms are to complex for BD+. An interesting idea though.

js2• 16 years ago

Here's a paper discussing how this key could have been derived:

http://www.cs.rice.edu/~scrosby/pubs/hdcppaper.ps

http://www.cypherpunks.ca/~iang/pubs/hdcp-drm01.pdf

Here's the fun bit:

"We observe that attackers can exploit a well-known cryptographic design mistake: the shared secret generation is entirely linear. The attack only needs 40 public/private key pairs such that the public key pairs span M ⊂ (Z/256Z)40, the module generated by all public keys. Since HDCP devices divulge their public keys freely, one can easily test whether a set of 40 devices have public keys spanning M before expending the effort to extract their private keys. With these keys, the authority’s secret can be recovered in only a few seconds on any desktop computer."

Edited to add the next paragraph (paper was published in 2001):

"The consequence of these flaws is that, after recovering the private keys of 40 devices, we can attack every other interoperable HDCP device in existence: we can decrypt eavesdropped communications, spoof the identity of other devices, and even forge new device keys as though we were the trusted center. Note that this allows us to bypass any revocation list or “blacklisting”: such mechanisms are rendered completely ineffective by these flaws in HDCP. Therefore we recommend that the current HDCP cryptosystem should be abandoned and replaced with standard cryptographic primitives."

nitrogen3• 16 years ago

Therefore we recommend that the current HDCP cryptosystem should be abandoned and replaced with standard cryptographic primitives.

So does this mean that all new equipment will quickly switch to DisplayPort, necessitating another round of TV/monitor upgrades? Or will the HDMI organization add DPCP (AES) to the HDMI standard?

[Edit: it was mentioned elsewhere* in the thread that HDCP 2.0 uses AES]

* http://news.ycombinator.com/item?id=1691794

reduxredacted8• 16 years ago

Worth noting (again, assuming this is credible): Version 2.0 of HDCP is likely not affected.

According to their FAQ: http://www.digital-cp.com/faqs "HDCP revision 2.0 uses industry-standard public-key RSA authentication and AES 128 encryption. It also supports protection of compressed content, making it feasible to use relatively slow 50 to 200 Mbps interfaces."

... and ...

"HDCP 1.x technology offers protection for uncompressed content transmitted over several common wired interfaces including DVI, HDMI and DisplayPort. HDCP revision 2.0 adds strengthened encryption..."

wmf2• 16 years ago

"The wireless interfaces which utilize HDCP revision 2.0 so far include: Digital Interface for Video and Audio (DiiVA), NetHD, Wireless Home Digital Interface (WHDI), and Wireless HD (WiHD)."

In other words, no equipment that anyone has.

b3b0p• 16 years ago

Comments keep mentioning Blu-ray playback, but it's referring to HDCP. That's the connection between devices I thought?

I don't think this does anything for Blu-ray as it has it's own encryption scheme.

Edit: Oops, I see someone mentioned this already. Missed that comment.

uuoc• 16 years ago

The Cory Doctorow info-graphic is quite appropriate here:

http://boingboing.net/2010/02/18/infographic-buying-d.html

toodoo• 16 years ago

And here come the T-Shirts http://www.cafepress.com/HDCP

nitrogen3• 16 years ago

I was a minor participant in the tvtime project years ago. HDMI and HDCP came around and made that kind of thing highly improbable for HD content. CPUs and GPUs are now at speeds that make advanced HD video manipulation practical. I hope this HDCP crack, if verified, makes a tvtime-like application for HDMI video possible. Better yet, a PC-based realtime compositing and overlay system, requiring only a $100 GeForce GPU and HDMI capture cards.

HDCP master key allegedly posted

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