 vpokoPremium
join:2003-07-03
Boston, MA | Wow, I didn't realize it had such a glaring weakness What's the purpose of a "processing key"? Why introduce a weakness like that into their protocol? |
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| The processing key is the Bob of the Alice and Bob crypto schema. In order to encrypt a disc, you need two things, a public key (alice) and a private key (alice). For Bob to decrypt something from alice, he needs to know Alice's public key (i.e. the HD-DVD). That's what the studios are looking to 'blacklist', so if a player is compromised, they could make the new dvd's NOT work with that player. Thus, every HD-DVD and Blu-Ray contains a section of 'disabled' players (public keys).
If what he said is correct, he's found alice's PRIVATE key. With that key, you don't need to care about the public key. EVERY DVD uses the private key, so you can decrypt everything.
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said by vpoko:What's the purpose of a "processing key"? Why introduce a weakness like that into their protocol? I can't remember the source of the information (Ed Felton maybe, at Freedom to Tinker?), but if you read the history of these DRM methods, it appears that some decisions have been made based on things such as how many circuit cards would be needed to implement the DRM - the circuitry for really robust DRM would take 2 ckt boards, but this would add cost and the decision was made to go with a one ckt board, less robust "protection" to keep costs down.
I'm not saying that's why this weakness occurred, just that these DRM schemes are so easily compromisable sometimes because of decisions like these. |
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vpokoPremium
join:2003-07-03
Boston, MA | reply to karlmarx
said by karlmarx:The processing key is the Bob of the Alice and Bob crypto schema. In order to encrypt a disc, you need two things, a public key (alice) and a private key (alice). For Bob to decrypt something from alice, he needs to know Alice's public key (i.e. the HD-DVD). That's what the studios are looking to 'blacklist', so if a player is compromised, they could make the new dvd's NOT work with that player. Thus, every HD-DVD and Blu-Ray contains a section of 'disabled' players (public keys). If what he said is correct, he's found alice's PRIVATE key. With that key, you don't need to care about the public key. EVERY DVD uses the private key, so you can decrypt everything. I don't claim to be a crytologist, but I think I'm missing something from your explanation. In asymmetrical encryption, there are two keps. Private and public. Something is encrypted with one, and then decrypted with the other. The key that did the original encryption can't also be used to decrypt the cyphertext. |
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 peter_mPremium
join:2005-07-13
Canada, QC | reply to vpoko
Ever seen a downloadable movie before it was ever released in theatres???? Well, DRM is just one aspect. The problem also resides with industry insiders. A combination of DVD screeners and DVD masters end-up on the net....
The solution is not DRM. Just like for music, DRM hinders and limits the honest users and not the crooks. If the price is right, people will stop bothering with pirated copies... If you ask me, it's a shame to pay 25$ for movies like "click". |
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vpokoPremium
join:2003-07-03
Boston, MA | reply to vpoko
said by vpoko:What's the purpose of a "processing key"? Why introduce a weakness like that into their protocol? But I'm just wondering about the DRM - this crack has nothing to do with masters or other unencrypted content. |
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