|Originally posted by trbarry:
That's an interesting point and I guess I'm too lazy to go look it up.
Will 5C/DTCP send non copy protected material to an unauthorized box? Or will it refuse to talk at all?
To get a 5C source of a copy-protected program to talk to you, you must initiate an Athentication and Key Exchange (AKE) sequence. During this, you present credentials proving your right to receive the data that you've asked for which can be checked by the source. You're also supposed to check the credentials of the source and refuse to talk to it if it doesn't pass muster. Both you and the source check to see if you're on each other's current Certificate Revocation Lists, and if one finds the other there, it is not to communicate with it. There are two types of AKE--Full AKE, required for reception of "Copy Never" content, which uses a public-key scheme with very long keys and some hairy algorithms, and Restricted AKE, which is all that's required to receive "Copy One Generation" or "Copy No More" (replayed "Copy One Generation") stuff, which involves four sets of shared 64-bit secret keys. This last would be a lot easier to break, but not trivial and is designed for recorders other than PVRs, which typically have limited computational capability. Such recorders aren't given the public/private key stuff it takes to acheive Full AKE, so they can never establish a connection to receive "Copy Never". PVRs will be provisioned with such, since people will want to watch "Copy Never" through them for the pause and rewind capability, though they won't be allowed to archive it.
"Copy Freely" content is not encrypted and does not require any AKE, so you could probably write a program for a computer firewire interface to request and record such from a 1394/DTCP source. You could write a program to receive copy-protected data if you had stolen keys and the secret portions of the DTCP protocol, but that would be illegal under the DMCA. Stealing the keys would probably break other laws as well.
-- Mike Scott
[This message has been edited by michaeltscott (edited 10-02-2001).]