On Thu, 19 Feb 1998 18:59:25 -0800 (PST), you wrote:
I can hardly believe that any of these schemes are undefeatable.
As soon as the CPU starts talking to a video and sound board, this whole thing becomes easily breakable. All one needs to do is to capture the signals that go to these boards and re-record them.
In general, there's no way of building a secure system that prevents copying of information, but permits its consumption. The two are too closely related.
The best you could do is a tamper-resistant hardware key on the audio/video card. (This locks you into a design where the content is decoded on the card, which may be suboptimal.) And anyone who can crack the crypto chip can get unprotected digital copies and distribute them. This is probably doable by the same kind of people who set up pirate CD factories.
<snip> Ala VideoCypher from the 80's. It didn't take much to cause the cpu in the box to spill its guts. Then again, it may have been because the cpu was from TI. -Doug ------------------- Douglas L. Peterson mailto:fnorky@geocities.com http://www.geocities.com/SiliconValley/Heights/1271/