Warp wrote:
>   Btw, one interesting application of assymetric encryption is adding
> signatures to files.

When I was at Bellcore, there was a lot of cool research expanding this. 
They had for example what they called "face to face encryption." I could 
have an encrypted conversation with you, and I'd know 100% sure it was you, 
you'd know 100% sure it was me, but nobody outside the conversation could 
prove either of us had actually said anything, just like a face-to-face 
conversation. I can't prove you said anything in that conversation, and I 
might have made up the whole conversation from scratch, even if I give a 
judge the whole stream of conversation and every key I have. But I still 
know with certainty that it was you (or at least your key) on the other side 
of the conversation.

They also had a timestamping service, where hashes were chained together, 
and then published in (for example) the New York Times every couple of 
weeks, whereby you could prove that you'd had a certain piece of text at a 
certain point in time without revealing that text to the timestamp service.

Lots of cool stuff can be put together with layers of the basic primitives.

> It's ROM will refuse to run anything that hasn't been signed by Sony, and

The set-top box I'm using has the same thing. I have to sign every compile 
before the machine will boot. And there's separate chips for developers and 
production, so the developers can't get to the production keys. :-)

-- 
   Darren New, San Diego CA, USA (PST)
   "We'd like you to back-port all the changes in 2.0
    back to version 1.0."
   "We've done that already. We call it 2.0."

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