> Symetric cryptography does a much easier thing. It combines data and some 
> mysterious data (key) in a way that you cannot extract data without the 
> mysterious data from the result. It's like a + b = c. Given c you need b to 
> find a. The tricks that are involved are mostly about sufficiently mixing 
> data, to make sure there's enough possible b's to never guess it correctly 
> and that all those b's have the same chance of being the one b. Preferably 
> even when you have both A and C, but that's really hard. 
> So I'd say Bruce said that in an effort to move to more well understood 
> cryptography. It is also a way to move people towards simply better 
> algorithms, as most public key systems are very, very bad.

Funny. I would have said exactly the opposite: public key crypto is much better 
understood because it is based on mathematical theorems and reductions to 
(admittedly presumed) hard problems, whereas symmetric crypto is really a black 
art that mixes some simple bit wise operations and hopes for the best (yes, I 
know this is a bit of caricature...)

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