Mysterious taglines

[Maurice Valmont]

At 04:55 PM 8/5/98 -0700, Tim May <tcmay at got.net> wrote in his .sig:

>"The tree of liberty must be watered periodically with the blood of
>tyrants...."

I suspect this is unlikely to happen until the oppressed realize that the
tree 
of liberty needs also be watered with the blood of patriots.

>Crypto Anarchy: encryption, digital money,
>anonymous networks, digital pseudonyms, zero
>knowledge, reputations, information markets,
>black markets, collapse of governments.

I'm curious: What exactly is "zero knowledge"?