[Twisol]

"Minimum information" is much more accurate than "zero information". A necessary condition for a good cryptographic hash function F is that F(X) is a uniform distribution if X is a uniform distribution. This is a property of F, not of X, which is where the article is a bit muddy.

The article seems to want to say that "zero information" ought to be a probability distribution such that for all functions f, f(X) is the same zero-information distribution, i.e. from nothing we get nothing. The point is that no such X exists, because every probability distribution encodes some amount of information. What we want is some function F such that for every X in a large class of probability distributions, F(X) is uniform. Which is exactly why x^2 is a terrible hash function.