On 26/04/07, der Mouse <mouse at rodents.montreal.qc.ca> wrote:
Surprisingly,
I've had students who had been taught that ALL one-way
functions are completely and totally uncrackable.
I don't find that surprising - which fact I find somewhat depressing.
Actually, couldn't one argue that if the function is crackable, it is
not one-way?
if f(A) = C and we can find B s.t. f(B) = C then the function is NOT
one-way for B.
Thus, unless you have a reliable way of determining if A is NOT in a
set comprising of all values that can be found by some hypothetical
f^-1() you do not have a one-way function. (Brute force exhaustive
search doesn't count, IMHO)
Thus, all one-way functions are uncrackable. But there are fewer
one-way functions than one would think...
Joe.