What is a Pricing Function
A pricing function is a function of the form y=f
(x) or a relation R such that pair (x,y) satisfies it, with the property that it is moderately hard (but not intractable) to compute, yet easy to verify.
The formal definition given by Cynthia Dwork∞
and Moni Naor∞
in their paper "Pricing via Processing or Combatting Junk Mail"∞
is reproduced below:
A function f
is a pricing function if:
- f is moderately easy to compute
- f is not amenable to amortization: given l values m1 Â
ml, the amortized cost of computing f(m1) Â
f(ml) is comparable to f(mi) for any 1<=i<=l
- Given x and y it is easy to verify y = f(x)
A difference parameter
can be used to make the function harder
to compute for the sender.
are pricing functions.