Ideal hash functions Theorem Let Fx, be an"ideal"family of hash functions If h is a random function in Fx, Y and Xo is the subset of queried messages then Prl h(x)=y]=1/M for all x in Xo and all y in Y, where m is the cardinality of y.10 Ideal hash functions Theorem Let FX,Y be an “ideal” family of hash functions. If h is a random function in FX,Y and X0 is the subset of queried messages then Pr[ h(x)=y ] = 1/M for all x in X\X0 and all y in Y, where M is the cardinality of Y