Ideal hash functions Theorem Let Fx, r be an ideal family of hash functions If h is a random function in ek, r and yo is the subset of queried messages then Pr[ h(x)=y]=1/M for all x in X 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