Polynomial approximation of bilinear Diffie-Hellman maps

The problem of computing Bilinear-Diffie-Hellman maps is considered. It is shown that the problem of computing the map is equivalent to computing a diagonal version of it. Various lower bounds on the degree of any polynomial that interpolates this diagonal version of the map are found that shows that such an interpolation will involve a polynomial of large degree, relative to the size of the set on which it interpolates.