  The weak gravitational lensing of high redshift type Ia supernovae has the
potential of probing the structure of matter on galaxy halo scales. This is
complementary to the weak lensing of galaxies which probes structure of larger
scales. There are already several organized searches for these supernovae being
carried out for the purposes of cosmological parameter estimation. A method is
proposed for extracting from future supernovae data information on lensing and
the structures responsible. This method utilizes the correlations between SN
luminosities and foreground galaxies. Simulations of the lensing and
uncertainties will be presented. It is found that with a hundred supernovae or
more at $z\simgt 1$ or larger, significant measurements of the mass, shape and
extent of dark matter halos could be made if they contain a significant
proportion of the matter in the universe.
