  Miniati and Bell (2011) proposed a mechanism for the generation of magnetic
seeds that is based the finite resistivity of the low temperature IGM in the
high redshift universe. In this model, cosmic-ray protons generated by the
first generation of galaxies, escape into the intergalactic medium carrying an
electric current that induces return currents, $j_t$, and associated electric
fields, $\vec E=\eta\vec j_t$ there. Because the resistivity, $\eta$, depends
on the IGM temperature, which is highly inhomogeneous due to adiabatic
contraction and shocks produced by structure formation, a non-vanishing curl of
the electric field exists which sustains the growth of magnetic field. In this
contribution we have developed an approximate numerical model for this process
by implementing the source terms of the resistive mechanism in the cosmological
code CHARM. Our numerical estimates substantiate the earlier analysis in
Miniati and Bell (2011) which found magnetic seeds between 10$^{-18}$ and
10$^{-16}$ Gauss throughout cosmic space at redshift z~6, consistent with
conservative estimates of magnetic fields in voids at z~0 from recent gamma-ray
experiments.
