  We revisit in detail the paradox of black hole information loss due to
Hawking radiation as tunneling. We compute the amount of information encoded in
correlations among Hawking radiations for a variety of black holes, including
the Schwarzchild black hole, the Reissner-Nordstr\"{o}m black hole, the Kerr
black hole, and the Kerr-Newman black hole. The special case of tunneling
through a quantum horizon is also considered. Within a phenomenological
treatment based on the accepted emission probability spectrum from a black
hole, we find that information is leaked out hidden in the correlations of
Hawking radiation. The recovery of this previously unaccounted for information
helps to conserve the total entropy of a system composed of a black hole plus
its radiations. We thus conclude, irrespective of the microscopic picture for
black hole collapsing, the associated radiation process: Hawking radiation as
tunneling, is consistent with unitarity as required by quantum mechanics.
