  We study the fidelity of information retrieval in the black hole final state
model by taking into account the interactions between the collapsing matter and
the infalling Hawking radiation inside the event horizon. By utilizing a
scrambling unitary operator to model these interactions, our direct
calculations suggest that the information is almost lost during the process of
black hole evaporation. We then proceed to employ the Yoshida-Kitaev decoding
strategy for information retrieval. Although we observe a finite improvement in
decoding fidelity, it does not reach unity. This indicates that the issue of
unitarity in black hole evaporation may not be fully resolved within the
framework of the final state model.
