  Recently it was found that scrambled information can be partially recovered
by a time-reversed evolution, even after being damaged by an intruder. We
reconsider the origin of the information recovery, and argue that the presence
of classical chaos does not preclude it and only leads to a quantitative
reduction of the recovery ratio. We also show how decoherence (i.e.
entanglement with the intruder) limits the recovery, by proving an upper bound
on the recovery ratio in terms of the entangling power of the intruder's
action.
