  A battery charging policy that provides privacy guarantees for smart meter
systems with finite capacity battery is proposed. For this policy an upper
bound on the information leakage rate is provided. The upper bound applies for
general random processes modelling the energy consumption of the user. It is
shown that the average energy consumption of the user determines the
information leakage rate to the utility provider. The upper bound is shown to
be tight by deriving the probability law of a random process achieving the
bound.
