  The diffusion of charged particles in a graph can be modeled using random
walks on a weighted graph. We give strategies to hide (or cloak) changes in a
subgraph from the perspective of measurements of expected net particle charges
made at nodes away from the cloaked subgraph. We distinguish between passive
and active strategies, depending on whether the strategy involves injecting
particles. The passive strategy can hide topology and edge weight changes. In
addition to these capabilities, the active strategy can also hide sources of
particles, at the cost of prior knowledge of the expected net particle charges
in the reference graph. The strategies we present rely on discrete analogues of
classic potential theory, that include a Calder\'on calculus on graphs.
