  We present an active cloaking method for the parabolic heat (and mass or
light diffusion) equation that can hide both objects and sources. By active we
mean that it relies on designing monopole and dipole heat source distributions
on the boundary of the region to be cloaked. The same technique can be used to
make a source or an object look like a different one to an observer outside the
cloaked region, from the perspective of thermal measurements. Our results
assume a homogeneous isotropic bulk medium and require knowledge of the source
to cloak or mimic, but are in most cases independent of the object to cloak.
