  There is solid observational evidence on the existence of massive, $M\sim
1~M_\odot$, highly magnetized white dwarfs (WDs) with surface magnetic fields
up to $B\sim 10^9$ G. We show that, if in addition to these features, the star
is fast rotating, it can become a rotation-powered pulsar-like WD and emit
detectable high-energy radiation. We infer the values of the structure
parameters (mass, radius, moment of inertia), magnetic field, rotation period
and spin-down rates of a WD pulsar death-line. We show that WDs above the
death-line emit blackbody radiation in the soft X-ray band via the magnetic
polar cap heating by back flowing pair-created particle bombardment and discuss
as an example the X-ray emission of soft gamma-repeaters and anomalous X-ray
pulsars within the WD model.
