  We derive black hole entropy based on the near-horizon symmetries of black
hole space-times. To derive these symmetries we make use of an $(R,T)$-plane
close to a Killing horizon. We identify a set of vector fields that preserves
this plane and forms a Witt algebra. The corresponding algebra of Hamiltonians
is shown to have a non-trivial central extension. Using the Cardy formula and
the central charge we obtain the Bekenstein-Hawking entropy.
