Power Analysis: A Complete Break of the KeeLoq Code Hopping Scheme (2008) [pdf]
emsec.ruhr-uni-bochum.de
emsec.ruhr-uni-bochum.de
I can only imagine that shielding a device intended to be a radio transmitter would not be an easy proposition. :)
Would it really be that much of an improvement to remove one vector when there is another equally good vector immediately available?