Question about the Clipper Chip

["Paul Elliott" <paul.elliott@hrnowl.lonestar.org>]

I have heard that the Clipper Chip is only supposed to be used
for voice applications. Does anyone know if  the inputs and outputs
of the Clipper Chip digital or analog? That is does the clipper
chip input/output an analog signal with some sort of internal
analog to digital converter or does have purely digital inputs
and outputs?

The reason I ask is, if the chip does analog IO, then it
would be possible for the chip to be designed to deliberately
leak its own key disguised as a measurement error in the
low bits of the analog to digital/analog conversion.