
It just occurred to me why the algorithm is secret.  If it were
published, one could then build physically identical clone versions
of the chip that would interoperate with official Clipper chips.  But
the cloner wouldn't provide the keys to the escrow houses.  Hmmn.

Or is there a technical hack that I've missed?  E.g. how about if the
chips were made unprogrammed but serialized, and then shipped to the
two escrow houses who programmed in their halves of the keys, but
in a way that requires that secret keys known only to the escrow houses
be installed as well, without which clone versions wouldn't
interoperate?  This is getting awfully complicated, but that's
crypto for you.
