If strong crypto were illegal

Curriously the chip ostensibly makes it nearly impossible
for the government to prove that you are using strong crypto
on top of skipjack (Clipper).
 
I suppose that the a govenrment agency could use a trap-door
to discover that plain text was not plain, then get a warrant,
then present evidence that you were using strong crypto.
Such might eventually lend credence to the belief that there
was a trap-door.