I can't think of any good, practical way to do it.
Theoretically, running the software on a server in Sealand or something like that would put the physical hardware beyond the reach of a subpoena but then, they could lock you up for contempt if you don't give your password to it.
Theoretically, running the software on a server in Sealand or something like that would put the physical hardware beyond the reach of a subpoena but then, they could lock you up for contempt if you don't give your password to it.