Nick Odell posted
I'm not a big data user: all the sensitive data I own can be contained
in one memory stick. In fact all the sensitive data I own IS contained
in one, hardware encrypted, password protected ten-false-guesses-and-it
wipes-itself memory stick.

I can't possibly memorise the password so when I travel abroad, I write
it down on a piece of paper......

...and post it in advance to my destination address. It's quite safe
because the paper is useless without the memory stick and the memory
stick is useless without the piece of paper. Apart from thwarting any
bad actors and possibly annoying people at immigration control am I
doing anything illegal by being unable to divulge a password I don't know?

The pertinent question is not whether you are doing anything illegal but
whether you can be convicted. And the answer to that [in the UK] is, yes
you can, because a court will assume that you know the password, unless
you can persuade them otherwise.

Moreover, if you try this at US immigration, they will probably just put
you on the next flight back without even arguing about it, because they
can.
--
Evremonde