What do you make of the argument that if you give the police your phone, you are in fact fully cooperating by giving them all data on that phone, and it's not y

What do you make of the argument that if you give the police your phone, you are in fact fully cooperating by giving them all data on that phone, and it's not your fault if they don't have sufficient information to interpret that data? To take a different example, if Bob is writing things down in a notebook, but using some kind of secret language or code that he made up, it seems pretty clear that while the police have the right to seize the notebook, Bob correspondingly has the right to refuse to translate for law enforcement. Similarly, maybe Bob's code is a little more complicated, and requires using a calculator to compute what each codeword should be. It still seems like Bob has a right not to answer. Is using a computer rather than a calculator to do the encryption the final straw?