Again, the best analog is a document handwritten in a made-up cipher. If someone finds a paper in a notebook that looks like it contains useful information but

Again, the best analog is a document handwritten in a made-up cipher. If someone finds a paper in a notebook that looks like it contains useful information but the actual glyphs used are unreadable to the masses, or the order of the letters are scrambled, or whatever other personal encryption scheme the defendant used when he wrote that note, can the government compel the defendant to reveal the key to his personal cipher? Can the government compel the defendant to not hand over the key to the cipher but provide a decoded interpretation of the message? That is the correct analogy for this situation much more than safes or doors. Computer encryption is the same thing, just uses a common cipher and the information is encrypted millions of times faster than a human could crypt by hand.