I can't begin to make sense of your scenario.
I'm sorry, let me be more explicit. You wrote that forcing a defendant to disclose the contents of his mind was unconstitutional, but forcing a defendant to disclose the contents of his mind and running it through an automated process was OK. According to what you wrote, you think a court cannot order a defendant to "tell us where you hid the body" because it comes solely from his mind, but a court
could order the defendant to do this
"Go through this PDF file of a dictionary, picking out the sentences word-by-word that tell us where you hid the body. Type the page number and number of the word on that page in to this program. When you are done, the program will automatically produce the sentences telling us how to find the body."
You claim this is acceptable because the result it isn't produced solely from information in the defendant's mind.
In practice, don't you just order them to produce the documents you want? The physical thing, I mean. So, for example, if the judge ordered I produce "all documents I have related my association with the KKK" and I gave him a bunch of shredded papers, I don't suppose the judge would have any difficulty seeing through my ruse and finding me guilty of interfering with an investigation (or worse).
You're missing the point. The files were not encrypted after the seizure order, but well before. It's not a ruse. It's as if the judge ordered that you "all documents I have related my association with the KKK" and you say "I take the 5th, I will not say whether or not I had any association with the KKK. I shredded all my documents weeks before this investigation started. I've given you all the output from my shredder."
If it were within my power to reconstruct those shredded papers, wouldn't the obligation be on me to do so?
How is that different from "If it were within my power to take the police to the body, wouldn't the obligation be on me to do so?"
Remember, in the U.S. justice system, a defendant does not have to prove his innocence.
Again, in this I am discussing a "fishing expedition" by the government, not one where they already have evidence that a crime been committed and more evidence is stored in the encrypted data. In a "fishing expedition" the government has no evidence that you committed the crime, but are hoping that there's evidence in the encrypted data.