This whole encryption/warrant issue makes me ponder:
Imagine you killed someone. Shot them dead with a pistol. Questionable/bad shooting. You get charged, you make bail. The State is building charges against you, but they don't have the murder weapon.
You know where you put the pistol. The prosecution doesn't. They have a warrant for your home, vehicle, workplace, etc. Search comes up empty.
They don't have a warrant for your HEAD. For your information.
Is it destruction of evidence if you don't tell them where the pistol is? Is it a crime to not tell where the pistol is? Compelling to tell where it is, is involuntary testimony against self.
With the proviso that I am not an attorney -- I am an author, editor, and native speaker of English who owns more than one dictionary. It cannot be destruction of evidence if you have not destroyed evidence. If they want to charge you with destruction of evidence, they have to be able to prove that you destroyed evidence. "We can't find it" is not proof that you destroyed it.
Or even a step further. You have a safe full of firearms. You send one off to a gunsmith for some work. You are somehow associated with a crime you didn't commit. The police have a warrant for all your firearms. They come and empty out your safe. They're testing them against the crime scene in question. Weeks/months go on. Your gunsmith notifies you that your pistol is done with work. Are you compelled to tell the police about this firearm? It's certainly not in your best interest, and it's information in your head. Compelling this information is basically testimony against self.
You answered your own question. The 5th amendment says that no person shall be compelled to be a witness against himself in a criminal proceeding. Ironically, there has been case law precedent to the effect that criminals carrying guns illegally are not required to admit that they are carrying, because that would be incriminating, yet citizens carrying lawfully with (or without) a permit cannot decline to answer, because admitting they are carrying would NOT be incriminating.
As dogmush pointed out -- it would hinge somewhat on the exact wording of the warrant. In general, search warrants must spell out the exact place to be searched and the item or items expected to be found. If the warrant follows that pattern (as it should), it would be a warrant to search a 2-story residential structure at 127 Elm Street, for firearms owned or possessed by Mr. AZ Redhawk. If they don't ask the judge for a warrant to look for guns at a gunsmith's shop -- they don't have permission to get guns at a gunsmith's shop.
