Wow. Interesting that the legal community even talk about this.
I don't see where the problem is.
One of the most basic rules is that a suspect does not have to self-incriminate. He cannot be forced to give away information that would cause him harm. If giving away his PGP key might do that, then that's it. End of story. I don't see how this could be compared to handing over a "phyical key". A passcode is clearly non-physical, therefore "information". I am surprised that this actually had to be decided by a judge. This should be something any DA should have learned in the first 2 hours of their penal processual law course. At least, that's the case in Germany.
As a sidenote: I am also surprised that a suspect could be compelled to hand over physical objects in the USA. In Germany, this also falls under self-incrimination. The reason why it surprises me is that, if a suspect could be forced to hand over objects to incriminate him, why do we need things like search warrants? Why not simply walk up to the suspect and detain him until he hands over the evidence? It would save the cops a lot of time searching thru his stuff. I hope that makes the absurdity of this clear.
Another sidenote: The comparison to a suspect being forced to submit to fingerprinting and DNA sequencing is not valid. In these instances, because it is not about the suspect giving the information to finding evidence, but providing evidence that is basically in plain sight. I.e. his DNA or fingerprints are not hidden but already there and can be taken (by force if necessary). The cops know where it is (in his cells/on his fingers). In contrast to this, if an object is hidden, the cops do not know where it is (obviously), so the emphasis is not on the object itself but on the information of where to find it.
Another reason why the comparison with a physical key just doesn't work is also a very simple one: If the suspect refuses to hand over the key to a safe for example and the cops think there is evidence inside, there is nothing easier than acquiring a search warrant which also involves opening that safe the old fashioned method in case of refudal to hand over the key = a strong drill and a cutting torch. So the question whether a suspect can be forced to hand over a physical key is really a moot point (and this example makes even more obvious the difference between the object and information about its location).
