[mikorym]

I think what I have in mind is essentially a customisation option. And I think your answer (and others) does make a good case that there is not a more general solution to this at the moment (and not even conceptually).

As a custom solution there are many ways to solve this if we introduce a third parameter (such as simply encrypting your files with a password). I think however the point that many people are making is that the debate is about what the default should be, and without introducing a third factor.

The two step de-hash case (IP hash + salt) suggests interesting research topics on whether there are ways to have other combinations e.g.: (IP hash + x) or (IP hash + x + y) but with the assumption that we don't want any further apriori information. The point that you are making is that in fact we only have one variable (the IP) and the salt is simply a obfuscation step. Any other approach requires more parameters (hardware, fingerprints, etc.).