On Sun, Jul 12, 2015 at 6:22 PM, R0b0t1 <r03...@gmail.com> wrote: > > But, simpler: if you combine a random stream of data with what is on the > drive, the result looks just like random data. You need only overwrite the > drive once.
I think that assumes that the two get averaged together in some way and cannot be separated. If you could determine the orientation of individual magnetic domains it is possible that you might be able to determine which ones are which. For example, if in a given location you found 90% of the grains had one orientation, and 10% had another, you might be able to infer that the 10% was the previous value of that location. That probably isn't practical with current technology, but I see no reason that it should be impossible. -- Rich
