I&#x27;m going to assume from the context is what they actually did was use a crypto-grade RNG to introduce bumps into the geoid surface.  That is, instead of everything being 2 meters to the west (or whatever) things were randomly offset from their reported positions.<p>You could &quot;map&quot; the whole thing or somehow steal the source and crypto parameters in order to transform between geoids, but you couldn&#x27;t do something simple like subtraction.