Re: An old but solved problem
Plus what if the server routinely alters uploaded pictures, potentially mangling most stego?
That's why most image sites do it. Sites such as FB would otherwise become a conduit for stego messages by every crook on the planet. The only problem is that they mangle too much - some data is illegal to mess with, and some lawyers are waking up to the rather large financial potential that has (and it could not happen to a nicer set of organisations, so I gave that awakening a leg up when I talked to a group of lawyers a while back :) ).