Wed 14th October 2009, 3:27pm
QUOTE(Krimpet @ Wed 14th October 2009, 4:13am)
Well, speaking of "hiding" things in pictures, back in 2007 it was discovered that a ring of file sharers was uploading pictures with steganographically
hidden files inside. It seems users of a something-or-other-"Chan" message board were sharing pirated e-books with each other, and hit upon the idea of using Wikipedia as a free file host by hiding them in pictures they uploaded. It was pretty clever; we probably wouldn't have found out had a participant on the message board not ratted 'em out. Theoretically, it's impossible to stop, save for disallowing image uploads completely.
Somehow I doubt the file host could realistically be held liable for something which is by definition undetectable unless one already knows what they are looking for.
However in an IP-doomsday scenario where this is deemed something to worry about, it seems like it would be easy enough for the server to resample all raster images upon upload in a way that makes no difference visible to the human eye, but garbles enough of the hidden data to make it useless. That is, unless the hidden data is in fact another (super-imposed) photo...
Of course SVG's would be a whole other can of worms...