In particular this also means that a message can not contain hidden information that the signer is unaware of, and that can be revealed after the signature has been applied.
While invisible to the naked eye, metadata -- or hidden information within documents -- can actually cause more damage if exposed than the visible data would.
This granulation-based fitness approximation scheme is applied to solve various engineering optimization problems including detecting hidden information from a watermarked signal in addition to several structural optimization problems.