In fact, the article is not talking about "signature", but a declaration. A signature can not be reproduced, and is used to identify the creator, so before the "digital signature" is supported, wiki does not support the real signature.
With a digital signature, the information can not be reproduced, and its integrity is guaranteed. A digital signature is not a picture, not hand made, but a result of a pretty complex tool as PGP, GPG, etc. —The preceding comment was added by jackiszhp (comments • contribs) .