To tell the truth I had never heard of 'ksig' until you opened this topic.
From a search at packages.debian.org: http://packages.debian.org/search?keywo ... ection=all
it looks like ksig was a KDE3 package/app and wasn't carried over to KDE4.
There might be a KDE4 app that performs the same function as 'ksig', but I'm not sure what it is. (Danum might know)