RGhost is a document creation and conversion API. It uses the Ghostscript framework for the format conversion, utilizes EPS templates and is optimized to work with larger documents. Support(PDF,PS,GIF,TIF,PNG,JPG,etc)
Haha, I just saw this too. Maybe it's an old copy/pasta error from RGhost::PdfSecurity, perhaps? Not having the original source history (from when it was moved from SVN) make digging too deep impossible.
https://github.com/shairontoledo/rghost/blob/master/lib/rghost/document.rb#L324-L334