JSignPdf is a open-source Java application which adds digital signatures to PDF documents.
Used as a standalone application or as an Add-On in OpenOffice.
visible signatures – image and/or description located visualy in a PDF file (page and position can be specified)
several different keystore types
timestamps from authority in signature (TSA)
certificate validation through CRL and/or OCSP
setting certification level
setting hash algorithm
PDF encryption and setting rights