There are free programs available to create digital signatures with certificates on PDF documents:
GUI and commandline tool for Linux, OSX, and Windows
A command-line application written in Java which allows to add an invisible signature to PDF documents
A Java application which adds digital signatures to PDF documents. It can be used as a standalone application or as an Add-On in OpenOffice.org
- license: GNU LGPL
A Java GUI application which lets you open PDF documents and add visible and invisible digital signatures to them. Supports smartcards. Available for Windows, Mac and Linux.
CAcert PDF Signer
Command-line tool only for Linux, OSX, and Windows
Nautilus Script for PdfSigner: http://svn.cacert.org/CAcert/Software/PdfSigner/pdfsigner-nautilus.sh
Supports Smartcards and Timestamping
PDF Writer and Signer
- Java 1.6+ library
PDFCreator easily creates PDFs from any Windows program.Use it like a printer in Word, StarCalc or any other Windows application.
- Adobe´s documentation on PDF Security:
- A new software, which I haven´t tested yet:
OpenOffice feature request with voting: