BlackBerry(QNX) App for signing with a certificate pdf files

App for BlackBerry (for QNX) that does the follow: "Sign Electronically PDF documents using the Blackberry device" - Development of a system that sign a PDF file. To sign the PDF file you must use a certificate. Certificates can be in .PFX or .P12 format. - Won't be necessary to develop any kind of access to any web service, all files (original PDF, signed PDF and certificates) must reside in the file system of the Blackberry phone. Path must be hardcoded. - The GUI must be simple, there should be a button that performs the functionality of signed.