This is a sample java program showing how to sign a PDF document using a certificate loaded from a p12 file. The signature appearance is customized with an image, signer’s name and date. A signature field is added to the PDF document and then signed. This code uses jPDFSecure library but could very easily be adapted to use jPDFProcessby replacing PDFSecure with PDFDocument.

// Load the document
PDFSecure pdfDoc = new PDFSecure ("C:\\test\\myfile.pdf", null);
// Load the keystore that contains the digital id to use in signing
// which can be loaded from a pfx file, a p12 file, etc... 
FileInputStream pkcs12Stream = new FileInputStream ("C:\\test\\Leila.p12");
KeyStore store = KeyStore.getInstance("PKCS12");
store.load(pkcs12Stream, "mypassword".toCharArray());
// Create signing information using the "Leila" alias
SigningInformation signInfo = new SigningInformation (store, "Leila", "mypassword");
// Customize the signature appearance
SignatureAppearance signAppear = signInfo.getSignatureAppearance();
// Show an image instead of the signer's name on the left side of the signature field
// Only show the signer's name and date on the right side of the signature field
// Create signature field on the first page
Rectangle2D signBounds = new Rectangle2D.Double (36, 36, 144, 48);
SignatureField signField = pdfDoc.addSignatureField(0, "signature", signBounds);
// Apply digital signature
pdfDoc.signDocument(signField, signInfo);
// Save the document
pdfDoc.saveDocument ("C:\\test\\output.pdf");

This is a preview of what the electronic signature looks like on the page of the signed PDF:

This is the signature as it appears on the PDF page. The green page was the image chosen. The right side shows “Digitally signed by” with the signer’s name and the signature date.