Q: How can I add a digital signature to a document using Qoppa’s java library jPDFSecure?

A: This Java program loads a document, then loads a digital ID from a PKCS#12 file, and then creates and signs a signature field on the first page of the document.

 // Load the document
PDFSecure pdfDoc = new PDFSecure ("input.pdf", null);
// Load the keystore that contains the digital id to use in signing
FileInputStream pkcs12Stream = new FileInputStream ("keystore.pfx");
KeyStore store = KeyStore.getInstance("PKCS12");
store.load(pkcs12Stream, "store_pwd".toCharArray());
// Create signing information
SigningInformation signInfo = new SigningInformation (store, "key_alias", "key_pwd");
// 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 ("output.pdf");

Download Full Java Sample Code to Sign a PDF

You can create a sample PKCS#12 file using Java’s keytool program. The command line to create a test file is as follows:

keytool -genkey -keystore test.pfx -storetype pkcs12 -storepass store_pwd -keypass key_pwd -alias key_alias