public static PdfStamper createSignature(PdfReader reader, java.io.OutputStream os, char pdfVersion, java.io.File tempFile, boolean append) throws DocumentException, java.io.IOExceptionApplies a digital signature to a document, possibly as a new revision, making possible multiple signatures. The returned PdfStamper can be used normally as the signature is only applied when closing.A possible use for adding a signature without invalidating an existing one is:KeyStore ks = KeyStore.getInstance("pkcs12"); ks.load(new FileInputStream("my_private_key.pfx"), "my_password".toCharArray()); String alias = (String)ks.aliases().nextElement(); PrivateKey key = (PrivateKey)ks.getKey(alias, "my_password".toCharArray()); Certificate[] chain = ks.getCertificateChain(alias); PdfReader reader = new PdfReader("original.pdf"); FileOutputStream fout = new FileOutputStream("signed.pdf"); PdfStamper stp = PdfStamper.createSignature(reader, fout, "", new File("/temp"), true); PdfSignatureAppearance sap = stp.getSignatureAppearance(); sap.setCrypto(key, chain, null, PdfSignatureAppearance.WINCER_SIGNED); sap.setReason("I"m the author"); sap.setLocation("Lisbon"); // comment next line to have an invisible signature sap.setVisibleSignature(new Rectangle(100, 100, 200, 200), 1, null); stp.close();