PDF with an unsigned signature field : Security « PDF « Java Tutorial

import java.io.FileOutputStream;

import com.lowagie.text.Document;
import com.lowagie.text.Paragraph;
import com.lowagie.text.pdf.PdfAcroForm;
import com.lowagie.text.pdf.PdfWriter;

public class MainClass {

  public static void main(String[] args) throws Exception {
    Document document = new Document();
    PdfWriter writer = PdfWriter.getInstance(document, new FileOutputStream("2.pdf"));
    document.add(new Paragraph("This is a message."));
    PdfAcroForm acroForm = writer.getAcroForm();
    acroForm.addSignature("yoursig", 73, 705, 149, 759);

29.75.1.PDF with an unsigned signature field
29.75.2.Add Certificate to Pdf document