java program to add digital signature into a pdf file

[pavithra murthy]

dear all ,

1. i need to write a java program for adding digital signature to a page in a pdf file .

* i have to use the profile created by the user where private key ,certificate and public key are stored .
* i need to use the signature found in that profile . may be i have to extract it and add it to the pdf page .

could anyone please help me out regarding this because have not worked earlier on this .

what are the requirements and how to go about it .

thank you .

[Ulf Dittmer]

The iText library can sign PDFs; see How to sign a PDF using iText for details. I don't think it's possible to sign individual pages, though.

[pavithra murthy]

hello friend ,

i am encountering this error when i compile this program ..i have used itext.jar file

pdfsign1.java:27: reference to Certificate is ambiguous, both class java.securit
y.cert.Certificate in java.security.cert and class java.security.Certificate in
java.security match
Certificate[] chain = ks.getCertificateChain(alias);
^
1 error

could you please help me out ..

import com.lowagie.text.pdf.*;
import com.lowagie.text.Rectangle;
//import com.lowagie.text.pdf.pdfSignatureAppearance;
//import com.lowagie.text.pdf.pdfStamper;
import java.security.*;
import java.io.*;
import java.awt.*;
import java.security.cert.*;
import java.lang.*;

import java.io.FileInputStream;
import java.security.KeyStore;
import java.security.cert.CertPath;
import java.security.cert.CertificateFactory;
import java.util.ArrayList;
import java.util.List;



public class pdfsign1{
  public static void main(String args[]) {
try {
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());
[b]Certificate[] chain = ks.getCertificateChain(alias);[/b]
PdfReader reader = new PdfReader("original.pdf");
FileOutputStream fout = new FileOutputStream("signed.pdf");
PdfStamper stp = PdfStamper.createSignature(reader, fout, '\0');
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();
  }
catch(Exception e) {}
}
}

[Ulf Dittmer]

Both the java.security and the java.security.cert package have a "Certificate" class/interface. You can only import one with a wildcard. In this case, you want the one in java.security.cert.

catch (Exception e) {}

That's a bad idea. How a will you know what's going wrong with the code?

[pavithra murthy]

hello friend ,

i have written a java code for adding digital signature to pdf file .

i am encountering an exception when the program is run .

C:\excel>java pdfsign1
java.io.IOException: DerInputStream.getLength(): lengthTag=109, too big.
at sun.security.util.DerInputStream.getLength(Unknown Source)
at sun.security.util.DerValue.init(Unknown Source)
at sun.security.util.DerValue.<init>(Unknown Source)
at com.sun.net.ssl.internal.pkcs12.PKCS12KeyStore.engineLoad(Unknown Sou
rce)
at java.security.KeyStore.load(Unknown Source)
at pdfsign1.main(pdfsign1.java:23)

i am creating a key with name "my_private_key.pfx" specified in the program using the command
keytool -genkey -keyalg RSA -alias myname -keypass password -keystore my_private_key.pfx

import com.lowagie.text.pdf.*;
import com.lowagie.text.Rectangle;
import java.security.*;
import java.io.*;
import java.awt.*;
import java.lang.*;
import javax.net.ssl.*;
import javax.net.ssl.KeyManager;
import javax.naming.*;
import javax.naming.Context;

public class pdfsign1{
  public static void main(String args[]) throws IOException{
try {
//KeyManagerFactory kmf = KeyManagerFactory.getInstance("SunX509"); 
//KeyStore ks = KeyStore.getInstance("pkcs12");
//ks.load(new FileInputStream("D:\\pdf\\pdf2\\digital\\my_private_key.pfx"), "my_password".toCharArray());
//kmf.init(ks, "my_password".toCharArray());

SSLContext ctx=SSLContext.getInstance("SSL");
KeyManagerFactory kmf = KeyManagerFactory.getInstance("SunX509"); 
KeyStore ks = KeyStore.getInstance("pkcs12");
ks.load(new FileInputStream("c:\\excel\\my_private_key.pfx"), "my_password".toCharArray());
kmf.init(ks, "my_password".toCharArray());
ctx.init(kmf.getKeyManagers(),null,null);

//initSSLContext(kmf.getKeyManagers());
//KeyStore ks = KeyStore.getInstance(KeyStore.getDefaultType());
//ks.load(new FileInputStream("keystore.ks"), "my_password".toCharArray());
String alias = (String)ks.aliases().nextElement();
PrivateKey key = (PrivateKey)ks.getKey(alias,"my_password".toCharArray());
java.security.cert.Certificate[] chain = ks.getCertificateChain(alias);
PdfReader reader = new PdfReader("original.pdf");
FileOutputStream fout = new FileOutputStream("signed.pdf");
PdfStamper stp = PdfStamper.createSignature(reader, fout, '\0');
PdfSignatureAppearance sap = stp.getSignatureAppearance();
//sap.setCrypto(key, chain, null, PdfSignatureAppearance.WINCER_SIGNED);
sap.setCrypto(key, chain, null, PdfSignatureAppearance.SELF_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();
  }
catch(Exception e) {e.printStackTrace();}
}
}

[pavithra murthy]

hello friends ,

i have written a code using jPDFProcess.jar file . there are two classes SignDocument and ExportFields.java
exportfields is super class
signdocument is subclass

i am creating a key sample PKCS#12 file using the command

keytool -genkey -keyalg RSA -alias myname -keypass store_pwd -keystore keystore.pfx


both classes are compiling fine but while running i am getting the same following exceptions
could anyone please help me out
-------------------------------------------------
Exception in thread "main" java.lang.IncompatibleClassChangeError: class com.qop
pa.pdfProcess.PDFDocument has interface com.qoppa.pdfViewer.g.k as super class
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(Unknown Source)
at java.security.SecureClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.access$000(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClassInternal(Unknown Source)

-----------------------------------------

import java.awt.geom.Rectangle2D;
import java.io.FileInputStream;
import java.security.KeyStore;
import java.net.*;

import com.qoppa.pdf.SigningInformation;
import com.qoppa.pdf.form.SignatureField;
import com.qoppa.pdfProcess.PDFDocument;
import com.qoppa.pdfProcess.PDFPage;

public class SignDocument 
{

    public static void main (String [] args)
    {
        try
        {
            // Load the document
            PDFDocument pdfDoc = new PDFDocument ("c:\\sign\\Z08V3_ICB_RECHNG.pdf", null);
            
            // Load the keystore that contains the digital id to use in signing
            FileInputStream pkcs12Stream = new FileInputStream ("c:\\sign\\keystore.pfx");
            KeyStore store = KeyStore.getInstance("PKCS12");
            store.load(pkcs12Stream, "store_pwd".toCharArray());
			pkcs12Stream.close();
            
            // Create signing information
            SigningInformation signInfo = new SigningInformation (store, "key_alias", "key_pwd");

            // Create signature field on the first page
            PDFPage firstPage = pdfDoc.getPage (0);
            Rectangle2D signBounds = new Rectangle2D.Double (36, 36, 144, 48);
            SignatureField signField = firstPage.addSignatureField("signature", signBounds);
            
            // Apply digital signature
            pdfDoc.signDocument(signField, signInfo);
            
            // Save the document
            pdfDoc.saveDocument ("output.pdf");
        }
        catch (Throwable t)
        {
            t.printStackTrace();
        }
    }
}

import com.qoppa.pdfProcess.PDFDocument;
import java.security.*;
public class ExportFields
{

    public static void main (String [] args)
    {
        try
        {
            // Load the document
            PDFDocument pdfDoc = new PDFDocument ("c:\\sign\\Z08V3_ICB_RECHNG.pdf", null);

            // Export field values
            pdfDoc.getAcroForm().exportAsFDF("output.fdf");
        }
        catch (Throwable t)
        {
            t.printStackTrace();
        }
    }


}

[Rao Jr]

Generate key using the following command

keytool -genkey -keypass key_pwd -keystore test.pfx -storepass store_pwd -storetype PKCS12 -alias key_alias