java program to password protect a signed pdf file

[pavithra murthy]

hello ,

i am trying to password protect a signed pdf file using jPDFSecure api and also making use of jPDFSecure.jar file .

but in this program i am getting an error when i am trying to set the permissions in setSecurity method . Please could anyone help me

/**
 * Qoppa Software - Source Code Sample
 */
//package jPDFSecureSamples;

import com.qoppa.pdf.PDFPermissions;
import com.qoppa.pdfSecure.PDFSecure;
import java.lang.*;
import java.security.*;
import com.qoppa.pdfSecure.*;
import com.qoppa.pdf.*;

public class SetPermissions
{
    public static void main (String [] args)
    {
        try
        {
            // Load the document
            PDFSecure pdfSecure = new PDFSecure ("d:\\signed.pdf", null);
            
            // Create permissions object to allow printing only
            PDFPermissions perms = new PDFPermissions (true);
            perms.setPrintAllowed(true);

            // Set document security
          -->    pdfSecure.setSecurity("owner", "user", perms, null);


            
            // Save the document
            pdfSecure.saveDocument ("signedoutput.pdf");
        }
        catch (Throwable t)
        {
            t.printStackTrace();
        }
    }

}

the error i am getting is

D:\>javac SetPermissions.java
SetPermissions.java:24: setSecurity(java.lang.String,java.lang.String,com.qoppa.
pdf.PDFPermissions,java.lang.String,int) in com.qoppa.pdfSecure.PDFSecure cannot
be applied to (java.lang.String,java.lang.String,com.qoppa.pdf.PDFPermissions,<
nulltype>)
pdfSecure.setSecurity("owner", "user", perms, null);
^
1 error

[Moojid Hamid]

Look at the signature of the method you are calling, in your method call you are missing the last parameter of type int.

[pavithra murthy]

hi ,
thanks a lot . i gave the int parameter but when i run the program even password correctly entered is not opening the pdf file

It is asking for the password but its giving a message "There was an error opening this document .Bad Encrypt Dictionary"

please could you help me out

But the last parameter is expected to be an integer ..so i gave like 777

[Moojid Hamid]

For that last parameter you can either specify RC4, or AES. AES only works for newer versions of acrobat reader, you can either use RC4 or update to a newer version of acrobat reader.

[pavithra murthy]

But the last parameter is expected to be an integer ..so i gave like 777

pdfSecure.setSecurity("owner", "user", perms, null,777);

Is it correct ?

[Bear Bibeault]

Please read this.

[Moojid Hamid]

Have a look at the Java Doc.

encryptType - - The encryption type to use, this value can be either PDFPermissions.ENCRYPTION_RC4 or PDFPermissions.ENCRYPTION_AES.

[pavithra murthy]

pdfSecure.setSecurity(null, "user", perms, null,PDFPermissions.ENCRYPTION_AES);

hi tried with the above command .now its working but

the signature is becoming invalid in the locked signed document ..

i had written another java code for digital signing on pdf using itext . the output signed pdf document from this code which i got as output ...now i am trying to password protect it .

Signed pdf document is opening but the signature is becoming invalid . please could you help me out

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.security.KeyStore;
import java.security.PrivateKey;
import java.security.cert.CertificateFactory;
import java.security.cert.X509Certificate;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Collection;
import java.util.Iterator;

import com.lowagie.text.Rectangle;
import com.lowagie.text.pdf.AcroFields;
import com.lowagie.text.pdf.PdfPKCS7;
import com.lowagie.text.pdf.PdfReader;
import com.lowagie.text.pdf.PdfSignatureAppearance;
import com.lowagie.text.pdf.PdfStamper;

public class pdfsign11{
  public static void main(String args[]) {
try{
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("Z08V3_ICB_RECHNG.PDF");

int nomPage = reader.getNumberOfPages();
			System.out.println("nomPage: "+nomPage);
			for (int i=1; i<=nomPage; i++)
			{

				FileOutputStream fout = new FileOutputStream("signed"+i+".pdf");
				//PdfStamper stp = PdfStamper.createSignature(reader, fout, '\0');
				PdfStamper stp = PdfStamper.createSignature(reader, fout, '\0', null, true);
				//PdfStamper.setEncryption(chain,AllowDegradedPrinting,STANDARD_ENCRYPTION_128);
				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), i, null);
				stp.close();
				reader = new PdfReader("signed"+i+".pdf");
			}
    		for(int i=1;i<=nomPage;i++)
			{
				File fileStr = new File("signed"+i+".pdf");
				if(i!=nomPage)
				{
					fileStr.delete();
				}
				//to verify sign
				if(i == nomPage)
				{
					try {
						CertificateFactory cf = CertificateFactory.getInstance("X509");
						Collection col = cf.generateCertificates(new FileInputStream("export.cer"));
						KeyStore kall = KeyStore.getInstance(KeyStore.getDefaultType());
						kall.load(null, null);
						for (Iterator it = col.iterator(); it.hasNext();) {
						    X509Certificate cert = (X509Certificate)it.next();
						    kall.setCertificateEntry(cert.getSerialNumber().toString(Character.MAX_RADIX), cert);
						}
						//KeyStore kall = PdfPKCS7.loadCacertsKeyStore();
						PdfReader reader2 = new PdfReader("signed"+i+".pdf");
						AcroFields af = reader2.getAcroFields();
						ArrayList names = af.getSignatureNames();
						for (int k = 0; k < names.size(); ++k) 
						{
							String name = (String)names.get(k);
							System.out.println("Signature name: " + name);
							System.out.println("Signature covers whole document: " + af.signatureCoversWholeDocument(name));
							System.out.println("Document revision: " + af.getRevision(name) + " of " + af.getTotalRevisions());
							
							PdfPKCS7 pk = af.verifySignature(name);
							Calendar cal = pk.getSignDate();
							java.security.cert.Certificate pkc[] = pk.getCertificates();
							System.out.println("Subject: " + PdfPKCS7.getSubjectFields(pk.getSigningCertificate()));
							System.out.println("Document modified: " + !pk.verify());
							Object fails[] = PdfPKCS7.verifyCertificates(pkc, kall, null, cal);
							if (fails == null)
								System.out.println("Certificates verified against the KeyStore");
							else
								System.out.println("Certificate failed: " + fails[1]);
						}
					}
					catch(Exception e) {e.printStackTrace();}
				}

			}

}
catch(Exception e) {e.printStackTrace();}
}
}

[Moojid Hamid]

instead of using pdfSecure try the setEncription methods of pdfStamper, that way you can sign and lock using same pdfStamper (stp) object.

[pavithra murthy]

hi
i tried with the old itext code according to the syntax but its giving out an error

E:\>javac pdfsignencryption.java
pdfsignencryption.java:39: cannot resolve symbol
symbol : variable STANDARD_ENCRYPTION_128
location: class pdfsignencryption
PdfStamper.setEncryption(STANDARD_ENCRYPTION_128
,"owner","user",777);
^
pdfsignencryption.java:39: non-static method setEncryption(boolean,java.lang.Str
ing,java.lang.String,int) cannot be referenced from a static context
PdfStamper.setEncryption(STANDARD_ENCRYPTION_128
,"owner","user",777);
^
2 errors

syntax of setEncryption i got it from this link

http://1t3xt.info/api/com/lowagie/text/pdf/PdfStamper.html#setEncryption(int,%20java.lang.String,%20java.lang.String,%20int)

[Moojid Hamid]

Well, both error messages are self-explanatory: first one is telling you that it cannot find that constant that you are referring to (you need to qualify it with the class/interface name it is defined in). Second error message is telling you that the method is not static method, you need an object of type PdfStamper before you can call this method (remember stp object?)

IMHO, what it shows is that you need to get up to speed with java basics, copy pasting code from different sources is not going to take you very far. I am not attempting to be rude, you need to pick-up a good book on java and practice a little, it will help you figure out many things on your own.

This thread seems more suitable for OtherOpenSourceProjects forum.