[jira] [Comment Edited] (PDFBOX-837) Wrong RevisionNumber when disabling all permissions and using 128bit encryption

["Martin Brown (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/PDFBOX-837?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13791359#comment-13791359 ] 

Martin Brown edited comment on PDFBOX-837 at 10/10/13 10:00 AM:
----------------------------------------------------------------

StandardSecurityHandler.computeRevisionNumber() refers to PDF Spec 1.6 p98. This says:
{panel}
[Revision] A number specifying which revision of the standard security handler
should be used to interpret this dictionary:
• 2 if the document is encrypted with a V value less than 2 (see Table 3.18) and does not have any of the access permissions set (by means of the P entry, below) that are designated “Revision 3 or greater” in Table 3.20
• 3 if the document is encrypted with a V value of 2 or 3, or has any “Revision 3 or greater” access permissions set
• 4 if the document is encrypted with a V value of 4
{panel}
However, the current code in computeRevisionNumber() is looking at the first test where V == 2 rather than V < 2. Following the spec, the method should look like this:
{code}
private int computeRevisionNumber()
    {
        if(version < 2
            && !policy.getPermissions().canFillInForm()
            && !policy.getPermissions().canExtractForAccessibility()
            && !policy.getPermissions().canPrintDegraded() )
        {
            return 2;
        }
        return 3;
    }
{code}


was (Author: martin_w_brown):
StandardSecurityHandler.computeRevisionNumber() refers to PDF Spec 1.6 p98. This says:
{panel}
[Revision] A number specifying which revision of the standard security handler
should be used to interpret this dictionary:
• 2 if the document is encrypted with a V value less than 2 (see Table 3.18) and
does not have any of the access permissions set (by means of the P entry, below) that are designated “Revision 3 or greater” in Table 3.20
• 3 if the document is encrypted with a V value of 2 or 3, or has any “Revision 3 or greater” access permissions set
• 4 if the document is encrypted with a V value of 4
{panel}
However, the current code in computeRevisionNumber() is looking at the first test where V == 2 rather than V < 2. Following the spec, the method should look like this:
{code}
private int computeRevisionNumber()
    {
        if(version < 2
            && !policy.getPermissions().canFillInForm()
            && !policy.getPermissions().canExtractForAccessibility()
            && !policy.getPermissions().canPrintDegraded() )
        {
            return 2;
        }
        return 3;
    }
{code}

> Wrong RevisionNumber when disabling all permissions and using 128bit encryption
> -------------------------------------------------------------------------------
>
>                 Key: PDFBOX-837
>                 URL: https://issues.apache.org/jira/browse/PDFBOX-837
>             Project: PDFBox
>          Issue Type: Bug
>          Components: PDModel
>    Affects Versions: 1.2.1
>            Reporter: Bernd Engelhardt
>         Attachments: StandardSecurityHandler_patch.patch
>
>
> When disabling all permissions and using a 128bit encryption the following exception is thrown when saving the PDF document:
> org.apache.pdfbox.exceptions.COSVisitorException: Error: Expected length=5 actual=16
>         at org.apache.pdfbox.pdfwriter.COSWriter.write(COSWriter.java:1022)
>         at org.apache.pdfbox.pdmodel.PDDocument.save(PDDocument.java:911)
>         at org.apache.pdfbox.pdmodel.PDDocument.save(PDDocument.java:892)
>         at pdfbox.Main.main(Main.java:53)
> This is reproducable with the following code:
> public class Main {
>     public static void main(String[] args) {
>         try {
>             AccessPermission ap = new AccessPermission();
>             StandardProtectionPolicy spp = null;
>             ap.setCanAssembleDocument(false);
>             ap.setCanExtractContent(false);
>             ap.setCanExtractForAccessibility(false);
>             ap.setCanFillInForm(false);
>             ap.setCanModify(false);
>             ap.setCanModifyAnnotations(false);
>             ap.setCanPrint(false);
>             ap.setCanPrintDegraded(false);
>             spp = new StandardProtectionPolicy(null, null, ap);
>             spp.setEncryptionKeyLength(128);
>             PDDocument document = null;
>             FileInputStream sourceFile = new FileInputStream(new File("C:\\Web\\NetBeansProjects\\pdfBox\\test.pdf"));
>             document = PDDocument.load(sourceFile);
>             document.protect(spp);
>             document.save("C:\\Web\\NetBeansProjects\\pdfBox\\test_encrypted.pdf");
>             document.close();
>         } catch (Exception ex) {
>             Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
>         }
>     }
> }
> The problem is based on "computeRevisionNumber" in "StandardSecurityHandler.java". If all flags are disabled, the routine returns a value of 2. But if the 128bit encryption is enabled, the revision should be 3. If not, the method "computeUserPassword" will fail.
> A solution would be to check the key length in "computeRevisionNumber".
>    private int computeRevisionNumber()
>     {
>         if(version == 2
>             && !policy.getPermissions().canFillInForm()
>             && !policy.getPermissions().canExtractForAccessibility()
>             && !policy.getPermissions().canPrintDegraded()
>             && keyLength == 40 )
>         {
>             return 2;
>         }
>         return 3;
>     } 



--
This message was sent by Atlassian JIRA
(v6.1#6144)