Am 20.02.2016 um 08:06 schrieb M. Niedermair:
On this occasion I would like to see if you used as Owner password
null (new StandardProtectionPolicy(null, null, ap)), a PW is randomly
generated (as it does for example iText).
Sorry, I don't understand you. AES256 does have a random component but
this is a salt.
i use:
final AccessPermission ap = new AccessPermission();
ap.setCanPrint(true);
ap.setCanPrintDegraded(true);
ap.setCanModify(false);
ap.setCanAssembleDocument(false);
ap.setCanExtractContent(false);
ap.setCanFillInForm(false);
ap.setCanExtractForAccessibility(false);
ap.setCanModifyAnnotations(false);
final StandardProtectionPolicy spp = new
StandardProtectionPolicy(null, null, ap);
spp.setEncryptionKeyLength(256);
document.protect(spp);
output:
pdfbox : 2.0.0-RC3
Version : 1.5
encrypted : true
enc_accesspermission : true
enc_extractcontent : true
enc_extractforaccessibility : true
enc_fillinform : true
enc_modify : true
enc_modifyannotations : true
enc_print : true
enc_printdegraded : true
enc_length : 256
enc_sh_length : 40
enc_sh_name : AES
The rights are not set correctly when I use a null pw.
This is correct because you entered the owner password (which is null).
Use the following code it works.
final MessageDigest md5 = MessageDigest.getInstance("MD5");
String ownerpw = null;
if (ownerpw == null) {
ownerpw = new String(md5.digest((System.nanoTime() + " x " +
Runtime.getRuntime().freeMemory()).getBytes()));
}
final StandardProtectionPolicy spp = new
StandardProtectionPolicy(ownerpw, null, ap);
spp.setEncryptionKeyLength(256);
document.protect(spp);
Output:
pdfbox : 2.0.0-RC3
Version : 1.5
encrypted : true
enc_accesspermission : false
enc_extractcontent : false
enc_extractforaccessibility : false
enc_fillinform : false
enc_modify : false
enc_modifyannotations : false
enc_print : true
enc_printdegraded : true
enc_length : 256
enc_sh_length : 40
Therefore, my suggestion is to generate a pw, if it is not set.
Yes, itext does this:
http://developers.itextpdf.com/reference/com.itextpdf.text.pdf.PdfStamper#6pjfi6ejm84
"Sets the encryption options for this document. The userPassword and the
ownerPassword can be null or have zero length. In this case the
ownerPassword is replaced by a random string."
Our API doesn't have such a concept. I don't see why this should be
done. If you want a random password, then set it yourself.
Tilman
By
Michael
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