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From Tilman Hausherr <THaush...@t-online.de>
Subject Re: Need help to protect PDF with owner password
Date Wed, 22 May 2019 16:57:23 GMT
Hi,

One could still use the content by transferring the page content. The 
command line applications do respect the settings (almost... I'll fix a 
few issues soon). The PDFBox library is a toolkit to build an 
application, so your application should respect these settings.

http://gitlab.itextsupport.com/itext/sandbox/raw/master/resources/pdfs/hello_encrypted2.pdf
can be decrypted with pdfbox, so it can be reencrypted too.

Tilman

Am 22.05.2019 um 03:28 schrieb RJC 2009:
> Thanks Tilman Hausherr and Marc Kaufman for your time & help.
>
> I came across following post at iText tech support faq talking about
> similar topic.
> https://itextpdf.com/en/resources/faq/technical-support/itext-7/how-decrypt-pdf-document-owner-password
>
> Seems the following pdf file which they have shared is encrypted and does
> not allow to overwrite the owner password using PDFBox (2.0.15).
> http://gitlab.itextsupport.com/itext/sandbox/raw/master/resources/pdfs/hello_encrypted2.pdf
>
> I'm just wondering how does this works and are there any similar
> implementation in PDFBox.
>
> On Wed, May 22, 2019 at 7:45 AM Marc Kaufman <marc@eeph.com> wrote:
>
>> Which is, of course, a violation of the "agreement" between PDF and
>> Readers (ignored by everyone, it seems, except Adobe). In
>> Acrobat/Reader, you need to open with the Owner password in order to
>> change permissions. Opening with the User password should honor
>> permissions and not allow changing of permissions.
>>
>> Marc
>>
>> On 5/21/2019 9:42 AM, Tilman Hausherr wrote:
>>> Am 17.05.2019 um 09:47 schrieb RJC 2009:
>>>> Here is my test program which is trying to disable the printing
>>>> option and
>>>> protect the document with an owner password.
>>>>
>>>> However, if I use the resultant PDF and run the program again with a
>>>> DIFFERENT owner password then it ENABLE the printing option.
>>>>
>>>>
>>>>
>>>> Basically I need to disable the printing option in PDF with an owner
>>>> password and the printing option cannot be enabled back without using
>>>> the
>>>> original owner password.
>>>
>>> I should have read the text more carefully (and continue reading after
>>> "2.0.5"). This is by design. When you open with the user password then
>>> the file is decrypted and can be manipulated, reencrypted, everything.
>>> The owner password is just an extra so that a software can decide that
>>> you're the owner. That is why there are so many tools on the internet
>>> that allow to change the permissions of PDF files.
>>>
>>> Read also this:
>>>
>>> https://www.cs.cmu.edu/~dst/Adobe/Gallery/anon21jul01-pdf-encryption.txt
>>>
>>>
>>> Tilman
>>>
>>>
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