Q:
We're currently using PDFTron PDFNet SDK to encrypt PDF documents using
the standard 128bit rc4 mechanism. We want to investigate moving to
other algorithms like AES.
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A:
AES, should work out of box. You don't need to do anything special if
you are opening AES encrypted files.
To apply AES encryption to new or existing PDF document you can create
a new security handler as follows:
// C++
StdSecurityHandler* new_handler = new
StdSecurityHandler(SDF::StdSecurityHandler::e_AES);
// C#
StdSecurityHandler new_handler = new
StdSecurityHandler(SDF.StdSecurityHandler.AlgorithmType.e_AES);
pdfdoc.SetSecurityHandler(new_handler);
and use it as illustrated in 'EncTest' sample project.
Q:
Is it AES supported in Acrobat?
We use PDFTron to encrypt the PDF and we have our own Acrobat Security
Handler that connects to our access control servers to retrieve the
decryption key. Currently this decryption key is just passed back to
acrobat - and the decryption of the PDF document is handled via
Acrobat's built in RC4 algorithm.
If we turn on the AES encryption in PDFTron how will we decrypt the
document? Do we have to add AES to our security handler and hook it
into the Acrobat callback mechanism (so we would be handling the
decryption) or is it fully supported in current and previous versions
of Acrobat? Or does PDFTron provide a client side piece that does this
that we can use?
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A:
AES encryption is supported beginning with PDF 1.6 (i.e. Acrobat 7).
Viewing AES encrypted documents in earlier versions of Acrobat will
fail (unless you install additional plug-in extensions that can handle
AES documents).
With PDFNet SDK you can apply AES encryption on any valid PDF
document.
You can also open AES encrypted documents, remove AES encryption,
change security settings, permissions, etc.
If you are customizing AES encryption (i.e. it is not a standard PDF
security handler) the only way you can open these documents in Acrobat
is by implementing a custom security handler. In this case you can
also use PDFNet SDK to implement a custom security plug-in for
Acrobat.