RE: 687347 Implementation of the PDF 1.5 encryptionfeature: EncryptMetadata

Igor,

>Hmm, Distiller 5 inserts some metadata with no special effort.
>Attaching a sample.

Thank you for the test file.  Here are the results of my testing
with the file and with variations in encryption and EncryptMetadata.

1.  R = 3, EncryptMetadata not present
    /U does not have 0xffffffff in the calculation.  Metadata is
    encrypted.

2.  R = 3, EncryptMetadata = false
    /U does not have 0xffffffff in the calculation.  Metadata is
    not encrypted.

Both Acrobat 5.0 and Acrobat 6.0 can view these files and their
enbedded metadata.  This implies that Acrobat 5.0 does indeed
look at the EncryptMetadata value.  This is consistent with the
statement in the PDF 1.5 spec. that EncryptMetadata is an
undocumented feature of PDF 1.4.  However this also repeats the
previous results about the 0xffffffff not being used when R = 3.
Which is in contradiction to statements in the PDF 1.5 spec. about
the EncryptMetadata = false implies that the 0xffffffff should be
used in the calculation of /U with R = 3.

3.  R = 4, EncryptMetadata not present
    /U does not have 0xffffffff in the calculation.  Metadata is
    encrypted.

4.  R = 4, EncryptMetadata = false
    /U does have 0xffffffff in the calculation.  Metadata is
    not encrypted.

The repeats the results of pervious testing.  EncryptMetadata
affects the encryption of metadata as expected.


>I haven't got Acrobat 6.

Obviously we will see more and more PDF files from Acrobat 6.0.
I strongly recommend getting a copy.


Dan


-----Original Message-----
From: Igor V. Melichev [mailto:[email protected]]
Sent: Monday, March 08, 2004 11:58 PM
To: [email protected]
Subject: Re: [gs-code-review] 687347 Implementation of the PDF 1.5
encryptionfeature: EncryptMetadata


Dan,

> From: "Dan Coby" <[email protected]>
> To: "Igor V. Melichev" <[email protected]>
> Cc: "Gs-Code-Review" <[email protected]>
> Sent: Tuesday, March 09, 2004 10:21 AM
> Subject: RE: [gs-code-review] 687347 Implementation of the PDF 1.5
encryptionfeature: EncryptMetadata

Thank you for improvements.


> A final note:  I do not know how to actually get Acrobat 6.0 to
> actually generate some metadata.  Thus my test files do not actually
> contain any real metadata.  A test file with real metadata may show
> more problems.  (This comment has been added to the log message.)

Hmm, Distiller 5 inserts some metadata with no special effort.
Attaching a sample.
I haven't got Acrobat 6.

> There is
> absolutely no intent to ever execute the given group of
> statements more than once.  Thus this is a very curious use
> of a 'loop' construct.

{
    ....
  exit
} loop

The last 2 lines explicitely tell that it is executed only at once.

> I disagree.  I believe that the summary statement should include the
> report number.  This makes it easier for someone who is scanning the
> HistoryX.htm files to easily find more information on a particular
> issue.

Not sure why he can't scan Details.htm .

Igor.