[SignServer-develop] PDF 2.0

[Kevin DG <ke...@du...>]

Hello all,

I checked to sign a PDF in version 2.0 (
https://github.com/pdf-association/pdf20examples/blob/master/Simple%20PDF%202.0%20file.pdf)
with worker pdf signer.

It's works but ... there is always a "but" :-).

This is a pdfinfo result before the signature:

>
> pdfinfo Simple\ PDF\ 2.0\ file\ \(1\).pdf
> Tagged:         no
> UserProperties: no
> Suspects:       no
> Form:           none
> JavaScript:     no
> Pages:          1
> Encrypted:      no
> Page size:      612 x 396 pts
> Page rot:       0
> File size:      5207 bytes
> Optimized:      no
> PDF version:    2.0


This is a pdfinfo result after the signature:

▶ pdfinfo Simple\ PDF\ 2.0\ file\ \(1\)\ \(1\).pdf
> Producer:       iText 2.1.7 by 1T3XT
> ModDate:        Wed Jan  8 14:04:29 2020 CET
> Tagged:         no
> UserProperties: no
> Suspects:       no
> Form:           AcroForm
> JavaScript:     no
> Pages:          1
> Encrypted:      no
> Page size:      612 x 396 pts
> Page rot:       0
> File size:      37897 bytes
> Optimized:      no
> PDF version:    1.6


The PDF version is downgrade from 2.0 to 1.6, so it's works but it can be i
think generate problem or lost functionality linked to 2.0 format.

When we review signserver code, we understand why the downgrade is
processed. Signserver use an old version of iText.
iText handle the PDF version detection in the form of integer (0 => 1.0, 6
=> 1.6, 7 => 1.7), so the PDF in version 2.0 is detected to 0....
Signserver upgrade the PDF in 1.6 also to handle the digest algorithm (in
my case SHA256).

Any ideas about that ?

Regards,