[reportlab-users] adding a digital signature when generating a pdf

[Henning von Bargen]

Original question was:

> > There are two different functionnalities :

> > - signing directly the generated pdf

> > - adding of a tag in the generated pdf to authorize the 

> signing with adobe

> > reader (version >= 7)

> > Is it planned for ReportLab


Andy Robinson wrote:

> ... there are no existing free solutions...


Well, if you slightly modify the requirement and say:
"I need free open source software in whatever language
(not necessarily Python) to digitally sign an existing PDF
(generated with ReportLab or whatever library)",
then there IS at least one solution (and this is how we do it:)
Take a look at the Java iText library (www.lowagie.com/iText).
Adding a signature is a snap (though, internally, it's hard).
See http://itext.ugent.be/itext-in-action/chapter.php?chapter=16

And if someone really needs a Python solution, the first person 
that comes to my mind if I needed such a feature is Mathieu Fenniak, 
the author of the pyPdf library (http://pybrary.net/pyPdf/).
pyPdf support encryption and decryption; and to my knowledge, 
digitally signing and encrypting a PDF needs quite similar techniques.
For the necessary number cruncher libraries, 
pycrypto (pycrypto.sourceforge.net) seems to be a good candidate.

Just my 2 EUR-cents
Henning