[Tex/LaTex] Inserting a digitally signed PDF to an article

pdfpagespdftexsignatures

I need to add some digitally signed documents (pdf format) to a report I'm writing and, for some reason, when I import the document both the document's number and digital signature are gone. Documents signed through a web application and are numbered once they receive their final signature.

This is the command I'm using:

\includepdf[ pages={1,2},pagecommand={\subsection{AGG}}]{AGG.PDF}

This is an image of what the digital signature looks like and what is missing on the final document where this is imported.

Is there a way to have digital signatures show on Latex? I'm using Overleaf if it makes any difference.

Best Answer

For future users, I solved this by first printing the signed PDF to PDF, and then the signature showed up in my Latex document using \includepdf.

The `digsig` package

This is a small package that enhances the form capabilities of the hyperref package to support signature fields. It is not available on CTAN, but you can find it on the author's website. To use it, simply add \usepackage{digsig} to the preamble of your document (if you're already using hyperref, load it after \usepackage{hyperref}). Now you can add signature fields to your document using the \digsigfield macro, which expects the width and height of the form field and a freely chosen name. Note that you have to enclose the command in a Form environment, like this:

\documentclass{article}
\usepackage{digsig}
\begin{document}
\begin{Form}
  \digsigfield{5cm}{3cm}{My signature}
\end{Form}
\end{document}

The `eforms` package

eforms is another package to create PDF forms, with support for signature fields. You can find it on CTAN, but it is not included in TeX Live, so you may have to install it manually. It is very similar in use to the digsig package:

\documentclass{article}
\usepackage{eforms}
\begin{document}
\sigField{My signature}{5cm}{3cm}
\end{document}

In both cases, the output is a rectangular field you can fill with a digital signature using e.g. Adobe Reader or Adobe Acrobat:

a signature field as displayed by Adobe Reader

Note that many other PDF viewers don't support these fields and won't display anything at all. A "live" example of a signature field can be found in the eforms manual on page 17.

[Tex/LaTex] PDF form as background image – filling the form fields

I verified the first part of my concept based on the link Steven (@steven-b-segletes) provided in his comment. Here is a short, working example for A4 sized pdf as a background (don't mind the coordinates...):

\documentclass[finnish,a4paper,11pt]{article}
\usepackage[a4paper]{geometry}
\usepackage{setspace}
\usepackage[utf8]{inputenc}
\usepackage{graphicx}
\usepackage{ifthen}

\ifthenelse{\equal{\detokenize{$headertitle$}}{\detokenize{MyTitle}}}
{
    \newenvironment{myForm}{
        \clearpage % new page for pdf form
        \begin{singlespace}
            \begin{picture}(210,297)(113,460)
                \thispagestyle{empty} % no page numbers here
                \includegraphics[width=21cm, height=29.7cm]{file.pdf} % include pdf form
    }{
            \end{picture}
        \end{singlespace}
     }
    \newcommand\MyFirstField[1]{\put(-481,653){#1}}
}

\begin{document}

% load document body from Pandoc
$body$ 

% if name of current document equals MyTitle then add and fill form
\ifthenelse{\equal{\detokenize{$headertitle$}}{\detokenize{MyTitle}}}
{
    \begin{myForm}
        \MyFirstField{$MyFirstVariable$}
    \end{myForm}
}

\end{document}

I guess this could be done using pdfpages as well, but I am not able to tell pros/cons using pdfpages. I already made one template for a form that consisted of 25 fields and it took roughly 90 minutes for finding the right coordinates. Since I have dozens of forms (and counting) that I should implement this way, I need to either find or make a tool for accelerating this process. Some sort of point-n-click with mouse.

The 3rd part of my question, about Pandoc and command line variables is still open. What is the best practise when passing multiple variables to template that is used by Pandoc when generating a pdf. In my actual template I will provide all the form inputs as parameters/variables. I know how to do it with Pandoc's --variable, but if there is more robust way, I would be glad to explore that.

Best Answer

Related Solutions

[Tex/LaTex] How to create a PDF file that can be digitally signed

The digsig package

The eforms package

[Tex/LaTex] PDF form as background image – filling the form fields

Related Question

The `digsig` package

The `eforms` package