FalsiScan: Make it look like a PDF has been hand signed and scanned

Additional Information

⚠ You may need to tweak ImageMagick’s default security policy by adding

 <policy domain="coder" rights="read | write" pattern="PDF" />

just before </policymap> in /etc/ImageMagick-7/policy.xml, as recommended in https://stackoverflow.com/questions/52998331/imagemagick-security-policy-pdf-blocking-conversion

The policy is automatically added to the policy.xml via a RUN statement within the Dockerfile.

Docker

Михаил Полыковский was kind enough to provide a DockerFile, you can now clone this repository and run

docker build -t falsisign .

to build the container, then use

docker run -it --rm -v ~/Documents/falsisign/input:/input:rw -v ~/Documents/falsisign/output:/output:rw falsisign /bin/bash

to falsisign documents.

Usage

Create a signature sample

• Print the Signature_guide.pdf, preferably on A4 paper,
• sign in each of the full sized box (this will give 27 different signatures),
• scan the resulting paper and save it as a pdf (called e.g. signatures.pdf),
• run ./signdiv.sh -d signatures.pdf (run ./signdiv.sh -h to see offset and margin options, which will help you remove the red guide lines from your signatures),
• check in signatures that you have 27 png files correctly cropped. You can manually edit the .png files to your liking.

You can maintain multiple signature directories, or run the above again if you want more than 27 signatures.

False-sign and False-scan a document

• Get the PDF the bureaucrats want you to print, sign and scan (e.g. document.pdf),
• run ./falsisign.sh -d document.pdf -s signatures -x 1000 -y 2500 -o document-scanned.pdf:
  • The first argument is the document you need to sign/scan
  • The second argument is the directory with all your different signatures
  • The next two arguments are the X and Y coordinates of where your signature will be. The page dimension is 3560x4752.
  • The last argument is the output file name.

You can also initial and sign a document, and choose the pages where to sign and initial (don’t forget to quote the page numbers!). The full usage string is:

Falsisign.

Usage:
    falsisign -d <input_pdf> -x <X> -y <Y> [-p <pages>] -s <sign_dir> [-S <scale>] [-c] [-i <init_dir> -z <Z> -t <T> [-q <pages>]] [-r <density>] -o <output_pdf>

Options:
    -d <input_pdf>   The PDF document you want to sign
    -x <X>           The horizontal position in pixels of where the signature will be
    -y <Y>           The vertical position in pixels of where the signature will be
    -p <pages>       Optional space-separated list of pages to sign, e.g. '2 4 10'
                     Defaults to all or only the last if -i is specified
    -s <sign_dir>    Directory where the signatures will be randomly chosen
    -S <scale>       Scaling of the randomly chosen signature in percentage
    -c               Make a clean scan (disable noise and rotation)
    -i <init_dir>    Optional directory where the initials will be randomly chosen
    -z <Z>           Optional horizontal position in pixels of the initials
    -t <T>           Optional vertical position in pixels of the initials
    -q <pages>       Optional space-separated list of pages to initial
                     Defaults to all but the last
    -r <density>     Specify the dpi to use in intermediate steps
    -a <angle>  Specify the rotation (in degrees) to use for all pages
    -o <output_pdf>  The output file name

Finding the coordinates for the signature and initials

Finding the coordinates in pixels where the signature and initials will be is a bit of a pain. One must know that the pages are normalized to a size of 2480x3508, and do a cross-multiplication.

To ease the process, run the falsicoord.py utility, you will see a gray canvas that has the same shape as a portrait A4 page. When you click on it, the window will close and on the standard output will be printed the -x and -y options with the correct values in pixel. You can then copy paste those values in your call to falsisign.sh.

Integrate falsicoord in falsisign.sh and display it for each page, with the page as the canvas background

Thanks

Thank you to all those to reported issues and contributed patches, in particular:

• Михаил Полыковский
• Anthony Scemama
• Gabriel Volpe
• bocekm
• Francesco Frassinelli’s
• FalcoSuessgott
• Karsten Dambekalns
• Barak A. Pearlmutter