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README.md

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+# pdf-sign
+
+## What
+
+A tool to sign PDF files.
+We are here referring to the visible, non-cryptographic squiggles.
+
+## How
+
+First, create one or several signatures in the form of small PDF files with transparent backgrounds.
+The recommended way is:
+* Use the included `pdf-create-empty` tool to create an empty, transparent PDF file.
+* Use an application of your choice to sign it.
+  You can for example use Okular's Freehand Line, or transfer it to your smartphone and use Adobe Acrobat Reader.
+* Put the signed file in `~/.pdf_signatures/`.
+
+You can now use the `pdf-sign` tool interactively (or non-interactively) to sign PDF files.
+
+Run `pdf-sign -h` or `pdf-create-empty -h` for details.
+
+Installation:
+Copy one or both tools to a directory in your `$PATH`.
+Dependencies:
+* `python3`
+* `pdftk`
+* `gs` (ghostscript)
+* `mv` (coreutils)
+* `pdfinfo` (poppler-utils)
+
+## Why
+
+There appears to be a lack of applications that run on Linux and allow for attaching free-hand signatures to PDF files in a good way.
+
+(Non-)alternatives include:
+
+* Okular: Allows for drawing 'Freehand Line' annotations, but not saving those for later use.
+  Allows for inserting custom saved stamps, but these will not be visible in other PDF readers.
+* Evince: Allows for certain kinds of annotations, but nothing that can serve as a signature.
+* pdftk, ghostscript, and other command-line tools: Allows for inserting stamps, but not interactively selecting where.