With the recent CJEU ruling, libraries can lend ebooks like normal books if the book cannot be used after the lending period. Therefore I wanted to try building a PDF with JavaScript which blacks out the content based on the date.
I found the example for hiding form fields with insdljs, but I did not manage to simply hide all existing text and instead show a message on every page like "lending period expired". With this method, it might be possible to fulfil the requirements of the CJEU ruling without any actual DRM and using TeX.
Can this be done in a way which at least works in Adobe Reader and in Firefox and Chrome? If yes, how?