I remember seeing this presentation a few years ago on the security of PDF encryption: https://media.ccc.de/v/36c3-10832-how_to_break_pdfs https://media.ccc.de/

I remember seeing this presentation a few years ago on the security of PDF encryption: https://media.ccc.de/v/36c3-10832-how_to_break_pdfs https://media.ccc.de/v/36c3-10832-how_to_break_pdfs I think this is a quick summary of one of their findings: https://pdf-insecurity.org/#how-to-break-pdf-encryption-november-2019 https://pdf-insecurity.org/#how-to-break-pdf-encryption-nove... This is perhaps something to be aware of.