Blog
Practical, no-hype writing about how the PDF format actually works — and where it can bite you. I take apart PDF internals (what really happens when a file is converted to Word, how far the format can be pushed) and, above all, PDF security: how malicious PDF files are built, how encrypted documents are attacked, what metadata quietly leaks from your files, and how much digital signatures are really worth. Everything here follows the same principle as the app itself: your files stay on your computer. No affiliate links, no cloud upsell — just what I learn while building an offline PDF toolkit.
Password-protecting a PDF is genuinely worth doing — but the protection is only as strong as the password, and researchers found a way to read encrypted PDFs without cracking anything at all.
A valid signature on a PDF means less than most people assume. Researchers showed a document can display one thing to the signer and something else to everyone afterwards — with the signature still checking out.
"Offline is safer" gets repeated so often it has stopped meaning anything. Here is the part that is genuinely true, the part that is oversold, and how to decide which files deserve which treatment.
Most advice about dangerous documents assumes the file came to you. This one is about the file you went looking for yourself, on a site you had every reason to trust.