"Also security is virtually no issue: using PDF.js is as secure as opening any other website."
I can't even begin to express how much this sentiment troubles me.
Edited to add: A big part of my concern regarding PDFs these days has to do with embedded malware, but in general I'm wary of active content. I'm all for faster rendering, but I wonder how well PDF.js protects against malicious content. I don't use the native PDF reader for that very reason.
The point he is making is that PDF.js is just a combination of JavaScript, DOM and Canvas rendering. It does nothing more than a website can do, and running websites is already something that needs to be secure. So this means that all the existing security measures already present in browsers make PDF.js safe to run.
> I'm all for faster rendering, but I wonder how well PDF.js protects against malicious content.
It doesn't need to; that's what the browser is for. PDF.js doesn't need to -- in any way -- concern itself with security; that's pretty unquestionably a good thing.
Why? The point he's making is that not having to install a third-party browser plugin to view a PDF is a big win for security.
Edit in reply to your edit: embedded malware is tailored to exploit a bug in a specific viewer implementation... so I doubt there's much floating around that targets PDF.js, I imagine Adobe Reader is a juicer target. In any case, JS running in the browser is usually well isolated (e.g. no filesystem access), can wreak havoc in the tab but not much else.
The wins on confining the content to the browser sandbox as well as integrating .pdf viewing into the browser experience greatly outweigh the current limitations for large file sizes. I hope ongoing work will fix the latter. Pdf.js is an awesome improvement that makes me breathe easier every time I click on a pdf link.
I can't even begin to express how much this sentiment troubles me.
Edited to add: A big part of my concern regarding PDFs these days has to do with embedded malware, but in general I'm wary of active content. I'm all for faster rendering, but I wonder how well PDF.js protects against malicious content. I don't use the native PDF reader for that very reason.