[deathanatos]

Even if it did it in-browser and didn't show you an upload message, you still need to trust the JavaScript that gets downloaded when you load the page. It could upload behind your back. Or, it could embed your password in the image, encrypted with a known key.

You MUST trust the software you feed your unencrypted data to. And if that softare is downloaded each time from the web, it's rather hard to do.

[tagawa]

Right, but at least it would be locally-run code that you can (potentially) verify and run offline, similar to existing Bitcoin/Dogecoin paper wallet generators. I agree most people wouldn't or couldn't though.