Thanks for your feedback. However, Github Pages only allows static content as far as I know and I need a database in the background with some logic around it. Therefore, I don't see how this would add more security, right? As long as you can be sure that your secret has been correctly encrypted on the client side, it shouldn't matter that match if the storage server is trustworthy or not.

Fair point and thanks for your feedback! I have added an option to download a HTML file that you can open and use locally. That way you can be sure that the code does not change and you are always using the correct encryption. ;) Let me know if it works for you.