I’m trying to create a web app that involves sharing of user-generated content, but one of the goals is that the service host operator should be blind to the content. Only authorized users should be able to see the content shared with them. This implies the content must be encrypted at rest, and users must hold custody of their private signing key.
I figure the situation requires an open source browser extension to hold onto a user’s keys and decrypt content for them. The web app would still be able to browse all of the site’s metadata, but any plaintext content must be siloed in the extension. The reason for using an extension is that the source code would be open source and independently verifiable, while building the same functionality into the web app would require trusting the host to serve the code you expect.
Do you think that’s a reasonable tradeoff or is this asking too much from users?
The other option would be just requiring users to download an open source app for content viewing.
EDIT: Perhaps an important followup: are you OK placing trust in the host to never access your confidential data if it means you don’t have to install additional client software or worry about verifying that client software’s authenticity?
That’s true. On the other hand, the extension gains a much larger attack surface since it has access to a lot more data (every site you visit vs. only the site that serves the JS code). At the end of the day, people wouldn’t use your site if they didn’t trust your site, especially if they use it for privacy and integrity reasons, so for most users I think JS is the better option. I suppose there’s no reason you can’t offer both though.
I think that’s the prevailing sentiment in this thread. People would rather trust the site to run the code as advertised and get some added convenience rather than verify the code for themselves.
Perhaps it makes more sense to have an extension that checks that the served javascript is correct? That should be a very simple, basic extension that doesn’t increase the attack surface much. Users who care to verify the code can use that and everyone else can live with the convenience.
Not sure if it makes much sense, it’s probably more work than it’s worth and maybe leads to doing the same thing twice.
Another commenter just told me about WAICT and there is also an experimental extension called WEBCAT by the freedom of the press foundation. Going to look into these more.