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?
It’s not the server code which is the question though, it’s the client side, which either way is downloaded from somewhere you control (whether in minified js to run in the browser, or binary blob of a desktop app). A malicious developer can quite easily insert different code rather than the published source in either situation.
I guess if you have a traceable build pipeline which is entirely under control of a trusted cloud provider, that might do it.
But if so then there’s no reason you can’t make the web client “binary” available in the same way, as say a webroot zip or a container image. People can run it themselves against your backend api, or audit the frontend code your server is serving against the trusted version.
Or for the hell of it, write your web client with its encryption code in plain js rather than minifying it or using a framework. Then someone can view source on the web page and literally see the client source which is running.
Not the most maintainable solution of course, but highly transparent.
OK but that requires everyone to be a vigilant user. It’s much easier for users to just install the software themselves and verify the checksum matches.