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?

  • lawks@aussie.zone
    2·
    20 hours ago

    It seems that ignorance abounds in this post’s comments. People are apparently unaware that one can write an extension that has no more privileges than a normal web page, and unlike a page, the code cannot change on every load. Your idea is good. I’d recommend not using any minification or obfuscation in the extension, and keep it as brief as is possible, for maximum transparency.

    In a parallel situation, I’ve always been wary of hosted password managers’ web interfaces like those of Lastpass, 1Password, and even Bitwarden, because one has to accept the code served at every access is clean. Ultimately, one enters their master password/secret keys, as plain text, into a web page that’s difficult to audit & unlikely to be, on every view. Whereas offline/client-side encryption outside the transmission medium is far more trustworthy (e.g. KeePass).