Show HN: Exploiting Slack's video embeds to achieve E2EE communication

A developer created an end-to-end encrypted messaging system for Slack by exploiting the platform's video embed feature, which accepts any accessible URL and renders it as an iframe without content validation. The app uses browser crypto APIs to encrypt messages client-side with key pairs, leveraging Slack's video blocks to perform decryption operations while keeping the server from ever accessing unencrypted keys. The open-source project demonstrates how Slack's flexible embed system could enable more sophisticated client-side applications if the platform officially supported them.