A simple encrypted channel for file transfer. A great way to send a file to a stranger who is near you but shares nothing with you, e.g. at a conference.

/* A modern version should, of course, work in a browser, so that there'd be no Python packages to install. But the browser security model does not allow listening, so a signaling server would be needed to create a WebRTC connection. It could run on one of the devices involved, but still can't be a pure web app. */