Oddbean

Keychat and Damus are both applications based on the Nostr protocol. What are the design differences between Keychat, as an application for posting private notes, and Damus, as an application for posting public notes? In our view, the Nostr protocol has three main innovative points. First, it boldly allows users to use public keys directly as IDs. Second, it has chosen a relay model where relays do not communicate with each other. Third, it is equivalent to having built-in RSS. For Keychat, it utilizes Nostr’s public keys as identities and the relay model but does not use the built-in RSS. Keychat’s contact list is only saved locally for better privacy. Keychat has implemented three unique designs. To address the issue of message encryption security, Keychat employs the Signal protocol to achieve end-to-end encryption. To tackle metadata privacy issues, Keychat separates the sending and receiving addresses from the ID and continuously updates these addresses. To ensure that relays can operate sustainably, Keychat uses Bitcoin ecash as postage stamp for messages.

the “ecash as postage stamp for relays” idea seems like a major innovation that applies outside of DMs. have you discussed your plans of this with other clients/relays (e.g. for public posting). how do you think about storage commitments for the value of the stamp?

We haven't discussed this with relay operators yet, but adding a postage feature to relays is very simple. For chat apps, messages do not need to be stored for a long time; in the best case scenario, once the recipient has received the message, the relay can delete it immediately. For the Damus app, the issue of storage duration is more complex. Perhaps it will depend on competitive pricing in the relay market. We are not sure.

Are you planning to make the Keychat chat app open source or are you planning to keep to closed-source/commercial? I’m curious how you imagine interoperability with various nostr-ecosystem/clients might work. I like this idea enough that I hope it can get adopted, but there might be certain philosophical choices that help nostr community members get on board.

Of course, we can work together to refine the Double Ratchet Algorithm used in message encryption. Keychat not only incorporates the Double Ratchet Algorithm used for message encryption but also includes metadata privacy and ecash as stamps. Therefore, we might need an NIP that describes all aspects of Keychat’s design. Furthermore, Keychat is an application focused on chatting, not just DMs. DM implies that it's merely an ancillary feature of a Twitter-like application.