Decentralized message protocol idea

It seems the FOSS community is still without a universal protocol for decentralized messaging. IRC has the most adoption. XMPP is also popular. Matrix is gathering momentum. All of these are client/server. None of them fully satisfy modern needs.

Here is the wishlist:

• E2EE
• peer/peer architecture
• identity-based (instead of address-based)
• simple and easy to understand
• group messaging support

I am envisioning a simple protocol which uses message content and basic metadata to maintain approximate continuity with reasonable qualifiers. A message should consist of the following:

• sender (public key)
• recipients (public keys)
• timestamp
• message content

When a message is sent, the sender's instance sends a copy of the message to each recipient encrypted with that user's public key. This protocol is agnostic about the transport method. The recipient's address can be determined on a per-network basis.

Recipients decrypt the message and check the recipients line to determine what conversation this message belongs to. This has the effect of making one group per list of recipients. If more than one group is required for the same recipient list, a dummy recipient may be added. Messages will not be sent to the dummy.

A special type of message may be sent to add a recipient to a group. This effectively archives the conversation. Future messages that omit the new recipients will trigger a resubmission of the add-recipient message.

Messages are sorted by timestamp (send time). Peers can send requests to one another for message history to compare for missing messages.