DEN Chat

A decentralized, encrypted chat system built on Nostr.

What is DEN Chat?

DEN Chat brings hub-based group communication to Nostr — channels, categories, roles, permissions — all without trusting a central server. Messages are encrypted by default using a shared hub secret, so non-members can't read your conversations.

The familiar hub/channel structure you'd expect — but your identity is your Nostr keypair, your messages live on relays you choose, and no corporation controls your community.

How It Works

Hubs

A hub is a community space. It has channels for conversation, categories to organize them, and roles to manage permissions. The entire hub structure lives in a single Nostr event owned by the creator.

Encryption

Every hub has a shared secret. All messages are encrypted with it — non-members see nothing but ciphertext. Private channels can use additional per-group secrets for extra isolation (e.g., a staff-only channel that even regular members can't read).

Membership

Member lists are stored on Blossom servers as content-addressed files. The creator maintains the canonical list, but any member can facilitate access for others via their own LKH tree — a "mesh membership" model that prevents any single point of failure.

Filter Relays

For hubs that want stronger access control, optional filter relays gate who can read and write. These specialized relays check the creator's member list before accepting or serving messages.

Documentation

• NIP-CHAT Specification — the full protocol spec (event kinds, crypto model, relay behavior, client behavior, and security model)

Architecture Overview

┌─────────────────────────────────────────────────┐
│                    Hub Event                     │
│              (kind 36942, on relays)             │
│                                                  │
│  Roles · Categories · Channels · Permissions     │
│  Relay list · Blossom servers · Index file hash  │
└──────────────────────┬──────────────────────────┘
                       │
          ┌────────────┼────────────┐
          ▼            ▼            ▼
   ┌────────────┐ ┌─────────┐ ┌──────────┐
   │  General   │ │ Filter  │ │ Blossom  │
   │  Relays    │ │ Relays  │ │ Servers  │
   │            │ │         │ │          │
   │ Hub events │ │Messages │ │ Member   │
   │ Join reqs  │ │ (gated) │ │ files    │
   │            │ │         │ │ Block    │
   │            │ │         │ │ lists    │
   │            │ │         │ │ History  │
   │            │ │         │ │ Media    │
   └────────────┘ └─────────┘ └──────────┘

Protocol Summary

Kind	Event	Purpose
36942	Hub Event	Hub structure, roles, channels, permissions
36943	Message	Encrypted channel message
36944	Join Request	Signal intent to join a hub
16942	User Hub List	User's personal list of joined hubs

Key Design Decisions

• Encrypted by default — all messages use AES-256-GCM. Non-members can't read content.
• No MLS — uses ECDH + HKDF + AES-GCM for simplicity and scale. No complex tree state.
• Mesh membership — no single point of failure for member lists. Creator is canonical but not exclusive.
• Full history access — new members can read all past messages. Removed members lose access to everything.
• Client-side permissions — the protocol doesn't gatekeep. Clients decide what to render based on roles.
• Domain-separated keys — NIP-CHAT keys can never collide with NIP-04/NIP-17/NIP-44 DM keys.

Security Model

DEN Chat is designed for group communication with encryption, not private messaging:

• ✅ Messages encrypted against outsiders
• ✅ Removed members lose all access (including history)
• ✅ Relay operators can't read message content
• ✅ Multiple relays and Blossom servers prevent single points of failure
• ⚠️ No forward secrecy (by design — group chat history is a feature, not a bug)
• ⚠️ Any current member could leak the hub secret
• ⚠️ Filter relays are trusted for access control (but not for content)

Project Status

📋 Specification: Draft v3 (NIP-CHAT.md)
🔨 Client: In development — hub creation, messaging, reactions, editing, deleting, profiles functional
🔌 Filter Relay: Not yet started

Other NIPs & Kinds Involved

Standard Nostr Kinds Used

Kind	Name	NIP	Usage
0	User Metadata	NIP-01	Profile display (name, avatar, about)
3	Contact List	NIP-02	Follow lists
5	Deletion	NIP-09	Request deletion of messages
7	Reaction	NIP-25	Emoji reactions on messages
1059	Gift Wrap	NIP-59	Encrypted envelope for join requests
1060	Sealed Sender	NIP-59	Inner sealed message
10002	Relay List	NIP-65	User's preferred relay list
10063	Blossom Server List	Blossom	User's preferred Blossom servers
24134	UPV2	UPV2	Username-password vault login

NIPs Referenced

NIP	Usage
NIP-01	Event structure, relay communication
NIP-02	Contact/follow lists
NIP-07	Browser extension signer (window.nostr)
NIP-09	Event deletion requests (kind 5)
NIP-19	Bech32 encoding (npub, naddr, nevent)
NIP-25	Emoji reactions on messages (kind 7)
NIP-44	Encrypted payloads (message content encryption)
NIP-46	Remote signer via bunker:// or nostrconnect://
NIP-59	Gift wrap / sealed sender for join requests
NIP-65	Relay list metadata

Version Management

To bump the app version across all config files, run from the DEN Chat directory:

node scripts/bump-version.mjs 0.2.0

This updates:

File	Purpose
client/package.json	npm/Vite version + __APP_VERSION__ UI constant
client/package-lock.json	Lockfile consistency
src-tauri/tauri.conf.json	Tauri installer filenames & update manifests
src-tauri/Cargo.toml	Rust crate version
client/public/version.json	Web update detection (polled by running clients)

The web app displays the current version in Settings → Updates and automatically detects when a newer version has been deployed (shows a refresh toast).

---

Built on Nostr · Encrypted with AES-256-GCM · Stored on Blossom