Anonymous Private Forums

Functional requirements (F of FURPS)

Note: here "subscribed" and "topic" refer to app layer terminology. The first version is just text and ephemeral. V2 uses storage for larger sized content (images) and backing up/restoring chats

Forums

• A user installs the forum Basecamp app, which has an initial default forum called "Logos Forum"
• V2: They can add/create other forums by name (or alternatively clone the forum app and change the default name).

Posts

• A user will receive posts to forums they're subscribed to ("Logos Forum" is initially subscribed to)
• A user can send a few types of public messages to the forum:

Type	Topic	Text	Img (v2)	reply	Author
New topic	New	post	opt.	NA	sig
Existing topic	(id)	post	opt.	opt.	sig

• Public posts directed to a subscribed forum are received and stored locally to render in a UI
• V2: Images
• V2: Private posts can also be sent to a forum, encrypted for a particular group

Identity (v2?)

• A user has one (v2: or many) unique identifiers
• Posts are signed
• On installation, the app generates a new id for the user
  • A user may wish to import their own id
• It should be practically impossible for a user to create the identity of another user

V2: Post history

• A user can browse past posts that were sent when they were not subscribed to receive them

Usage overview

graph TD
    User["User"]
    Identity["Identity<br>(pub/priv key pair)"]
    ForumApp["Forum App<br>(Basecamp)"]
    Forum["Forum<br>(e.g. 'Logos Forum')"]
    Topic["Forum Topic<br>& Posts"]
    Post["Post<br>(signed by Identity)"]
    Network["Network<br>(posts)"]
    LocalStorage["Local<br>Storage"]
    RemoteStorage["Logos-Storage<br>(V2: offline sync)"]

    User -->|installs| ForumApp
    ForumApp -->|generates| Identity
    ForumApp -->|subscribes to| Forum
    User -->|creates| Post
    Identity -->|signs| Post
    Post -->|new topic →<br>forum hash + name| Network
    Post -->|old topic →<br>Forum hash + name + topic| Network
    Network -->|received| Forum
    Forum -->|contains| Topic
    Forum -->|persists to| LocalStorage
    Forum -.->|V2: remote sync| RemoteStorage

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Arch/components (ADR)

NB: Based on current state of modules depended on, will evolve with updates to functionality & documentation.

Overview

Like logos-chat, but public with shared messaging topics to subscribe to.

graph TD
    ForumUI <-->|linked| AppBackend["App<br>Backend"]
    AppBackend <-->|send/receive<br>posts per forum| ForumComms[Forum Comms<br>module]
    ForumComms <-->|send/receive<br>msgs per topic| logos-delivery
    ForumComms <--> MsgCodec[msg codec<br>lib/module]
    AppBackend <-->|persist/restore<br>state| ForumStorage[Forum Storage<br>module]
    LocalStorage -->|read| ForumStorage
    ForumStorage -->|write| LocalStorage[Local<br>Storage]
    ForumStorage <-.-> SyncStore[V2:<br>Sync Store<br>module]
    ForumStorage -.-> BlobCodec[blob codec<br>lib/module]
    SyncStore -.->|store| LocalStorage
    LocalStorage -.->|share| SyncStore
    SyncStore <-.->|sync| logos-storage

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Assumptions

• msg topics assumed to be long lived, so can be used between generic delivery and storage sync ("Sync Store")

Forum UI

The user interacts with the UI as specified in functional reqs. Action is taken via the C++ backend:

• modify forum & topic subscriptions
• send/receive posts
• persist/load state to/from local storage

Forum Comms module

• Wraps logos-delivery
• Manages msg-topic subscriptions
• Uses a module (starting as just a lib) to encode/decode forum posts to/from msgs
  • helper functions between forum name/topics converstions can be here
• Send/receive forum posts as delivery msgs

Forum Storage module

• Saves forum posts to local storage, so previously received msgs can be restored.
• Uses a module (start as a lib) to encode/decode many delivery msgs into blobs
  • blobs scoped per forum/topic, and time-based
• V2: sync blobs with others on the network via a wrapper to logos-storage

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Forums (aka "cells")

Each forum should start with a name, this can be used with a domain prefix to uniquely specify messages on the network intended for a forum. For example: hash("Forum") + "Logos Forum" can be an initial forum people join, and discover other forums.

Posts

• created locally and shared on the forum topic
• To begin a all posts can be shared to: hash("Forum") + "Logos Forum"
  • Consider only sending new forum topics to entire forum's messaging topic
  • Then posts to existing forum topics sent to: hash("Forum") + "Logos Forum"+ "Forum topic"

Identity

• public/private identity key pair
• Posts signed by private key so post authors can be verified

V2: Post History

• Data blobs of past msgs per topic saved to storage
• app can participate in backup
• A form of pagination to incrementally trace back msg history