Chat Island

Instant messaging is built on the top of websocket in real time.

Sequence

Register

Chat Island uses public and private key authentication. A public key represents a user.

sequenceDiagram
    participant Client
    participant Server
    Client->>Server: Public key
    Server->>Server: Check if not exists <br/> and register it
    Server-->>Client: Registered

Authentication

After building a websocket connection, sending a challenge for authentication.

sequenceDiagram
    participant Client
    participant Server
    Client->>Server: Public key
    Server->>Server: Check if registered
    Server-->>Client: A random string encrypted by <br/> client's public key
    Client->>Client: Decrypted challenge by <br/> my private key
    Client->>Server: Send back raw string

Whisper

Users can talk with each other via public keys.

sequenceDiagram
    participant Arthur
    participant Server
    participant Julia
    Arthur->>Server: "Hello, Julia."
    Note over Arthur,Server: Encrypted by Julia's public key
    Server->>Server: Save it to DB and instantly forward.
    Server->>Julia: Encrypted "Hello, Julia."
    Julia->>Julia: Decrypted by my private key.

Chat Room

Uers can create chat rooms, and invite others by adding their public keys into the member list.

Members can query the member list anytime.

sequenceDiagram
    participant Arthur
    participant Server
    participant Other Members
    loop For each member
      Arthur->>Server: "Hello, everyone"
      Note over Arthur,Server: Encrypted by their public keys
    end
    Server->>Server: Save them to DB and immediately forward
    loop For each member
      Server-->>Other Members: Encrypted "Hello, everyone"
    end