Bla Bla Bla Protocol

The Bla Bla Bla Chat is built over the Bla Bla Bla Protocol, an application-level protocol for simple, encrypted peer-to-peer message exchanging. The protocol is based in the client-server architecture, with the server centralizing both clients and their messages.

Connection

Before exchanging messages, both users must connect with the server. The process of establishing a connection is described in the diagram below:

sequenceDiagram
    Client_1->>Server: Starts connection with the Server
    Server->>Client_1: Accepts the connection
    Client_2->>Server: Starts connection with the Server
    Server->>Client_2: Accepts the connection

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Encryption setup

After the socket connection is established, the encryption keys should be setup before message exchanging. The encryption used in the protocol is aes. The aes key must be passed from the server to the clients though, and each client has their own unique key. For exchanging aes keys, rsa asymmetric encryption is used. The process for trading keys is describedi in the following diagram:

sequenceDiagram
    Client_1->>Server: Sends rsa public key to the Server created by Client_1
    Server->>Client_1: Sends rsa-encrypted aes key for communication with Client_1 during in the rest of the connection
    Client_2->>Server: Sends rsa public key to the Server created by Client_2
    Server->>Client_2: Sends rsa-encrypted aes key for communication with Client_2 during the rest of the connection
    Client_1->>Server: Sends aes encrypted message
    Server->>Client_1: Sends aes encrypted message
    Client_2->>Server: Sends aes encrypted message
    Server->>Client_2: Sends aes encrypted message

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Message exchanging

After establishing connection and setting up the encryption keys, the chat is ready to start the conversation between both users. The behavior of the protocol during the message exchanging is described in the diagram below, and it was optimized to be able to keep the user updated in the situation of the message, including a reading confirmation.

sequenceDiagram    
    Client_1->>Server: Sends a message to the Server
    Server->>Client_1: Confirms the message was sent
    Server->>Client_2: Sends the message to Client_2
    Client_2->>Server: Confirms the message was received
    Server->>Client_1: Confirms the message was received by Client_2
    Client_2->>Server: [WHEN WINDOW IS OPEN] Confirms the message was read
    Server->>Client_1: Confirms the message was read by Client_2

    Client_2->>Server: Sends a message to the Server
    Server->>Client_2: Confirms the message was sent
    Server->>Client_1: Sends the message to Client_2
    Client_1->>Server: Confirms the message was received
    Server->>Client_2: Confirms the message was received by Client_2
    Client_1->>Server: [WHEN WINDOW IS OPEN] Confirms the message was read
    Server->>Client_2: Confirms the message was read by Client_2

    Client_1->>Server: Sends leaving request 
    Server->>Client_2: Sends leaving confirmation
    Server->>Client_1: Sends leaving confirmation  
    Client_1->>Server: Closes connection 
    Client_2->>Server: Closes connection 

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Bla Bla Bla Chat

A cross-platform chat application designed over the Bla Bla Bla Protocol to run on a local network using sockets, following a client-server architecture.

User Instructions

To use this application as an end user, no setup is required. Simply run the provided executables in "dist" folder. Choose the folder with the operational system you use and run the executable. No errors should arise during this process.

Development Setup

To set up the development environment, follow the steps below.

1. Create a Virtual Environment Ensure you are in the root directory of the project and that a requirements.txt file is present. Python must be installed. Then, create a virtual environment named .venv:

python -m venv .venv

2. Activate the Virtual Environment Activate the environment according to your operating system:

On Windows (Command Prompt):

.venv\Scripts\activate

On Windows (PowerShell):

.\.venv\Scripts\Activate.ps1

On macOS/Linux:

source .venv/bin/activate

3. Install Project Dependencies With the virtual environment activated, install all required dependencies using:

pip install -r requirements.txt

In case any error arises, try updating pip. If the error persists, try removing the versions from requirements.txt, leaving only the name of the dependencies, but be aware that version compatibility issues might arise.

Starting the application

In order to start the application locally for testing purposes, execute start_on_windows.bat (for Windows users) or start_on_linux.sh (for Linux users). Those scripts will open three terminal windows: one for the server to control the chat and two clients to interact with it. Errors in execution might arise mostly in linux because requirements work differently in linux.