In4chan

End-to-End Encrypted chat application

System Design

In this project I used Firebase as the server and for frontend, I used android xml.

• It has a persistent server which means even if you lose network, whenever the internet connection is live again it will receive and send message automatically.
• Chats are stored on the local database using Android and SQLite.

sequenceDiagram
    Alice->>+John: Hello John, how are you?
    Alice->>+John: John, can you hear me?
    John-->>-Alice: Hi Alice, I can hear you!
    John-->>-Alice: I feel great!

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• Server only holds the message as long as the receiver is offline.
  
  
• Messages sent to server are encrypted on the client device first and then decoded on the receiver device.

flowchart TD;
    A[Sender App] -->|Message| B(Encoder);
    B --> |Encoded Message| C{Server};
    C -->|Encoded Message| D[Receiver App];
    D --> |Encoded Message| E(Decoder);
    E --> |Decoded Message| F(Receiver);

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System GUI

The app is easy-to-use and user-friendly. Everything is labeled and easy to access.

• Log in and Sign up.
  
  
• Profile List and Chat List.
  
  
• Sending Message and Clearing Chat UI flow.
  
  
• Menu for Browsing Profile and Chat List.