Implement an application that enables private communication between 2 users (at least).
The project was brought to its end. Unfortunately because of the small-time left before the deadline one of the necessary features could not be implemented: Save a conversation in the database between two users. We more time we could have implemented Group Chats (thus communication with multiple people at teh same time).
This project runs on JavaFX 1.8. Please download this version if you want the app to work on your device. If you want to Compile yourself (.jar file are already prepared, read en section of requirements to see how to launch app): You need to compile java with javafx, the best method is to simply use Intellij IDEA. Other methods to compile seem to be more complicated. We tried making them with makefiles, but the compilation never included the fxml files with the .class files, we thus had error. To overcome this problem we let Intellij IDEA take care of the compilation and just enabled multiple instances of a given code to run. To do this left click on the application you want to run in the top right corner next to the green arrow "run" (on its left) and select "edit information". in the menu, for the client app only go on the same level as "build and run" there is a modify button. left click on it a thick to allow multiple instances box. Once this done, apply the changes, and you can now run multiple instances of client in IntelIJ IDEA.
No compatibility issues. This project was tested on Ubuntu 20.04 and Windows 10+11
To Make it easier for a client to install the app, .jar files have been Created. They can be launched using the makefile command "make server" to launch the server and "make client" to launch the client. They have to be launch in SEPARATE terminal. By default, the command line make launches the server.
- Possibility to launch a conversation with as many users (you can launch as many as you want) as you want.
- The conversations are private as the messages are encrypted using the Diffie-Hellman procedure.
- As a User you can log out from the app and come back later on (log in) without having to register again as all your information (firstname, lastname, email, password, username) have been saved in the database.
- An automatic check is run when you want to log in, you will not be able to if you use wrong information (wrong username for instance)
- An already connected username can't log in if he is already logged in.
- You can choose the recipient of your message. If the recipient is not connected, a security feature is built in to prevent the exchange of key of a not connected user. There is a timer built in to wait 10 seconds for the key to be exchanged. If this time is exceeded then the recipient will be forgotten and the message not sent.
- To "kill" all the users we may just push the "RIP" button, appearing on the Server interface. This is equivalent to turn off the app and disconnect all user currently connected.
- You can send messages to yourself (if you feel lonely), these messages will be encrypted following the same procedure.
To start we first creat a ServerSocket object. We then start a Thread which will take care off the reception of connection of all new client connected. For a client to connect to the server he will have to create a socket with the server port number. Once a client is connected to the server, a new thread and socket on the server will start just for the specific client to verify its login/register information. This enables the server to have multiple client connect at once. Once a client enter valid information, the thread taking care of the correct connection will be terminated and a new one will be created in the conversation controller to take care of all the conversation this client may have with other client or the server directly (ex : disconnect message, key exchange message, etc...).
We used th socket library provided by java. Since it is directly implemented in java it was much easier to implement in our code and troubleshoot if any problem was encountered.
To use the sockets provided by java, 2 things to be considered:
- the server socket receives 1 argument, its port. ex : "4321"
- the client socket receives 2 arguments, the first is its address (to make it easier we always put localhost, and it will automatically assign an available local ip address.) and the second is the server port, so in this case : "4321".