Cryptography Practice - Chat App

Author:

• Rosa Reyes

This project implements an application that enables encryption and decryption of messages using symmetric encryption (AES-GCM) and asymmetric encryption (RSA). It also incorporates the use of digital signatures, certificates, and a Public Key Infrastructure (PKI) for enhanced security and authenticity.

Additionally, the application includes a web interface for user registration and authentication, as well as the exchange of encrypted messages.

Folder Structure

The folder structure of this project is as follows:

cryptography-project/
│
├── backend/ 
    ├── backend.py           # Backend for authentication and storing passwords and users in a database.
    ├── crypto.py            # Functions for encryption and decryption of messages and keys.
├── frontend/ 
    ├── components.py        # Auxiliary components for forms and messages.
├── certificates/            # Folder to store the PKI
├── main.py                  # Main file to run the application server.
├── requirements.txt         # File of necessary dependencies to run the project.
└── users.db                 # SQLite database to store registered users.

Prerequisites

1. Python 3.7 or higher

2. Virtualenv: It is recommended to install a virtual environment to avoid dependency conflicts:

   pip install virtualenv

Installation and Configuration

Step 1: Clone the repository

Clone this repository to your local machine:

git clone https://github.com/rosareyes/crypto-lab1
cd crypto-lab1

Step 2: Create and activate the virtual environment

1. Create a virtual environment:

   python3 -m venv venv

2. Activate the virtual environment:
   • On Windows:

     venv\Scripts�ctivate

   • On MacOS/Linux:

     source venv/bin/activate

Step 3: Install dependencies

Install the required dependencies by running:

pip install -r requirements.txt

Usage

1. Run the server

To start the server and run the application, execute:

python main.py

2. Access the application

Open your web browser and go to http://localhost:5001/ to view the user interface.

3. Register and authenticate

• Use the registration forms to create users (User-1 and User-2).
• Each user can log in and send encrypted messages to the other user.
• Messages are encrypted using AES-GCM (symmetric encryption), and the symmetric keys used are encrypted with RSA (asymmetric encryption).

Main Features

• Message encryption and decryption: Using AES-GCM for message encryption and RSA for encrypting symmetric keys.
• User registration and authentication: Securely stores users in the SQLite database, using Scrypt to derive and store password hashes.
• Digital signatures and certificates: Use of digital signatures and certificates generated with OpenSSL.

Terminal Logs

The terminal provides detailed logs of the cryptography processes, such as encryption, decryption, and key exchanges. Below are sample screenshots:

1. Terminal Logs: Sender process

2. Terminal Logs: Receiver process

Notes

• certificates/ directory: This directory contains certificates for CA1, user 1, and user 2.
• Database: The users.db database securely stores user credentials.

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Running Tests

To test the functionality, register two users (User-1 and User-2) and log in with each to send messages. Observe the terminal output to see the encryption and decryption process steps.