Suppose there are n users A (clients) want to securely access the files stored in the database of a user B (server). At first, each client will make a connection using socket with the server B and then will establish three symmetric keys, say K1 , K2 and K3 which will be used for encryption and decryption using the 3DES with three keys symmetric cryptosystem.

• python3 is needed in order to run the server and client. It can be installed using the following command.

apt-get install python3

• All the dependencies of the project are given in requirements.txt, which can be installed using:

pip3 install -r requirements.txt

# If you don't have pip3 installed on your system, run:
apt-get install python3-pip

To run the server and client, follow the given steps:

cd path-to-directory/server
python3 server.py

# Open a new terminal
cd path-to-directory/client
python3 client.py 127.0.0.1

# Type 'help' to find out all the commands

The protocol messages used in the implementation are provided below

• All the global settings are stored in settings.py present in the root directory.
• The common data structures and functions used by server and client side are stored in common.py also present in the root directory.
• All the extra dependencies for running the server are stored in requirements.txt, which can be installed as described above.