3DES implementation with Diffie Hellman key exchange

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.

Dependencies

• 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

Opcode	Message	Description
10	PUBKEY	Public key Ya/Yb sent to the server/client by the client/server
20	REQSERV	Request for service (transferring a requested file) from the server to the client
30	ENCMSG	Sending encrypted message(s) for the file from the server to the client
40	REQCOM	Request completion message from the server to the client
50	DISCONNECT	Disconnect request message sent from the client to the server

Extra files information

• 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.