In this lab you will implement a simplified version of The Signal Protocol, which is the basis for WhatsApp's end-to-end encryption.

The first versions of Whatsapp protocol were described here. A more recent document is available here. WhatsApp's security is based on the Signal protocol, which was first used by TextSecure. The Signal protocol is described in detail in this paper.

For the Elliptic Curves, you can use this library.

For installation, follow these steps (NOTE: on ARM machines, you will have to resort to using an emulated x86 VM or an x86 instance):

• Install the necessary tools: sudo apt install build-essential python3-dev
• Install pip: sudo apt install python3-pip
• Install donna via pip: pip install cryptography donna25519

Find the required zip here - lab07.zip.

Create a common master_secret for two clients which communicate through a server. (TODO 1.1 & TODO 1.2) Print it on both clients and make sure they both have the same secret.

Open three different terminals.

First terminal (start the server):

python main_server.py

Second terminal (start the first client and enter RECV mode:

python main_client.py
RECV

Third terminal (start the second client and send a message):

python main_client.py
MSG <id_other_client> Hello!