Introduction

The chat app utilizes TCP/IP together with Diffie-Hellman mutual authentication protocol and md5 HMAC for message integrity. Diffie-Hellman was also chosen for establishing session key for perfect forward secrecy. The integrity-protection in the app utilizes a md5 hash which hashes our message using the pre-established shared secret. The receiver checks the decrypted message against the HMAC to detect alteration on the message.

Requirement

• Python 2.7
• kivy 1.9.0
• pycrypto

Run from command line

python main.py

Usage

• Run server instance, the default is in server mode. Click Open Connection button and type in a listening port number.
• Run another instance as client, click Client button to change to client mode. Click Open Connection button and type in respective host and port to connect to server.
• Enter shared secret value into client and click Use Secret button
• Enter shared secret value into server and click Use Secret button
• The server and client should now be mutually authenticated.
• Type in message to send between client and server, the message exchanged is displayed in console.
• Close client and server connection and quit program.