Needham and Schroeder Protocol1 encryption messaging client-server application.
- Alice send request to communicatee with bob to the server plus nonce.
- The server respond with payload of 2 versions of the session key, one encrypted with Alice key, the other is encryptd with Bob key, and put the same nonce alice sent.
- Alice send Bob section from the payload to Bob along.
- Bob receive and decrypt the session key with his key, generate a nonce and encrypt it with the session key, then send to Alice.
- Alice receive the nonce, decrypt with the session key, add 1 to it then encrypt with the session key and send to bob.
- bob receive and confirm the nonce.
- session is confirmed and both can send messages encrypted with the session key
###Sequence Diagram
Alice->Server: connect me to Bob
Note right of Server: server validate\nAlice nonce
Server-->Alice: encrypted Session keys
Note right of Alice: Alice validate\nServer nonce
Alice->Bob: Are you Bob?!
Note right of Bob: Bob decrypt\nand validate
Bob-->Alice: Yes!
Note right of Alice: Alice validate\nBob nonce
Alice->Bob: Are you sure?!
Note right of Bob: Bob validate\nnew nonce
Bob-->Alice: Yes, I am sure we can talk!
###End
To Compile the program simple run make command Note: "I used simple encryption and not AES, there might be some bugs in the communication, for example right when the session start the nonce will be sent again. The good part there is no known major problem, yet!."
- run the server with argument '-p <port number>':
sudo ./server -p 445
- in separated window or a computer run a client with arguments '-s <Server name> -g <server port> -n <client name> -p <secure channel port>':
sudo ./client -s localhost -g 445 -n Alice -p 2225
- Choose option 2 to wait for connection.
- in separated window or a computer run a client with arguments '-s <Server name> -g <server port> -n <client name> -p <secure channel port>':
sudo ./client -s localhost -g 445 -n Bob -p 2225
- Choose option 1 to request communication.
- When prompted put the name of the other party (case sensitive, the server will use this name to know the other person encryption key) for example Alice.
- When prompted put the server name or IP address of the other party for example here localhost.
- When the secure channel is granted start chatting when prompted.
-s followed by server name or IP address: define the server.
-g followed by a port number: define the server port.
-n followed by username: to define a name for the client.
-p followed bz a port number: define the client port number.