**** RSA Project for Puneet Vohra and Belig Borjiged CIT595 ****

HOW TO RUN:
To compile: "make"
To run server: server [port number]
To run client: client [host name] [port number]
To run bruteforce: bruteforce  // Once it asks for the key, enter [public e] [public N]

** Note: when prompted to enter numbers for the mth and nth prime numbers, it is best to use numbers under 30 for better response times (the numbers entered will be used to find the corresponding prime numbers to use to generate the public/private keys).  Also, due to some issues with testing between PCs in the ENIAC lab, we did the majority of our testing using "localhost" as the host name.

URL FOR REPOSITORY: 
https://beligb@github.com/beligb/CIT595-RSA.git

PROCEDURE/METHOD:
We worked off of HTTP Server code (from the previous assignment) as a starting point for our RSA chat server.  It was rather tricky to convert the HTTP Server into the Server that we needed, but once that was done, we had a good foundation for the Client side, as it did basically the same thing, but in a different order to prevent deadlocking.  It was very difficult to get the different programs to tell each other when they wanted to quit, as they both had multiple threads that sometimes needed to be killed before exiting, and the Server had to tell the Client it was going to quit so that the Client could acknowledge it and quit itself. In our case, the Client can quit but the Server will still run and be ready to be connected to again unless someone from the Server side actually explicitly quits the Server. There was a bit of confusion about what the "Totient" was and what its formula was (whether it was (p-1) * (q-1) or just the total number of prime numbers less than the mod component of the public key). In the end, we just used the (p-1) * (q-1) as our "M" as it gave us a correct encryption/decryption.

Another difficult aspect of this project was encrypting and decrypting the messages to be sent over the sockets, especially, converting each letter into a corresponding number and back again. We needed to take care of lots of overflow problems, which we managed to do by restricting the size of our prime numbers that we generate, as well as printing out long integers instead of the regular ones.  For user input in the beginning of our program, it is best to use smaller numbers no larger than 30 for the best response time.  This way the program only has to search up to the first 30 prime numbers, minimizing the numbers it needs to cycle through to retrieve a corresponding prime number.  We noticed that the larger our numbers got, the more painfully slow our program became.  

To conclude, we learnt a lot through this project.  It was interesting to see how RSA could be used when sending messages between two parties, and sort of demystified the process a bit.  It was also nice to get a working chat server up, as it seemed like an impossible task when it was first brought up in class, but was much more manageable after having done the HTTP Server.


TEST RUN:
/********************** SERVER SIDE *************************/
beligb@CELERITY:/mnt/castor/seas_home/b/beligb/CIT595 HW/Project> server 9019

Enter two numbers (m n) to generate keys based on the mth and nth primes: 21 23

Generating keys...
Your public key (will be sent to server): 3691 6059
Your private key (will not be sent): 739 6059
The client's public key is 5183 2339
hi

Message received from Client: 2594 2508 5586 5586 692 
Client's message decrypted: hello

Message received from Client: 5742 5586 3334 2594 
Client's message decrypted: blah

Message received from Client: 105 
Client's message decrypted: i

Message received from Client: 105 
Client's message decrypted: i

Message received from Client: 105 
Client's message decrypted: i

Message received from Client: 105 
Client's message decrypted: i
lel
l
l
l
l
l
f
this is running right?

Message received from Client: 105 105 32 2594 692 3681 2508 32 3684 692 
Client's message decrypted: ii hope so

Message received from Client: 4433 5249 2594 
Client's message decrypted: ugh
ok
cit595 is the best class ever!

Message received from Client: 3544 41 
Client's message decrypted: :)

Message received from Client: 3544 5048 
Client's message decrypted: :D
Jimmy JOhns sandwitch is awesome.....aaahhhhhg
haha
^

/********************** CLIENT SIDE *************************/
beligb@CELERITY:/mnt/castor/seas_home/b/beligb/CIT595 HW/Project> client localhost 9019

Enter two numbers (m n) to generate keys based on the mth and nth primes: 20 21

Generating keys...
Your public key (will be sent to server): 2339 5183
Your private key (will not be sent): 4859 5183
The server's public key is 6059 3691

Message received from Server: 186 673 
Server's message decrypted: hi
hello
blah
i
i
i
i
i
Message received from Server: 2238 3225 2238 
Server's message decrypted: lel

Message received from Server: 2238 
Server's message decrypted: l

Message received from Server: 2238 
Server's message decrypted: l

Message received from Server: 2238 
Server's message decrypted: l

Message received from Server: 2238 
Server's message decrypted: l

Message received from Server: 2238 
Server's message decrypted: l

Message received from Server: 297 
Server's message decrypted: f

Message received from Server: 2246 186 673 33 600 673 33 600 2393 798 3944 3944 673 3944 3156 600 2393 673 3156 186 2246 4183 
Server's message decrypted: this is running right?
i hope so
ugh

Message received from Server: 3821 4395 
Server's message decrypted: ok

Message received from Server: 2861 673 2246 3004 3910 3004 600 673 33 600 2246 186 3225 600 38 3225 33 2246 600 2861 2238 3647 33 33 600 3225 4951 3225 2393 115 
Server's message decrypted: cit595 is the best class ever!
:)
:D

Message received from Server: 512 673 3648 3648 327 600 512 645 186 3944 33 600 33 3647 3944 3696 3385 673 2246 2861 186 600 673 33 600 3647 3385 3225 33 3821 3648 3225 4845 4845 4845 4845 4845 3647 3647 3647 186 186 186 186 186 3156 
Server's message decrypted: Jimmy JOhns sandwitch is awesome.....aaahhhhhg

Message received from Server: 186 3647 186 3647 
Server's message decrypted: haha

Message received from Server: 1088 
Server's message decrypted: ^