In this assignment, we implemented authentication and sending of encrypted data over a network.

Running the programs is simple. First clone the repository and go to the folder "src" on your command prompt or terminal.

Next, compile the relevant java files. For example if you want to run CP1,

javac ServerCP1.java
javac ClientCP1.java

Finally, run the Server program on the machine that will be receiving the files, and run the Client program on the machine sending the file.

java ServerCP1
java ClientCP1 <ip-address-of-server> <path-to-file>

Here is an example of how we run our program. On the server side:

javac ServerCP2.java
java ServerCP2

And on the client side:

javac ClientCP2.java
java ClientCP2.java 10.12.90.175 rr.txt

Our program has two parts. Authentication (AP) and Encrypted Data Transfer (CP1 and CP2).

Here are the specs of AP:

Here are the specs of CP1:

Here are the specs of CP2:

If you have seen the specs of our program, you might have noticed that we used a nonce during authentication. This is to prevent the possibility of a playback attack. With the nonce, an attacker can no longer record the message encrypted using the server's private key, and send it to the client at a later time, pretending to be the correct server.

We tested both CP1 and CP2 over 350 text files of varying sizes and plot the file transfer time to compare the performance of the two different encryption methods.

Here are the results.

For the high quality and interactive version, visit http://rpubs.com/nosyarlin/Programming_Assignment2

Note: The programs were written and tested on a Mac machine.