RSA encryption simulation

This project is a simulation of sending encrypted packets across a network. It makes use of my Symmetric Key and RSA Cryptosystem algorithims. The simulation allows a user to create Computer objects and send Packet's between them. It encrypts the packet, sends it over, then decrypts it on the other side. The program also allows a user to inspect a Packet object which encapsulates all the information about the message.

How it Works

The first step of the simulation is to create two Computer objects.

Computer computer1 = new Computer();
Computer computer2 = new Computer();

Then, on one of them, call the sendMessage() method. Provide the other key, the text to send, and the key size you would like to use to encrypt the message. (The larger the key size the more secure the encryption will be.) Store this information in a Packet object.

Packet packet = computer1.sendMessage(computer2, text, OneTimePad.KEY_SIZE.ONE_HUNDRED_TWENTY_EIGHT);

Sending the Message

The Computer classes sendMessage() method provides an algorithim to encrypt the text, key, and key size. It works in 7 steps:

1. Generate a key from the OneTimePad class. Store it as key.
2. Convert the text to binary and encrypt it using key.
3. Encrypt key using the other computers public key and modulus.
4. Encrypt key_size using the other computers public key and modulus.
5. Package the encrypted binary, encrypted key, and encrypted key_size in a Packet object and store it as packet.
6. Call recieveMessage() on the other computer and pass in packet.
7. Return packet.

Recieving the Message

The Computer's class recieveMessage() method is the exact opposite of it's sendMessage() method. It decrypts the key, decrypts the key size, and uses those to decrypt the binary.

1. Decrypt key_size by using the Computer's private key and modulus.
2. Decrypt key through the same method, but also pass in the decrypted key_size to the convertKeyToBinaryAndDecrypt() method.
3. Use the OneTimePad classes decryptBinary() method and decrypt the binary.
4. Add the decrypted binary to the recentMessages List.

To access the recieved message simply call the getRecentMessages() method from the second Computer object.

System.out.println(computer2.getRecentMessages().get(0));

Testing the Code

Testing the code is a relatively simple process. A user can access all the information through a Packet Object.

First, as shown above, create the Computer objects.

 Computer computer1 = new Computer();
 Computer computer2 = new Computer();

Then, choose some sample text to send.

 String text = "I LOVE eating some stuff occasionally and having friends.";

Finally, send the message from one computer to the other and store the results in a Packet object.

 Packet packet = computer1.sendMessage(computer2, text, OneTimePad.KEY_SIZE.ONE_HUNDRED_TWENTY_EIGHT);

For greater encryption choose a larger key size.

To ensure that the message has been succesfully encrypted a user can check the Packet objects stored information.

Check it's binary with, packet.getBinary(), check it's key with, packet.getKey(), and check it's key size with, packet.getKeySize().

Sample Code

import java.math.BigInteger;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.stream.Collectors;

public class Main {
    public static void main(String[] args) {

        String text = "I LOVE eating some stuff occasionally and having friends.";

        Computer computer1 = new Computer();
        Computer computer2 = new Computer();

        Packet packet = computer1.sendMessage(computer2, text, OneTimePad.KEY_SIZE.ONE_HUNDRED_TWENTY_EIGHT);

        System.out.println("Encrypted Key Size: " + packet.getKeySize());
        System.out.println("Encrypted Key: " + packet.getKey());
        System.out.println("Encrypted Binary: " + OneTimePad.decryptBinary(packet.getBinary(), convertDecimalToBinary(packet.getKey(), packet.getKeySize().intValue())));

        System.out.println("Decrypted Text: " + computer2.getRecentMessages().get(0));

    }

    private static int[] convertDecimalToBinary(BigInteger decimal, int keySize) {
        ArrayList<Integer> binaryList = new ArrayList<>();
        while (!decimal.equals(BigInteger.ZERO)) {
            BigInteger[] divideAndRemainder = decimal.divideAndRemainder(BigInteger.TWO);
            binaryList.add(divideAndRemainder[1].intValue());
            decimal = divideAndRemainder[0];
        }

        int[] binary = new int[binaryList.size()];
        for (int i = 0; i < binary.length; i++) {
            binary[i] = binaryList.get(binary.length - 1 - i);
        }

        if (binary.length < keySize) {
            int[] newBinary = new int[keySize];
            int difference = keySize - binary.length;
            for (int i = 0; i < difference; i++) {
                newBinary[i] = 0;
            }
            if (keySize - difference >= 0)
                System.arraycopy(binary, 0, newBinary, difference, keySize - difference);
            binary = newBinary;
        }
        return binary;
    }
}

Sample output:

Encrypted Key Size: 562949953421312
Encrypted Key: 6655747628909150883605321113682484283950432275675827238929313750103518226623821161969841086812304745766931580047114874586148809581822087125906199241297766612126657313367502198359615779323116292574309772774650197477680886284305286631742040464958083373139190487751069901
Encrypted Binary: �Anm+�gx�¡¶ª^I¦]*��Q	"!{˺¼§X�¼]) NN�w&s�õ·¥O »Ug�PK�9#nÅ
Decrypted Text: I LOVE eating some stuff occasionally and having friends.

Contributing

Contributions are what make the open source community such an amazing place to learn, inspire, and create. Any contributions you make are greatly appreciated.

If you have a suggestion that would make this better, please fork the repo and create a pull request. You can also simply open an issue with the tag "enhancement". Don't forget to give the project a star! Thanks again!

1. Fork the Project
2. Create your Feature Branch (git checkout -b feature/AmazingFeature)
3. Commit your Changes (git commit -m 'Add some AmazingFeature')
4. Push to the Branch (git push origin feature/AmazingFeature)
5. Open a Pull Request

License

Distributed under the MIT License. See LICENSE.txt for more information.

Contact

unpluggedsam - @SamJaco13689394 - unpluggedsam990@gmail.com

Project Link: https://github.com/unpluggedsam/RSA-symetric-key-hybrid