need to complete the following program in JAVA I have already provided code below please use only that code as I have already been working with this

/**

* Write a description of class RC4 here.

*

* @author (your name)

* @version (a version number or a date)

*/

import java.util.ArrayList;

import java.util.Collections;

public class RC4 {

/**

* Encrypt plaintext with key. Place output in ciphertext.

*/

public void encrypt(ArrayList plaintext, ArrayList key,

ArrayList ciphertext) {

//Ensure key length is between 5 to 16 bytes

assert key.size() >= 5 : "Key too short";

assert key.size() <= 16 : "Key too long";

//Create our state s and set key schedule

ArrayList s = new ArrayList();

genKSA(key, s);

//create a key stream and call genKeyStream() to create the key bytes

// according to the schedule s

ArrayList keyStream = new ArrayList();

for (int i = 0; i < 256; i++)

keyStream.add(i);

genKeyStream(s, keyStream, plaintext.size());

//For debugging

System.out.print("keyStream: ");

for (int c=0; c < plaintext.size(); c++)

System.out.print(Integer.toHexString(keyStream.get(c))+" ");

System.out.println();

//encrypt the plaintext using the key stream

for (int i = 0; i < plaintext.size(); i++)

{

ciphertext.add(plaintext.get(i) ^ keyStream.get(i));

}

}

/**

* Decrypt cyphertext with key. Place output in plaintext.

*/

public void decrypt(ArrayList ciphertext, ArrayList key,

ArrayList plaintext) {

//Need decrytion code

}

/**

* Generate the schedule s corresponding to the key.

*/

private void genKSA(ArrayList key, ArrayList s) {

//This code needs to be done

}

/**

* Generate a key stream keyStream of numBytes bytes, using the schedule s.

*/

private void genKeyStream(ArrayList s, ArrayList keyStream,

int numBytes) {

// need to generate the key stream code for this part

}

/**

* Encrypt the phrase "Attack at dawn" using key "Secret". Use the

* ciphertext and the key to recover the plaintext in order to verify your

* answer.

*

* DO NOT MODIFY

*/

public static void main(String[] args) {

RC4 rc4 = new RC4();

//Use "Secret" as the key

ArrayList key = new ArrayList();

String k = "Secret";

for (int i=0; i < k.length(); i++) {

key.add((int)k.charAt(i));

}

//Set up our plaintext "Attack at dawn"

ArrayList pt = new ArrayList();

String p = "Attack at dawn";

for (int i=0; i < p.length(); i++) {

pt.add((int)p.charAt(i));

}

//Call the encrypt() method and print out the hex representation

ArrayList ct = new ArrayList(pt.size());

rc4.encrypt(pt, key, ct);

System.out.print("Ciphertext: ");

for (int c=0; c < ct.size(); c++)

System.out.print(Integer.toHexString(ct.get(c))+" ");

System.out.println();

//Call the decrypt() method and reproduce the original plaintext

pt.clear();

rc4.decrypt(ct, key, pt);

System.out.print("Recovered plaintext: ");

for (int c=0; c < pt.size(); c++)

System.out.print((char) pt.get(c).intValue());

System.out.println();

}

}

Need to fill in decryption code, genKSA, and genKeyStream please see those methods