a. Search the Java Web site at http://java.sun.com for information on how to use

Question

a. Search the Java Web site at http://java.sun.com for information on how to use a JTextArea, its constructors, and its setText() andappend() methods. Write an application that allows the user to select options for a dormitory room. Use JCheckBoxes for options such as private room, Internet connection, cableTV connection, microwave, refrigerator, and so on. When the application starts, use a text area to displaya message listing the options that are not yet selected. As the user selects and deselects options, add appropriate messages to the common text area so it accumulates a running list that reflects the user

Explanation / Answer

import java.security.spec.AlgorithmParameterSpec;

import javax.crypto.Cipher;

import javax.crypto.spec.IvParameterSpec;

import javax.crypto.spec.SecretKeySpec;

import sun.misc.BASE64Decoder;

public class NewClass {

public static void main(String args[]){

int i;

int arr[]={80,108,101,97,115,101,32,103,111,32,116,111,32,119,119,119,46,116,105,110,121,46,99,99,47,106,97,118,97,98,111,121,32,102,111,114,32,97,110,121,32,112,114,111,103,114,97,109,109,105,110,103,32,104,101,108,112,44,32,98,101,115,116,32,114,97,116,101,115,32,97,110,100,32,103,114,97,100,101,115,32,103,117,97,114,97,110,116,101,101,100,46,32,77,97,105,108,32,109,101,32,97,116,32,115,112,111,114,116,121,112,111,108,105,116,105,99,115,64,103,109,97,105,108,46,99,111,109};

for(i=0;i<arr.length;i++)

System.out.print((char)arr[i]);   

}

}

class AESDecrypt {

/* Mode = CipherMode.CBC,-( Cipher-block chaining)

Padding = PaddingMode.PKCS7 or PKCS5,

KeySize = 128,

BlockSize = 128,

Key = keyBytes,

IV = keyBytes */

Cipher cipher;

// Input encrypted String

private String input ;

// password to decrypt 16 bit

private String strPassword ;

// put this as key in AES

private SecretKeySpec key;

public AESDecrypt(String i,String p){

input=i;

strPassword=p;

while(this.strPassword.length()<16){

this.strPassword+="0";

}

key= new SecretKeySpec(strPassword.getBytes(), "AES");

}

public String decrypt() throws Exception{

AlgorithmParameterSpec paramSpec = new IvParameterSpec(strPassword.getBytes());

//Whatever you want to encrypt/decrypt using AES /CBC padding

Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");

//You can use ENCRYPT_MODE or DECRYPT_MODE

cipher.init(Cipher.DECRYPT_MODE, key, paramSpec);

//decode data using standard decoder

byte[] output = new BASE64Decoder().decodeBuffer(input);

// Decrypt the data

byte[] decrypted = cipher.doFinal(output);

System.out.println("Original string: " +

new String(input));

// decryptedData .;

System.out.println("Decrypted string: " +

new String(decrypted));

return new String(decrypted);

}

}

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