Category: System Security

Program Language: Java | C
List of Programs: Substitution Cipher, Transposition Cipher, Product Cipher, Diffie Hellman Key Exchange Algorithm, RSA Algorithm, Data Encryption Standard, Basic OTP, OTP Client, OTP Server, CAPTCHA Client, CAPTCHA Server, Buffer Overflow problem, Denial of Service (DoS) attack.
P.S. Sorry for the misalignment, copy the code to any text editor & the alignment problem will be solved.

System Security

Data Encryption Standard (Java)

import java.util.*;
import java.io.*;
class des
{

static int ip[] = new int[] {2,6,3,1,4,8,5,7};
static int ip_inv[] = new int[] {4,1,3,5,7,2,8,6};
static int p_4[] = new int[] {2,4,3,1};
static int p_10[] = new int[] {3,5,2,7,4,10,1,9,8,6};
static int p_8[] = new int[] {6,3,7,4,8,5,10,9};
static int left_one[] = new int[] {2,3,4,5,1,7,8,9,10,6};
static int left_two[] = new int[] {3,4,5,1,2,8,9,10,6,7};
static int expand[] = new int[] {4,1,2,3,2,3,4,1};
static int sbox0[][] = new int[][] {{1,0,3,2},{3,2,1,0},{0,2,1,3},{3,1,3,2}};
static int sbox1[][] = new int[][] {{0,1,2,3},{2,0,1,3},{3,0,1,0},{2,1,0,3}}; Continue reading “Data Encryption Standard (Java)”

Darshan GajaraLeave a comment
System Security

Basic OTP (Java)

import java.util.*; class TimeOutTask extends TimerTask { boolean isTimedOut = false; public void run() { isTimedOut = true; } } class BasicOTP { public static void main(String args[]) { Random r = new Random(); String otp = new String(); for(int i=0 ; i<8 ; i++) { otp += r.nextInt(10); } System.out.println(otp); TimeOutTask task = new TimeOutTask(); Timer t = new Timer(); t.schedule(task, 10000L); ClientThread c … Continue reading Basic OTP (Java)

Darshan GajaraLeave a comment
System Security

OTP Client (Java)

import java.util.*; import java.io.*; import java.net.*; class OTPClient { public static void main(String args[]) throws IOException { Scanner scan = new Scanner(System.in); System.out.println(“Connecting to the server…”); Socket clientSocket = new Socket(“localhost”, 7777); PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true); BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream())); // Client enters ID. This will be used by the program for verifying who // is communicating as well as check … Continue reading OTP Client (Java)

Darshan GajaraLeave a comment
System Security

OTP Server (Java)

import java.util.*; import java.io.*; import java.net.*; class TimeOutTask extends TimerTask { boolean isTimedOut = false; public void run() { isTimedOut = true; } } class OTPServer { public static void main(String args[]) throws IOException { ServerSocket serverSocket = new ServerSocket(7777); System.out.println(“Server running and waiting for client…”); Socket clientSocket = serverSocket.accept(); PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true); BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream())); // Server waits … Continue reading OTP Server (Java)

Darshan GajaraLeave a comment
System Security

CAPTCHA Client (Java)

import java.util.*; import java.io.*; import java.net.*; import java.awt.*; import java.awt.image.*; import javax.swing.*; import javax.imageio.*; class ImagePanel extends JPanel { BufferedImage img; ImagePanel(BufferedImage img) { this.img = img; } public void paint(Graphics g) { g.drawImage(img, 0, 0, this); } } class CaptchaClient { static BufferedImage img; public static void main(String args[]) throws Exception { JFrame frame = new JFrame(); Scanner scan = new Scanner(System.in); System.out.println(“Connecting to … Continue reading CAPTCHA Client (Java)

Darshan GajaraLeave a comment