Untitled

8
Client Side:

package pgm8;

import java.io.*; 
import java.net.*;
import java.net.InetAddress; 
class UDPClient
{
public static void main(String[] args)throws Exception
{
BufferedReader inFromUser=new BufferedReader(new
InputStreamReader(System.in));
DatagramSocket clientSocket=new DatagramSocket(); 
InetAddress 
IPAddress=InetAddress.getByName("localhost"); 
byte[] sendData=new byte[1024];
byte[] receiveData=new byte[1024];
System.out.println("Enter the sting to be converted in 
to Upper case"); 
String sentence=inFromUser.readLine(); 
sendData=sentence.getBytes();
DatagramPacket sendPacket=new
DatagramPacket(sendData,sendData.length,IPAddress,9876);
clientSocket.send(sendPacket);
DatagramPacket receivePacket=new
DatagramPacket(receiveData,receiveData.length);
clientSocket.receive(receivePacket);
String modifiedSentence=new
String(receivePacket.getData()); 
System.out.println("FROM SERVER:"+modifiedSentence); 
clientSocket.close();
}
}
Server Side:

package pgm8;

import java.net.*;
import java.net.InetAddress; 
class UDPServer
{
public static void main(String args[])throws Exception
{
DatagramSocket serverSocket = new DatagramSocket(9876); 
byte[] receiveData=new byte[1024];
byte[] sendData=new byte[1024];
while(true)
{
System.out.println("Server is Up"); 
DatagramPacket receivePacket=new
DatagramPacket(receiveData,receiveData.length);
serverSocket.receive(receivePacket);
String sentence=new
String(receivePacket.getData()); 
System.out.println("RECEIVED:"+sentence);
InetAddress IPAddress=receivePacket.getAddress(); 
int port=receivePacket.getPort();
String capitalizedSentence=sentence.toUpperCase(); 
sendData=capitalizedSentence.getBytes();
DatagramPacket sendPacket=new
DatagramPacket(sendData,sendData.length,IPAddress,port);
serverSocket.send(sendPacket);
}
}
}


9
package pgm9;

import java.io.DataInputStream;

import java.io.IOException;
import java.math.BigInteger;
import java.util.Random;
public class RSA
{
 private BigInteger p,q,N,phi,e,d;
 private int bitlength = 48;
 private Random r;
 public RSA()
 {
 r = new Random();
 p = BigInteger.probablePrime(bitlength, r);
 q = BigInteger.probablePrime(bitlength, r);
 System.out.println("Prime number p is"+p);
 System.out.println("prime number q is"+q);
 N = p.multiply(q);
 phi = 
p.subtract(BigInteger.ONE).multiply(q.subtract(BigInteger.ONE));
 e = BigInteger.probablePrime(bitlength / 2, r);
 while (phi.gcd(e).compareTo(BigInteger.ONE) > 0 && 
e.compareTo(phi) < 0)
 {
 e.add(BigInteger.ONE);
 }
 System.out.println("Public key is"+e);
 d = e.modInverse(phi);
 System.out.println("Private key is"+d);
 }
 public RSA(BigInteger e, BigInteger d, BigInteger N)
{

 this.e = e;

 this.d = d;
 this.N = N;
 }
 
 public static void main(String[] args) throws IOException
 {
 RSA rsa = new RSA();
 DataInputStream in = new DataInputStream(System.in);
 String teststring;
 System.out.println("Enter the plain text:");
 teststring = in.readLine();
 System.out.println("Encrypting String: " + teststring);
 System.out.println("String in Bytes: " + 
bytesToString(teststring.getBytes()));
 // encrypt
 byte[] encrypted = rsa.encrypt(teststring.getBytes());
 // decrypt
 byte[] decrypted = rsa.decrypt(encrypted);
 System.out.println("Decrypting Bytes: " + 
bytesToString(decrypted));
 System.out.println("Decrypted String: " + new
String(decrypted));
 }
 private static String bytesToString(byte[] encrypted)
 {
 String test = "";
 for (byte b : encrypted)
 {
 test += Byte.toString(b);
 }
 return test;
 }
// Encrypting message

 public byte[] encrypt(byte[] message)

 {
 
 return (new BigInteger(message)).modPow(e, N).toByteArray();
 }
 // Decrypting message
 public byte[] decrypt(byte[] message)
 {
 return (new BigInteger(message)).modPow(d, N).toByteArray();
 
 }
}


10
package cnlab;

import java.util.Scanner;

public class Leakybucket
{
public static void main(String [] args)
{
int i;
int a[]=new int[20];
int buck_rem=0, buck_cap=4, rate=3, sent, recv;
Scanner in=new Scanner(System.in);
System.out.println("Enter the number of Packets");
int n=in.nextInt();
System.out.println("Enter the Packets");
for(i=1;i<=n;i++)
a[i]=in.nextInt();
System.out.println("Clock \t Packet size \t accept \t 
sent \t remaining");
for(i=1;i<=n;i++)
{
if(a[i]!=0)
{
if(buck_rem+a[i]>buck_cap)
recv=-1;
else
{
recv=a[i];

buck_rem+=a[i];

}
}
else
recv=0;
if(buck_rem!=0)
{
if(buck_rem<rate)
{
sent=buck_rem;
buck_rem=0;
}
else
{
sent=rate;
buck_rem=buck_rem-rate;
}
}
else
sent=0;
if(recv==-1)
System.out.println(+i+ "\t\t" +a[i]+ "\t 
dropped \t" + sent + "\t" +buck_rem);
else
System.out.println(+i+ "\t\t" +a[i] +"\t\t"
+recv +"\t" +sent +"\t" +buck_rem);
}
}
}