DiffieHellmanApplet-Applet

 DiffieHellman dh= new DiffieHellman();
   long a,b,g,p,sa,sb,s;
   public void generatePimeActionPerformed(ActionEvent evt) {
   p= dh.newP();
   tp.setText(p+"");
   }

 public void generateGeneratorActionPerformed(ActionEvent evt) {
   g= dh.newG();
   tg.setText(g+"");

 }

 public void generateSecretAActionPerformed(ActionEvent evt) {
   a= dh.newA();
   ta.setText(a+"");
   }

 public void generateSecretBActionPerformed(ActionEvent evt) {
   b= dh.newB();
   tb.setText(b+"");
   }

 public void losActionPerformed(ActionEvent evt) {
   if (tp.getText().equals("")) {
   	p= dh.newP();
   	tp.setText(p+"");
   }
   else p=Long.parseLong(tp.getText());
   protokoll.append("Primzahl p ist: "+p+"\n");
   if (tg.getText().equals("")) {
   	g= dh.newG();
   	 tg.setText(g+"");
   }
   else g=Long.parseLong(tg.getText());
   protokoll.append("Generator g ist: "+g+"\n");
   if (ta.getText().equals("")) {
   	a= dh.newA();
   	ta.setText(a+"");
   }
   else a=Long.parseLong(ta.getText());
   protokoll.append("Geheimzahl a ist: "+a+"\n");
   if (tb.getText().equals("")) {
   	b= dh.newB();
   	tb.setText(b+"");
   }
   else b=Long.parseLong(tb.getText());
   protokoll.append("Geheimzahl b ist: "+b+"\n");
   sa=dh.modulFunktion(g,a,p);
   sb=dh.modulFunktion(g,b,p);
   tsa.setText(sa+"");
   protokoll.append("öffentlicher Schlüssel sa ist: "+sa+"\n");
   tsb.setText(sb+"");
   protokoll.append("öffentlicher Schlüssel sb ist: "+sb+"\n");
   s=dh.modulFunktion(sb,a,p);
   protokoll.append("Schlüssel s von Alice: "+s+"\n");
   s=dh.modulFunktion(sa,b,p);
   protokoll.append("Schlüssel s von Bob: "+s+"\n");
   ts.setText(s+"");
 }

import java.util.*;
import java.math.BigInteger;

public class DiffieHellman {
   static int bits=20;
   private long p;
   private long g;
   private long a;
   private long b;
   private long sa;
   private long sb;
   private long s;
   public DiffieHellman(){
     p=randomPrime(bits);
     g=randomPrime(bits-2);
     a=randomPrime(bits/2);
     b=randomPrime(bits/2);
   }
   public long getP(){
     return p;
   }
   public long getG(){
     return g;
   }
   public long getA(){
     return a;
   }
   public long getB(){
     return b;
   }
   public long newP(){
     p= randomPrime(bits);
     return p;
   }
   public long newG(){
     g= randomPrime(bits-2);
     return g;
   }
   public long newA(){
     a= randomPrime(bits/2);
     return a;
   }
   public long newB(){
     b= randomPrime(bits/2);
     return b;
   }
   //zufällige Primzahl
   public long randomPrime(int bits){
     BigInteger pr= new BigInteger(bits,10000,new Random());
     return pr.longValue();
   }
   public long modulFunktion(long a, long b, long p){
     // Berechnet a^b mod p
     long i= b/2; long r= b%2;
     long mod=1;
     for (long j=0;j<i;j++){
       mod=(mod*(a*a))%p;
     }
     if (r!=0) mod=(mod*(r*a))%p;
     return mod;
   }
}