Interpreter-Fehler RSA Verschlüsselung Fehler

[Lucaaa]

Hallo! Ich möchte einen String mit RSA verschlüsseln. allerdings bekomme ich immer folgenden Fehler:

Exception in thread "main" java.lang.NullPointerException
 at RsaVerschlüsselung.main(RsaVerschlüsselung.java:21)

Weiß gemand woran es liegt?
Hier der Code:

import java.awt.RenderingHints.Key;
import java.security.InvalidKeyException;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
public class RsaVerschlüsselung {
  static int keysize = 1024;
  private static KeyPair key = null;
 
 public static void main(String[] arg) {
  gen();
  byte[] enc = encrypt("Hallo", key.getPublic());
  System.out.println(new String(enc));
 }
  
  
  
  
 public static void gen() {
  KeyPairGenerator keygen = null;
  
  try {
   keygen = KeyPairGenerator.getInstance("RSA");
  } catch (NoSuchAlgorithmException e) {
   e.printStackTrace();
  }
  keygen.initialize(1024);
  KeyPair key = keygen.generateKeyPair();
 }
 
 
 
 
 
 
 
 public static byte[] encrypt (String message, PublicKey pk) {
  Cipher cipher = null;
  try {
   cipher = Cipher.getInstance("RSA");
   cipher.init(Cipher.ENCRYPT_MODE, pk);
  } catch (NoSuchAlgorithmException | NoSuchPaddingException e) {
   e.printStackTrace();
  } catch (InvalidKeyException e) {
   e.printStackTrace();
  }
  byte[] chifrat = null;
  try {
   chifrat = cipher.doFinal(message.getBytes());
  } catch (IllegalBlockSizeException e) {
   e.printStackTrace();
  } catch (BadPaddingException e) {
   e.printStackTrace();
  }
  return chifrat;
 }
 
 
 public static String decrypt(byte[] chifrat, PrivateKey sk) {
  byte[] dec = null;
  
  Cipher cipher = null;
  try {
   cipher = Cipher.getInstance("RSA");
   cipher.init(Cipher.DECRYPT_MODE, sk);
  } catch (NoSuchAlgorithmException | NoSuchPaddingException e) {
   e.printStackTrace();
  } catch (InvalidKeyException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
  
  try {
   dec = cipher.doFinal(chifrat);
  } catch (IllegalBlockSizeException | BadPaddingException e) {
   e.printStackTrace();
  }
  return new String(dec);
 }
 
}

 

[Robat]

byte[] enc = encrypt("Hallo", key.getPublic());

Deine globale Key-Variable wird nirgends initialisiert.

 

[Lucaaa]

Okay danke habs behoben.