KeyPairGenerator not available

Question

I am creating a program to generate a key pair but i have this error:

Exception in thread "main" java.lang.NullPointerException
at generateAESKey.main(generateAESKey.java:43)

This is currently what I have been working. The

key.getEncoded());

is not being read.

public class generateAESKey {
    public static void main(String[] args) throws Exception {
        generateAESKey generatekey = new generateAESKey();    
        KeyGenerator keyGen = KeyGenerator.getInstance("AES");
        keyGen.init(256);
        SecretKey skey = keyGen.generateKey();
        byte[] raw = skey.getEncoded();
        FileOutputStream fos2 = new FileOutputStream("C:\\Users\\win8.1\\Desktop\\AES\\test.txt");
        fos2.write(raw);
        fos2.close();


        KeyPairGenerator keyGen1 = KeyPairGenerator.getInstance("RSA");
        SecureRandom random = SecureRandom.getInstance("SHA1PRNG", "SUN");
        keyGen1.initialize(1024, random);
        KeyPair generatedKeyPair = keyGen1.genKeyPair();
        savePublicKey(generatedKeyPair.getPublic(), "C:\\Users\\win8.1\\Desktop\\AES\\public");
        savePrivateKey(generatedKeyPair.getPrivate(), "C:\\Users\\win8.1\\Desktop\\AES\\private");


        PublicKey key = null;

        X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(
        key.getEncoded());
        FileOutputStream fos3 = new FileOutputStream("C:\\Users\\win8.1\\Desktop\\AES\\public.txt");
        fos3.write(x509EncodedKeySpec.getEncoded());
        fos3.close();

        PrivateKey key1 = null;
        PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(
        key1.getEncoded());
        FileOutputStream fos4 = new FileOutputStream("C:\\Users\\win8.1\\Desktop\\AES\\private.txt");
        fos4.write(pkcs8EncodedKeySpec.getEncoded());
        fos4.close();
        System.out.println("SAVE");

    }
        private static void savePrivateKey(PrivateKey private1, String string) {
        // TODO Auto-generated method stub

    }
        private static void savePublicKey(PublicKey public1, String string) {
        // TODO Auto-generated method stub

    }

        public SecretKeySpec getKeySpec() throws IOException, NoSuchAlgorithmException {
            byte[] bytes = new byte[16];
            File f = new File("aes.key");
            SecretKey key = null;
            SecretKeySpec spec = null;
            if (f.exists()) {
              new FileInputStream(f).read(bytes);
            } else {
               KeyGenerator kgen = KeyGenerator.getInstance("AES");
               kgen.init(256);  //128 kalagay
               key = kgen.generateKey();
               bytes = key.getEncoded();
               new FileOutputStream(f).write(bytes);
            }
            spec = new SecretKeySpec(bytes,"AES");
            return spec;
          }
}

Any help will be greatly appreciated. Thanks.

I have already edited it.

https://docs.oracle.com/javase/7/docs/technotes/guides/security/StandardNames.html#KeyPairGenerator read the section `KeyPairGenerator Algorithms` — Jérôme, Mar 15 '17 at 22:09
`KeyPairGenerator.getInstance("ALGORITHM")` - instead of "ALGORITHM" you should pass the algorithm name (check the link provided by @Jérôme in the comment above) — , Mar 15 '17 at 22:14

Jérôme · Accepted Answer · 2017-03-15T22:26:38.890

1

First error: KeyPairGenerator.getInstance(String algorithm) can only handle the following input Strings:

DiffieHellman
DSA
RSA
EC

For mor infos look in the docs

Possible call KeyPairGenerator.getInstance("RSA");

Second error (nullptr): You have to create a PublicKey! You are doing PublicKey key = null; and then you Fall:

X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(
key.getEncoded());//key is null so nullpointer will occur

You have to assign a value to your key variable. I assume you want to take your created PublicKey so do: PublicKey key = generatedKeyPair.getPublic();

edited Mar 15 '17 at 22:26

answered Mar 15 '17 at 22:15

Jérôme

1,254
2
20
25

I have already edited it and got a different error. Thanks for the help! – Salvatore Mar 15 '17 at 22:21

score 0 · Answer 2 · answered Mar 15 '17 at 22:15

0

This line is wrong:

KeyPairGenerator keyGen1 = KeyPairGenerator.getInstance("ALGORITHM");

You must supply the name of the algorithm that you want to use, e.g.:

KeyPairGenerator keyGen1 = KeyPairGenerator.getInstance("RSA");

answered Mar 15 '17 at 22:15

Farrandu

371
1
7

I have already edited it and got a different error. Thanks for the help! – Salvatore Mar 15 '17 at 22:21

KeyPairGenerator not available

2 Answers2