How to generate key pair in asymmetric encryption in java?

Question

I am trying to generate a key pair in asymmetric encryption in Java, but I am getting an invalid key exception error and it says No installed provider supports this key: sun.security.rsa.RSAPrivateCrtKeyImpl.

private static byte[] encrypt(byte[] inpBytes, PrivateKey prvk,
      String xform) throws Exception {
    Cipher cipher = Cipher.getInstance(xform);
    cipher.init(Cipher.ENCRYPT_MODE, prvk);
    return cipher.doFinal(inpBytes);
}

@Override
public byte[] uploadFile(byte[] data, String name, String file, int size)
      throws RemoteException {
    // TODO Auto-generated method stub
    byte[] keyss=null;
    try {
        OutputStream out =
          new FileOutputStream(new File("C:\\Users\\Amaresh\\Documents\\Cloud\\"
          + name + "\\" + file));
        String xform = "DES/CTR/NoPadding";
        KeyPairGenerator kpg = KeyPairGenerator.getInstance("RSA"); // Original
        kpg.initialize(1024); // 512 is the keysize.//try 1024 biit
        KeyPair kp = kpg.genKeyPair();
        PublicKey pubk = kp.getPublic();
        PrivateKey prvk = kp.getPrivate();
        keyss = pubk.getEncoded();
        byte[] encBytes = encrypt(data, prvk, xform);
        System.out.println("Keypair generated");
        out.write(encBytes, 0, encBytes.length);
        out.close();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (NoSuchAlgorithmException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (NoSuchProviderException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (Exception e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    return keyss;
}

I just want to do asymmetric encryption where I encrypt the data with private key and store the public key to decrypt it. I am a beginner and I am sorry for my blunt mistakes.

Answer 1

You are generating the keys correctly.

KeyPairGenerator kpg = KeyPairGenerator.getInstance("RSA");
kpg.initialize(1024);
KeyPair keys = kpg.generateKeyPair();

The problem is in your:

byte[] encBytes = encrypt(data, prvk, xform);

Most likely because you are passing in the String "DES/CTR/NoPadding". You cannot encrypt using DES with an RSA key pair.