Simple RSA encrypt and decrypt message in JAVA

Question

I have been trying for couple of days and simply can't make it work. If I have a private and public key pair. I am just trying to encrypt a message using public key and then decrypt using private key. My code looks something like this:

    String message = "Secure Message";
    KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
    keyPairGenerator.initialize(2048);

    KeyPair keyPair = keyPairGenerator.generateKeyPair();

    Key privateKey = keyPair.getPrivate();
    Key publicKey = keyPair.getPublic();

    Cipher cipher = Cipher.getInstance(publicKey.getAlgorithm());

    cipher.init(Cipher.ENCRYPT_MODE, publicKey);

    byte[] encryptData = cipher.doFinal(message.getBytes());

    cipher.init(Cipher.DECRYPT_MODE, privateKey);

    byte[] decryptData = cipher.doFinal(encryptData);

    System.out.println(encryptData.toString());
    System.out.println(decryptData.toString());

But it doesn't seem to be working. Output I get is something like this:

    [B@4e33967b
    [B@1cdc8d59

If someone may be interested, this is how I converted my encrypted byte arrays to String and then back to bytes. String encodedString = new String(Base64.encodeBase64(encryptData)); byte[] decodedBytes = Base64.decodeBase64(encodedString); — Omer Arshad
– Omer Arshad, Commented Jul 18, 2014 at 21:38

Elliott Frisch · Accepted Answer · 2014-07-18 20:57:40Z

1

Two very minor issues with your code,

 // System.out.println(encryptData.toString());
 // System.out.println(decryptData.toString());

 System.out.println(Arrays.toString(encryptData));
 System.out.println(new String(decryptData));

The encrypted string is in binary. So you probably would not enjoy seeing it directly mapped to ASCII. It looks like garbage.
Java arrays do not override Object.toString(), so you are getting Object.toString() and that is basically the hashCode() and essentially a reference address.
My second println() above outputs the expected "Secure Message" here.

answered Jul 18, 2014 at 20:57

Elliott Frisch

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