AES encryption and Decryption Java

Question

I am encrypting a string using AES and want to decrypt it on other pc. The encryption and decryption works if i execute on the same pc. But for decryption on other pc my encryption algo is generating a "Cipher cipher" which is needed for decryption on other side along with the key. I am not sure how do I transfer the cipher to the other side.

here is my code

 public class AESCrypt {

    static String plainText;
    static byte[] plainBytesDecrypted = new byte[1024];
    static byte[] cipherBytes = new byte[1024];
    static SecretKey key;
    static Cipher cipher;

    public AESCrypt() throws NoSuchAlgorithmException {
        KeyGenerator generator = KeyGenerator.getInstance("AES");

        generator.init(128);
        key = generator.generateKey();

    }

    public static byte[] encryption(String plainBytes) {

        try {
            Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());

            cipher = Cipher.getInstance("AES/CBC/PKCS5Padding", "BC");
            cipher.init(Cipher.ENCRYPT_MODE, key);
            cipherBytes = cipher.doFinal(plainBytes.getBytes());
            System.out.println("Encrypted data : " + new String(cipherBytes));

        } catch (Exception ex) {
            ex.printStackTrace();
        }
        return cipherBytes;
    }

    private static String bytesToHex(byte[] hash) {

        return DatatypeConverter.printHexBinary(hash);

    }

    public static String Decryption() throws InvalidKeyException, IllegalBlockSizeException, InvalidAlgorithmParameterException, BadPaddingException {

        cipher.init(Cipher.DECRYPT_MODE, key, cipher.getParameters());
        plainBytesDecrypted = cipher.doFinal(cipherBytes);

        System.out.println("Decrypted data : " + new String(plainBytesDecrypted));

        return (new String(plainBytesDecrypted));
    }
}

viraptor viraptor · Accepted Answer · 2015-11-09T08:08:59

You have 3 choices in general:

Hardcode the cipher/mode/padding, so that both sides are aware you're always using the same format.
Send the cipher/mode/padding before the secret messages, so the other side knows what cipher to initialise.
Use an existing protocol, which already includes all those things for you and does it securely. You can send your data inside of TLS connection, for example.

AES encryption and Decryption Java

1 Answers