import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.xml.bind.DatatypeConverter;


public class AES {


    public static void main(String[] args) throws Exception {

        String plainText = "Secret Message";
        SecretKey secKey = getSecretEncryptionKey();
        byte[] cipherText = encryptText(plainText, secKey);
        String decryptedText = decryptText(cipherText, secKey);

         

        System.out.println("Original Text:" + plainText);
        System.out.println("AES Key (Hex Form):"+bytesToHex(secKey.getEncoded()));
        System.out.println("Encrypted Text (Hex Form):"+bytesToHex(cipherText));
        System.out.println("Descrypted Text:"+decryptedText);
    } 
    //End of main class
     
    
    //Gets encryption key. Would normally be stored differently in a real world situation. 
    public static SecretKey getSecretEncryptionKey() throws Exception{

        KeyGenerator generator = KeyGenerator.getInstance("AES");
        generator.init(128); // AES key size. More secure than the 56 bit DES
        SecretKey secKey = generator.generateKey();
        return secKey;
    }

     
    //ENCRYPT our text using the secret key to byte array
    public static byte[] encryptText(String plainText,SecretKey secKey) throws Exception{

        Cipher aesCipher = Cipher.getInstance("AES");
        aesCipher.init(Cipher.ENCRYPT_MODE, secKey);
        byte[] byteCipherText = aesCipher.doFinal(plainText.getBytes());
        return byteCipherText;
    }

     
    //DECRYPTS the byte array using the key
    public static String decryptText(byte[] byteCipherText, SecretKey secKey) throws Exception {

        Cipher aesCipher = Cipher.getInstance("AES");
        aesCipher.init(Cipher.DECRYPT_MODE, secKey);
        byte[] bytePlainText = aesCipher.doFinal(byteCipherText);
        return new String(bytePlainText);

    }

     

    //Converts binary byte array into readable hex
    private static String  bytesToHex(byte[] hash) {

        return DatatypeConverter.printHexBinary(hash);

    }

}