import javax.crypto.Cipher;
import javax.crypto.spec.GCMParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.nio.charset.Charset;
import java.util.Base64;


public class AESCipher {
    private String key;
    private String iv;

    public AESCipher(String key, String iv) {
        this.key = key;
        this.iv = iv;
    }

    String encrypt(byte[] data) throws Exception{
        SecretKeySpec keySpec = new SecretKeySpec(key.getBytes(Charset.forName("UTF-8")), "AES");
        Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
        cipher.init(Cipher.ENCRYPT_MODE, keySpec, new GCMParameterSpec(128, iv.getBytes(Charset.forName("UTF-8"))));
        byte[] result = cipher.doFinal(data);
        return Base64.getEncoder().encodeToString(result);
    }

    byte[] decrypt(String data) throws Exception {
        SecretKeySpec keySpec = new SecretKeySpec(key.getBytes(Charset.forName("UTF-8")), "AES");
        Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
        cipher.init(Cipher.DECRYPT_MODE, keySpec, new GCMParameterSpec(128, iv.getBytes(Charset.forName("UTF-8"))));
        byte[] result = cipher.doFinal(Base64.getDecoder().decode(data));
        return result;
    }

    public static void main(String[] args) throws Exception{
        String key = "dcbbad6765e14139a07d34b92292a672"; //key 32 bits
        String iv = "df25d188a061"; // iv 12 bits
        String data = "hello world";

        AESCipher cipher = new AESCipher(key, iv);
        String encryptedData = cipher.encrypt(data.getBytes());
        System.out.println("encrypted data: " + encryptedData);

        String decryptedData = new String(cipher.decrypt(encryptedData));
        System.out.println("decrypted data: " + decryptedData);
    }
}