createCipher.java

public static Cipher createCipher(int mode,SecretKey key,String iv) throws Exception {

Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding", "BC");

         cipher.init(
                 Cipher.DECRYPT_MODE,
                 new SecretKeySpec(key, "AES"), 
                 new IvParameterSpec(Util.HexEncoder.toByte(iv))
         );
         
         
    }