Advanced Encryption Standard (AES) is an encryption algorithm for securing sensitive unclassified material by U.S. Government agencies and, as a consequence the de facto encryption standard for commercial applications worldwide. Performing concurrent error detection (CED) for protection of such a widely deployed algorithm is an issue of paramount importance. We present a low-cost CED method for AES. In this method, we make use of invariance properties of AES to detect errors. For the first time, the invariance properties of the AES, which are for the most part used to attack the algorithm, are being used to protect it from fault attacks. Our preliminary ASIC synthesis of this architecture resulted in an area overhead of 13.8% and a throughput degradation of 16.67%.