AES starts with 16 bytes and then encrypts it to 16 bytes. So there is no good place to hide extra data. Even a single bit that did not meet the AES spec for th

AES starts with 16 bytes and then encrypts it to 16 bytes. So there is no good place to hide extra data. Even a single bit that did not meet the AES spec for the key in use would produce complete garbage at decryption. So attempts to leak the key would at least leave a mark.