`` The design and strength of all key lengths of the AES algorithm ( i.e. , 128 , 192 and 256 ) are sufficient to protect classified information up to the SECRET level . In June 2003 , the U.S. Government announced that AES may be used to protect classified information : The design and strength of all key lengths of the AES algorithm ( i.e. , 128 , 192 and 256 ) are sufficient to protect classified information up to the SECRET level .