Orthogonal frequency-division multiple passive optical network(OFDM-PON) has emerged as one of the most promising solutions to meet the requirements for the next-generation wide-band optical access network with high capacity, strong fiber dispersion tolerance, and flexible resource allocation. However, like other optical access network in which the downstream signal is broadcasted to all the optical network units(ONUs), OFDM-PON is vulnerable to being eavesdropped. Thus the security of OFDM-PON should be ta...