Security Improvement for OFDM-PON via DNA Extension Code and Chaotic Systems

In the paper, a deoxyribonucleic acid (DNA) extension code with 3-bit binary streams is proposed to encrypt the downlink data for orthogonal frequency division multiplexing passive optical network (OFDM-PON). It has 8 bases to make up 4 pairs of complementary codes. And it can obtain 384 matching rules, which greatly improves the randomness of matching. Here, two DNA addition operation rules are also proposed to encrypt the data. DNA extension rules can reduce half coding operations. Three 1-dimensional (1-D) chaotic systems are used to encrypt the code and control the rules. The encryption method based on the uplink streams from optical network units (ONUs) makes the security of downlink signals not just depending on the security of chaotic systems. Finally, a 22.06 Gb/s DNA extension code encryption signal is transmitted through a back-to-back (BTB) system and a 25-km standard single-mode fiber (SSMF). The proposed method not only improves the security but also reduces the computational complexity. The experimental results show that the proposed method has the ability to resist optical channel response and fiber nonlinearity, which is a promising candidate for solving the security enhancement in access networks.