A Physical Layer Security-Enhanced Scheme in CO-OFDM System Based on CIJS Encryption and 3D-LSCM Chaos

In this paper, a security enhanced physical layer encryption scheme is proposed for coherent optical orthogonal frequency division multiplexing (CO-OFDM) system. This scheme is based on a concatenated inter-domain joint scrambling (CIJS) method, while adopting the three-dimension logistic sine cascading mapping (3D-LSCM) as a chaos key system to improve the security. Thrice inter-domain cat mappings are implemented, which fully exploits the characteristic domains of OFDM data and greatly increases the possible permutations. An experiment of the encryption scheme is realized successfully in a 16QAM CO-OFDM system at a symbol rate of 40 Gbaud over an 80 km standard single mode fiber. The experiment shows that no bit error rate (BER) and peak to average power ratio (PAPR) penalties are introduced in this scheme. The proposed 3D-LSCM chaos system shows superior properties of high sensitivity to initial values and improved uniform distribution, which guarantees the large entropy and further the system's security. This scheme can effectively prevent against a chosen-text attack which is the most effective attack method due to the extremely small tolerabledeviation and the large key space of 1.12 × 10
²⁰⁷
.