High-Security Orthogonal Circulant Multiplexing Encryption Scheme with Three-Dimensional Index Modulation

This paper proposes a high-security orthogonal circulant multiplexing (OCM) chaotic encryption scheme based on three-dimensional index modulation (3D-IM). We introduce an innovative OCM scheme based on a modified Zadoff-Chu (ZC) sequence (MZCS), which demonstrates superior the bit-error rate (BER) performance compared to orthogonal chirp division multiplexing (OCDM) and orthogonal frequency division multiplexing (OFDM). To ensure high security, the 3D Chua chaotic system and the 1D Logistic chaotic model are used to encrypt the bit stream and subcarriers in the frequency and time domain. The performance of the scheme is compared and verified using a passive optical network (PON) architecture within intensity-modulation/direct-detection (IM/DD) systems. Results indicate that the receiver sensitivity of MZCS-based OCM improves by 1.3 dB and 0.91 dB compared with OFDM and OCDM, respectively. The scheme can achieve a key space of 10142, which significantly verifies system security and feasibility.