In this Letter, we propose a secure orthogonal frequency division multiplexing (OFDM) transmission scheme based on chaotic encryption and noise-masking key distribution. With the implementation of a three-dimensional digital chaotic system, the security performance is effectively enhanced by scrambling the phase, symbol, and subcarrier frequency of the OFDM signal. The proposed noise-masking key distribution can mask the key information of the chaotic system into noise and transmit it with the chaotic encrypted signal simultaneously. By this mechanism, the legal receiver can realize uninterrupted authentication and decryption even if the key is constantly updated. Transmission of a 62.2-Gb/s quadrature phase shift keying (QPSK) and 124.4-Gb/s 16 quadrature amplitude modulation (16QAM) OFDM signal over a 2-km 7-core fiber using the proposed scheme is experimentally demonstrated. The results show that the proposed scheme can realize security enhancement and cost-effective key distribution without significant bit error ratio (BER) performance degradation.
In this Letter, we propose a secure orthogonal frequency division multiplexing (OFDM) transmission scheme based on chaotic encryption and noise-masking key distribution. With the implementation of a three-dimensional digital chaotic system, the security performance is effectively enhanced by scrambling the phase, symbol, and subcarrier frequency of the OFDM signal. The proposed noise-masking key distribution can mask the key information of the chaotic system into noise and transmit it with the chaotic encrypted signal simultaneously. By this mechanism, the legal receiver can realize uninterrupted authentication and decryption even if the key is constantly updated. Transmission of a 62.2-Gb/s quadrature phase shift keying (QPSK) and 124.4-Gb/s 16 quadrature amplitude modulation (16QAM) OFDM signal over a 2-km 7-core fiber using the proposed scheme is experimentally demonstrated. The results show that the proposed scheme can realize security enhancement and cost-effective key distribution without significant bit error ratio (BER) performance degradation.
In this Letter, we propose a highly secure three-dimensional orthogonal frequency division multiplexing (3D-OFDM) transmission scheme based on two-level noise masking key-accompanying transmission. The original signal is encrypted with a spherical constellation to ensure the system's security with a 4D Lorenz-like model. The key realizes two-level noise masking by introducing additional noise bits at the bit level and hiding in a noise-like spherical shell at the constellation level. Moreover, the proposed method of placing the key in the encrypted signal can simultaneously transmit the encrypted signal and the key. A 101.06-Gb/s 3D-OFDM encrypted signal with the proposed scheme over a 2-km 7-core fiber experiment was successfully implemented. Experimental results show that the security performance of the system can be guaranteed under the conditions of partial key leakage and key misplacement at the illegal receiver. At the same time, the key masking degree (KMD) of the proposed two-level noise masking can reach 3267, which effectively guarantees the safe transmission of the key.
In this Letter, we propose a highly secure OFDM scheme based on multi-level masking and performance-enhanced key-accompanying transmission. Our scheme exploits a four-dimensional hyperchaotic model and uses subcarriers and symbols to scramble the signal, thereby achieving chaotic encryption and enhancing system security. The dual-mode index technique is employed to conceal the key within the encrypted signal, enabling cooperative transmission of both the key and the signal. We conducted experiments that successfully transmitted a 28 Gb/s dual-mode QPSK (DM-QPSK) signal and a 42 Gb/s dual-mode 8QAM (DM-8QAM) signal over a 2-km stretch of 7-core fiber. The results demonstrated that our proposed key-accompanying transmission scheme did not compromise the system's transmission performance. Moreover, the key space of this scheme is as large as 10 135 , effectively ensuring system security. Under the received optical power corresponding to the bit error rate of 3.8 × 10 −3 , the minimum number of key repetitions in DM-8QAM that makes the key bit error rate zero is less than 9 times. This demonstrates that our proposed scheme effectively enhances the transmission performance of the key, achieving high-quality joint transmission of both the key and the signal.
In this article, we propose a high-security transmission scheme of power division 3-D carrier-less amplitude and phase (PD-3D-CAP) based on polling-permutation encryption and noise masking key distribution. By implementing the 6D Lorenz digital chaotic system, we scramble the 3D-CAP signal, effectively enhancing the security performance of the system. In our scheme, the proposed noise-masking key distribution can be considered noise-like and transmitted along with the chaotic encrypted signal in the channel. It is important to note that our mechanism also enables uninterrupted authentication and decryption at the receiver to handle continuous key updates. We experimentally demonstrate the transmission of a 12.67 Gb/s 3D-CAP signal over a 2 km 7-core fiber using the proposed scheme. The scheme allows for simultaneous key transmission without a significant increase in the bit error rate. Additionally, we compare the performance of the PD-3D-CAP scheme to that of the PD-2D-CAP scheme, and observe a sensitivity gain of 0.4 dB with the proposed PD-3D-CAP scheme.
A lossless key-accompanying transmission method based on noise-masked three-dimensional (3D) index mapping over four-core fiber is proposed. This scheme utilizes a four-dimensional (4D) chaotic model to mask the bits of the original data and orthogonal frequency division multiplexing (OFDM) symbols. Its initial value key is transformed into binary bits, and the error-free transmission of the key is ensured by periodic key repetition. And the masking of the key is achieved by introducing noise bits. In the process of constellation mapping, the 16 constellation points are divided into inner constellations and outer constellations. The traceless loading of the key is achieved by controlling the mapping rule using noisy key bits. A 115-kilometer four-core fiber transmission experiment of the noise-masked 3D index mapping method was successfully verified. The experimental results show that the difference between different cores of the four-core fiber is no more than 0.35 dB. There is almost no signal-noise ratio (SNR) penalty before and after signal encryption. The difference in sensitivity at the receiver is only 0.05 dB, which proves that this scheme can achieve lossless key transmission. As this scheme adopts the method of key repetition, it can ensure the correct demodulation of the key and the precise index of the constellation B. Compared with the traditional 16 quadrature amplitude modulation (QAM) signal, a sensitivity gain of 0.75 dB can be achieved. As for the illegal receiver, due to the lack of correct keys and encryption methods, the accuracy rate of key extraction is 0%, and the bit error rate (BER) remains at around 0.5. Even if the key index position is displaced by one bit, the BER will soar above 0.48. And through five repetitions, 100% correct recovery of the key at the legitimate receiver can be guaranteed. This scheme has excellent transmission effect and security, and can effectively guarantee the performance of the next-generation communication system.
This paper proposes a physical layer security enhancement scheme for optical orthogonal frequency-division multiplexing (OFDM) based on a fractal Sierpiński triangle model and DNA encryption. The scheme encrypts image data at the bit level by integrating fractal Sierpiński triangle arrangement and rotation, chaotic systems, as well as DNA encoding, operations, and decoding. Simulation experiments were conducted on a 16-quadrature amplitude modulation (16-QAM) coherent optical OFDM system with a symbol rate of 30 Gbaud over 80 km of single-mode fiber. The results demonstrate that the proposed encryption scheme enables authorized users to successfully decrypt and recover the transmitted encrypted data without degrading transmission performance, while unauthorized users can only obtain meaningless information with a bit error rate of approximately 0.5. Moreover, by leveraging chaotic systems, the key space of the scheme reaches 2 256 , providing strong resistance against brute-force attacks.
In this paper, we propose a block compressive sensing (BCS) based chaotic embedded encryption scheme for multi-core fiber orthogonal frequency division multiplexing (MCF-OFDM) system. BCS technology is used to recover the entire desired information from the small amounts of data. Meanwhile, a four-dimensional discrete chaotic encryption model generates four masking factors, which are respectively used for coefficient random permutation (CRP), measurement matrix, diffusion and singular value decomposition (SVD) embedding to achieve ultra-high security encryption of four different dimensions. In terms of compressive sensing, CRP can make the discrete cosine transform (DCT) coefficient distribute randomly to improve the sampling efficiency of BCS. Compared with the data without compressive sensing, the data volume is reduced by 75%. In chaotic encryption, SVD technology embeds secret images of noise-like after initial encryption into carrier images to generate encrypted images with visual security. The key space reaches 10120 and it realizes the dual protection of source image data and external representation. The proposed scheme using a 2km 7-core optical fiber achieves a 78.75 Gb/s transmission of encrypted OFDM signals. The received optical power is greater than -14 dBm, and the bit error rate (BER) of core1-core7 is lower than 10−3. When the compression ratio sets to 0.25 and the attack range of encrypted data is up to 30%, the image can still recover the outline and general information. The experimental results show that this scheme can improve the security performance and reduce the complexity of information transmission system. Furthermore, the scheme combines The BCS chaotic embedded encryption technology with MCF-OFDM system, which has a good application prospect in the future optical networks.