A probabilistic shaping probability distribution scramble (PSPDS) scheme based on chaotic systems is proposed to fulfill both secure transmission and adaptive key updating. The chaotic Chen and logistic systems are adopted to generate a chaotic random sequence. The probabilistic shaping is achieved by constant composition distribution matching (CCDM) and probabilistic amplitude shaping architecture. The chaotic, random sequences are used to scramble the probability distribution of CCDM, improving security. The session key is embedded into a probability distribution. The legal receiver extracts the error-free session key when OSNR is higher than the requirement of the forward error correction threshold. We employ a coherent OFDM 16QAM transmission experiment on 120 km fiber, confirming our proposed scheme with a net rate of 9.95 Gbit/s. The results show that the PSPDS scheme has no encryption penalty compared with the baseline without encryption. The key updating rate has the ability to vary adaptively and reaches 224.2 Mbit/s by adjusting the block length of CCDM in our experiment. The key space reaches 10 136 . Even if an illegal party obtains a ciphertext signal, the plaintext and session key can hardly be inferred due to a probability distribution scramble.
A probabilistic shaping probability distribution scramble (PSPDS) scheme based on chaotic systems is proposed to fulfill both secure transmission and adaptive key updating. The chaotic Chen and logistic systems are adopted to generate a chaotic random sequence. The probabilistic shaping is achieved by constant composition distribution matching (CCDM) and probabilistic amplitude shaping architecture. The chaotic, random sequences are used to scramble the probability distribution of CCDM, improving security. The session key is embedded into a probability distribution. The legal receiver extracts the error-free session key when OSNR is higher than the requirement of the forward error correction threshold. We employ a coherent OFDM 16QAM transmission experiment on 120 km fiber, confirming our proposed scheme with a net rate of 9.95 Gbit/s. The results show that the PSPDS scheme has no encryption penalty compared with the baseline without encryption. The key updating rate has the ability to vary adaptively and reaches 224.2 Mbit/s by adjusting the block length of CCDM in our experiment. The key space reaches 10 136 . Even if an illegal party obtains a ciphertext signal, the plaintext and session key can hardly be inferred due to a probability distribution scramble.
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.
This paper proposes a high-security probabilistic shaping 16-7QAM mapping method via constellation-level chaotic tagging. A novel, to the best of our knowledge, constellation-level chaotic tagging rule is devised that re-maps the original 16 signal points, each encoded by 4 bits, onto predefined 3-bit modulation symbols. Simultaneously, a Lorenz chaotic system is employed to generate a chaotic sequence, from which a 2-bit tag corresponding to each 3-bit modulation symbol is extracted to form the constellation-level chaotic tag. Subsequently, each signal point is combined with a 2-bit tag generated by a Lorenz chaotic system to form the final output consisting of 7 signal points. Experimental validation over a seven-core fiber transmission system shows that, at a bit error rate of 3.8 × 10 −3 , the proposed probabilistic shaping 16-7QAM constellation achieves a 0.49 dB improvement in receiver sensitivity compared with conventional 16-QAM. Moreover, the encryption scheme has almost no impact on the transmission performance of the probabilistic shaping signal itself. Additionally, the key space of the scheme reaches 10 105 , effectively ensuring physical layer security. The proposed method exhibits robust performance and strong security, enhancing both the transmission performance and security of the system.
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 key generation and distribution scheme in coherent optical system is proposed, which is compatible with the current fiber infrastructure. The random key is generated by quantifying system noise which is obtained according to the training sequence. The key signal with the low power is hidden in the 212×212 TQAM signal. The legal party can extract the key signal from 16 QAM signals, but the attacker can only extract the key signal from 212×212 TQAM signals. Compared with processing 212×212 TQAM signals, existing algorithms are more effective at processing 16 QAM signals. It provides the security of key distribution and is verified by experiment. The concatenated coding including LDPC coding and differential coding is employed to get error-free key and expand the security space. Since differential coding leads to cumulative errors, the key error rate is ∼50% when the key error rate is above the LDPC threshold. The proposed scheme achieves an error-free key with KDR of 2.5 Gbps over 80 km SSMF, which does not require the presetting, external random source, and additional device.
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 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 × 10207.