Physical layer authentication is an important way to ensure the security of optical communication network. We hereby propose a scheme to realize it by measuring the variation of the bit error rate (BER) on both sides of communication. In this scheme, the legitimacy of the receiver is identified by analyzing the BER variation of the optical fiber loop based on the short-term correlation of the channels. We then simulate a 16 PSK optical transmission system with intensity modulation direct detection-orthogonal frequency division multiplexing (IMDD-OFDM). The authentication effect is analyzed in the case of disturbance and beam split, as well as replacement of optical fiber channels caused by eavesdropper (Eve). The results show that this scheme is sensitive to the three kinds of attacks. A high probability of detection (PD) and a low false alarm rate (FAR) can be obtained. The experimental results show that with the increase of the frequency test, PD and FAR tend to be stable, and the authentication effect is better with the accuracy rate 100%.
Physical layer authentication is an important way to ensure the security of optical communication network. We hereby propose a scheme to realize it by measuring the variation of the bit error rate (BER) on both sides of communication. In this scheme, the legitimacy of the receiver is identified by analyzing the BER variation of the optical fiber loop based on the short-term correlation of the channels. We then simulate a 16 PSK optical transmission system with intensity modulation direct detection-orthogonal frequency division multiplexing (IMDD-OFDM). The authentication effect is analyzed in the case of disturbance and beam split, as well as replacement of optical fiber channels caused by eavesdropper (Eve). The results show that this scheme is sensitive to the three kinds of attacks. A high probability of detection (PD) and a low false alarm rate (FAR) can be obtained. The experimental results show that with the increase of the frequency test, PD and FAR tend to be stable, and the authentication effect is better with the accuracy rate 100%.
In this paper, a physical layer security scheme is proposed for index modulation aided orthogonal time frequency space (IM-OTFS) modulation systems working in Frequency Division Duplex (FDD) mode. In FDD systems, the channel reciprocity, which is the basic assumption for most physical layer security (PLS) techniques, is not applicable. To deal with the security challenge in FDD IM-OTFS systems, Chaos sequence is generated by exploiting the angular reciprocity of the legitimate link to construct the secure mapping rule between the information bits and the modulation symbols as well as the symbol indices. A PLS scheme based on the proposed secure mapping is introduced. The secrecy performance of the proposed PLS scheme is analyzed in terms of Bit Error Rate (BER) and the ergodic secrecy rate. Furthermore, a close-form approximated ergodic secrecy rate is derived to reduce the computational complexity. A truncation method is proposed to obtain robust secure transmissions when the angles of the uplink and downlink legitimate channels are estimated with errors. Simulation results show that the theoretical BER curve approaches the simulated BER curve closely for medium and high signal to noise ratio (SNR) regions, and the eavesdropper’s BER is always around 0.5 for all SNRs. The closed-form approximated ergodic secrecy rate fits the ergodic secrecy rate exactly in low and high SNR regions, and can work as a lower bound of the ergodic secrecy rate in medium SNR region. The secure mapping at the legitimate users is not affected by the angle estimation errors by using the truncation method, while the eavesdropper’s BER is influenced and the influence is analyzed.
Aiming at the current eavesdropping security issues in the physical layer of optical networks, a new hybrid optical encryption scheme based on Highly Nonlinear Fiber (HNLF) and Super Structured Fiber Bragg Grating (SSFBG) is proposed in this paper. In the scheme, degenerate Four Wave Mixing (FWM) is used to encrypt and decrypt user information, and optical coding technology is used to encode and decode the key information. Therefore, the encoding and secret transmission of the key signal can be realized simultaneously. The security of the system is measured by comparing the waveform of the encrypted signal transmitted in the channel with the waveform of the original transmitted signal, and the effectiveness of the system is measured by the bit error rate at the system receiver side. The simulation results show that the frequency and phase of the user data information are disturbed, and the optical power of the encoded key signal is as low as -34.4 dBm. Therefore, the eavesdropping channel cannot obtain effective data information nor detect the key signal, which demonstrates the safe transmission of Quadrature Phase Shift Keying (QPSK) signal.
This paper proposes a key distribution system based on short-time correlation of optical fiber channels. The communicating parties adopt the odd-even interleaved data transmission method to send binary random number sequences to each other. Taking advantage of the close arrangement of data parity, the data obtained by the communicating parties has short-time correlation characteristics. By analyzing the bit error rate (BER) of the transmitted data, quantizing and encoding the BER, and executing the key negotiation protocol, the short-time correlation characteristics of the channel can be extracted, and the original key with good consistency can be obtained. The experimental results show that when the optical fiber length between Alice and Bob is 40 km, the signal is modulated by Quadrature Phase Shift Keying with Orthogonal Frequency Division Multiplexing (QPSK-OFDM), the signal transmission rate is 1 Gbit/s, and the channel BER is about 0.2, the change trend of the BER sampling values measured by Alice and Bob has good consistency. After the BER sampling value is quantized and encoded, the original key with a consistency rate of 95.93% is finally obtained. We further analyze the impact of the quantization threshold on the number of keys and key error rate under different BER. When L = 50, L×ασ = 2.5, and BER = 0.12, 146 keys can be obtained, and the key error rate is 0, which is the best key generation effect.
This paper proposes a novel key distribution system based on the measurement of the bit error rate (BER) in a fiber channel. By carrying out the loopback BER measurement at both the transmitting and the receiving end, the BER is quantified and codified to generate consistency keys. Alice and Bob respectively encrypt the signal with the help of the public key base at the transmitting end. At the receiving end the data are decrypted and then the BER is measured. The security of generated keys in the system is enhanced by the use of the encryption base and the randomness of the channel. Additionally, noise sources are added to the channel so that the random noise conceals signals and Eve cannot eavesdrop the useful information in it. Due to the randomness of the channel noise, the generated keys have good randomness. This system at a high key generation rate is compatible with the existing communication device and its measurement is simple. The 10G bit/s-200 km coherent optical communication system is used to measure the BER of the security feature information of the extracted channel. The experimental results show that the key distribution system obtains a consistency rate of 98% with the key generation rate 2 Mbps, both of which have been significantly improved.
Orthogonal frequency division multiplexing (OFDM) offers a promising solution for emerging high-data-rate services. Moreover, physical layer security was proposed as an alternative way to provide information security in wireless communications. In this work, we focus on improving physical layer security in OFDM systems. Our approach perturbs the effective channels observed at eavesdroppers by nonlinear distortion, while maintaining the same effective channel experienced at the intended receiver. At the transmitter, the perturbation on eavesdropper's effective channel is random and can be changed on a symbol-by-symbol basis based on the known original channel state information (CSI). At the intended receiver, no additional information or information exchange with the transmitter is required for data detection. We derive the results of the proposed scheme for the multiple-input single-output single-antenna-eavesdropper (MISOSE) wiretap channel. According to simulations, the proposed scheme can severely degrade the receiving performance at eavesdroppers and outperform the artificial-noise-based approaches in the performance measure of BER.
Exploiting the inherent physical properties of wireless channels to complement or enhance the traditional security mechanisms has attracted prominent attention recently. However, the existing secret key generation schemes suffer from miscellaneous extracting procedure. Many PHY-layer authentication schemes assume that the knowledge of the shared key is preknown. In this paper, we propose PHY-layer secret key generation and authentication schemes for orthogonal frequency-division multiplexing (OFDM) systems. In the secret key generation scheme, to simplify the extracting procedure, only one legitimate party is chosen to probe the channel and quantize the measurements to obtain the preliminary key. The preliminary key is masked by the channel-phase after the mapping and before equalization and distributed to the other party. The final shared key is used for the PHY-layer authentication scheme in which random signals and the shared key masked by the channel-phase are exchanged at the PHY-layer. Then, a binary hypothesis test is formulated for authentication. Simulation results show that the proposed secret key generation scheme outperforms the existing schemes. For the PHY-layer authentication scheme, it is immune to various passive and active attacks and a high successful authentication rate is acquired even at low signal-to-noise ratio region.