A physical layer digital encryption system and method for fronthaul scenarios

Abstract

The present invention relates to the field of optical fiber and terahertz communication technology, and discloses a physical layer digital encryption system and method applied to a fronthaul scenario. As a key part of the physical layer encryption scheme, the signal to be encrypted is first preprocessed and divided into two paths to independently encrypt each dimension. At the same time, dynamic keys and chaotic signals are generated successively for time domain masking encryption and frequency domain masking encryption. The signal to be encrypted is first mixed with the amplified chaotic signal to mask the signal time domain information. Then it enters the Delta‑sigma modulator to modulate and generate an encrypted QPSK signal. Finally, the DSM‑QPSK signal enters the frequency domain masking encryption, and the frequency domain feature information is masked to complete the encryption. In terms of application scenarios, the present invention can become an excellent candidate for the research and application of confidentiality schemes in future low-cost fronthaul systems.

Description

Technical Field

[0001] The present invention relates to the field of optical fiber and terahertz communication technology, and in particular to a physical layer digital encryption system and method applied to a fronthaul scenario. Background Art

[0002] Nowadays, communication systems that combine optical, electrical, and wireless hybrid links are becoming increasingly advanced and complex, and it is necessary to encrypt the physical layer to prevent eavesdropping on any link in the complex system. Chaotic encryption systems are extremely attractive in physical layer encryption. Due to their excellent unpredictability, initial sensitivity, and non-periodicity, chaotic encryption systems have a huge key space and are difficult to crack. Compared with the traditional multi-level and multi-round mathematical function operations on plaintext and keys, chaotic encryption generation has a simple structure and has more unique characteristics, which can be applied to physical layer encryption in many ways. As the experimental verification distance of millimeter waves increases to several kilometers, although millimeter wave transmission can achieve extremely small beam widths, the radiation radius of its signal will exceed hundreds of meters under several kilometers of transmission, which greatly increases the possibility of eavesdropping.

[0003] Therefore, it becomes extremely necessary to apply and enrich the physical layer encryption method in the fiber-wireless integrated system, and it is necessary to provide a physical layer digital encryption system and method applied to the fronthaul scenario to solve the above technical problems. Summary of the invention

[0004] The purpose of the present invention is to provide a physical layer digital encryption system and method based on chaotic encryption and Delta-sigma modulation for use in fronthaul scenarios, so as to achieve real-time encryption and decryption of high-speed communications and ensure the reliability and stability of encryption.

[0005] To achieve the above object, the present invention provides a physical layer digital encryption system applied to a fronthaul scenario, comprising:

[0006] In the data preprocessing module, the original input serial data stream is divided into two paths, and after serial-to-parallel conversion, it is divided into two parallel data streams x and y;

[0007] A dynamic key generation module extracts data from a data stream to generate a dynamic initial key. The dynamic key generation module includes an initial key extractor for generating an initial key based on frame real-time information and an initial key generator for generating keys required for time domain masking and frequency domain encryption. The dynamic key is obtained by performing function calculation on the pre-processed data extraction information. The dynamic key enters the chaotic signal generation module as the initial key of the encryption module.

[0008] A chaotic signal generation module is used to generate a chaotic encryption signal. The chaotic encryption signal is generated by a third-order chaotic difference equation. The chaotic signals in the x and y dimensions are used for time domain encryption. The chaotic signal in the z dimension enters the frequency domain encryption module and is further processed by a function operation to serve as the initial key of the encryption module.

[0009] The first-level time domain masking module is used to perform time domain encryption operation on the pre-processed two-way parallel data, and to mix the x and y data with the two dimensional components x and y of the chaotic encryption signal in proportion to obtain a masked time domain signal;

[0010] The second-stage Delta-sigma modulation part performs Delta-sigma modulation on the masked time-domain signal. After modulation, the signal is quantized into a QPSK-DSM signal with dual levels in the time domain and a spray-pot-shaped characteristic in the frequency domain.

[0011] The third-level frequency domain encryption module encrypts the Delta-sigma modulated signal using a digital encryption method controlled by a key generated by the z dimension of the chaotic encryption signal, and finally outputs a frequency-domain flat signal to achieve frequency domain encryption.

[0012] Preferably, the chaotic signal generating module comprises:

[0013] A chaotic signal generator based on differential operation (such as an arbitrary waveform generator AWG) is used to generate encrypted signals in the time domain and frequency domain;

[0014] A signal amplitude amplifier is used to adjust the amplitude of the time domain mask.

[0015] Preferably, the time domain masking module includes a time domain signal complex adder for masking the chaotic signal on the real and imaginary parts of the communication signal.

[0016] Preferably, the Delta-sigma modulation part includes two Delta-sigma modulators, which are used to modulate the real and imaginary part signals after time domain masking into 1-bit information respectively.

[0017] Preferably, the frequency domain encryption module includes a stream data digital encryptor for encrypting the signal passing through the Delta-sigma modulator.

[0018] The present invention also proposes a physical layer digital encryption method applied to a fronthaul scenario, the method being applied to the above-mentioned physical layer digital encryption system applied to the fronthaul scenario, comprising the following steps:

[0019] S1. First, the original bit data stream is divided into two paths to be encrypted. After serial-to-parallel conversion, each data stream is divided into two parallel data streams;

[0020] S2, the dynamic key is obtained by performing function operation on the pre-processed data extraction information, and the dynamic key enters the chaotic signal generation module as the initial key of the encryption module;

[0021] S3, the chaotic encryption signal is generated by the third-order chaotic difference equation. The chaotic signals in the x and y dimensions are used for time domain encryption. The chaotic signal in the z dimension enters the frequency domain encryption module and is further processed by function operation as the initial key of the encryption module.

[0022] S4, the chaotic encrypted signal is amplified and mixed with the signal to be encrypted to obtain a time domain masking signal;

[0023] S5, the time domain masking signal is modulated by a Delta-sigma modulator to generate a DSM-QPSK signal;

[0024] S6, DSM-QPSK signal undergoes a new round of digital bit-level encryption, the frequency domain characteristic information is masked, and finally the time-frequency domain masking encryption is completed.

[0025] Compared with the related art, the physical layer digital encryption system and method provided by the present invention for use in the fronthaul scenario have the following beneficial effects:

[0026] Compared with the prior art, the present invention utilizes DSM signals to transmit high-quality chaotic encrypted signals, and masks the unique spectral characteristics of DSM signals through further digital encryption to achieve multi-dimensional masking and encryption in the time-frequency domain. This encryption method is compatible with flexible modulation formats, and can adjust the DSM structure according to channel requirements to provide a suitable encrypted modulation format. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the physical layer digital encryption system proposed by the present invention for use in the fronthaul scenario.

[0028] Figure numerals: 1. Encrypted signal; 2. Time domain constellation point masking; 3. Dynamic key generator; 4. Chaotic signal generator; 5. Chaotic signal amplifier; 6. Delta-sigma modulation; 7. Bit-level digital encryption. DETAILED DESCRIPTION

[0029] The present invention will be further described below in conjunction with the accompanying drawings and implementation modes.

[0030] Please refer to Figure 1 , Figure 1 Schematic diagram of the physical layer digital encryption system provided by the present invention for use in the fronthaul scenario.

[0031] The physical layer digital encryption system used in the fronthaul scenario includes:

[0032] ① Chaotic signal generation system:

[0033] A chaotic signal generator 4 based on differential operation (such as an arbitrary waveform generator AWG): used to generate encrypted signals in the time domain and the frequency domain;

[0034] A signal amplitude amplifier, namely the chaotic signal amplifier 5, is used to adjust the amplitude of the time domain masking.

[0035] ②Time domain masking system:

[0036] A time domain signal complex adder: used to mask the chaotic signal on the real and imaginary parts of the communication signal.

[0037] ③Dynamic key management system:

[0038] An initial key extractor: used to generate an initial key based on frame real-time information;

[0039] An initial key generator: used to generate the keys required for time domain masking and frequency domain encryption.

[0040] ④Delta-sigma modulation system:

[0041] Two Delta-Sigma modulators: used to modulate the real and imaginary part signals after time domain masking into 1-bit information respectively.

[0042] ⑤Frequency domain encryption system:

[0043] A streaming data digital encryptor: used to encrypt the signal passing through the Delta-Sigma modulator

[0044] The encryption method is:

[0045] The dynamic key generator 3 extracts part of the information in the encrypted signal 1 to generate the key, and generates encryption keys for time domain masking 2 and frequency domain masking encryption 7 respectively. The function operation expression refers to the attached formula (1). The chaotic signal generator 4 uses the initial key generated by the dynamic key generator 3 as the initial value and generates a chaotic signal according to the third-order Jerk chaotic difference equation. The function expression of the third-order chaotic difference equation refers to the attached formula (2). The amplitude of the chaotic signal is controlled and amplified by the chaotic signal amplifier 5. Finally, the time domain of the modulated signal 1 is masked and encrypted in the time domain masking encryption 2.

[0046] After the time domain masking and encryption 2, the signal enters the Delta-Sigma modulator 6 for modulation. The real and imaginary parts of the signal are modulated into OOK signals carrying 1 bit of information. The mathematical function expression of the Delta-Sigma modulator is shown in the attached formula (3). Finally, the frequency domain masking and encryption are performed at the frequency domain masking and encryption 7 by a bit-level digital encryption method.

[0047] Formula (1) Dynamic key generation function expression:

[0048]

[0049] Formula (2-1) Chaotic difference equation function expression:

[0050]

[0051] Formula (2-2) Chaotic difference equation function expression:

[0052]

[0053] Formula (3) Second-order DSM function expression:

[0054] y[n]=x[n]+(1-z -1 ) 2 e[n]

[0055] Those skilled in the art will appreciate that the above embodiments are specific examples for implementing the present invention, and in actual applications, various changes may be made thereto in form and detail without departing from the spirit and scope of the present invention.

Claims

1. A physical layer digital encryption system applied to a fronthaul scenario, characterized in that: include: In the data preprocessing module, the original input serial data stream is divided into two paths, and after serial-to-parallel conversion, it is divided into two parallel data streams x and y; A dynamic key generation module extracts data from a data stream to generate a dynamic initial key. The dynamic key generation module includes an initial key extractor for generating an initial key based on frame real-time information and an initial key generator for generating keys required for time domain masking and frequency domain encryption. The dynamic key is obtained by performing function calculation on the pre-processed data extraction information. The dynamic key enters the chaotic signal generation module as the initial key of the encryption module. A chaotic signal generation module is used to generate a chaotic encryption signal. The chaotic encryption signal is generated by a third-order chaotic difference equation. The chaotic signals in the x and y dimensions are used for time domain encryption. The chaotic signal in the z dimension enters the frequency domain encryption module and is further processed by a function operation to serve as the initial key of the encryption module. The first-level time domain masking module is used to perform time domain encryption operation on the pre-processed two-way parallel data, that is, to mix the x and y data with the two dimensional components x and y of the chaotic encryption signal in proportion to obtain the masked time domain signal; The second-stage Delta-sigma modulation part performs Delta-sigma modulation on the masked time-domain signal. After modulation, the signal is quantized into a QPSK-DSM signal with dual levels in the time domain and a spray-pot-shaped characteristic in the frequency domain. The third-level frequency domain encryption module encrypts the Delta-sigma modulated signal using a digital encryption method controlled by a key generated by the z dimension of the chaotic encryption signal, and finally outputs a frequency-domain flat signal to achieve frequency domain encryption.

2. The physical layer digital encryption system applied to the fronthaul scenario according to claim 1, characterized in that: The chaotic signal generating module comprises: A chaotic signal generator based on differential operation is used to generate encrypted signals in time domain and frequency domain; A signal amplitude amplifier is used to adjust the amplitude of the time domain mask.

3. The physical layer digital encryption system for fronthaul scenarios according to claim 1, characterized in that: The first-level time domain masking module includes a time domain signal complex adder, which is used to mask the two components of the chaotic encryption signal x and y on the real and imaginary parts of the communication signal.

4. The physical layer digital encryption system for fronthaul scenarios according to claim 1, characterized in that: The delta-sigma modulation part includes two delta-sigma modulators, which are used to modulate the real and imaginary part signals after time domain masking into 1-bit information respectively.

5. The physical layer digital encryption system applied to the fronthaul scenario according to claim 1, characterized in that: The frequency domain encryption module includes a stream data digital encryptor for encrypting the signal passing through the Delta-Sigma modulator.

6. A physical layer digital encryption method applied to a fronthaul scenario, characterized in that: The method is applied to the physical layer digital encryption system applied to the fronthaul scenario as described in any one of claims 1 to 5 above, and comprises the following steps: S1. First, the original bit data stream is divided into two paths to be encrypted. After serial-to-parallel conversion, each data stream is divided into two parallel data streams; S2, the dynamic key is obtained by performing function operation on the pre-processed data extraction information, and the dynamic key enters the chaotic signal generation module as the initial key of the encryption module; S3, the chaotic encryption signal is generated by the third-order chaotic difference equation. The chaotic signals in the x and y dimensions are used for time domain encryption. The chaotic signal in the z dimension enters the frequency domain encryption module and is further processed by function operation as the initial key of the encryption module. S4, the chaotic encrypted signal is amplified and mixed with the signal to be encrypted to obtain a time domain masking signal; S5, the time domain masking signal is modulated by a Delta-sigma modulator to generate a DSM-QPSK signal; S6, DSM-QPSK signal undergoes a new round of digital bit-level encryption, the frequency domain characteristic information is masked, and finally the time-frequency domain masking encryption is completed.

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