Pulse random number generation method based on chaotic laser energy reconstruction

Abstract

The invention provides a pulse random number generation method based on chaos laser energy reconstruction, which belongs to the technical field of random number generation and comprises the following steps of: firstly, applying time domain second-order phase modulation to any chaos laser generated by a chaos laser signal source as input; secondly, frequency domain second-order phase modulation is applied to the chaotic laser subjected to time domain second-order phase modulation; thirdly, performing photoelectric conversion on the signal subjected to frequency domain second-order phase modulation, and outputting a chaotic pulse signal subjected to energy reconstruction; and finally, realizing random number generation based on the chaotic pulse signal. By applying simple time domain second-order phase modulation and frequency domain second-order phase modulation, energy reconstruction of any input chaotic laser is achieved, periodic sampling and passive amplification of the chaotic laser can be achieved at the same time without using a sampling pulse and an amplifier, and the method has the advantages of being simple, low in power consumption, good in stability and the like. And flexible and adjustable random number generation rate can be realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of random number generation, and relates to a method for generating pulsed random numbers based on chaotic laser energy reconstruction. Background Art

[0002] With the wide application of the new generation of information technology, information security has gradually become a core issue in the digital process of human society. Among the various technologies for ensuring information security, random numbers play an indispensable role in encryption technology, identity authentication, and various communication security protocols. Therefore, the generation of high-quality and high-rate random numbers is one of the cornerstones for ensuring the secure development of information technology.

[0003] Traditional physical random number generators use physical entropy sources such as thermal noise and chaotic circuits to generate random numbers, but the random number generation rate is limited. Due to the characteristics of broadband, noise-like, and synchronizable of chaotic lasers based on semiconductor lasers, a large number of studies have been conducted on their applications in physical random number generation. In the academic paper "Fast physical random bit generation with chaotic semiconductor lasers" published by Atsushi Uchida et al. in the academic journal "Nature Photonics", a physical random number generation scheme using an optical feedback semiconductor laser was experimentally demonstrated for the first time, achieving a random number generation rate of 1.7 Gb / s. The random number generation methods based on chaotic lasers proposed on this basis usually require using a photodetector to convert the chaotic laser into an electrical signal and using a high-speed analog-to-digital converter (ADC) to sample and quantize it. The requirement for a high-speed sampling clock in this process limits the development of chaotic laser random numbers due to the electronic rate bottleneck. In the "Adaptive real-time true random number generation device based on ultra-high frequency laser chaos" (CN106293613B) proposed by Li Pu et al., the amplitude information of the chaotic laser is loaded onto the optical pulse sequence output by the mode-locked laser through the use of an all-optical sampling method to form a chaotic laser pulse sequence, and the power of the chaotic laser pulse sequence is amplified by using an optical amplifier, avoiding problems such as high-speed sampling clock jitter introduced by using an analog-to-digital converter. However, the random number generation rate generated by this method directly depends on the repetition frequency of the mode-locked laser, lacking flexibility; and compared with traditional methods, the introduction of a mode-locked laser and its supporting optical sampling processing link increases the system complexity; the power amplification of the laser pulse further increases the power consumption of the system. Summary of the Invention

[0004] The present invention mainly aims at the problem that the existing chaotic laser-based random number generation method relies on a high-speed sampling clock or sampling pulses, and proposes a pulse random number generation method based on chaotic laser energy reconstruction. The present invention has the advantages of simple implementation method, flexible adjustment, etc.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A pulse random number generation method based on chaotic laser energy reconstruction, the pulse random number generation method is based on a system implementation. The system includes a chaotic laser signal source, a polarization controller, a phase modulator, a second-order dispersion medium, a photodetector, and a data processing module. Among them, the chaotic laser signal source, the polarization controller, the phase modulator, the second-order dispersion medium, and the photodetector are sequentially connected in series by a single-mode optical fiber to form an optical path, and the photodetector and the data processing module are connected by a radio frequency cable. The method includes the following steps:

[0007] The first step is to use any chaotic laser generated by the chaotic laser signal source as the system input.

[0008] Further, in the first step, the polarization state of any chaotic laser is adjusted by the polarization controller to obtain the maximum modulation efficiency.

[0009] The second step is second-order phase modulation in the time domain.

[0010] Apply second-order phase modulation in the time domain to the input chaotic laser; the phase modulation waveform involved in the second-order phase modulation in the time domain is: where represents the phase shift amount required for the nth phase step, m is defined as the number of phase steps per cycle, and τ is defined as the duration of each phase step.

[0011] Further, in the second step, the application of second-order phase modulation in the time domain is realized by the phase modulator.

[0012] The third step is second-order phase modulation in the frequency domain.

[0013] Apply second-order phase modulation in the frequency domain to the chaotic laser that has undergone second-order phase modulation in the time domain;

[0014] Further, in the third step, the second-order phase modulation in the frequency domain is realized by using the transmission of the second-order dispersion medium. The second-order dispersion medium generally uses dispersion compensation fiber, linearly chirped fiber Bragg grating, etc. The second-order dispersion amount provided by the second-order dispersion medium should satisfy:

[0015] The fourth step is to output the chaotic pulse signal after energy reconstruction.

[0016] The signal output after frequency-domain second-order phase modulation undergoes photoelectric conversion, producing a chaotic pulse signal with energy reconstruction. The chaotic pulse signal has a pulse repetition frequency of 1 / mτ, and its peak path coincides with m times the amplitude of the arbitrary chaotic laser input in the first step. Through energy reconstruction, this step achieves periodic sampling and passive amplification of the chaotic laser.

[0017] Furthermore, in the fourth step, the photoelectric conversion is achieved through a photodetector.

[0018] The fifth step is to realize random number generation based on chaotic pulse signal.

[0019] For the chaotic pulse signal output in the fourth step, the peak points of each pulse in the chaotic pulse signal are extracted in turn, each peak point is quantized, each peak point is converted into an n-bit bit sequence, the k least significant bits are taken and output in sequence according to the peak point order, and finally, random number generation is achieved through operations such as self-delayed XOR, where n is an integer and n≥1, and k is an integer and 1≤k≤n.

[0020] Furthermore, in the fifth step, a data processing module is used to process the chaotic pulse signal, specifically:

[0021] Step 5.1, input the chaotic pulse signal to the "+" input port of the n-bit parallel comparator; use an adjustable power supply to set the threshold voltage and input it to the "-" input port of the parallel comparator, wherein the threshold voltage is set to the average value of the amplitude of each pulse peak point in the chaotic pulse signal; quantize the peak point of each chaotic pulse signal in turn, and convert each peak point into an n-bit bit sequence.

[0022] Step 5.2: For the n-bit bit sequence output by the parallel comparator, take the k least significant bits and output them in sequence according to the peak point order.

[0023] In step 5.3, a data processing circuit composed of a buffer and an XOR logic gate is used to perform self-delayed XOR operations on the bit sequence output after the valid bit is intercepted in step 5.2 to achieve random number generation.

[0024] The beneficial effects of the present invention are:

[0025] (1) The present invention realizes energy reconstruction of any input chaotic laser by applying simple time-domain second-order phase modulation and frequency-domain second-order phase modulation. It can simultaneously realize periodic sampling and passive amplification of chaotic laser without using sampling pulses and amplifiers. It has the characteristics of simple method, low power consumption and good stability.

[0026] (2) Compared with the existing random number generation method based on chaotic laser optical sampling, the repetition frequency of the output chaotic pulses of the present invention can be adjusted by time-domain second-order phase modulation and frequency-domain second-order phase modulation. Therefore, the random number generation rate can be flexibly adjusted. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a flowchart for the implementation of the present invention.

[0028] Figure 2 It is a schematic structural diagram of a specific embodiment of the present invention.

[0029] Figure 3 It is a simulation result diagram of a specific embodiment of the present invention. Figure 3 (a) is the input chaotic laser signal; Figure 3 (b) is the phase modulation waveform diagram generated by MATLAB, Figure 3 (c) is the simulation comparison diagram between the output chaotic pulse signal and the input chaotic laser signal.

[0030] In the figure: 1 chaotic laser signal source, 2 polarization controller, 3 phase modulator, 4 dispersion compensation module, 5 photodetector, 6 single-mode optical fiber, 7 data processing module, 8 RF cable. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] To make the method problems solved by the present invention, the method solutions adopted, and the method effects achieved clearer, the present invention will be further described in detail below with reference to the drawings and embodiments.

[0032] Figure 1 It is a flowchart for the implementation of a pulse random number generation method based on chaotic laser energy reconstruction provided by the present invention, Figure 2 It is a schematic structural diagram of a specific embodiment of a pulse random number generation method based on chaotic laser energy reconstruction provided by the present invention. As Figure 1 shown, a pulse random number generation method based on chaotic laser energy reconstruction provided by an embodiment of the present invention includes the following steps:

[0033] First step, use any chaotic laser generated by a chaotic laser signal source as the system input.

[0034] In this embodiment, a group of master-slave structured single-mode semiconductor lasers is selected to form the chaotic laser signal source 1, and the chaotic laser generated by it is used as the system input. Specifically, the light emitted by the master laser is unidirectionally injected into the slave laser through an optical circulator, and the slave laser is made to be in a chaotic emission state by controlling the optical injection parameters. In this embodiment, the polarization state of the chaotic laser generated by the chaotic laser signal source 1 is adjusted by the polarization controller 2 to obtain the maximum modulation efficiency.

[0035] Second step, time-domain second-order phase modulation.

[0036] In this embodiment, a phase modulator 3 is used to apply a second-order time-domain phase modulation to the input chaotic laser. The phase modulation waveform involved in the second-order time-domain phase modulation is as follows: where represents the phase shift amount required for the nth phase step, m is the number of phase steps per period, and τ is the duration of each phase step. In this embodiment, (m, τ) = (3, 23.8 ps) is selected.

[0037] Step 3: Second-order frequency-domain phase modulation.

[0038] The second-order dispersion medium used in this embodiment is a dispersion compensation module 4 (specifically, dispersion compensation fiber). The dispersion compensation module 4 is used to apply a second-order frequency-domain phase modulation to the chaotic laser that has undergone the second-order time-domain phase modulation. The second-order dispersion amount provided by the dispersion compensation module 4 should satisfy: According to the design method described above and the design parameters of the phase modulation waveform selected in Step 3, the second-order dispersion amount provided by the dispersion compensation module 4 is calculated to be: or 212.1 ps / nm.

[0039] Step 4: Output the chaotic pulse signal after energy reconstruction.

[0040] The photodetector 5 used in this embodiment has a bandwidth of 40 GHz. It performs photoelectric conversion on the signal output after the second-order frequency-domain phase modulation and outputs the chaotic pulse signal after energy reconstruction. The pulse repetition frequency of the chaotic pulse signal is: 1 / mτ = 14 GHz, and the peak point path trajectory of the chaotic pulse signal exactly coincides with 3 times the amplitude of the input chaotic laser in Step 1. This step realizes the periodic sampling and passive amplification of the input chaotic laser.

[0041] Step 5: Realize random number generation based on the chaotic pulse signal.

[0042] For the chaotic pulse signal output in Step 4, this embodiment uses a data processing module 7 to perform data processing on the chaotic pulse signal, which specifically includes the following steps:

[0043] Step 5.1: Input the chaotic pulse signal into the “+” input port of an 8-bit parallel comparator that does not require a high-speed electronic clock drive. Use an adjustable power supply to set the threshold voltage and input it into the “-” input port of the parallel comparator. The threshold voltage set in this embodiment is the average value of the amplitudes of the peak points of each pulse in the chaotic pulse signal; quantize the peak points of each chaotic pulse signal in turn, and convert each peak point into an 8-bit bit sequence.

[0044] Step 5.2: For the 8-bit bit sequence output by the above parallel comparator, take the 5 least significant bits and output them in the order of peak points.

[0045] Step 5.3: Use a data processing circuit composed of a buffer and an exclusive-OR logic gate to perform operations such as 20-bit self-delay exclusive-OR on the bit sequence output after the significant bit truncation above to realize random number generation. The final random number generation rate is: 70 Gb / s (14 GHz × 5 bits).

[0046] As Figure 2 shown, a specific embodiment structure of a pulse random number generation method based on chaotic laser energy reconstruction provided by the present invention includes a chaotic laser signal source 1, a polarization controller 2, a phase modulator 3, a dispersion compensation module 4, and a photodetector 5. The above components are sequentially connected in series by a single-mode optical fiber 6 to form an optical path, and the photodetector 5 and the data processing module 7 are connected by a radio frequency cable 8. The functions of the above components in the present invention are: the chaotic laser signal source 1 is used to input chaotic laser; the polarization controller 2 is used to adjust the polarization state of the input chaotic laser to obtain the maximum modulation efficiency; the phase modulator 3 is used to apply a second-order phase modulation in the time domain to the chaotic laser, and the phase modulation waveform is provided by an arbitrary waveform generator; the dispersion compensation module 4 is used to apply a second-order phase modulation in the frequency domain to the chaotic laser; the photodetector 5 is used to perform photoelectric conversion on the signal output after the second-order phase modulation in the frequency domain and output a chaotic pulse signal after energy reconstruction; the data processing module 7 is used to perform data processing such as quantization, least significant bit extraction, and self-delay exclusive-OR on the chaotic pulse signal.

[0047] In a specific embodiment, the chaotic laser input to the system is directly converted into an input chaotic laser signal by the photodetector 5, and its simulation result is as Figure 3 (a) shown, showing fast-changing, noise-like irregular fluctuations. To realize chaotic laser energy reconstruction, the simulation result of the phase modulation waveform involved in the second-order phase modulation in the time domain applied to the input chaotic laser is as Figure 3 (b) shown, and the phase modulation waveform involved is a stepped periodic signal. The number of phase steps included in each period is m = 3, and the duration of each phase step is τ = 23.8 ps. Therefore, the period of the phase modulation waveform involved is mτ = 71.4 ps. The simulation comparison result between the chaotic pulse signal output after energy reconstruction and the input chaotic laser signal is as Figure 3 (c) shown. It can be seen that the peak point path trajectory of the output chaotic pulse signal exactly coincides with Figure 3 (a) the 3 times of the amplitude of the input chaotic laser signal shown, proving that this method successfully realizes the periodic sampling and passive amplification of the input chaotic laser.

[0048] To test the randomness of the random numbers generated by the present invention, the generated random numbers were tested using the Special Publication 800-22 random number test suite provided by the National Institute of Standards and Technology (NIST) of the United States. Table 1 shows the randomness test results of the random numbers generated by specific embodiments of the present invention. The P-values of all tests are greater than 0.01, the passing rate of each test is greater than 0.9806, and all 15 tests are successfully passed, meeting the standards specified for random number testing, proving that the random numbers generated by the present invention have good randomness.

[0049] Table 1 Randomness test results of the random numbers generated by specific embodiments of the present invention

[0050]

[0051] The above-described embodiments merely represent the implementation manners of the present invention and should not be construed as limiting the scope of the patent of the present invention. It should be noted that for those skilled in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all fall within the protection scope of the present invention.

Claims

1. A method for generating pulse random numbers based on chaotic laser energy reconstruction, characterized in that The described method for generating pulsed random numbers includes the following steps: In the first step, any chaotic laser generated by a chaotic laser signal source is used as the input. Second step, apply a second-order time-domain phase modulation to any input chaotic laser; the phase modulation waveform involved in the second-order time-domain phase modulation is as follows: where represents the phase shift amount required for the nth phase step, m is defined as the number of phase steps per period, and τ is defined as the duration of each phase step; In the third step, a frequency-domain second-order phase modulation is applied to the chaotic laser that has undergone time-domain second-order phase modulation. In the fourth step, the signal output after the frequency-domain second-order phase modulation undergoes optoelectronic conversion to output a chaotic pulse signal after energy reconstruction. The pulse repetition frequency of the chaotic pulse signal is 1 / mτ. In the fifth step, random number generation is realized based on the chaotic pulse signal. For the chaotic pulse signal output in the fourth step, the peak points of each pulse in the chaotic pulse signal are sequentially extracted, each peak point is quantized, each peak point is converted into an n-bit bit sequence, the k least significant bits are taken and output sequentially in the order of the peak points, and finally random numbers are generated through processing, where n is an integer and n≥1, and k is an integer and 1≤k≤n.

2. The pulse random number generation method based on chaotic laser energy reconstruction according to claim 1, wherein, In the first step, the polarization state of any chaotic laser is adjusted by a polarization controller to obtain the maximum modulation efficiency.

3. A pulse random number generation method based on chaotic laser energy reconstruction according to claim 1, characterized in that In the third step, the second-order phase modulation in the frequency domain is achieved by transmission through a second-order dispersion medium, and the second-order dispersion amount provided by the second-order dispersion medium satisfies:

4. A pulse random number generation method based on chaotic laser energy reconstruction according to claim 1, characterized in that In the fourth step, the peak point path trajectory of the chaotic pulse signal coincides with m times the amplitude of any chaotic laser input in the first step.

5. A pulse random number generation method based on chaotic laser energy reconstruction according to claim 1, characterized in that In the fourth step, through energy reconstruction, periodic sampling and passive amplification of the chaotic laser are realized.

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