CN112865874B - Self-adaptive decryption optical encryption transmission system and method based on optical self-interference elimination - Google Patents
Self-adaptive decryption optical encryption transmission system and method based on optical self-interference elimination Download PDFInfo
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Abstract
The invention provides a self-adaptive decryption optical encryption transmission system based on optical self-interference elimination, which comprises a sending end module, a receiving end module and a decoding module, wherein the sending end module is based on a dual-drive Mach-Zehnder modulator framework, utilizes electric delay and electric attenuation to adjust analog noise to serve as a two-dimensional orthogonal key, and completes analog optical encryption of useful signals; the optical fiber transmission module completes the radio over fiber transmission of optical signals from the transmitting end to the receiving end and the compensation of transmission damage; the receiving end module is based on a self-adaptive optical self-interference elimination framework, and the optimal key is found by self-adaptively adjusting the delay and attenuation of a receiving end reference path and self-adaptively searching according to the quality of the demodulated useful signal by operating a regular triangle algorithm, so that the self-adaptive receiving of the useful signal and the self-adaptive elimination of the analog noise are completed. The invention does not need to distribute the key between the receiving and transmitting ends, and the transmitting encryption end can modify the encryption key at any time, thereby greatly reducing the complexity and the cost of the whole system and improving the anti-interference performance and the flexibility of the whole system.
Description
Technical Field
The invention relates to the technical field of microwave photonics optical fiber transmission, in particular to an adaptive decryption optical encryption transmission system and method based on optical self-interference elimination, and particularly relates to an adaptive decryption analog optical encryption transmission system and method based on optical self-interference elimination.
Background
With the rapid development of mobile communication technology, wireless services have undergone explosive growth, and meanwhile, users have made higher and higher requirements on the stability and security of transmission systems, and how to safely transmit data between various networks and users becomes an important research issue. The optical analog encryption technology has the advantages of low time delay and low cost, and is widely applied to secret communication transmission. Common optical encryption technologies include optical chaotic encryption, optical logic gate encryption, optical analog noise encryption, and the like. The optical analog noise encryption system has the advantages that strict synchronization between the receiving end and the transmitting end is not needed, and the encrypted signals are analog noise, so that the encrypted signals are not easy to be cracked by an attacker through a DSP (digital signal processor).
Based on the prior literature search, Ben Wu et al published an article entitled "Analog noise protected optical encryption with two-dimensional key space" in Optics Express (Vol.22, No.12, June 2014) in 2014, and first proposed a two-dimensional key optical Analog noise encryption system based on optical self-interference cancellation. In the system, a sending end combines signals in an electrical mode, adds analog noise added with a secret key and a useful signal really needing to be transmitted, and protects the useful signal by utilizing the analog noise. The combined signal is modulated to the optical domain and then transmitted to the receiving end together with the analog noise through the single mode fiber, the receiving end is divided into 2 paths through a wavelength division multiplexing filter, and the lower path matches the analog noise through the time delay and attenuation obtained after the key distribution in advance, so that the analog noise loaded on the useful signal is removed, and the useful signal to be received is recovered. However, the system needs to distribute the key between the transmitting end and the receiving end through a special way, so that the risk of attack and interception by an attacker can be greatly increased, and meanwhile, at the transmitting end, the combination of signals and the electro-optical modulation are separately performed, and the complexity of the system can be correspondingly increased.
Through the existing literature search, an article entitled "Digital chaos-masked optical encryption scheme enhanced by two-dimensional key space" was published by Ling Liu et al in 2017 in Optics Communications (vol.398, Septem error rate 2017), and the article uses a combination of Digital chaotic encryption and analog noise encryption to encrypt transmission signals. The scheme is based on a Dual-Drive Mach-Zehnder Modulator structure and also utilizes a self-interference elimination principle, and signal combining encryption at a sending end and signal elimination decryption at a receiving end are completed by offset subtraction of a Dual-Drive Mach-Zehnder Modulator (Dual-Drive Mach-Zehnder Modulator, referred to as Dual-Drive Mach-Zehnder Modulator architecture for short). Compared with the traditional analog noise encryption, the scheme has the advantages that one layer of digital chaotic encryption is added, and the safety and the stability of the whole system are improved. However, the implementation of the system only stays in the simulation verification stage, no experiment is carried out, and the system does not have strong reference value. In addition, signals reaching a receiving end need to be restored to an electric domain first, and then electro-optical modulation is carried out through a dual-drive Mach-Zehnder modulator framework, so that the linearity of the system can be greatly damaged in the optical-electric-optical process, and noise in the system is increased. Meanwhile, the system also needs key distribution between the transmitting side and the receiving side, so that the risk of attack is greatly increased.
Through search, Lizhuo Zheng et al published an article entitled "Adaptive over-the-air RF self-interference using a signal-of-interest driven three algorithm" on Optics Letters (Vol.45, No.5/1March 2020) in 2020, and proposed an Adaptive regular triangle algorithm based on the useful signal error rate as an evaluation index, and verified under an antenna Adaptive Optics self-interference cancellation system. The scheme is based on an optical self-interference cancellation architecture of an electro-absorption modulator and balanced photodetectors. By operating the regular triangle algorithm, the system can realize the fastest convergence, the used sampling times are the lowest, and the algorithm has stability.
Through search, patent document CN106788579B discloses an in-band full-duplex wireless communication system and a broadband optical self-interference cancellation system thereof, including: the first communication unit and the second communication unit respectively comprise a transmitting antenna and a receiving antenna, and are used for realizing real-time two-way communication, and the first communication unit and the second communication unit are provided with a broadband-based optical self-interference elimination system, comprising: the device comprises an electro-absorption modulator, a variable optical attenuator, a variable optical delay line, a balanced receiver and a predistortion filter; for canceling the generated self-interference signal. Although the prior art solves the problem of serious reduction of the suppression bandwidth caused by uneven wireless channel, the risk of attack and interception by an attacker is greatly increased in the whole passband.
Therefore, in order to improve the security and stability of the encryption system, increase the anti-interference performance of the system, and reduce the complexity of the system, so that the system can be better applied to, for example, an optical fiber transmission system of radio over fiber, a new design needs to be performed on the whole optical analog encryption system.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide an adaptive decryption optical encryption transmission system and method based on optical self-interference elimination, and the invention optimizes the traditional optical analog encryption transmission system, utilizes the adaptive optical self-interference elimination to enable a legal user at a receiving end to find an optimal key by utilizing an algorithm in an adaptive way on the premise of not needing to know the key in advance, completes decryption and reception of useful transmission signals, and is one-time improvement on the flexibility and anti-interference performance of the optical analog encryption system.
The invention provides an adaptive decryption optical encryption transmission system based on optical self-interference elimination, which comprises:
a sending end module: based on the dual-drive Mach-Zehnder modulator architecture, the delay and attenuation of analog noise are adjusted by utilizing an electrical delay device and an electrical attenuation device to serve as a two-dimensional orthogonal key to encrypt signals, the signals are inverted by matching with a Bayer electric inverter, and optical encryption signals are generated inside the dual-drive Mach-Zehnder modulator;
an optical fiber transmission module: completing optical fiber transmission of optical encrypted signals from a transmitting end to a receiving end and compensation of transmission damage;
a receiving end module: based on an adaptive optics self-interference elimination framework, by operating a regular triangle algorithm, the time delay and attenuation of a reference path of a receiving end are dynamically adjusted in a self-adaptive manner according to the quality of a demodulated useful signal; the optimal key is found in a self-adaptive mode, self-adaptive receiving decryption of the useful signal and self-adaptive elimination of the analog noise are completed, and the optimal key is generated.
Preferably, the transmitting end module includes:
dual drive mach-zehnder modulator: the light carrier provided by the light source passes through the dual-drive Mach-Zehnder modulator, a useful signal is input into the upper port of the dual-drive Mach-Zehnder modulator, and analog noise is input into the lower port of the dual-drive Mach-Zehnder modulator;
adjustable electric attenuator: the analog noise is attenuated by the adjustable electric attenuator;
adjustable electric delay line: the simulation noise passing through the adjustable electric attenuator is delayed by an adjustable electric delay line to complete two-dimensional key encryption;
a bayer-electric inverter: and the analog noise which finishes the two-dimensional key encryption enters the lower port of the dual-drive Mach-Zehnder modulator after being inverted by the Bayer electric inverter.
Preferably, the dual-drive mach-zehnder modulator is biased at an orthogonal point, signals of an upper port and a lower port of the dual-drive mach-zehnder modulator can be subtracted, and analog optical encryption is completed by means of combination addition and electro-optical modulation of the signals to obtain optical encryption signals.
Preferably, the optical transmission module includes:
single-mode optical fiber: transmitting the optical encrypted signal output by the dual-drive Mach-Zehnder modulator from the transmitting end module to the receiving end module;
an erbium-doped fiber amplifier: the erbium-doped fiber amplifier is placed in an optical fiber link to compensate signal power lost after long-distance optical fiber transmission.
Preferably, the receiving end module includes:
electroabsorption modulated laser: analog noise is converted to an optical domain after passing through an electro-absorption modulated laser;
adjustable light delay line and adjustable optical attenuator: analog noise converted to an optical domain after passing through an electric absorption modulation laser sequentially passes through an adjustable optical delay line and an adjustable optical attenuator to be subjected to key matching;
balancing the photodetector: and the signal after key matching enters a negative port of the balanced photoelectric detector.
Preferably, the optical encrypted signal transmitted from the transmitting end module is input to the positive port of the balanced photodetector, and is subtracted from the signal after key matching, which enters from the negative port of the balanced photodetector, to recover the demodulated useful signal.
Preferably, the adaptive regular triangle algorithm takes the error rate or the error vector magnitude of the transmission signal as an objective function, the modeling abstraction is an unconstrained two-dimensional convex function optimization problem, and the optimization problem has a unique global minimum value point.
Preferably, when the delay and attenuation of the reference path converge to the best matching point, the encrypted signal is completely eliminated, and the self-interference elimination system achieves the optimal elimination.
Preferably, the adaptive key searching process in the receiving end module demodulates signals for legal users, starts to calculate the bit error rate of the transmission signals,
-if the error rate is less than the set threshold, ending the adaptation process to obtain the desired encrypted signal, where the time-delay attenuation is the best key;
if the error rate is larger than the set threshold, running an adaptive algorithm, calculating the error rate again after adjusting the delay and attenuation, and judging again to obtain the optimal key.
The invention provides a self-adaptive decryption optical encryption transmission method based on optical self-interference elimination, which comprises the following steps:
step 1: when information transmission is needed, a sending end module sends a useful signal to be transmitted into the dual-drive Mach-Zehnder modulator through an upper port of the dual-drive Mach-Zehnder modulator;
and 2, step: after the analog noise source is subjected to electric attenuation and electric delay, performing two-dimensional orthogonal encryption;
and 3, step 3: through a Bayer electric phase inverter, matching with a dual-drive Mach-Zehnder modulator with direct current bias at an orthogonal point, entering from a lower port of the dual-drive Mach-Zehnder modulator to generate an optical encryption signal;
and 4, step 4: the optical encrypted signal after the encryption process is transmitted and compensated through the optical fiber transmission module and reaches the receiving end module in the form of an optical signal;
and 5: the optical encrypted signal enters an upper path of a receiving end module from a forward port of the balanced photoelectric detector;
step 6: after the copied analog noise passes through an electric absorption modulation laser of a lower path of the receiving end module, key matching is completed through an optical delay and an optical attenuator in sequence, and then the copied analog noise enters a negative port of the balanced photoelectric detector;
and 7: the optical encrypted signal entering from the positive port and the key-matched signal entering from the negative port are subtracted to recover the demodulated useful signal.
Compared with the prior art, the invention has the following beneficial effects:
1. compared with a digital encryption method, the analog noise has randomness and is difficult to be cracked by an illegal attacker DSP, so that the whole system has good safety performance.
2. According to the self-adaptive decryption analog optical encryption transmission system based on optical self-interference elimination, the added analog protection noise is eliminated through a self-adaptive optical self-interference elimination framework, a receiving end module does not need to receive an encryption key from a sending end, an optimal key can be found in a self-adaptive mode through judging the quality of a currently demodulated useful signal according to a self-adaptive regular triangle algorithm, the removal of the encryption noise is completed, and a received signal is recovered.
3. The sending end module in the invention can modify the encryption key at any time without informing and distributing the key to the receiving end module, and the receiving end module can also find the optimal key again on the original basis according to the self-adaptive algorithm, thereby greatly improving the flexibility and the safety of the whole system.
4. According to the self-adaptive decryption analog optical encryption transmission system based on optical self-interference elimination, encryption of a sending end is based on a dual-drive Mach-Zehnder modulator framework, the orthogonal bias subtraction principle of the dual-drive Mach-Zehnder modulator is utilized, and the Bayer electric inverter is matched to complete the combined encryption of signals, so that the encryption protection of the signals is completed, meanwhile, the modulation from an electric domain to an optical domain is also completed, the framework of the system is greatly simplified, and meanwhile, the self-adaptive decryption analog optical encryption transmission system is also suitable for optical fiber transmission application such as radio over fiber and the like.
5. The self-adaptive decryption simulation optical encryption transmission system based on optical self-interference elimination uses the self-adaptive control unit to dynamically monitor the quality of output useful signals in real time, and can dynamically, real-timely and self-adaptively adjust the key of a receiving end: optical time delay and attenuation improve the quality of the demodulated output signal in time, and improve the performance of the self-interference cancellation system, i.e. the decryption system.
6. The invention does not need to carry out complicated wavelength division multiplexing filtering shunt operation and repeated modulation of light-electricity-light at a signal receiving end, and the optical signal output by the dual-drive Mach-Zehnder modulator can directly enter the photoelectric detector as the optical signal after being transmitted to the receiving end through the optical fiber, thereby greatly improving the linearity of the system and simultaneously avoiding the increase of system noise caused by electro-optical conversion.
Drawings
Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:
FIG. 1 is a system block diagram of an adaptive decryption analog optical encryption transmission system based on optical self-interference cancellation provided by the present invention;
fig. 2 is a flowchart of a key adaptive search process of the adaptive decryption analog optical encryption transmission system based on optical self-interference cancellation according to the present invention.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that it would be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit of the invention. All falling within the scope of the present invention.
Example 1:
according to fig. 1 and fig. 2, the present invention provides an adaptive decryption optical encryption transmission system based on optical self-interference cancellation, including:
a sending end module: based on the dual-drive Mach-Zehnder modulator architecture, the delay and attenuation of analog noise are adjusted by utilizing an electrical delay device and an electrical attenuation device to serve as a two-dimensional orthogonal key to encrypt signals, the signals are inverted by matching with a Bayer electric inverter, and optical encryption signals are generated inside the dual-drive Mach-Zehnder modulator.
An optical fiber transmission module: completing optical fiber transmission of optical encrypted signals from a transmitting end to a receiving end and compensation of transmission damage;
a receiving end module: based on an adaptive optics self-interference elimination framework, by operating a regular triangle algorithm, the time delay and attenuation of a reference path of a receiving end are dynamically adjusted in a self-adaptive manner according to the quality of a demodulated useful signal; the optimal key is found in a self-adaptive mode, self-adaptive receiving decryption of the useful signal and self-adaptive elimination of the analog noise are completed, and the optimal key is generated.
Further, the sending end module includes:
dual drive mach-zehnder modulator: the light carrier provided by the light source passes through the dual-drive Mach-Zehnder modulator, a useful signal is input into the upper port of the dual-drive Mach-Zehnder modulator, and analog noise is input into the lower port of the dual-drive Mach-Zehnder modulator;
adjustable electric attenuator: the analog noise is attenuated by the adjustable electric attenuator;
adjustable electric delay line: the simulation noise passing through the adjustable electric attenuator is delayed by an adjustable electric delay line to complete two-dimensional key encryption;
a bayer-electric inverter: and the analog noise which finishes the two-dimensional key encryption enters the lower port of the dual-drive Mach-Zehnder modulator after being inverted by the Bayer electric inverter.
Wherein an analog noise source is used to provide the encrypted signal required for optical analog encryption, the noise usually has relatively high power, relatively wide bandwidth and unpredictable characteristics, and the analog noise is difficult to crack by an illegal attacker through a digital method such as DSP. The light source provides light carrier for the dual drive Mach-Zehnder modulator, and the upper and lower ports of the dual drive Mach-Zehnder modulator are respectively provided with radio frequency RF signal input and analog noise input. The encrypted useful signal to be transmitted enters the dual-drive Mach-Zehnder modulator through the upper port. The analog noise of the lower branch circuit sequentially passes through the adjustable electric attenuator and the adjustable electric delay line to complete two-dimensional key encryption, and finally enters the lower port of the dual-drive Mach-Zehnder modulator after being inverted by the Bayer electric inverter. The dual-drive Mach-Zehnder modulator is biased at an orthogonal point, so that signals of the upper port and the lower port can be subtracted, namely signal combination is achieved, and finally the transmitting end completes analog optical encryption to obtain a transmission useful signal covered by analog noise.
Still further, the fiber optic transmission module comprises: erbium-doped fiber amplifiers and single-mode fibers. The erbium-doped fiber amplifier is used for compensating the signal power lost after long-distance fiber transmission; the single mode optical fiber is used to transmit the optical encrypted signal output by the dual drive mach-zehnder modulator from the transmitting end to the receiving end.
Further, the receiving end module includes:
electroabsorption modulated laser: analog noise is converted to an optical domain after passing through an electro-absorption modulated laser;
adjustable light delay line and adjustable optical attenuator: the analog noise converted to the optical domain after passing through the electro-absorption modulated laser sequentially passes through the adjustable light delay line and the adjustable optical attenuator to be subjected to key matching;
balancing the photodetector: and the signal after key matching enters a negative port of the balanced photoelectric detector.
Specifically, the upper branch of the encrypted signal and the branch of the electro-absorption modulated laser are respectively denoted as a first path and a second path. In the first path, the optical encryption signal transmitted to the receiving end directly enters the balanced photoelectric detector; an electric absorption modulation laser, a variable optical attenuator and a variable optical delay line are sequentially arranged in the second path; the reference signal, namely the analog noise enters the balanced photoelectric detector after sequentially passing through the electric absorption modulation laser, the adjustable light delay line and the adjustable optical attenuator;
the two paths of signals output by the first path and the second path are subjected to signal subtraction in the balanced photoelectric detector, analog noise is eliminated, a useful signal is recovered, and the useful signal is converted into an electrical domain.
And the self-adaptive unit is used for self-adaptively changing the key of the receiving end according to the quality of the currently demodulated useful signal by operating a self-adaptive regular triangle algorithm, matching the analog noise until the optimal key is converged, removing the protected analog noise, recovering the useful signal and completing the self-adaptive searching process of the optimal key and the self-adaptive decryption of the useful signal. The self-adaptive regular triangle algorithm takes the error rate or the error vector magnitude of a transmission signal as an objective function, models and abstracts the target function into an unconstrained two-dimensional convex function optimization problem, and the optimization problem has a unique global minimum value point.
Continuing further, the adaptive key search in the receiving-end module means that in the whole optical analog encryption transmission system, the receiving end does not need to receive the encryption key from the transmitting end through a special key distribution path, and can adaptively find the optimal key according to an adaptive regular triangle algorithm. Specifically, a valid user at a receiving end firstly demodulates and receives a useful signal to be received, because the protection analog noise is not removed at the moment, the bit error rate of the received signal is always greater than a preset threshold value and is not in accordance with the requirement. At the moment, a receiving end changes the delay and attenuation of a reference path by operating a self-adaptive algorithm, so that useful signals are continuously updated and demodulated, when the whole process is operated until the useful signals can be correctly demodulated and the error rate is less than a certain threshold value, the whole system is in an optimal state, the delay and attenuation values of the reference path are the optimal key found in a self-adaptive mode, under the key, analog noise serving as protection noise is successfully matched and eliminated, a legal user successfully obtains the useful signals to be received, and self-adaptive decryption is completed. Through the self-adaptive searching of the key, on one hand, extra key distribution is not needed between the transmitting side and the receiving side, on the other hand, the transmitting side can dynamically change the encryption key at any time and does not need to inform the receiving side, and the flexibility and the safety of the whole encryption transmission system are greatly improved.
Example 2:
in this embodiment, an optical analog encryption transmission system is provided, where a sending end module and a receiving end module respectively encrypt and adaptively decrypt signals by an optical method, and the receiving end module also searches for an adaptive key by an adaptive regular triangle algorithm. Wherein:
the signal encryption process of the sending end module is based on signal combination of the dual-drive Mach-Zehnder modulator, and the combination principle can be summarized as follows: the phases of the upper and lower arms of the dual drive mach-zehnder modulator may be represented as:
wherein, V1 and V2 respectively represent the driving voltage of the upper and lower ports of the dual-drive Mach-Zehnder modulator structure, and the driving voltage is DC bias voltage VBIASAnd the sum of the radio frequency RF voltages. V0Representing an inherent voltage within the dual drive mach-zehnder modulator architecture. Bias voltage of upper port is set to VπAnd the lower port is set to be 0, so that the whole dual-drive Mach-Zehnder modulator structure is biased at an orthogonal point through a bias voltage difference value between the upper port and the lower port, and the subtraction between input signals of the upper port and the lower port is completed. Optical domain output and power output of dual drive Mach-Zehnder modulator architectureIs shown in formulas (3) and (4), wherein EinAnd PinIs the optical domain and power expression of the laser light produced by the laser.
As can be seen from equation (4), due to the use of the bayer inverter, the signal c (t) entering from the lower port of the dual-drive mach-zehnder modulator architecture is subtracted from the original negative direction to be added in the positive direction, and the addition of the upper and lower branch signals is completed. In practical system application, the analog noise is inverted, so that the analog noise and a signal to be transmitted can be combined, and the covering encryption of the signal is completed.
The elimination principle of the studied optical self-interference elimination system located in the receiving end module can be summarized as follows: the two optical powers P1, P2 entering the positive port and the negative port of the balanced photodetector can be respectively expressed as:
P1＝kβUSI(t-τ′)+kU0+kUSOI， (5)
P2＝kαURef(t-τ)+kαU0， (6)
the expression for balancing the residual signal voltage output by the photodetector is:
Ur＝γ(P1-P2) (7)
＝γk[βUSI(t-τ′)-αURef(t-τ)]+γkUSOI. (8)
where k is the slope of the modulator modulation curve, UrRepresenting the subtracted residual signal voltage, U, of the balanced photodetector outputSOIVoltage, U, representing useful signalSIVoltage, U, representing a self-interference signalRefRepresenting the voltage of the reference signal, gamma representing the response slope of the balanced photodetector, and beta representing the useful signalThe attenuation of a signal channel, tau' represents the time delay of a useful signal channel, alpha represents the amplitude modulation of a variable optical attenuator of a reference path, tau represents the time delay of a variable optical delay line of the reference path, and t represents time. It can be seen from formula (8) that when the keys (delay, attenuation) of the transmitting end and the receiving end are respectively close to or even equal to each other, the first term in the formula is close to 0, and at this time, only useful signals exist in the output signals of the balanced photodetector, so that the encryption noise is completely removed, and the optical self-interference cancellation system completes the decryption of the signals while achieving the best cancellation effect.
The working process of the optical analog noise encryption transmission system in this embodiment can be summarized as follows: when information needs to be transmitted, a transmitting end module sends a useful signal to be transmitted into a dual-drive Mach-Zehnder modulator framework through an upper RF (radio frequency) port of the dual-drive Mach-Zehnder modulator framework, an analog noise source can generate analog noise which is higher in power and wider in bandwidth relative to the signal to be transmitted, two-dimensional orthogonal encryption is carried out after the analog noise source passes through an electric delay and electric attenuation device of the transmitting end, and finally the analog noise enters from a lower port through a Bayer electric inverter and the dual-drive Mach-Zehnder modulator framework biased at an orthogonal point to complete negative-positive subtraction, namely addition, of the signal.
And the optical signal after the encryption process is transmitted and compensated through the optical fiber by the optical fiber transmission module and reaches a receiving end in the form of the optical signal. The receiving end module is divided into an upper path and a lower path, an encrypted signal of the upper path enters a positive port of the balanced photoelectric detector, copied analog noise passes through the electric absorption modulation laser of the lower path, then sequentially passes through the optical delay line and the optical attenuator, and then enters a negative port of the balanced detector, so that subtraction and photoelectric detection are completed.
Firstly, a receiving end carries out decryption demodulation and error rate test on a useful signal received after a balanced detector, the error rate is still higher than a set threshold value at the stage that analog noise is not removed, at the moment, the receiving end starts a self-adaptive regular triangle algorithm, a key of a reference path is dynamically changed through algorithm self-adaptation, namely delay and attenuation, the error rate value is updated at any moment, and the algorithm is continued. When the key delay and attenuation of the receiving end converge to a certain position, the amplitude and the phase of the matched analog noise and the analog noise of the upper branch at the moment are basically consistent and can be cancelled in the balanced photoelectric detector, so that the error rate of useful signals obtained by decryption and demodulation is lower than a threshold value, the delay and the attenuation at the moment are the optimal key obtained by the self-adaptive searching of the receiving end, the protective analog noise of the sending end is successfully removed, and a legal user of the receiving end completes the self-adaptive decryption and the smooth receiving of the signals.
The invention also provides a self-adaptive decryption optical encryption transmission method based on optical self-interference elimination, which comprises the following steps:
step 1: when information transmission is needed, a sending end module sends a useful signal to be transmitted into the dual-drive Mach-Zehnder modulator through an upper port of the dual-drive Mach-Zehnder modulator;
step 2: after the analog noise source is subjected to electric attenuation and electric delay, performing two-dimensional orthogonal encryption;
and step 3: through a Bayer electric phase inverter, matching with a dual-drive Mach-Zehnder modulator with direct current bias at an orthogonal point, entering from a lower port of the dual-drive Mach-Zehnder modulator to generate an optical encryption signal;
and 4, step 4: the optical encrypted signal after the encryption process is transmitted and compensated through the optical fiber transmission module and reaches the receiving end module in the form of an optical signal;
and 5: the optical encrypted signal enters an upper path of a receiving end module from a forward port of the balanced photoelectric detector;
step 6: after the copied analog noise passes through an electric absorption modulation laser of a lower path of the receiving end module, key matching is completed through an optical delay and an optical attenuator in sequence, and then the copied analog noise enters a negative port of the balanced photoelectric detector;
and 7: the optical encrypted signal entering from the positive port and the signal noise which enters from the negative port and is subjected to key matching are subjected to subtraction, and the demodulated useful signal is recovered.
Compared with a digital encryption method, the analog noise has randomness and is difficult to be cracked by an illegal attacker DSP, so that the whole system has good safety performance.
Those skilled in the art will appreciate that, in addition to implementing the system and its various devices, modules, units provided by the present invention as pure computer readable program code, the system and its various devices, modules, units provided by the present invention can be fully implemented by logically programming method steps in the form of logic gates, switches, application specific integrated circuits, programmable logic controllers, embedded microcontrollers and the like. Therefore, the system and various devices, modules and units thereof provided by the invention can be regarded as a hardware component, and the devices, modules and units included in the system for realizing various functions can also be regarded as structures in the hardware component; means, modules, units for performing the various functions may also be regarded as structures within both software modules and hardware components for performing the method.
In the description of the present application, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing the present application and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present application.
The foregoing description has described specific embodiments of the present invention. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.
Claims (8)
1. An adaptive decryption optical encryption transmission system based on optical self-interference cancellation, comprising:
a sending end module: based on the framework of the dual-drive Mach-Zehnder modulator, the delay and attenuation of analog noise are adjusted by utilizing an electrical delay and an electrical attenuation device to be used as a two-dimensional orthogonal key to encrypt signals, the signals are inverted by matching with a Bayer electric inverter, and optical encryption signals are generated in the dual-drive Mach-Zehnder modulator;
an optical fiber transmission module: completing optical fiber transmission of optical encrypted signals from a transmitting end to a receiving end and compensation of transmission damage;
a receiving end module: based on an adaptive optics self-interference elimination framework, by operating a regular triangle algorithm, the time delay and attenuation of a reference path of a receiving end are dynamically adjusted in a self-adaptive manner according to the quality of a demodulated useful signal; adaptively searching an optimal key, completing adaptive receiving and decryption of a useful signal and adaptive elimination of analog noise, and generating the optimal key;
the receiving end module comprises:
electroabsorption modulated laser: analog noise is converted to an optical domain after passing through an electro-absorption modulated laser;
adjustable light delay line and adjustable optical attenuator: analog noise converted to an optical domain after passing through an electric absorption modulation laser is subjected to key matching by sequentially passing through an adjustable optical delay line and an adjustable optical attenuator;
balancing the photodetector: the signal after key matching enters a negative port of the balanced photoelectric detector, and is subtracted from the signal entering a positive port to recover a useful signal;
the receiving end module also comprises a self-adaptive unit which matches the analog noise with the key of the self-adaptive receiving end according to the quality of the currently demodulated useful signal by operating a self-adaptive regular triangle algorithm until the optimal key is converged, removes the protected analog noise, recovers the useful signal and completes the self-adaptive searching process of the optimal key and the self-adaptive decryption of the useful signal.
2. The adaptive decryption optical encryption transmission system based on optical self-interference cancellation according to claim 1, wherein the sending-end module comprises:
dual drive mach-zehnder modulator: the light carrier provided by the light source passes through the dual-drive Mach-Zehnder modulator, a useful signal is input into the upper port of the dual-drive Mach-Zehnder modulator, and analog noise is input into the lower port of the dual-drive Mach-Zehnder modulator;
adjustable electric attenuator: the analog noise is attenuated by the adjustable electric attenuator;
adjustable electric delay line: the analog noise passing through the adjustable electric attenuator adjusts the time delay through an adjustable electric delay line to complete the encryption of the two-dimensional key;
a bayer-electric inverter: and the analog noise which finishes the two-dimensional key encryption enters the lower port of the dual-drive Mach-Zehnder modulator after being inverted by the Bayer electric inverter, and the signals are inverted by the Bayer electric inverter, so that the signals are added by the dual-drive Mach-Zehnder modulator.
3. The adaptive decryption optical encryption transmission system based on optical self-interference cancellation according to claim 2, wherein the dual-drive mach-zehnder modulators are biased at orthogonal points, signals at upper and lower ports of the dual-drive mach-zehnder modulators can be subtracted from each other, and analog optical encryption is completed by means of combined addition and electro-optical modulation of the signals to obtain optical encryption signals.
4. The adaptive decryption optical encryption transmission system based on optical self-interference cancellation according to claim 1, wherein the optical fiber transmission module comprises:
single-mode fiber: transmitting the optical encrypted signal output by the dual-drive Mach-Zehnder modulator from the transmitting end module to the receiving end module;
an erbium-doped fiber amplifier: the erbium-doped fiber amplifier is placed in an optical fiber link and compensates signal power lost after long-distance optical fiber transmission.
5. The adaptive decryption optical encryption transmission system based on optical self-interference cancellation according to claim 1, wherein the optical encryption signal transmitted from the transmitting end module is input to a positive port of the balanced photodetector to be subtracted from a signal entering from a negative port of the balanced photodetector after key matching, so as to recover the demodulated useful signal.
6. Adaptive decryption optical encryption based on optical self-interference cancellation according to claim 1
The transmission system is characterized in that when the time delay and attenuation of the reference path converge to the best matching point, the encryption noise is completely eliminated, and the self-interference elimination system achieves the optimal elimination.
7. The adaptive decryption optical encryption transmission system based on optical self-interference cancellation as claimed in claim 1, wherein the adaptive key search process in the receiving end module demodulates the signal for the legal user, starts to calculate the bit error rate of the transmission signal,
-if the error rate is less than the set threshold, ending the adaptation process to obtain the desired encrypted signal, where the time-delay attenuation is the best key;
if the error rate is larger than the set threshold, running an adaptive algorithm, calculating the error rate again after adjusting the delay and attenuation, and judging again to obtain the optimal key.
8. An adaptive decryption optical encryption transmission method based on optical self-interference elimination is characterized by comprising the following steps:
step 1: when information transmission is needed, a sending end module sends a useful signal to be transmitted into the dual-drive Mach-Zehnder modulator through an upper port of the dual-drive Mach-Zehnder modulator;
step 2: after the analog noise source is subjected to electric attenuation and electric delay, performing two-dimensional orthogonal encryption;
and step 3: simulating noise enters from a lower port of the dual-drive Mach-Zehnder modulator through a Bayer electric inverter and the dual-drive Mach-Zehnder modulator with direct current bias at an orthogonal point to generate an optical encryption signal;
and 4, step 4: the optical encrypted signal after the encryption process is transmitted and compensated through the optical fiber transmission module and reaches the receiving end module in the form of an optical signal;
and 5: the optical encrypted signal enters an upper path of a receiving end module and enters a balanced photoelectric detector from a forward port;
step 6: after the copied analog noise passes through an electric absorption modulation laser of a lower path of the receiving end module, key matching is completed through an optical delay and an optical attenuator in sequence, and then the copied analog noise enters a negative port of the balanced photoelectric detector;
and 7: the optical encrypted signal entering from the positive port and the noise matched by the key entering from the negative port are subtracted to recover the demodulated useful signal.
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