CN106972921A - The asymmetrical optical information safety system of double optical key is combined based on wavefront sensing - Google Patents

Abstract

The invention relates to an asymmetric optical information security system based on wavefront sensing combined with a double optical key, belonging to the technical field of optical instruments. The system mainly includes an aberration key distortion wavefront generation module, a wavefront sensing module and a phase encoding encryption module. The invention has a compact and flexible structure, and uses the ideal lattice obtained by the wavefront sensing principle and the distorted wavefront lattice to form an asymmetric public key cryptosystem, which greatly improves the potential safety hazards of the traditional symmetric cryptosystem. When decrypting, the public key and the The private key compensates the wave aberration, and the use of double passwords enhances the robustness of the cryptosystem and the ability to resist attack algorithms, and solves the problem of key distribution in the cryptosystem, and uses liquid crystal spatial light modulators to replace aberration encryption The Zernike sub-mirror and random phase plate of the key distortion wavefront generation module can realize the precise control of the two keys, so that the system has better control flexibility and can be widely used in the field of information security.

Description

Asymmetric Optical Information Security System Based on Wavefront Sensing Combined with Double Optical Key

technical field

The invention belongs to the technical field of optical instruments, and relates to an asymmetric optical information security system based on wavefront sensing combined with a double optical key, and is particularly suitable for information security fields such as optical encryption, optical information hiding, and optical authentication.

Background technique

With the rapid development of the global Internet and the deepening of the networking of social activities, information security technology is becoming increasingly important. Since the 1990s, information security technology based on optical theory and methods has gradually developed into a new generation of research hotspots in the field of information security. Compared with the traditional mathematics-based information encryption method, the unique parallel data processing capability of the optical system can provide faster speed for processing large amounts of two-dimensional or multi-dimensional data such as images and videos, and realize high-speed processing of large-capacity information. At the same time, optical information has multiple dimensions, including wavelength, amplitude, phase, frequency, and polarization state, etc. Therefore, there are various methods applicable to information security in optical theory, and different dimensions can be used as part of the security key. The entire information security system has extremely high With a large degree of freedom and key space, optical information security technology has unique advantages in information security fields such as information encryption, information hiding, information authentication, and information anti-counterfeiting.

A domestic patent similar to the present invention "has an asymmetric encryption and decryption method and device based on virtual wavefront encoding", the patent number is 200610014905. Specific wavefront coding preprocessing is performed on the original image to be encrypted. The irregular lattice of wavefront sensing is mainly determined by the wavefront coding processing method. The coding method needs to be carefully designed by humans. The original image to be encrypted cannot be reused, and the system flexibility is crossed. In addition, although the patent uses the optical model of wavefront sensing, the entire system uses digital processing modules based on electronic circuits to simulate the optical information processing process, that is, the virtual optical process, and does not use the actual optical system for optical information processing. Although the processing is compatible with the computer network, the speed and effect of the encryption-decryption of the whole process mainly depend on the performance of the hardware, and do not take into account the real situation of optical space transmission and processing.

The asymmetric optical information security system designed by the present invention is completely realized through the pure optical optical path, and the complete design of the optical device of the asymmetric pure optical information security system based on wavefront sensing combined with aberration key and double random phase encoding, and auxiliary electronic control The liquid crystal spatial light modulator increases the flexibility of system processing and the accuracy of control. The encryption of the system uses the aberration key and the random phase key. In terms of information, while inheriting the advantages of the two ciphers, the new hybrid cryptography system improves the hidden dangers of the symmetric cryptography system when dealing with attacks. The system analyzes and utilizes the aberrations of the actual optical imaging system, and quantitatively introduces different types and sizes of aberrations as aberration keys. The wavefront distortion of the wavefront is jointly determined, because the wave aberration of the aberration key can be introduced into the asymmetric public key cryptosystem, and the ideal wavefront lattice and the distorted wavefront lattice obtained by wavefront sensing can be used as the private key respectively. Key and public key, the whole process can be actively controlled by the optical system using the principle of adaptive optics, while adding different encryption aberration keys, the decryption aberration key corresponding to the aberration compensation is generated in real time, the encryption-decryption key pair generation and The distribution is convenient and fast, and the first encryption after the asymmetric aberration key encryption needs to be double-encrypted through the double random phase encoding system to generate a stable white noise image, and the asymmetric key and the symmetric key are organically introduced into the In the same password system, the security of the system is further enhanced.

Contents of the invention

The purpose of the present invention is to explore a new type of real-time active control optical information security system, which uses the principle of wavefront sensing and combines aberration keys and double random phase keys for double encryption, and is used for the security of the public key-private key system at the same time Seriously, realize a flexible and fast optical information security system with pure optical scheme combined with auxiliary control of liquid crystal spatial light modulator.

The concrete scheme that the present invention solves technical problem is:

A hybrid optical information security system based on the principle of wavefront sensing combined with aberration asymmetric keys and random phase symmetric keys, characterized in that it includes a laser light source (1), a beam expander (2), and a collimating lens (3), spherical mirror with positive focal power (4), liquid crystal spatial light modulator (SLM) (reflection or transmission) (5), beam splitter (6), microlens array (7), split Scribed CCD detector (8), Fourier transform lens (9), two random phase masks (RPM) (or transmissive liquid crystal spatial light modulator (TSLM)) with independent random white noise distribution (10 ), a CCD detector (11) and a plane reflector (12); including an aberration key distortion wavefront generation module, a wavefront sensing module, and a phase encoding encryption module: wherein: the coherent light source is produced by a laser light source (1), As the light source of the asymmetric information security system; the beam expander (2) expands the thin laser beam into a divergent beam with a large divergence angle, increasing the irradiation area of the laser; the collimator lens (3) with positive refractive power Collimate the divergent light beams to generate parallel plane wavefronts; in the transmission type aberration key distortion wavefront generation module, the parallel plane waves after the beam collimation are directly introduced into the aberration density through the transmission type liquid crystal spatial light modulator (TSLM) (5) The key generates the distorted wavefront, the collimating optical system and the transmissive liquid crystal spatial light modulator (TSLM) (5) are used as the aberration key generator of the optical information security system; in the reflective aberration key distortion wavefront generation module , the aperture stop of the system is located in the primary mirror (4) of the spherical reflector with positive refractive power, which forms a reflective afocal system together with the secondary mirror of the reflective liquid crystal spatial light modulator (RSLM) (5). The reflective afocal system is used as the aberration key generator of the optical information security system, the spherical mirror main mirror (4) and the reflective liquid crystal spatial light modulator (RSLM) (5) have a certain offset in the X direction, Avoid central occlusion; it should be noted that the transmissive and reflective aberration-key distortion wavefront generation modules can be used in different ways, and the transmission-type aberration-key distortion wavefront generation module is suitable for small-aperture optical systems, and its beam The beam expansion ratio is determined by the beam expander (2), so the aperture size and design requirements for the beam expander (2) and the collimator lens (3) with positive refractive power are relatively high; while the reflective aberration key The distorted wavefront generation module is suitable for use in large-aperture optical systems, and its beam expansion ratio is mainly composed of a spherical mirror with a positive focal power (4) and a reflective liquid crystal spatial light modulator (RSLM) (5). Mirrors together form a reflective afocal system, so the requirements for the design of the beam expander (2) and the collimator lens (3) with positive refractive power are not high; The wavefront sensor is used as the wavefront sensing and measuring beam, and the other line of light is used as the main beam through the post-installed double encryption optical system; the microlens array (7) is an important part of the wavefront sensor, and a complete laser wavefront in space It is divided into many tiny parts, and each part is focused on the focal plane by a corresponding small lens. A series of micro lenses is A plane composed of a series of focal points can be obtained, which is used to detect the ideal plane wavefront and the distorted wavefront after introducing the aberration key; the CCD detector (8) with reticles is a special detector dedicated to wavefront sensing , the relative position of the ideal wavefront and the distorted wavefront in the detector can be known after division, which is convenient for subsequent wavefront reconstruction; two identical Fourier transform lenses (9) constitute a conventional 4f optical information processing system; two mutual The random phase mask (RPM) (10) independently distributed as random white noise is respectively placed on the front focal plane and spectral transformation plane of the first Fourier transform lens (9) as an important component of double random phase encoding, wherein The random phase mask (RPM) can be simulated by two transmissive liquid crystal spatial light modulators (TSLM) (10); the encrypted image encrypted by the asymmetric optical information security system is detected by the CCD detector (11); the flat mirror (12) Polarize the parallel light separated by the beam splitter (6), which is used to reduce the volume of the experimental light path to make the entire optical information security system more compact and easy to install and adjust.

Preferably, the aberration key distortion wavefront generating module of the optical information security system includes two design structures of a transmission type and a reflection type, wherein the transmission type includes a beam expander (2), a quasi- A transmissive beam expander collimation system system composed of a straight lens (3) and a transmissive liquid crystal spatial light modulator (TSLM) (5); wherein, the reflective type includes a spherical mirror main mirror (4 ) and a Zernike freeform secondary mirror fitted with a reflective liquid crystal spatial light modulator (RSLM) (5), the two constitute a radial two-mirror afocal optical system with a magnification ratio of 4 times, and the aperture stop is located At the mirror, in order to eliminate the central occlusion, the primary mirror and the secondary mirror have a certain offset relative to the X direction.

Preferably, the aberration key distortion wavefront generation module of the optical information security system, in order to control the type, quantity and size of the added aberration key, uses a liquid crystal spatial light modulator (5) to fit to represent different image Poor Zernike polynomials, making the aberration key distortion wavefront generation module more flexible and adjustable, and the Zernike polynomials have more free variables to increase the aberration key space while compensating the residual in the expanded beam collimation system aberrations.

Preferably, the aberration key distortion wavefront generating module of the optical information security system must use the ideal wavefront lattice obtained by the wavefront sensing module wavefront detection and The distorted wavefront lattice is respectively used as a private key and a public key in an asymmetric cryptosystem, and the wavefront sensing module is composed of a microlens array (7) and a CCD detector (8) with reticles.

Preferably, the phase encoding encryption module is used as a double encryption, and two identical Fourier transform lenses (9) constitute a conventional 4f optical information processing system, which can directly use two random phase masks with independent random white noise distribution (RPM) or use two transmissive liquid crystal spatial light modulators (TSLM) (10) to simulate a random phase plate, respectively process the information space domain and frequency domain, after two reflections by the plane mirror (12), make The whole system is more compact, and the volume of the system is greatly reduced. Not only can symmetric encryption be introduced as double encryption on the basis of asymmetric encryption, but also the aberration encryption information after the first encryption can be processed to make it a stable white noise.

The present invention has the following remarkable advantages: the present invention modulates the incident plane wave by means of wavefront encoding, and introduces different aberrations as a new key by fitting Zernike polynomials through a liquid crystal spatial light modulator to make the incident plane wave into a distorted wavefront, and then The wavefront is sensed by the wavefront sensing module, and the ideal wavefront and distorted wavefront obtained by sensing are respectively used as the private key and public key in the public key-private key cryptosystem, and the aberration key becomes a special encryption - The authentication key, where both the focal length of the array lens in the wavefront sensing module and the incident illumination wavelength have an effect on the aberration key, further expanding the degree of freedom of the aberration key. The double random phase encoding system in the latter group is used as a secondary encryption system, and at the same time it improves the encryption effect of the single aberration key, making the encrypted image a stable white noise image. The aberration key distortion wavefront generation module is designed into two types of transmission type and reflection type, which can be applied to small-aperture and large-aperture optical information security systems respectively. Among them, the two random phase masks in the aberration key distortion wavefront generation module and the phase encryption coding module in the transmissive system can be realized by three transmissive liquid crystal spatial light modulators (TSLM); A reflective liquid crystal spatial light modulator (RSLM) and two transmissive liquid crystal spatial light modulators (TSLM) can be used for the reflective secondary mirror of the key distortion wavefront generation module and the two random phase masks in the phase encryption coding module Realize that the entire encryption system is completely realized through the photoelectric system, making the operation of the information security system more flexible and fast. Realized by using optical devices and electronically controlled optical devices, pure optical encryption is realized in the true sense, and combined with the wavefront sensing principle of adaptive optics, the encryption-decryption module of the entire information security system forms an active closed loop, which is convenient for information The real-time processing of encryption-decryption is especially suitable for the fields of encryption, concealment, authentication and identification of optical images and optical information.

Description of drawings

Figure 1a is a structural diagram of the transmissive optical system of the asymmetric optical information security system based on wavefront sensing combined with dual optical keys in the present invention

Figure 1b is a structural diagram of the reflective optical system of the asymmetric optical information security system based on wavefront sensing combined with double optical keys in the present invention

Figure 2a is the ideal wavefront diagram and the ideal wavefront lattice diagram private key obtained by simulating the simulated wavefront sensing.

Fig. 2b is the distorted wavefront diagram and the public key of the distorted wavefront dot matrix obtained by simulating the wavefront sensing.

Figure 3a is the plaintext to be encrypted to be encrypted in the experiment.

Figure 3b is the aberration key encrypted ciphertext when the focal length of the subaperture is 100mm and the wavelength is 550nm.

Figure 3c is the aberration key encrypted ciphertext when the focal length of the subaperture is 100mm and the wavelength is 825nm.

Figure 3d is the aberration key encrypted ciphertext when the focal length of the subaperture is 100mm and the wavelength is 1100nm.

Figure 3e is the aberration key encrypted ciphertext when the subaperture focal length is 200mm and the wavelength is 825nm.

Figure 3f is the aberration key encrypted ciphertext when the subaperture focal length is 300mm and the wavelength is 825nm.

Figure 4a is the plaintext to be encrypted to be encrypted in the experiment.

Figure 4b is the encryption result when aberration asymmetric key and double random phase symmetric key are used at the same time.

Figure 4c is the decryption result when both decryption keys are wrong.

Figure 4d is the decryption result when the double random phase key is correct and the aberration key is wrong.

Figure 4e is the decryption result when the double random phase key is wrong and the aberration key is correct.

Figure 4f is the correct decryption result when both decryption keys are correct.

The components in Figure 1 are as follows: 1 laser light source beam, 2 beam expander, 3 collimator lens, 4 spherical mirror with positive power, 5 liquid crystal spatial light modulator (SLM) (reflection or transmission), 6 beam splitters, 7 microlens arrays, 8 CCD detectors with reticles, 9 Fourier transform lenses, 10 transmissive liquid crystal spatial light modulators (TSLM), 11 CCD detectors and 12 flat mirrors.

detailed description

In order to better explain the present invention, below in conjunction with accompanying drawing and embodiment sub-invention is described in further detail:

Fig. 1 is an optical system structure diagram of an asymmetric optical information security system based on wavefront sensing combined with a double optical key in the present invention. The structure includes a laser light source (1), a beam expander (2), a collimator lens (3), a spherical reflector with positive power (4), a liquid crystal spatial light modulator (RSLM) (5), and a Beamer (6), microlens array (7), CCD detector with reticle (8), Fourier transform lens (9), two random phase masks (RPM) with independent random white noise distribution (or a transmissive liquid crystal spatial light modulator (TSLM)) (10), a CCD detector (11) and a plane mirror (12). In the direction of light propagation, the optical elements are arranged in order, and the aperture stop is located on the spherical reflector (4) with positive power. There is a certain amount of offset in the X direction between the secondary mirror composed of the spherical reflector (4) and the reflective liquid crystal spatial light modulator (RSLM) (5).

Firstly, the illumination light is emitted from the laser (1), expanded by the beam expander (2) and then collimated by the collimator lens (3) to form parallel plane wave illumination, so that the ideal wavefront of the parallel plane wave illumination passes through the microlens array (7) Carry out wavefront sensing for the first time, obtain the ideal lattice pattern of ideal plane wavefront on the CCD detector (8) that divides line, this ideal lattice pattern is the private key of asymmetrical aberration key ; Again, repeat the above operation, for the transmissive aberration key distortion wavefront generation module, the illuminating light is sent from the laser (1), and is collimated by the collimating lens after the beam expander (2) expands the beam directly (3 ), to form parallel plane wave illumination, and then the incident plane wave directly passes through a transmissive liquid crystal spatial light modulator (TSLM) (5) to introduce the aberration key distortion wavefront generation module composed of a Zernike freeform surface secondary mirror key to obtain the incident distorted wavefront with aberration; for the reflective aberration key distorted wavefront generation module, the illumination light is emitted from the laser (1), and the beam expands directly through the beam expander (2) and then the beam is expanded by the collimator The lens is collimated (3) to form a parallel plane wave illumination, and then the incident plane wave passes through a positive spherical reflector with a positive power. The main mirror (4) is fitted with a reflective liquid crystal spatial light modulator (RSLM) (5). The aberration key distortion wavefront generation module composed of free-form surface secondary mirrors introduces the aberration key to obtain the incident distortion wavefront with aberrations. The two methods can be applied to small-aperture and large-aperture optical information security systems respectively. The distorted wavefront passes through the beam splitter (6), which splits the distorted wavefront beam into two beams, and one beam enters the microlens array (7) of the wavefront sensing module, and then passes through the CCD detector (8) with reticles. Obtain the distorted wavefront lattice diagram containing the aberration key, this distorted wavefront lattice diagram is the public key of the asymmetric aberration key, after the other beam is reflected twice by two plane mirrors (12), Deflection 180° enters the phase encoding encryption module, first passes through the input image to be encrypted at the front focal plane of the first Fourier transform lens (9) and the first random phase mask (RPM) (or transmission) on the space domain Type liquid crystal spatial light modulator (TSLM)), carry out the phase modulation in the space domain, then undergo Fourier transform through the first Fourier transform lens (9), and get the Fourier transform spectrum on its rear focal plane, Then through the second random phase mask (RPM) (or transmissive liquid crystal spatial light modulator (TSLM)) on the Fourier transform spectrum surface, the phase modulation in the frequency domain is performed, and finally through the second Fourier transform The lens (9) obtains ciphertext information double-encrypted by the asymmetric aberration key and the symmetric double random phase key on its back focal plane, and the ciphertext information can be recorded by phase-shift interferometry or holography.

Fig. 2 shows two wavefront dot matrix images of direct sensing without the aberration key distortion wavefront generation module and sensing after introducing the aberration key through the aberration key distortion wavefront generation module in two operations. Figure 2a is the ideal wavefront diagram and the ideal wavefront lattice diagram private key obtained by simulating the simulated wavefront sensing. Fig. 2b is the distorted wavefront diagram and the public key of the distorted wavefront dot matrix obtained by simulating the wavefront sensing.

Fig. 3 is the computer simulation experiment data encrypted with a single aberration key, and the experimental results are obtained for different wavelengths and different array lens sub-aperture focal lengths. They are both 256x256 pixels. Figure 3a is the plaintext to be encrypted to be encrypted in the experiment. Figure 3b is the encrypted ciphertext when the focal length of the sub-aperture is 100mm and the wavelength is 550nm. Figure 3c is the encrypted ciphertext when the focal length of the sub-aperture is 100mm and the wavelength is 825nm. Figure 3d is the encrypted ciphertext when the focal length of the sub-aperture is 100mm and the wavelength is 1100nm. Figure 3e is the encrypted ciphertext when the focal length of the sub-aperture is 200mm and the wavelength is 825nm. Figure 3f is the encrypted ciphertext when the focal length of the sub-aperture is 300mm and the wavelength is 825nm.

Fig. 4 is the computer simulation experiment data after the encryption of the mixed double key and the attack result on the known part of the encryption key. They are both 256x256 pixels. Figure 4a is the plaintext to be encrypted to be encrypted in the experiment. Figure 4b is the encryption result when aberration asymmetric key and double random phase symmetric key are used at the same time. Figure 4c is the decryption result when both decryption keys are wrong. Figure 4d is the decryption result when the double random phase key is correct and the aberration key is wrong. Figure 4e is the decryption result when the double random phase key is wrong and the aberration key is correct. Figure 4f is the correct decryption result when both decryption keys are correct.

Claims (4)

1. An asymmetric optical information security system based on wavefront sensing combined with a double optical key, characterized in that it includes a laser light source (1), a beam expander (2), a collimator lens (3), and a focal power positive spherical mirror (4), liquid crystal spatial light modulator (SLM) (reflection or transmission) (5), beam splitter (6), microlens array (7), CCD detector with reticle ( 8), Fourier transform lens (9), two random phase masks (RPM) (or transmissive liquid crystal spatial light modulator (TSLM)) (10), CCD detector (11) with independent random white noise distribution ) and plane reflector (12); including aberration key distortion wavefront generation module, wavefront sensing module, phase encoding encryption module: wherein: The aberration key distortion wavefront generation module is used to generate the distortion key and introduce the aberration key; The wavefront sensing module is used for wavefront detection, the detected ideal wavefront lattice before adding the aberration key is used as the private key in the asymmetric information security system, and the detected distorted wave adding the aberration key The front lattice is used as the public key in the asymmetric information security system, and the aberration key is used as a key; The phase encoding encryption module is used as a double encryption, and encrypts the aberration encryption information after the aberration key first encryption to obtain stable white noise encryption information. 2. A kind of asymmetric optical information security system based on wavefront sensing combined with double optical key according to claim 1, characterized in that, the aberration key distortion wavefront generation module comprises: The aberration key distortion wavefront generation module can be designed into two types: transmission type and reflection type. Both of them are used to generate distortion wavefront and introduce aberration key, which can be applied to small-aperture and large-aperture optical information security respectively. system. The transmissive aberration key distortion wavefront generation module includes a beam expander (2), a collimator lens (3) and a transmissive liquid crystal spatial light modulator (TSLM) (5). The narrow beam laser emitted by the laser is expanded After the beam is collimated, it is shaped into a parallel plane beam with a larger aperture. The transmissive liquid crystal spatial light modulator (TSLM) (5) can fit the Zernike polynomial surface, introduce different types of aberrations, and control the aberration key type, quantity and size; the reflective aberration key distortion wavefront generation module is a reflective wireless reflective mirror (4) and a reflective liquid crystal spatial light modulator (RSLM) (5) with positive power Focusing system, the spherical reflector main mirror (4) and the reflective liquid crystal spatial light modulator (RSLM) (5) have a certain offset in the X direction to avoid center blocking, and the reflective liquid crystal spatial light modulator (RSLM) ( 5) It can fit the Zernike polynomial surface type, introduce different types of aberrations, and control the type, quantity and size of aberration keys. The ideal plane wave wavefront lattice that has not been detected by the aberration key distortion wavefront generation module is used as the private key of the asymmetric information security system, and the distorted wavefront lattice by the aberration key distortion wavefront generation module is used as the asymmetric The public key of the information security system. 3. A kind of asymmetric optical information security system based on wavefront sensing combined with double optical key according to claim 1, characterized in that, the wavefront sensing module comprises: The microlens array (7) is an important part of the wavefront sensor. It divides a complete laser wavefront into many tiny parts in space, and each part is focused on the focal plane by a corresponding small lens. A series of microlenses is A plane composed of a series of focal points can be obtained, which is used to detect the ideal plane wavefront and the distorted wavefront after introducing the aberration key; the CCD detector (8) with reticles is a special detector dedicated to wavefront sensing , after division, the relative positions of the ideal wavefront and the distorted wavefront in the detector can be known, which is convenient for subsequent wavefront reconstruction. 4. A kind of asymmetric optical information security system based on wavefront sensing in conjunction with double optical key according to claim 1, it is characterized in that, the phase code encryption module comprises: Two identical Fourier transform lenses (9) constitute a conventional 4f optical information processing system; two random phase masks (RPM) with independent random white noise distribution can be directly used or two transmissive liquid crystal spatial light modulators can be used (TSLM)(10) simulates a random phase plate, carries out phase modulation on the spatial and frequency domains of information, and places them on the front focal plane and spectral transformation plane of the first Fourier transform lens (9) respectively as a double random phase encoding An important component; the encrypted image encrypted by the asymmetric optical information security system is detected by the CCD detector (11), and the beam propagation direction is controlled by the plane mirror (12), so as to reduce the volume of the system and make the experimental optical path more compact.