CN113918962A - Optical information security system based on foveological duplex optical key - Google Patents

Abstract

The invention provides an optical information security system based on a concave double optical secret key, which includes an optical information encryption module and an optical information decryption module. In the optical information encryption module, the first encrypted spatial light modulator generates a small concave area in the imaging area that needs to be encrypted, and the second encrypted spatial light modulator performs secondary encryption through the action of the small concave area, which can realize the local and Double encryption improves the flexibility, real-time and security of the system. The present invention has its own imaging optical module, gets rid of the current technology's dependence on parallel light beams, and increases practicability. At the same time, the local encryption method is also beneficial to improve the real-time performance of the system. The invention introduces the small concave area through the function of the spatial light modulator to realize the encryption of image information. Since the position and mode of the small concave area are controllable, the system of the present invention has a large key space, and can realize one-time-one padding, to achieve higher security.

Description

An optical information security system based on concave double optical key

technical field

The invention relates to the technical field of optical instruments, in particular to an optical information security system based on a concave double optical key.

Background technique

In recent years, data encryption and information hiding technology based on optical theory and methods is a new generation of information security technology developed internationally. Optical instruments using this technology are called optical information security systems.

However, the current optical information security systems basically use parallel light beams as the information carrier. First, the pre-generated images to be encrypted must be irradiated by the parallel light beams, so that the parallel light beams carry the plaintext information that needs to be encrypted, and then use the optical encryption system. The ciphertext is obtained by processing the plaintext information carried by this part of the parallel light beam, so that the optical imaging system cannot directly become a component of the optical information security system, which greatly affects the practicability of the optical information security system. At the same time, most of the current optical information security systems encrypt an entire image, which undoubtedly increases the demand for computer computing resources for optical information security systems that combine digital computing, and reduces the system's real-time. For the remaining few optical information security systems that can realize local encryption, although they reduce the bandwidth requirements of the system and improve the real-time performance of the system, there are also local encryption areas with fixed area, fixed location, and a single number, which cannot be based on actual conditions. The problem of parallel encryption of sensitive information distributed in different areas, different quantities, and different areas in the same image.

Therefore, there is an urgent need for an optical information security system that can realize double encryption of local images, which can satisfy the requirements of being distributed in different areas, different numbers, and different areas in the same image under the premise of ensuring the real-time performance and practicability of the system. requirements for parallel encryption of sensitive information.

SUMMARY OF THE INVENTION

In view of this, the present invention provides an optical information security system based on a concave double optical key, which can realize double encryption of partial images, and does not require parallel light beams as the information carrier of the image to be encrypted.

In order to realize the above-mentioned purpose of the invention, the technical scheme of the present invention is:

An optical information security system based on a concave double optical key, comprising an optical information encryption module and an optical information decryption module.

The optical information encryption module is composed of an imaging optical module, a first encrypted spatial light modulator, a first relay module, a second encrypted spatial light modulator, a second relay module and an encrypted photodetector placed coaxially in sequence.

The optical information decryption module is composed of a collimated light source, a first decryption spatial light modulator, a second decryption spatial light modulator and a decryption photodetector placed coaxially in sequence.

In the optical information encryption module, the first encrypted spatial light modulator is located at the image plane position of the imaging optical module, the image beam passes through the first encrypted spatial light modulator, and the first spatial light modulation distribution function is set to perform phase modulation on the image beam in a specific area. , generate a small concave area in the imaging area that needs to be encrypted; the first relay module performs secondary imaging on the output image of the first encrypted spatial light modulator; the second encrypted spatial light modulator is located at the position of the secondary image plane, and the encrypted The image beam passes through the second encrypted spatial light modulator, and the second spatial light modulation distribution function is set to perform phase modulation on the image beam in a specific area, and a small concave area is generated in the imaging area that needs to be encrypted. The imaging area is encrypted twice; the second relay module images the output image of the second encrypted spatial light modulator three times, and forms the final image surface on the encrypted photodetector; the encrypted photodetector is connected to the PC terminal to decrypt the photoelectric The detector is connected to the PC terminal.

The PC terminal performs mathematical operations according to the known first spatial light modulation distribution function, the second spatial light modulation distribution function and the position distribution of the small concave area to obtain the comprehensive encryption key and inverse it to obtain the decryption key; the first The decryption spatial light modulator is used for intensity modulation, so that the illumination beam becomes the image to be decrypted; the second decryption spatial light modulator is used to load the decryption key to decrypt the image to be decrypted.

In the optical information decryption module, the collimated light source provides the illumination beam, the first decryption spatial light modulator performs intensity modulation on the illumination beam according to the intensity distribution on the encrypted photodetector, and the second decryption spatial light modulator modulates the illumination beam according to the decryption key. The deciphered illumination beam is phase-modulated, and the deciphering photodetector receives the deciphered image formed by the deciphered illumination beam. During the deciphering process, the position distribution of the small concave area generated on the second deciphering spatial light modulator is the same as that of the secondary encrypted small concave area. The location distribution of the concave areas is the same.

Further, the position distribution of the small concave areas on the first encrypted spatial light modulator is determined by the first spatial light modulation distribution function, and the position distribution of the small concave areas on the second encrypted spatial light modulator is determined by the second spatial light modulation distribution function. .

Further, the encryption photodetector is placed at the image plane of the optical encryption module, and the decryption photodetector is placed at the image plane of the optical decryption module.

Further, the first relay module and the second relay module are relay imaging lens groups.

Further, the optical information security system based on the concave double optical key does not require parallel light beams as the information carrier of the image to be encrypted.

Further, the collimated light source provides an illuminating beam, and the illuminating beam is enlarged by the two convex lenses and incident on the first decrypting spatial light modulator.

Beneficial effects: The present invention provides an optical information security system based on a concave double optical key, including an optical information encryption module and an optical information decryption module, which are used for optical information encryption of general imaging optical systems and improve optical information security. Usability of the system. In the optical information encryption module, the first encrypted spatial light modulator generates a small concave area in the imaging area that needs to be encrypted, and the second encrypted spatial light modulator performs secondary encryption through the action of the small concave area. The local and double encryption of image information is realized, which improves the flexibility, real-time and security of the system. The optical information encryption module has its own imaging optical module, which gets rid of the current optical information security system's dependence on parallel beams and increases its practicability. At the same time, the local encryption method is also beneficial to improve the real-time performance of the system. The invention introduces the small concave area through the function of the spatial light modulator to realize the encryption of image information. Since the position and mode of the small concave area are controllable, the light in different light areas is encrypted differently, so the system of the present invention has a large The key space can realize one-time pad to achieve higher security.

Description of drawings

FIG. 1 is a schematic diagram of the system structure of the present invention.

FIG. 2 is a schematic structural diagram of an optical information encryption system.

FIG. 3 is a schematic structural diagram of an optical information decryption system.

Wherein, 1-imaging optical module, 2-first encrypted spatial light modulator, 3-first relay module, 4-second encrypted spatial light modulator, 5-second relay module, 6-encrypted photodetector , 7 - collimated light source, 8 - first decryption spatial light modulator, 9 - second decryption spatial light modulator, 10 - decryption photodetector.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

As shown in FIG. 1, the present invention provides an optical information security system based on a concave double optical key, including an optical information encryption module and an optical information decryption module, which is used for optical information encryption of general imaging optical systems, and improves the Practicality of optical information security systems. The introduction of the concave technology can realize local and double encryption of image information, and improve the flexibility, real-time and security of the system.

As shown in Figure 2, the optical information encryption module consists of an imaging optical module 1, a first encrypted spatial light modulator 2, a first relay module 3, a second encrypted spatial light modulator 4, a second relay module 5 and an encrypted photoelectric The detectors 6 are arranged coaxially and sequentially. The encryption photodetector 6 is placed at the image plane of the optical encryption module. The first relay module 3 and the second relay module 5 are relay imaging lens groups.

The imaging optical module 1 is used for image information acquisition; the first encrypted spatial light modulator 2 and the second encrypted spatial light modulator 4 are used to generate small recessed areas for encryption; the first relay module 3 and the second relay module 5 are used for It is used to transmit the intermediate image; the encrypted photodetector 6 is used to receive the encrypted image.

The first encrypted spatial light modulator 2 is located at the image plane position of the imaging optical module 1, the image beam passes through the first encrypted spatial light modulator 2, and the first spatial light modulation distribution function is set to perform phase modulation on the image beam in a specific area. The encrypted imaging area generates a small concave area; the first relay module 3 performs secondary imaging on the output image of the first encrypted spatial light modulator 2; the second encrypted spatial light modulator 4 is located at the position of the secondary image plane, and the encrypted The image beam passes through the second encryption spatial light modulator 4, and the second spatial light modulation distribution function is set to perform phase modulation on the image beam in a specific area, and a small concave area is generated in the imaging area that needs to be encrypted. The imaging area is encrypted twice; the second relay module 5 images the output image of the second encrypted spatial light modulator 4 three times, and forms the final image plane on the encrypted photodetector 6; the encrypted photodetector 6 and the PC The terminal is connected, and the image to be decrypted is received by the encrypted photodetector 6 and transmitted to the PC terminal. The PC has the existing optical driver software to control the imaging of the spatial light modulator, and control the transmittance of the first decrypted spatial light modulator 8 according to the intensity distribution of the image (that is, the grayscale distribution), so that the illumination beam can pass through. After the first decryption of the spatial light modulator 8, the intensity distribution is consistent with the image to be decrypted.

The PC terminal performs mathematical operations according to the known first spatial light modulation distribution function, the second spatial light modulation distribution function and the position distribution of the small concave area, obtains the comprehensive encryption key and inverts it, obtains the decryption key and loads it into on the second decrypted spatial light modulator 9 . The specific mathematical operation method is as follows: Substitute the position of a specific small concave area into the corresponding spatial modulation distribution function, generate a phase map, and perform a convolution operation on the two phase maps to obtain a comprehensive encryption key.

As shown in FIG. 3 , the optical information decryption module is composed of a collimated light source 7 , a first decryption spatial light modulator 8 , a second decryption spatial light modulator 9 and a decryption photodetector 10 which are placed coaxially in sequence. The collimated light source 7 provides the illumination beam, and the PC terminal loads the intensity distribution on the encrypted photodetector 6 to the first decrypted spatial light modulator 8, so that the illumination beam is subjected to intensity modulation when passing through the first decrypted spatial light modulator 8 It becomes an image to be decrypted whose intensity distribution is consistent with the intensity distribution of the final image plane of the optical information encryption module. In the optical information decryption module, the first decryption spatial light modulator 8 performs intensity modulation on the illumination beam according to the intensity distribution on the encrypted photodetector 6, and the second decryption spatial light modulator 9 performs intensity modulation on the modulated illumination beam according to the decryption key. Phase modulation, decryption photodetector 10 receives the image formed by the decrypted illumination beam, during the decryption process, the position distribution of the small concave area generated on the second decrypted spatial light modulator 9 is the same as the position distribution of the small concave area after the secondary encryption .

In the embodiment of the present invention, the position distribution of the small concave areas on the first encrypted spatial light modulator 2 is determined by the first spatial light modulation distribution function, and the position distribution of the small concave areas on the second encrypted spatial light modulator 4 is determined by the second spatial light modulation distribution function. The light modulation distribution function is determined.

The specific working mode of the system of the present invention is as follows: the light from the external object passes through the imaging optical module 1 and then converges on the first encrypted spatial light modulator 2 placed at the intermediate image position, and the first encrypted spatial light modulator 2 generates the generated light in the area that needs to be encrypted. In the small concave area, aberration is introduced to modulate the spherical wave surface, and the modulated spherical wave is subjected to secondary imaging through the first relay module 3, and the formed secondary image is on the second encrypted spatial light modulator 4, through the small concave. After the double local encryption is completed, the second relay module 5 converges the diverging spherical wave on the encrypted photodetector 6 again to complete the acquisition process of the encrypted image.

Since on the first encrypted spatial light modulator 2 and the second encrypted spatial light modulator 4, the encryption keys used to modulate the spherical wave are different but the modulation process is the same, so the principle part here only modulates the first encrypted spatial light. The modulation principle on device 2 is introduced.

The encryption process of this system is that after the spherical wave emitted by the object point on the object surface passes through the imaging optical module 1, it converges on the primary image surface in the form of spherical wave to form an intermediate image first. Considering that there are aberrations in actual imaging, in order to simplify the analysis process, the imaging optical module 1 is equivalent to an equivalent lens with aberrations, then its complex amplitude transmittance is:

Among them, (ξ,η) is the coordinate system where the lens is located, P(ξ,η) is the pupil function, f is the equivalent lens focal length, W(ξ,η) is the phase delay introduced by the aberration of the imaging optical module 1 function.

The coordinate system where the object point is located is (x ₀ , y ₀ ), the complex amplitude distribution function on the object surface is U ₀ (x ₀ , y ₀ ) and the distance from the equivalent lens is d ₀ , and the primary image plane is The coordinate system is (x ₁ , y ₁ ), the complex amplitude distribution function on it is U ₁ (x ₁ , y ₁ ) and the distance from the equivalent lens is d ₁ . Using the Fresnel diffraction formula, U ₁ is established The corresponding relationship between (x ₁ , y ₁ ) and U ₀ (x ₀ , y ₀ ), after simplification, can be obtained:

为成像光学模块1等效透镜的放大倍数，h₁(x₁,y₁)为

的傅里叶变换，即含像差成像光学模块1的脉冲响应函数。in,

is the magnification of the equivalent lens of the imaging optical module 1, h ₁ (x ₁ , y ₁ ) is

The Fourier transform of , that is, the impulse response function of the imaging optical module 1 with aberration.

Therefore, after passing through the imaging optical module 1 with aberration, the light field distribution on the primary image plane of the system is equivalent to the convolution of the geometrical optics ideal image and the system impulse response. The function of the aberration of the system itself is to convert the pupil function of the system into a pupil function in the complex domain, and finally realize the modulation of the complex amplitude distribution of the incident light field by means of the system impulse response function.

Since all the spatial light modulators in this system are placed close to the primary image plane, it is considered that all the spatial light modulators modulate the complex amplitude distribution on the primary image plane point-to-point, ignoring the thickness of the spatial light modulator. Then after the modulation of the spatial light modulator, the complex amplitude distribution function of the output light field can be expressed as:

U' ₁ (x ₁ , y ₁ ) = U ₁ (x ₁ , y ₁ ) SLM(x ₁ , y ₁ ) (3)

Among them, SLM(x ₁ , y ₁ ) represents the modulation distribution function of the spatial light modulator. Under the action of this function, the complex amplitude distribution function of the light field on the primary image plane of the system changes, that is, the local aberration is realized. introduction process.

After U ₁ (x ₁ , y ₁ ) is modulated by the spatial light modulator, under the action of aberration, it is imaged on the secondary image plane in the form of a distorted spherical wave through the relay module in the encryption system, and the phosphine is used again. According to the Neel diffraction formula, the complex amplitude distribution function on the quadratic image plane can be obtained as:

M₂为后端系统的放大率，(x₂,y₂)为二次像面所在坐标系，h₂为中继模块的脉冲响应函数。in,

M ₂ is the magnification of the back-end system, (x ₂ , y ₂ ) is the coordinate system where the secondary image plane is located, and h ₂ is the impulse response function of the relay module.

Combining equations (2) and (4), we can get:

Therefore, the encryption of the image through aberration is essentially a process of using the spatial light modulator to introduce aberration to control the impulse response function of the back-end system, and finally obtain the required complex amplitude distribution of the light field on the image plane.

Since all spatial light modulators can generate a specific phase pattern in any area, the use of spatial light modulators can generate small dimples in a specific local area, that is, different dimples will have different spatial light modulations the modulation distribution function. Under the action of the modulation distribution function of the spatial light modulator, the phase information of the spherical wave can be modified, and finally the purpose of blurring the image information carried by the spherical wave can be realized. And in this system, the spatial light modulator is used to control the impulse response function of the system twice, that is, the double optical key encryption effect proposed by this information security system is realized.

It can be seen from the above principles that the present invention uses the general imaging system as a component of the optical information security system, which gets rid of the current optical information security system's dependence on parallel light beams and increases its practicability. At the same time, the local encryption method is also beneficial to improve the real-time performance of the system. The invention introduces the small concave area through the function of the spatial light modulator to realize the encryption of image information, and the encryption method is the reverse of the small concave technology. Since the position and mode of the small concave area are controllable, the light in different optical areas is encrypted differently, so the system of the present invention has a large key space, and can realize one-time pad, so as to achieve higher security.

When decrypting, since the system adopts the process of secondary encryption, it is necessary to generate two correct small concave areas on the second decryption spatial light modulator 9 in the decryption system to achieve complete decryption of the image, otherwise, Only partially correct images or completely wrong images are obtained.

In the embodiment of the present invention, unlike the existing optical information encryption system which needs to use parallel light as the information carrier, the optical information encryption system includes an imaging system, no parallel light generating device is required, and the information carrier is non-parallel light, which can be widely used In the fields of laser communication, bank security certification, etc.

To sum up, the above are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (6)

1. An optical information security system based on a foveal duplex optical key is characterized by comprising an optical information encryption module and an optical information decryption module;

the optical information encryption module is formed by coaxially and sequentially placing an imaging optical module (1), a first encryption spatial light modulator (2), a first relay module (3), a second encryption spatial light modulator (4), a second relay module (5) and an encryption photoelectric detector (6);

the optical information decryption module is formed by coaxially and sequentially placing a collimation light source (7), a first decryption spatial light modulator (8), a second decryption spatial light modulator (9) and a decryption photoelectric detector (10);

in the optical information encryption module, a first encryption spatial light modulator (2) is positioned at the image surface position of the imaging optical module (1), an image beam passes through the first encryption spatial light modulator (2), a first spatial light modulation distribution function is set to perform phase modulation on the image beam in a specific area, and a small concave area is generated in an imaging area needing to be encrypted; the first relay module (3) carries out secondary imaging on an output image of the first encryption spatial light modulator (2); the second encryption spatial light modulator (4) is located at the position of a secondary image surface, the encrypted image light beam passes through the second encryption spatial light modulator (4), a second spatial light modulation distribution function is set to perform phase modulation on the image light beam in a specific area, a small concave area is generated in an imaging area needing to be encrypted, and secondary encryption is performed on the imaging area needing to be encrypted under the action of the small concave area; the second relay module (5) images the output image of the second encryption spatial light modulator (4) for three times, and a final image surface is formed on the encryption photoelectric detector (6); the encryption photoelectric detector (6) is connected with a PC end, and the decryption photoelectric detector (10) is connected with the PC end;

the PC terminal performs mathematical operation according to the known first spatial light modulation distribution function, the known second spatial light modulation distribution function and the known position distribution of the small concave area to obtain a comprehensive encryption key and inverts the comprehensive encryption key to obtain a decryption key; the first decryption spatial light modulator (8) is used for intensity modulation, so that the illumination light beam becomes an image to be decrypted; the second decryption spatial light modulator (9) is used for loading a decryption key and decrypting an image to be decrypted;

in the optical information decryption module, a collimation light source (7) provides an illumination light beam, a first decryption spatial light modulator (8) performs intensity modulation on the illumination light beam according to the intensity distribution condition on an encryption photoelectric detector (6), a second decryption spatial light modulator (9) performs phase modulation on the modulated illumination light beam according to a decryption key, a decryption photoelectric detector (10) receives an image to be decrypted formed by the decrypted illumination light beam, and in the decryption process, the position distribution of small concave regions generated on the second decryption spatial light modulator (9) is the same as the position distribution of small concave regions subjected to secondary encryption.

2. The system according to claim 1, wherein the distribution of the location of the pits on the first encrypting spatial light modulator (2) is determined by a first spatial light modulation distribution function and the distribution of the location of the pits on the second encrypting spatial light modulator (4) is determined by a second spatial light modulation distribution function.

3. The system according to claim 2, characterized in that said encryption photodetector (6) is placed at the image plane of said optical encryption module and said decryption photodetector (10) is placed at the image plane of said optical decryption module.

4. A system according to claim 3, characterized in that said first relay module (3) and second relay module (5) are relay imaging lens groups.

5. The system of claim 1, wherein the foveal duplex optical key-based optical information security system does not require a parallel beam of light as an information carrier for an image to be encrypted.

6. A system as claimed in claim 1, characterized in that the collimated light source (7) provides an illumination beam which is enlarged in aperture by two convex lenses and is incident on the first decrypting spatial light modulator (8).

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