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Three-step generalized phase-shifting and cascade fractional Fourier transform optical image encryption method

A fractional Fourier, encryption method technology, applied in the field of optical image encryption based on three-step generalized phase-shift digital holography and cascaded fractional Fourier transform, can solve the problems of demanding phase shifters, wavefront reproduction errors, etc.

Inactive Publication Date: 2017-03-22
TIANJIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The three-step generalized phase-shift digital holography technology can effectively solve the problems of the phase shifter in the fixed-step or equal-step three-step phase-shift digital holography technology, which is demanding on the phase shifter and easily brings errors to the wavefront reproduction.

Method used

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  • Three-step generalized phase-shifting and cascade fractional Fourier transform optical image encryption method
  • Three-step generalized phase-shifting and cascade fractional Fourier transform optical image encryption method
  • Three-step generalized phase-shifting and cascade fractional Fourier transform optical image encryption method

Examples

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Embodiment 1

[0102] An optical image encryption method based on three-step generalized phase shift digital holography and cascaded fractional Fourier transform, the optical path diagram is as follows figure 1 As shown, the encryption method consists of three parts: the key generation part, the image encryption part and the image decryption part.

[0103] see figure 1 , where the key generation part consists of two chaotic random phase masks CRPM generated by the Duffing chaotic system 1 and CRPM 2 ; The image encryption part and the image decryption part include: lens (L, L 0 , L 1 , L 2 , L 3 , L 4 , L 5 ), mirror (M 1 ,M 2 ), spatial filter (SF), beam splitter (BS 1 , BS 2 ), phase shifter (PZT), laser, CCD camera, computer, etc.

[0104] (1) Key generation part:

[0105] In the encryption method provided by the present invention, two random phase mask keys are respectively generated by a Duffing chaotic system controlled by different chaotic parameters. The initial value a...

Embodiment 2

[0112] Combine below figure 1 1. The design principle introduces the scheme in embodiment 1 in detail, see the following description for details:

[0113] An optical image encryption method based on three-step generalized phase-shift digital holography and cascaded fractional Fourier transform. The optical path corresponding to the encryption and decryption process is as follows: figure 1 As shown, the encryption method consists of three parts: the key generation part, the image encryption part and the image decryption part. The specific implementation manners of these three parts will be described in detail below.

[0114] (1) Key generation part:

[0115] In the encryption method, two chaotic random phase masks act as the main key, and the wavelength of the object light wave, the Fresnel transform distance and the order of the fractional Fourier transform act as the auxiliary key. The following is a detailed introduction on how to use the Duffing chaotic system to generat...

Embodiment 3

[0153] Below in conjunction with specific accompanying drawing, the scheme in embodiment 1 and 2 is carried out feasibility verification, see the following description for details:

[0154] Adopt the encryption method provided by the implementation of the present invention to an image (such as figure 2 As shown in (a), after encryption, the obtained encrypted image is as follows figure 2 (b) shown.

[0155] Depend on figure 2 (b) It can be seen that any information of the original image is hidden. When all the keys are correct, the decrypted image is as follows figure 2 (c) shown. Depend on figure 2 (c) It can be seen that the original image can be well restored. It shows that the encryption and decryption of grayscale images using this system is successful.

[0156] In addition, when one key is wrong and other keys are correct, the decryption result is as follows: image 3 (a)-3(h). It can be seen that the security of the system can be guaranteed.

[0157] Fi...

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Abstract

The invention relates to the technical field of image information security and optical information processing, and provides an optical image encryption method capable of effectively resisting known plaintext attacks and selecting plaintext attacks. The problems of key management and transmission inconvenience are solved. A three-step generalized phase-shifting and cascade fractional Fourier transform optical image encryption method comprises the following concrete steps of (1) a key generation part: two random phase masks achieving the effect of main keys are respectively generated by Duffing chaotic systems controlled by different chaotic parameters; (2) an image encryption part: an image to be encrypted is subjected to Fresnel transform under the irradiation of incident light, and is then modulated by the first chaotic random phase mask; and the modulated image is subjected to fractional Fourier transform with the order being a1 and is then modulated by the second chaotic random phase mask; and (3) an image decryption part: the decrypted image is obtained. The optical image encryption method is mainly applied to image information security and optical information processing occasions.

Description

technical field [0001] The invention relates to the technical fields of image information security and optical information processing, in particular to an optical image encryption method based on three-step generalized phase shift digital holography and cascaded fractional Fourier transform. Background technique [0002] As one of the most popular multimedia forms at present, digital images are widely used in the fields of politics, economy, military affairs, education and so on. In today's highly developed Internet technology, how to protect digital images from tampering, illegal copying and dissemination has important practical significance. The research on image encryption technology has become one of the hotspots in the field of information security. [0003] Optical information processing technology has aroused great interest in the field of image encryption research because of its high processing speed, high parallelism, and fast realization of convolution and correla...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06F21/60H04L9/00H04L9/08
CPCG06F21/602H04L9/001H04L9/0816
Inventor 唐晨苏永钢李碧原谷帆程佳佳
Owner TIANJIN UNIV
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