Encryption and Decryption Method of Double Cylindrical Random Phase Encoding of Color Image

Abstract

The invention provides a bicylindrical random phase coding encryption method for a color image. The method comprises a color image encryption process and a color image decryption process, and is characterized in that the RGB format of the color image is firstly converted into the single-channel YCbCr4:2:0 format, the classic double random phase coding encryption technology is improved by replacinga planar phase plate with a cylindrical phase plate and twice continuous relay planar diffractions with twice reflective relay cylindrical diffractions, and imaging is carried out through the two-step phase shifting method to obtain encrypted ciphertext; and during encryption, reversible diffraction is carried out through conjugate phase plates used during encryption and correct cylindrical diffraction system parameters for correct decryption of the single-channel image, and a recovered color image is obtained through color space conversion. The method provided by the invention has the advantages that the single-channel YCbCr4:2:0 format is adopted for the encryption, so that encryption and transmission data volumes are reduced, and the encryption efficiency is improved; and the asymmetryof a twice reflective relay cylindrical diffraction process and a reversed process is utilized to greatly improve the safety of the encryption method, so that attacks from a phase recovery method canbe particularly resisted.

Description

1. Technical field [0001] The invention relates to the technical field of information security and information optics, in particular to a color image encryption method. 2. Background technology [0002] The application of dual random phase encoding technology and optical interference theory in color image encryption is a hot topic in the field of optical information security research in recent years. In 1995, two American experts, P.Réfrégier and B.Javidi, proposed the dual random phase encoding technology, which is an important application of optical theory in the field of information security. This technology has been protected by a US patent. However, due to the linear nature of the system, there are great hidden dangers in the security of the system. Asymmetric encryption method is a new hotspot in the field of color image encryption in recent years, this kind of encryption method has the ability to resist the attack of phase recovery method. Since the inside-to-out pr...

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Problems solved by technology

However, due to the linear nature of the system, there are great hidden dangers in the security of the system.

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