Multi-level key generation method and user hierarchical authentication method based on double-beam interference

Abstract

The invention relates to a multi-level key generating method based on dual-beam interference and a hierarchical authentication method. The generating method comprises the following steps: saving at least two standard reference images; selecting a random pure phase distribution function to serve as a phase lock; coding each of the at least two standard reference images into a sparse phase distribution corresponding to an input plane by an iterative phase recovery processing process; and overlaying the at least two obtained sparse phase distributions according to different quantities to obtain phase keys of different authentication levels. The hierarchical authentication method comprises the following steps: acquiring interference field strength distributions of the phase lock and the phase keys on an output plane; calculating an interference field strength distribution and non-linear correlation distributions of the at least two standard reference images by a non-linear correlation algorithm; and taking the quantity of the standard reference images in which remarkable nonlinear correlation peaks relative to the interference field strength distribution appear as the authorization levels of the phase keys.

Description

Technical field [0001] The invention relates to the technical field of optical cryptography, in particular to a multi-level key generation method and a hierarchical authentication method based on double-beam interference. Background technique [0002] In 2008, Zhang Yan and others from Capital Normal University proposed an optical image encryption technology based on the principle of double-beam interference, using analytical deduction methods to encrypt an original plaintext image onto two pure phase templates. Because of its clear working principle, simple system structure and simplicity and efficiency of encryption algorithm, it has received continuous attention from researchers. However, follow-up studies show that the system has an inherent "contour reproduction" problem, that is, any one of the two random phase masks generated by the analysis during the encryption process is diffracted and the original image is still observable on the output surface. Contour, which makes t...

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Problems solved by technology

However, the above-mentioned improvement schemes usually face new problems such as complex design and difficult implementation, and some improvement schemes do not completely eliminate the image problem

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