Research On Key Technologies Of General Model And Sharing Randomness Of Secret Image Sharing

Along with the rapid development of computer network and multimedia technology,digital image becomes more and more easier to acquire,transmit and modify.Digital im-age security has attracted extensive attention,especially the protection of important secret image information,such as military deployment plans,product design images and per-sonal privacy images,becomes extremely important.Compared with image encryption and information hiding,secret sharing has the unique characteristics,including:uncon-ditional security,permission control,loss tolerance and simple decryption.In the field of image security protection,many researchers have made in-depth research on secret image sharing,which results in wide applications.However,existing researches on secret image sharing still have some defects,such as lack of theoretical foundation and poor performances of concrete schemes.This paper give a research on secret image sharing from the following three aspects:general model research,general method design,and concrete scheme construction.Firstly,we provide a novel general model of secret sharing based on the basic definition of secret sharing,which is beneficial for deepening the understanding of the essence of secret sharing.Secondly,we provided a general method to utilize the randomness of the sharing phase.Thirdly,we propose three secret image sharing schemes with valuable characteristics,such as mean-ingful shares,two-in-one decryption and multi-secret sharing.Specific research contents are as follows:1.Starting from the basic definition of ideal perfect threshold secret sharing,the pa-per analyses the morphological characteristics for threshold schemes,and then provides a descriptive general model based on the sharing map.Based on the proposed general model,we prove the equivalence between threshold schemes and Latin hypercubes,and then utilize Latin hypercubes as the mathematical tool to extend researches on secret shar-ing from the finite field to the general integer domain,and from linear schemes to nonlin-ear schemes.The related conclusion is beneficial to deepen understanding of the nature of secret sharing.2.Based on the general model described by the sharing map,we analyze the random-ness of the sharing function,and design a general method of the randomness utilization.A threshold linear scheme is taken as the basic scheme,and constraint design and filter-ing operation are added as the core steps of the general method.Under the premise that the shared value and the secret value correspond to the same integer domain,the addi-tional information can be shared and recovered in various forms.Furthermore,the basic performance of the general method of randomness utilization is theoretically analyzed,and the relevant conclusions on the key attributes are provided,including:upper bound of the additional information,security and feasibility.The proposed general method can be used to guide the construction and evaluation of specific schemes with key functional characteristics.3.Based on the general method of the randomness utilization,a weight extended secret image sharing scheme with high visual quality is proposed.In order to generate shadow images with high visual quality,the proposed scheme adds constraint reduction step into the general method,which can guarantee the feasibility of single sharing phase with high weight summation.According to actual needs,participants can set weights to realize flexible control for the visual quality of different shadow image,meanwhile the equivalence of shadow image in recovery operation still remains.The weighted feature of meaningful shadow image is proposed for the first time in this paper,which effectively avoids the restriction relationship between the sharing information rate and the overall visual quality of the shadow images.The proposed scheme is suitable for the application scenarios in which the credibility of participants is different.Compared with the existing extended schemes,the proposed scheme has the advantages of no pixel expansion and simple recovery.4.Based on the general method of the randomness utilization,a two-in-one multi-decryption secret image sharing scheme is proposed.The proposed scheme deeply inte-grates the polynomial-based secret sharing scheme and visual encryption scheme,and can share different secret images with(k₁,k₂,n)-threshold access structure.A single shadow image has two decryption capabilities:the binary secret image can be restored by direct stacking in the absence of computing equipment?with the aid of the computing equipment,the gray secret image can be precisely recovered.Compared with the existing two-in-one schemes,this scheme has the advantages of no pixel expansion and high image quality of overlay restoration.5.Based on the general method of the randomness utilization,a kaleidoscopic multi-secret image sharing scheme is proposed,which is the concrete implementation of the gen-eral method of the randomness utilization in the field of image encryption.In the scheme,all possible additional secret image sharing methods and corresponding constraint design methods are given,and the multi-secret access structure with kaleidoscope character is de-fined.Compared with the existing multi-secret scheme,this scheme has the advantages of no pixel expansion,less public information and flexible and diverse access structure.