Research On Optical Identity Authentication Methods Based On Sparse Representation And Nonlinear Correlation

With the continuous improvement of the degree of informatization,information technology affects all aspects of people's lives,how to ensure the security of information has become the concern of the whole society.Optical information security technology has been extensively studied due to its inherent advantages,such as high-speed parallel data processing capability,multi-dimensional design freedom and large key space.Being on the research status of optical information security field,this thesis focuses on the research field of optical identity authentication technology.The thesis first introduces the research background of optical information security technology,and then briefly introduces its research status from three aspects:optical cryptography,optical information hiding and optical authentication technology.Secondly,it elaborates some theoretical bases involved in this thesis.On the basis of two kinds of classical optical cryptosystem,two types of optical identity authentication schemes are proposed respectively.The contributions of this thesis are mainly as follows:(1)A hierarchical identity authentication scheme based on two-beam interference is proposed.In the designing process of the authentication system,several standard reference images are respectively encoded into the corresponding sparse phase mask by a sparse sampling modified iterative phase retrieval algorithm,and then they are conducted the superposition multiplexing operation according to the agreed rules,so that the phase keys of users with different levels can be constructed.In the authentication process,the authenticity of the identity and its corresponding level can be authenticated by verifying the number of the standard reference images that the phase key can correctly match.The features of the proposed scheme are as follows:firstly,the phase keys of the users with different levels are the sparse phase mask with different sparse levels.Secondly,the output image of the system is a visually indistinguishable pseudo noise distribution,which reduces the risk of informationleakage and totally avoids the “silhouette problem” in the previous typical schemes.Thirdly,the scheme can not only judge the legitimacy of the user identity,but also identify its authorization level,thereby conferring the appropriate access authority to the system,which has a strong practical significance.(2)A joint identity authentication scheme based on joint transform correlator(JTC)is proposed.In the designing process of the authentication system,the joint power spectrum of the conventional JTC-based cryptosystem is sampled randomly and then stored in the database as the “lock” of authentication system.Then,the two random phase masks are sparsely sampled and then randomly exchange half the pixels,so that two sparse phase keys can be constructed,which are distributed to two users with different authorized.In the authentication process,both two phase keys of the authorized users are placed at the predetermined location on the input side,the authenticity of the identity can be authenticated according to whether the standard reference images can correctly match the phase key or not.The features of the proposed scheme are as follows: firstly,the sparse joint power spectrum could largely reduce the storage space requirements.Secondly,the two phase keys are the sparse distribution,which are easy to store and transmit.Thirdly,the output image of the system is a visually indistinguishable,which reduces the risk of information leakage.Fourthly,two authorized users could pass the authentication when they are jointly authenticated but any single one would be failed,which means the security of system has been enhanced in some ways.