| The rapid progress of information sciences and networks has greatly facilitated the storage and transactions of images,however,it also brings risks to the security of image applications.Especially,when tampered images with fake contents are spread widely,it will confuse the public,and even endanger national interests.Image authentication is one of the most effective approaches to detect whether an image has been tampered or not,and its biggest challenge is to distinguish benignant image operations from malicious ones.Since it is not easy for traditional image techniques to identify the rationality of image operations based on requirements of users,traditional image approaches can not satisfy their users in some specific situations.This thesis studies image authentication technology based on cryptographic primitives,which can distinguish benignant image operations from malicious ones from requirements of users.In this study,three kinds of schemes are developed to solve content extraction,editing restriction and user authorization respectively in image authentication.·Firstly,to satisfy requirements of image content extraction,an image authentication scheme is designed to support verifiable image content extraction,constructed with two cryptographic primitives:a digital signature and an accumulator.The proposed scheme allows image user to extract/cut several parts of the image and prove their authenticity,which provides solutions for privacy-aware image authentication/applications.(proposed in Chapter 3)·Then,inspired by image content extraction,another authentication scheme is designed to support controllable image editing based on more visitable requirements of users.The proposed scheme allows image user to edit an image according to an editing rule specified by the image holder and prove its validity.This scheme realizes the evolution from image content authentication to image editing authentication,which is more beneficial to users with more individual requirements(proposed in Chapter 4)·The last,based on reliable image editing,an image authentication scheme with authorization is designed by improving an accumulator with user designation.According to the design,only a(n)authroized/spedified user can prove authenticity of an image.The proposed scheme helps specify the entity of image operations,which benefits not only copyright protection,but also transmission restriction.(proposed in Chapter 5).The aforementioned three schemes are designed for different scenarios,and editing allowed in these schemes is specified by image holders based on requirements of image users.The security of these schemes is rigorously proved in the framework of provable security in cryptology.Different from those traditional non-cryptographic image authentication schemes,the security here is independent of the size of sample space or times of experiments,and just depends on the security of cryptographic primitives used in the constructions.Experiments show the efficiency and practicality of the schemes.Study in this paper can provide effective solutions for image applications where outsourced and authorizable image operations are desirable. |
