Research On Image Encryption&Hiding Algorithm Based On Chaos Theory And Wavelet Transform

With the mobile Internet era coming,posting and getting multimedia information has become an indispensable part of people's daily life.Among them,digital image is widely used because of the advantages of small storage space and low transmission bandwidth.Digital image,as a highly efficient information media,provides convenient access to information for people.However,with the digital image is widely used,some of them may involve individual or organizational privacy,thus how to protect the security of the digital image has become a problem to be solved.Chaos phenomenon is widespread in nature,but it's formed a set of theory system until the 20th century,then form a chaotic cryptography,and now chaotic cryptography has become an important branch of cryptography.In recent decades,image encryption algorithm based on chaos theory has become the focus of research at home and abroad,because of its good characteristics such as randomicity and the sensitivity of initial value.This thesis introduces the image encryption algorithm based on chaos theory,analyzes the image bit-level characteristics,and on this basis,an image bit-level encryption algorithm is proposed.The algorithm uses multiple Logistic chaotic sequences to scramble and diffuse each bit of the image,and each bit is guaranteed to be encrypted only once.In addition,this paper proposes a bit circulation image encryption scheme based on coupled random map.The scheme is divided into two stages:scrambling and diffusion.In the scrambling stage,the coupled random map is used to determine the pixel position.In the diffusion stage,bits cyclic shifting is used to modify the value of a pixel.Experimental results show that the two image encryption algorithms have good encryption effect and encryption efficiency.In fact,the traditional encryption algorithm has a very good security,and in order to further enhance the algorithm security,this paper proposes a new algorithm combining image encryption and image hiding.By analyzing the characteristics of the image after lifting wavelet transform,we can find that the high frequency coefficients are relatively unimportant while reconstructing the original image.Therefore,the middle cipher-image is hidden in the high frequency part,so as to realize the cipher-image security transmission.In addition,to increase the security of the system,the hidden rule is controlled by key.Experimental results show that this scheme has a good hidden effect.Whether it is a traditional image encryption algorithm,or an encryption hiding algorithm,which aims at providing a fast and safe method of image encryption.It can be found that the combination of different disciplines for image encryption is becoming the mainstream direction of research.