Research On Color Image Encryption Based On Chaotic System And Wavelet Transform

With the rapid advancement of the Internet and communications technologies,the medium for human interaction has also been changing with each passing day,which is from the beginning of the words to current voices,images,videos and so on.Digital image has an increasingly important influence in today's life.It can convey rich and colorful information vividly.It brings convenience and information to human beings,but it also faces security threats that are illegally stolen and tampered.At present encrypting images is one of the feasible ways to avoid the security threats.The spatial domain image encryption algorithm has the advantages of being simple and easy to implement,without generating graphics distortion in the encryption process,but the encryption strength is weak.Compared with the spatial domain algorithm,the frequency domain encryption algorithm has higher complexity,better security,and is easy to implement data compression.The main task of this paper is to use different chaos and wavelet transform to design a secure and reliable color image encryption scheme,and to achieve a digital image encryption algorithm with strong anti-jamming capability,good encryption effect,strong timeliness,and practical value.In this paper,the following three different encryption schemes are designed using chaotic systems and wavelet transforms:Color image encryption algorithm based on new chaos.Aiming at a one-dimensional chaotic system,the key space is small and the chaotic performance is not prominent.Lorenz and tent chaotic systems are used to construct a new chaotic system(Lorenz Control Tent,LCT)based on the dynamic parameter control chaotic system model.LCT has better randomness and larger key space.In addition,the low frequency wavelet coefficients are scrambled by overlapping block method,so that low-frequency wavelet coefficients in different sub-matrices are scrambled multiple times.Experimental results prove that this algorithm has the advantages of fast operation speed and strong resistance to illegal attack.A color image encryption algorithm based on spatiotemporal chaotic system.Aiming at a large number of distortions and high computational complexity of the decrypted image after discrete wavelet transform,the encryption algorithm has low efficiency and low fidelity.Integer lifting wavelet transform and spatiotemporal chaos system are used to design a color image encryption algorithm.The position of pixel is scrambled by the pseudo random sequence in the spatial domain and the wavelet domain respectively,which not only scrambles the pixel position,but also makes the grayscale value to shuffle accordingly.The algorithm uses block scrambling to solve the problem of invariant pixel locations in Zigzag scanning,the periodical shortcomings at the same time.The initial value of the chaotic system is related to the plaintext information.Through simulation experiments,it shows that the image after the algorithm has good effect of encryption security.Multi-image encryption algorithm based on chaotic system.Aiming at the complexity and low efficiency of many image encryption processes,to design a scheme to encrypt nine color images simultaneously.combine the R components of all images into a new image,and similarly compose all G and B components together.Rated image is separately subjected to integer wavelet transformation,and a block scrambling operation is performed on the low frequency coefficients.Using the Arnold map to design a new scrambling scheme,the security of the encryption algorithm will not be reduced due to the inherent periodicity of the Arnold map,as well as pixel scrambling and diffusion will be implemented at the same time.Using the scrambling scheme designed previously to perform scrambling and diffusion on the image pixels,eventually rendering the image unrecognizable.The simulation experiments show that this algorithm has the characteristics of a large number of encrypted images,high efficiency and high security.