Abstract
A visually meaningful image encryption scheme with an asymmetric structure based on the discrete wavelet transform (DWT) and Schur decomposition is proposed in this study. First, the RSA algorithm is used to generate the initial values for the chaotic system to produce the random sequence. Then, both scrambling and diffusion operations are performed on the plain image to obtain the preencrypted image. Moreover, the Schur decomposition is applied on the preencrypted plain image to obtain the upper triangular and orthogonal matrices. Second, the cover image is scrambled followed by a DWT operation. Four subbands are then formed, namely, LL, HL, LH, and HH. Finally, the former upper triangular matrix and orthogonal matrix are embedded into subbands LH and HH produced by the cover image. After the application of the inverse DWT and inverse scrambling operation, the final visually meaningful cover image embedded with a secret plain image can be obtained. No one can identify any useful information about the plain image from the final embedded cover image, nor can anybody know that there is any hidden secret image. Experimental simulations show that the normalized correlation values between the original cover image and the final visually meaningful cover image are approximately 0.9997. Therefore, the proposed encryption scheme is imperceptible for secret image communications.
Highlights
In the era of high-speed information operations manifested by the rapid development and wide applicability of network and multimedia technologies, an increased amount of information is spread conveniently and quickly on the network. is introduces inconvenience to the vast number of network users
By using discrete wavelet transform (DWT) and Schur decomposition, an asymmetric, visually meaningful image encryption scheme was described in this study
A secret image was embedded into another cover image to effectively hide the secret image and fully realize visually meaningful image encryption
Summary
In the era of high-speed information operations manifested by the rapid development and wide applicability of network and multimedia technologies, an increased amount of information is spread conveniently and quickly on the network. is introduces inconvenience to the vast number of network users. The security of plaintext images was improved Based on this encryption framework, many visually meaningful image encryption algorithms have been proposed [22,23,24,25,26,27,28,29,30]. A new visually meaningful image encryption algorithm is proposed by combining the 3D chaotic system, public-key cryptography algorithm, DWT, and Schur decomposition. Our contributions are as follows: (1) by using the embedding method, the secret plain image can be hidden in a cover image with imperceptible effect; (2) by employing the asymmetric RSA to generate the initial value of the chaotic system, it can solve the distribution of the key between the receiver and sender.
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