Search

Copyright of Journal of Chongqing University of Technology (Natural Science) is the property of Chongqing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Commutative encryption and watermarking ( CEW) is a combination of cryptographic and digital watermarking technology, which is used for multimedia information security and copyright protection. In order to ensure the security of carrier data, this paper proposed an exchange encryption watermarking algorithm based on ZUC. The algorithm used the ZUC sequence cipher to generate the key and used modular operation to encrypt the carrier information. The sequence of watermark embedding operation and data encryption operation did not affect the generation of watermark ciphertext data. When extracting the watermark, the algorithm could realize the exchange of password operation and watermark operation. The experimental results show that the watermark extraction in ciphertext domain is consistent with that in plaintext domain, the image containing watermark is of high quality, the efficiency of encryption and decryption, watermark embedding and extraction are higher, and the algorithm has a certain robustness. [ABSTRACT FROM AUTHOR]

In order to solve the weakness of existing medial image encryption algorithm based on chaotic system in considering the image' s texture feature, this paper proposed a medical image encryption and decryption method based on chaotic mapping and adaptive partitioning. Firstly, it used the 2D Sine Logistic chaotic system to generate two secure sequences with good chaotic characteristics . Then, it divided the original medical image into fixed size image blocks, and calculated their maximum pixel difference and variance . According to the given threshold, it divided these image blocks into texture smooth blocks and texture complex blocks. Finally, it used the first chaotic sequence with ciphertext feedback mechanism to encrypt the smooth blocks, and encrypt the complex blocks by using the second chaotic sequence with plaintext feedback mechanism. Therefore, it obtained the encrypted image. Because the presented algorithm efficiently considered the texture characteristics of image blocks and optimized the algorithm of chaotic encryption, it improved the encryption and decryption efficiency of medical images. Experimental simulation results show that the presented algorithm has high security and encryption efficiency. Compared with the existent method, it reduces the encryption and decryption time by about 0. 5 times . The presented algorithm is suitable for real-time medical images encryption and decryption with big data size. [ABSTRACT FROM AUTHOR]

Aiming at the shortage of medical images encryption algorithm in efficiency and security, this paper proposed a novel medical image encryption algorithm in frequent domain based on 2D sine Logistic chaotic mapping. Firstly, the proposed algorithm used the integer wavelet transform of LeGall5/3 to transform medical image from frequent domain to spatial domain. In this way, the high correlation among pixels has disappeared. Then, the proposed algorithm utilized 2D sine logistic chaotic mapping to generate the chaotic sequences. In order to improve the encryption efficiency, this algorithm chose the low frequency coefficients of three-level decomposed to encrypt with chaotic diffusion and scrambling mechanism. In the same time, this algorithm also selected the medium-high frequency coefficients of two-level decomposed to encrypt by chaotic diffusion mechanism for solving the problem of obvious outline in encrypted image. Finally, this algorithm transformed the encrypted wavelet coefficients by the inverse integer wavelet transform and obtained the encrypted image. Experimental simulation results demonstrate that the proposed algorithm is able to protect medical images with low time complexity and a high security level. Compared with the existing spatial method, it reduces the encryption time by about 0.025 times. In addition, the proposed algorithm has better image imperceptibility as well as an excellent encryption efficiency compared to the existing frequent method. [ABSTRACT FROM AUTHOR]

In order to solve the shortcomings of the traditional serial encryption method in single machine mode, such as the low density of data security, the difficulty in encrypting-efficiency to meet the requirement of increasing information data encryption and the excessive amount of memory in the running process, and so on. This paper designed a scheme of chaotic encryption algorithm based on Hadoop platform. The scheme used MapReduce parallel framework, chaotic encryption pseudorandom number and the principle of initial value sensitivity. And it proposed parallel chaotic encryption scheme for MapReduce framework and chaotic encryption optimization. It used the length of the plaintext as the initial value, and used Chen, Lorenz, Rossler chaotic system to generate secret key. At the same time, the paper proposed an idea of dividing plaintext data into blocks according to 1 MB. According to the offset, it judged each block to gene rate three key sequences of Chenn Lorenzi R0ssler whose length is 1 MB, to improve the security of data density, and reduce the amount of running memory and other purposes. This design framework used Chen sequence for plaintext messing operation, used Lorenz sequence for XOR diffusion ope ration and used Rössler sequence for modular auxiliary diffusion operation. Experiments prove that, for MapReduce, the optimization algorithm of using parallel framework and chaotic system can effectively reduce the amount of memory and improve the encryption speed, and the encryption ope ration associated with plaintext achieves the purpose of effectively defending against the attack of selected plaintext. [ABSTRACT FROM AUTHOR]

In the traditional attribute-based encryption scheme, there are problems that the attributes contained in the access policy may leak sensitive information of the user and the malicious user leaks the private key to gain illegal profits without being blamed. At the same time, with the increasing of the number of attributes the length of the private key, ciphertext, and the decryption operation will increase and it bring greater communication overhead and computational overhead. To solve these problems, this paper proposed an attribute-based encryption scheme that can track keys and hide the access structure. The scheme improved the security of the encryption algorithm without affecting the efficiency of encryption and decryption. The scheme adopted a two -factor authentication mechanism to achieve more secure and efficient access control, and it used a secure signature mechanism for supporting traceable keys to track malicious users. Finally, the theoretical analysis show that this scheme proved to be safe under the standard model based on the DBDH hypothesis. [ABSTRACT FROM AUTHOR]

Aiming at the problem of high complexity of image encryption algorithm at present, a new wavelet domain block encryption method was proposed. First, the algorithm decomposed the original image into multiple different resolution images using DWT(discrete wavelet transform), and the low-frequency coefficients of the image were scrambled by the hyperchaotic system. After IDWT(inverse discrete wavelet transform), bitwise XOR was performed on the reconstructured image with a sequence generated using hyperchaostic system. The experimental results verified that the grey information of the original image was hidden, this encrypting method had a large space of keys and high safety performance; and the scrambled image had good performance of the resisting statistic attack and differential cryptanalysis. [ABSTRACT FROM AUTHOR]