الفهرس 
Chapter 1: IntroductionOnly 14 pages are availabe for public view
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Abstract
Recently, digital communication and storage over the Internet through the cloud have increased in a rapid manner. Multimedia applications, especially, over wireless networks, can easily be intercepted, thus, making its security an essential and challenging issue. Fog computing comes to secure and facilitate the connection to the cloud. It works as an intermediary between the cloud and the peripheral devices. Accordingly, the channel between the fog and those devices must be secured against attacks. Multimedia encryption is the core enabling technology that provides confidentiality and prevents unauthorized access of the content. Real time constraints, large amount, and unique characteristics of multimedia data inhibits the use of traditional cryptographic algorithms over multimedia data. Chaotic maps contribute a vital part in modern cryptography. The algorithms utilizing chaotic maps are considered more effectual and secure than traditional cryptography algorithms. In this work, novel perturbation algorithms for multimedia encryption based on double chaotic are presented. As a new method of chaotification, parallels and combines two proposed chaotic maps for the proposed hybrid system. It based on Permutation, Diffusion and parameters of the proposed system which are then concerned in shuffling of pixels and operations of substitution respectively. In the adopted simulation scenarios, by using Python 2.7.12, Matlab 8.2R 2013b , Java SE8 programming we have created 500 files with random size between 500KB and 5GB on the server side and made 10,000 random requests with Gaussian random for file popularity. The simulation results showed that, the proposed model improves: Many analyses for security and statistical test indicate that the results of (i) decrypted text statistical test average results of UACI and NPCR are 33.09% and 99.33%, respectively, It is worth mentioning that the average processing time for our text encryption/decryption scheme with improvement ratios up to 25% (1.6 MB/sec), (ii) voice statistical test average results of SSSNR is reduced by -20.679 dB. It is also showed that when the two levels are combined, the overall reduction obtained is -21.76 dB, In terms of processing time, the proposed scheme takes about 325msec (2.16 MB/sec) for encryption or decryption stages. (iii) decrypted images and average values for UACI and NPCR are 33.63% and 99.67%, respectively, Additional advantage of our method is reduce the encoding time comparing with conventional methods by up to 55%, where that the encryption and decryption steps take about 242msec (1.57 MB/sec), and (iv) decrypted video average values for UACI and NPCR are 33.62% and 99.62%, respectively. The proposed method spends 1 second for creating the necessary parameters for the maps to be used and the time required to encrypt (decrypt) the test video data is about 408msec (2.15 MB/sec) The proposed method can achieve low residual intelligibility with high quality recovered data; high sensitivity, high security performance, and it show that the encrypted image has good resistance against attacks. Based on the results of comprehensive simulation and the results of security and statistical analysis, and compared to previous studies, it confirms that the proposed schemas and algorithms are highly efficient, secure and effective to provide optimum performance for mobile fog computing. These results were verified using both Performance matrices and ROC curves.