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Encryption is a technique of encoding data so that they can only be recognized by authorized receivers. More interactive media information is communicated in the medical, business, and military fields because of the rapid advances in various multimedia transmission and networking technologies, which may contain sensitive information that must be kept hidden from public users. Advanced encryption standards (AES) and data encryption standards (DES) are widely used encryption algorithms for text data. However, they are not appropriate for video data. To ensure that this information cannot be accessed by attackers, the demand for efficient video-protection techniques has been raised. This article provides multimedia design requirements to maintain a secure multimedia system occupied with a threat model for detecting and ranking the potential risks facing a multimedia system. the risks exposed to multimedia security and their impacts on users are typically described according to the textual description and also an overview of the current state-of-the-art video-encryption schemes are presented and their performance parameters have been examined. The relationship between encryption algorithms and compression techniques is also discussed and various multimedia applications have been presented in this paper; Additionally, as the synchronisation of real-time continuous streams is necessary for the interchange of these streams in multimedia conferencing services, multiple synchronisation strategies have been given in this study along with video synchronisation challenges.

The ability to obtain the accurate location of nodes in wireless sensor networks is crucial for practical applications. The sensed data is meaningless if it is not accompanied by its location. Range-free localization techniques are favored to overcome the hardware limitations of sensor nodes and to avoid the costly range-based techniques. DV-Hop is a range-free localization algorithm that is well-known for its simplicity. However, it suffers from low accuracy and poor stability. In this paper, an enhanced variant of the DV-Hop algorithm is used to estimate the distance between the unknown nodes and anchor nodes, then the position estimation phase is formulated as a minimization problem solved by means of the recently developed squirrel search algorithm (SSA). The SSA is utilized to find the locations of the unknown sensor nodes. Our proposed algorithm is thus called SSIDV-Hop algorithm. The performance of our proposed algorithm is compared to that of existing localization algorithms including the DV-Hop, PSODV-Hop, GADV-Hop, and DEIDV-Hop algorithms. Extensive simulations showed that our proposed algorithm is superior to other existing algorithms as it achieved higher localization accuracy, better stability and faster convergence rate.

Two new encryption algorithms for secure video transmission are proposed in this paper. The two algorithms employ different types of chaotic maps to generate the keystream for encrypting the video frames. Both algorithms involve a substitution step and a permutation step to achieve confusion and diffusion requirements. For efficient transmission, the video file is compressed before being encrypted. In the basic implementation of both algorithms, MPEG-2 standard is used for compression. However, the algorithms are shown to be compliant with other compression techniques. In the permutation step, the effect of the block size used in the shuffling process is examined. Smaller blocks result in increasing the processing time, while reducing both the correlation between adjacent pixels and the peak-signal-to noise ratio of an encrypted frame. The use of a Feistel structure is investigated to enhance security and its negative impact on the encryption time is demonstrated. The experimental results of the two proposed schemes confirm that they represent different tradeoffs between security and computational efficiency. Both schemes are sensitive to slight variations in the encryption key as apparent from the obtained differential measures. The conducted comparative study shows the competitiveness of the proposed schemes to existing schemes in literature.

Quantum cryptography utilizes the quantum properties of photons to construct an unbreakable crypto-algorithm in real-time. In this paper, based on quantum and classical computation principles, a new quantum encryption algorithm using the symmetric key is presented. It is a block-cipher algorithm which means that each message contains blocks in which 4 bits for each. Firstly, keyed rotations and permutation of the message bits are used. Secondly, the encrypted message is converted to qubits then several dynamic quantum gates are applied to them key dependently to make the ciphertext state reach the state of non-orthogonality. In consequence of the principles of quantum mechanics, the eaves cannot distinguish the non-orthogonal states of the encrypted message. The proposed algorithm is proofed to increase the message space, the various algorithm analysis proofed that our proposed algorithm has an improved strength against various attacks, including the brute force attack.

Quantum cryptography appropriates the features of photons to create a secured algorithm in real-time. In this study, a new algorithm is illustrated using the symmetric key based on the basics of quantum and classical computation. In this algorithm, the message contains blocks, the space of each block is 16 bits. First, the classical encryption process depends on the key that makes rotation and permutation in the bits of block message. Second, the bits of encrypted block messages are converted to qubits. Third, Pauli gates are used, and applies the output of the second stage to them depends on a key to achieving the non-orthogonality of ciphertext states. Because of the basis of quantum computing, the eavesdroppers cannot detect the encrypted message states that changed to non-orthogonal states. The proposed algorithm is proven to increase the message space, the various algorithm analysis proofed that our proposed algorithm has an improved strength against various attacks, including the brute force attack.

Electronic commerce, as exemplified by the popularity of the Internet, is becoming more important along with fast progress in communications and information technology. The SET (Secure Electronic Transaction) protocol is a scheme designed to ensure that merchants and cardholders can conduct business over a public network. Although the SET protocol has some disadvantages, but still it is the most commonly used protocol in the Internet shopping. Signcryption is a cryptographic primitive which simultaneously provides both confidentiality and authenticity in a single logical step. Signcryption based on elliptic curves provides the same level of security using smaller keys compared to schemes based on the discrete logarithm problem over finite fields. This paper examines the benefits of using signcryption rather than signaturethen-encryption in the SET protocol. Using identity-based signcryption in the SET protocol reduces the number of encryption and decryption operations. Moreover, signcryption is less time consuming than signature-then-encryption.

Electrical stimulation optimization is a challenging problem. Even when a single region is targeted for excitation, the problem remains a constrained multi-objective optimization problem. The constrained nature of the problem results from safety concerns while its multi-objectives originate from the requirement that non-targeted regions should remain unaffected. In this paper, we propose a mixed integer linear programming formulation that can successfully address the challenges facing this problem. Moreover, the proposed framework can conclusively check the feasibility of the stimulation goals. This helps researchers to avoid wasting time trying to achieve goals that are impossible under a chosen stimulation setup. The superiority of the proposed framework over alternative methods is demonstrated through simulation examples.

This paper blends the ideas from recent researches into a simple, yet efficient image encryption scheme for colored images. It is based on the finite field cosine transform (FFCT) and symmetric-key cryptography. The FFCT is used to scramble the image yielding an image with a uniform histogram. The FFCT has been chosen as it works with integers modulo p and hence avoids numerical inaccuracies inherent to other transforms. Fractals are used as a source of randomness to generate a one-time-pad keystream to be employed in enciphering step. The fractal images are scanned in zigzag manner to ensure decorrelation of adjacent pixels values in order to guarantee a strong key. The performance of the proposed algorithm is evaluated using standard statistical analysis techniques. Moreover, sensitivity analysis techniques such as resistance to differential attacks measures, mean square error, and one bit change in system key have been investigated. Furthermore, security of the proposed scheme against classical cryptographic attacks has been analyzed. The obtained results show great potential of the proposed scheme and competitiveness with other schemes in literature. Additionally, the algorithm lends itself to parallel processing adding to its computational efficiency.

In this paper, the firefly algorithm with a modified parameterless penalty function is used to determine the optimal settings of Flexible AC Transmission System (FACTS) devices including the Thyristor controlled phase shifting transformer TCPST, Thyristor controlled series capacitor (TCSC) and Static VAR Compensator (SVC). Use of FACTS in a power system reduces the active power losses and improves the voltage profile. The proposed algorithm solves an optimal power flow (OPF) problem for the system without FACTS devices as an initial step to determine the optimal settings for the generators' voltages and active powers and to calculate the initial active power losses. The optimal locations for FACTS devices are heuristically chosen by ranking the lines and the buses of the power system according to the reduction in the power losses. Finally, the optimal settings of the FACTS devices are selected to minimize the active power losses and to enhance the voltage profile. The proposed algorithm is tested on the IEEE 30-bus and the IEEE 57-bus power systems and gives high quality solutions in a relatively small computational time.

In this article, a novel approximate analytical solution is presented for solving the standard viral dynamic model. Basically, the standard model is used to study viral dynamics in patients for a wide range of viruses like HIV, HPV, HBV, and HCV. In this research work, the standard model for hepatitis C virus (HCV) is considered in detail; however, the analysis and results can be applicable for all other viruses. This standard model is used to study viral dynamics in patients treated with direct-acting antiviral agents (DAAs). Power series solution combined with Laplace–Padé resummation method (PSLP) is used to obtain the approximate analytical solutions for the model. To test the capability as well as the validity of the proposed method, results are compared with available viral load data published in the literature and with published simulation results. Good fits are obtained in the comparison for all cases considered. Given that medical specialists and physicians are more interested in solutions that yield direct and simple predictions, it is expected that the proposed approximate analytical solution would be attractive to them and help them to obtain a straightforward and a proper estimation regarding the viral load due to variations in treatment and/or patient’s parameters.

Cognitive radio (CR) is a technology that aims to enhance the use of the underutilized spectrum. Spectrum handoff plays this role by allowing the unlicensed secondary users (SUs) to use the licensed frequency bands of the primary users (PUs). Moreover, it helps the SU to vacate the channel at the presence of the PU and find a suitable channel for the interrupted SU to continue his unfinished transmission. In this paper, an analytical model for the general case of non-identical channels in CR networks is introduced for both fixed and probabilistic sequence approaches for target channel selection. Moreover, a new balancing model is suggested to generate the probabilistic sequence. Both the fixed and probabilistic sequence approaches are optimized using the meta-heuristic methods of particle swarm and genetic algorithm in the seek of finding an optimal approach to minimize the extended data delivery time of the SUs. The results are based on the pre-emptive resume priority M/M/1 queueing network model and are shown for different network cases. Based on the optimization results, a fast hybrid approach is proposed and found to achieve near optimal solution.

This paper presents a new approach for secure hiding of textual data in a colored digital image. Use of images as a cover media in steganography is based on the deficiencies in the human visual system (HVS). The proposed technique employs two independent chaotic sequences for specifying the locations where the message bits are embedded in the cover image using an adapted version of the least significant bit (LSB) method. Message bits are embedded using the 3-3-2 LSB insertion method for the chaotically selected pixels of the cover image. This technique provides sufficient security as the same sequence of numbers cannot be generated without knowing the exact key; that is; the initial conditions of the two chaotic maps used in the index selection process. Moreover, the preliminary results ensure that eavesdroppers will not have any suspicion that there is a message hidden within the sent image since the peak signal to noise ratio (PSNR) is high and the mean-squared-error (MSE) is low. Furthermore, the length of the secret message is another important component of the key, which standard steganography detection methods cannot estimate correctly. Finally, the proposed approach provides better PSNR values and MSE values compared to other existing techniques as apparent from our experimental results.

Background and objective Selective electrical stimulation of target brain locations (stimulation focality) is a difficult problem because it comprises conflicting goals. The stimulating current density field needs to be strong enough to stimulate targeted locations but weak enough not to stimulate near-by non-targeted locations. The objective of this study is to suggest a methodology for improving electrical stimulation focality based on time-division multiplexing principle. Proposed methodology The complex problem of exciting a group of target locations is decomposed into a series of simpler problems in which a single location is targeted. Time-division multiplexing between the solutions of the simpler problems achieves seemingly parallel excitation of the selected target locations with minimal excitation of non-targeted locations. Results A high fidelity finite element-based simulation of a cortical vision prosthesis is used to demonstrate the proposed idea and highlight important facts about neurons dynamics that must be taken into consideration in order to design a successful time-division multiplexing based stimulation scheme. Conclusion The study offers a clear detailed procedure for designing focal electrical stimulation setups based on time division multiplexing principle. The included results and experiments prove that the proposed strategy is a step forward towards more focal stimulation setups.

This paper investigates several alternative schemes for hiding a grayscale image in a colored cover image in the spatial domain. First, we consider the use of one-dimensional (Tent map) versus two-dimensional (Baker's map) chaotic maps for the selection of the set of pixels where the secret message bits are to be embedded. The red color channel of the cover image for the formerly selected pixels is affected by the embedding process since the eye is not very sensitive for slight variations in this color channel. Next, two LSB embedding schemes are examined; namely, embedding one bit per pixel and embedding two bits per pixel. The preliminary results ensure that, to eavesdroppers, there will be almost no suspicion regarding the existence of a secret message hidden within the sent image since the peak-signal-to-noise-ratio (PSNR) is high and the mean-squared-error (MSE) is low for the different alternatives investigated. However, there is a clear impact on the time required for the embedding process if two-dimensional maps and/or one bit per pixel LSB technique are used.

The use of capacitors in power systems has many well-known benefits that include improvement of the system power factor, improvement of the system voltage profile, increasing the maximum flow through cables and transformers and reduction of losses due to the compensation of the reactive component of power flow. By decreasing the flow through cables, the systems’ loads can be increased without adding any new cables or overloading the existing cables. These benefits depend greatly on how capacitors are placed in the system. In this paper, the problem of how to optimally determine the locations to install capacitors and the sizes of capacitors to be installed in the buses of radial distribution systems is addressed. The proposed methodology uses loss sensitivity factors to identify the buses requiring compensation and then a discrete particle swarm optimization algorithm (PSO) is used to determine the sizes of the capacitors to be installed. The proposed algorithm deals directly with discrete nature of the design variables. The results obtained are superior to those reported in Prakash and Sydulu (2007).

is an increased activity in research and development conducted to improve current payment systems in parallel with the progress of Internet. Signcryption combines the functionalities of encryption and digital signing in a single logical step. It is a cryptographic primitive that provides confidentiality, integrity, authentication and non-repudiation. Identity-based cryptography serves as an efficient alternative to the traditional certificate-based cryptosystems. This paper introduces an efficient electronic payment system based on signcryption without bilinear pairings. This e-cash system is more efficient than other schemes employing bilinear pairings and involves less computational cost. In the proposed protocol, the token is issued and authenticated by the bank to prevent double spending problem. The customer delegates his signing capability to the merchant. The bank verifies the identities of both the original signer (customer) and the proxy signer (merchant) and ensures the originality of the transaction. Unlike the existing e-payment systems, the problem of double spending of e-cash does not arise because each transaction is made uniquely identifiable. Hence, no separate protocol is needed to check double-spending. The performance and the security analysis of the proposed e-cash system are discussed revealing its strength from the viewpoint of security and efficiency with regard to computations required.

paper introduces a new authentication protocol using the tripartite signcryption scheme without bilinear pairings that provides confidentiality and authentication between three entities. Mobile communication seems very attractive to users as well as operators and service providers. However, despite of its numerous advantages, mobile communication has been facing many security problems. In this paper, it is demonstrated how the proposed tripartite signcryption scheme can be used to provide authentication and to guarantee secure communication. The use of the proposed tripartite signcryption scheme helps reduce the signaling overhead compared to the scheme in (1).

In this paper, a new image encryption scheme named (ArMTFr) is proposed. An image is encrypted using a combination of keyed permutations and substitution, where a fractal is XORed with the scrambled image. Fractal images are employed in order to improve the performance of the encryption scheme from the viewpoint of randomisation and to increase the encryption key space, thus boosting its security. The employed permutations are the Arnold map and Mersenne-Twister's permutation algorithm. Before the encryption process starts, histogram equalisation is used to enhance the contrast of the image by transforming the intensity values in it, so that the histogram of the output image approximately matches a uniform histogram. First, greyscale images are considered and then the basic algorithm is extended to handle coloured images. Three representations for coloured images are considered: RGB, YCbCr and HSI colour spaces. The security of the algorithm is enhanced in this case by applying RGB colour channels multiplexing. The experimental results show that the encrypted image has low correlation coefficients among adjacent pixels and a good histogram distribution, as well as resistance to various attacks.

key establishment protocol allows entities to establish a common secret key to ensure secure communications over an insecure public network. This paper proposes two new two- party key agreement protocols. Both protocols do not involve bilinear pairings. The first protocol is a certificate-based key agreement protocol that is more efficient than (1) due to its dependence on the elliptic curve discrete logarithm problem and the second is an extension to a certificateless key agreement protocol. Both protocols depend on the use of an authentication message to check that the shared session key is equal for both entities before using it. This authentication message prevents the key off-set attack that is valid for the Haiyan-Sun protocol (2). The security analysis of the second protocol is discussed. The proposed certificateless key agreement protocol is compared with other protocols in literature (2,3,4) and it requires minimal computational cost. Moreover, this protocol is implemented using the Mathematica (7) program.