Message Passing Interface (MPI) is a well know paradigm that is widely used in coding explicit parallel programs. MPI programs exchange data among parallel processes using communication routines. Program execution trace depends on the way that its processes are communicated together. For the same program, there are a lot of processes transitions states that may appear due to the nondeterministic features of parallel execution. In this paper we present a new algorithm that statically generates the execution trace of a given MPI program using data flow analysis technique. The performance of the proposed algorithm is evaluated and compared with that of two heuristic techniques that use a random and genetic algorithm approaches to generate trace sequences. The results show that the proposed algorithm scales well with the program size and avoids the problem of processes state explosion which the other techniques suffer from.

The Hash function has been studied by designers with the goal to improve its performances in terms of area, frequency and throughput. The Hash function is used in many embedded systems to provide security. It is become the default choice for security services in numerous applications. In this paper, we proposed a new design for the SHA-256 and SHA-512 functions. Moreover, the proposed design has been implemented on Xilinx Virtex-5 FPGA. Its area, frequency and throughput have been compared and it is shown that the proposed design achieves good performance in term of area, frequency and throughput.

WSNs is usually deployed in opening wireless environment, its data is easy to be intercepted by attackers. It is necessary to adopt some encryption measurements to protect data of WSNs. But the battery capacity, CPU performance and RAM capacity of WSNs sensors are all limited, the complex encryption algorithm is not fitted for them. The paper proposed a light-level symmetrical encryption algorithm: LWSEA, which adopt minor encryption rounds, shorter data packet and simplified scrambling function. So the calculation cost of LWSEA is very low. We also adopt longer-bit Key and circular interpolation method to produce Child-Key, which raised the security of LWSEA. The experiments demonstrate that the LWSEA possess better “avalanche effect” and data confusion degree, furthermore, its calculation speed is far faster than DES, but its resource cost is very low. Those excellent performances make LWSEA is much suited for resource-restrained WSNs.

This paper addresses mean response time that end-users experience when using the Internet. HTTP (Hyper Text Transfer Protocol) is a widely used transfer protocol to retrieve web objects in the Internet. Generally, HTTP uses TCP (Transmission Control Protocol) in a transport layer. But it is known that HTTP interacts with TCP inefficiently. As an example of such inefficiencies, HTTP does not require TCP to deliver the rigid order, which may cause head-of-line blocking. As another transport layer protocol, SCTP (Stream Control Transmission Protocol) has attractive features such as multi-streaming and multi-homing unlike TCP. Within an SCTP association, multi-streaming allows for independent delivery among streams, thus can avoid the head-of-line blocking. In addition, SCTP provides very large number of streams; therefore, it can transfer multiple objects more efficiently than the typical HTTP/1.1 over TCP which limits the number of pipelines. Mean response time is one of the main measures that end users using Internet concern. This paper presents the simple analytical model and algorithm to find the mean response time for HTTP over SCTP including the previous HTTP over TCP. Some computational experiences show that the proposed model and algorithm are well approximated to the real environment. Also, it is shown that mean response time for HTTP over SCTP can be less than that for HTTP over TCP.

With the increased radio frequency identification (RFID) applications different authentication schemes have been proposed in order to meet the required properties. In this paper we analyze the security of a server-less RFID authentication protocol which is proposed by Deng et al. in 2014. Deng et al. proposed an improvement over Hoque et al. protocol to overcome its vulnerability against data desynchronization attack. However, in this paper we show that their protocol is still vulnerable against data desynchronization attack. Furthermore we present an improved version of this protocol to prevent this attack.

Most of the protocols for enhancing the lifetime of wireless sensor networks (WSNs) are of a homogeneous nature in which all sensors have equal amount of energy level. In this paper, we study the effect of heterogeneity on the homogeneous protocols. The ALBPS and ADEEPS are the two important homogeneous protocols. We incorporate heterogeneity to these protocols, which consists of 2-level, 3-level and multi-level heterogeneity. We simulate and compare the performance of the ALBPS and ADEEPS protocols in homogeneous and heterogeneous environment. The simulation results indicate that heterogeneous protocols prolong the network lifetime as compared to the homogeneous protocols. Furthermore, as the level of heterogeneity increases, the lifetime of the network also increases.

There exists a great number of work related to chaotic systems investigated by many researchers, especially about Lorenz chaotic system. If the order of differentiation of variables are fractional, the systems are called fractional chaotic systems. In this work a web-based interface is designed for fractional composition of five different chaotic systems. The interface takes initial and fractional differentiation values and yields output signals and phase portraits. The paper first introduces design tools and then provides results obtained throughout the experiments.

Validation and verification of security policies is a critical and important task to ensure that access control policies are error free. The two most common problems present in access control policies are: inconsistencies and incompleteness. In order to detect such problems, various access control policy validation mechanisms are proposed by the researchers. However, comprehensive analysis and evaluation of the existing access control policy validation techniques is missing in the literature. In this paper, we have provided a first detailed survey of this domain and presented the taxonomy of the access control policy validation mechanisms. Furthermore, we have provided a qualitative comparison and trend analysis of the existing schemes. From this survey, we found that only few validation mechanisms exist that can handle both inconsistency and incompleteness problem. Also, most of the policy validation techniques are inefficient in handling continuous values and Boolean expressions.