DLFSR is promising for enhancing the security of stream ciphers. However, good inviolability and statistical properties of the DLFSR generator are only achievable when the parameters of the switching algorithm are properly selected. This paper describes a new experimental method for choosing suitable parameters for the algorithm of switching the polynomial in DLFSR. This method was used to enhance the Grain-128 stream cipher. The randomness of the modified Grain was evaluated using the NIST suite, and the results are encouraging. The modified Grain was also compared to the original, and the results indicated that the modified algorithm outperforms the original in several tests. arabic 12 English 82
Fayrouz Aljadi, Ibrahim Almerhag, Fardous Eljadi(3-2019)

Virtual Private Network (VPN) technology provides a way of protecting information being transmitted over the Internet, by allowing users to establish a virtual private “tunnel” to securely enter an internal network, accessing resources, data and communications via an insecure network such as the Internet. A VPN is a communications environment in which access is controlled to permit peer connections only within a defined community of interest, and is constructed though some form of partitioning of a common underlying communications medium, where this underlying communications medium provides services to the network on a nonexclusive basis. arabic 6 English 50
Mariam Abojela Msaad, Amer R. Zerek, Hana H. saleh(1-2012)

Abstract: In WiMAX networks, the biggest challenge is to overcome the effects of fading especially when nodes are mobile. The multipath nature of channel leads to ISI (Inter Symbol Interference) and the severity of ISI effects increases with bandwidth increase and this might get worse when nodes are moving . The radio link between the Base Station and Service Station/Mobile Station can be a LOS or it can be a NLOS. The environmental objects and features like buildings, weather conditions can severely obstruct NLOS signal. In this paper the effect of pedestrian multipath and node mobility in WiMAX network is studied under different codecs schemes in order to evaluate the effect of multipath channel fading when nodes are moving on the QoS parameters end to end delay, jitter, mean opinion score and throughput of a VoIP application. The obtained results showed that multipath fading with mobile nodes has sever effect on throughput and MOS value for all studied codecs and on the other parameters the effect varies depending on the implemented codecs. arabic 14 English 71
N. Aboalgasm, I. Almerhag , A. Daeri(3-2018)