مجله علوم و فناوری های پدافند نوین
سال هفتم شماره 2 (پیاپی 24، تابستان 1395)

Pairing-based cryptography is the use of a pairing between elements of two additive group on elliptic curve to a third multiplicative group on finite field to construct or analyze cryptographic systems. The Tate pairing is a common pairing and computed by use of Miller`s algorithm. Improved version for this algorithm on supersingular elliptic curve is named &etaT . Pairing is quite computationally expensive and time consuming. Therefore, it is more attractive to implement on hardware rather than software. In this paper we proposed a new architecture for computation of pairing on F2283. This architecture is resulted from merging two parts of algorithm including pairing and final exponentiation and using resource sharing technique. The base of Tate pairing is finite field arithmetic units. Design and synthesis of this implementation are conducted using Xilinx`s FPGA. Comparison between this result and other work shows that this implementation gains % 38 improvements on calculation time and %10 improvement on product of area and time. Also software implementation is done by SAGE mathematical software for justifying of the results and generating points on elliptic curve.

In this paper we describe a designed and implemented tester system for laser warning system.This warning system detects coded laser beams and decodes those that is used in laser guidance systems. This tester is able to generate laser coded pulses and decode received pulses and compare them. Experiments have shown that by this tester, we can check the ability of the laser warning systems in laser code detection and regenerate those codes. This system has a suitable accuracy for fault detection in laser warning systems

In this research, laser listening countermeasure using absorbing layers deposited on surface of glass, which is located infront of the sound source was investigated experimentally. To do this, samples with one, two and three-layers of Al2O3, TiO2, MgF2, have made and used. Deposition performed by evaporation technique on BK7 glass substrate using electron gune beam. During the deposition, the optical thickness was controlled by the thickness monitoring system.Reflectance of gayers and relative intensity of the reflected beam from the coated glass surface were measured due to investigation of the effect of anti-reflective layers. Using the TFD Scope simulation software the sound graph was evaluated too.The results showed that at 632.8 nm laser wavelength, the sample coated by three layers of Al2O3 and TiO2, MgF2 significantly reduces the reflection of the laser beam to less than one percent.

Issue of the electromagnetic launch technology in recent decades has been considered seriously. Power supply makes up sensitive and significant part of this launchers. in the previous power supplies that designed for launchers, the energy storage such as inductors and capacitors are used, that the major disadvantage of this power supplies is great weight and size of them and this problem is a serious limitation for implementation and expansion of these launchers. Also, in some of them, is used indirect method for frequency conversion (AC-DC-AC). In this paper a scheme is proposed that by using the matrix converters, obtains the specifications required for the supply of coil-induction launcher directly, that not required to any energy storages and uses power of electricity network instead of using the energy storage resources.

This paper deals with presenting a method for improving diode-based frequency selective limiter’s performance. High limiting level, low spike leakage, low recovery time, and simple design procedure made the diode-based frequency selective limiter a good option for protection of smart antenna system from high power microwave threat. Unfortunately, due to the method of nonlinear resonator realization in these limiters, in the presence of high power out of limiting band signals of each channel limiting band attenuation in passing state of these limiters increases. In this paper, band-pass filter is employed to decreasing the effect of high power out of limiting band signals on the attenuation in the passing state of limiter. By using this technique a 2-channel FSL in center frequencies of 4.2GHz and 4.6GHz, with 0dBm limiting threshold, 30dB limiting level, and 200MHz limiting bandwidth is designed. Simulation results show that using this technique can decrease the effect of out of limiting band signals on attenuation of passing state by 9dB, and increase the linearity of frequency selective limiter in the passing state of limiter.

Vulnerability assessment of critical infrastructure is always a major concern for the country's leaders in the field of strategic management, monitoring and evaluation of the safety and security situation. To deal with the vulnerability of infrastructure and the probability of threats against them and the use of safe and efficient deterrent, it’s necessary to identify the important factors that causes damage to the infrastructure .One of the effective factors contributing to identify infrastructure is sound waves emitted by the infrastructure that has so far received little attention. The main innovation of this study is the vulnerability assessment of the infrastructure against threats that use acoustic sensors. Due to the uncertainty in predicting the behavior of acoustic waves, sensors and radar systems and the need to spatial analysis to assess the vulnerability, in this study have been trying to use fuzzy logic to model the behavior of the parameters used in the framework of a Geographic Information System. The model was implemented for the region around Natanz with hypothetical information and vulnerability map was presented at the end. Distribution of acoustic waves around infrastructure, position of radar systems, the ability to define the space around by radars and sensors are effective factors in Vulnerability assessment. Considering the hypothetical positioning, infrastructure accessible by unmanned aerial threat in a path on the southeast side. Location of radar systems, the ability to define the space around the sensors detected by the system, as well as the vulnerability of infrastructure is a decisive factor. Location of radar systems can be used to cover the access paths to minimize the vulnerability of infrastructure.

In recent years, power system security has been discussed and experiences of recent wars and conflicts have emphasized it. Power system operator uses crisis management strategies to confront threats against power system. One of these strategies is response, which means that the operator start to inject reserve power into power system while attack is taking place. Since considering some power units as reserve units is costly, the value of reserve power must be economically optimized. In this paper, a new method for calculation of system’s Energy not supplied based on Monte Carlo approach is presented. Then reserve power is optimized based on cost/benefit Analysis to minimize operation cost and energy not supplied cost of system. In critical situation, value of lost load and unavailability of components are increased and consequently the optimized value of reserve power is increased rather that normal situation. The presented method is tested on IEEE 24-bus test system and results are discussed.