with the arrival of the information age and much more important information systems and communication in human everyday life, necessity immunization information and communication strategy were also raised. The easiest way to meet this necessity is conventional encryption algorithms. Encryption is a right tool for data protection in an unsecure channel. To this end, from two-method symmetric key encryption and public-key cryptography are used. In this paper we examine text cryptography, one of the most important topics in cryptography. A unique attribute of this kind of encryption has been of interest to many researchers in this field. This paper, considering the symmetric encryption algorithm, provides a text encryption algorithm using a 128-bit key. The proposed algorithm uses a 128-bit key, the text data using the XOR operator to convert the encrypted information. Therefore, the aim of this method is to provide a convenient method for symmetrically encrypting data not to be easily decoded, and finally, the results of the tests show that the proposed method is better in terms of security and speed of execution.

Inthispaper, a novel grid connected photovoltaic system is proposed which can function as an Active Power Filter (APF) with Maximum Power Point Tracking (MPPT). Filter reference current is derived using Fourier Transform. Considering 33% reduction in inverter switche s, cost of the gridconnect photovoltaic power plant can be reduced considerably. Using this approach, it is also possible to compensate for reactive and harmonic components of the local loads; moreover it can inject generated active power into grid at maximum power point of the photovoltaic cells. According to this, during daytime, the proposed system injects active power to the grid and at the same time compensates for the reactive power of the load. When there is no sunlight, the inverter only compensates local loads. Considering cost reduction, such capabilities may result in more application of the grid connected photovoltaic systems. Main novelty of the proposed system is simultaneous APF and MPPT functioning using single DC/AC converter. In fact, extra DC-DC converter is not required in the proposed system for MPPT. In order to verify the performance of the proposed method, some simulation is done using MATLAB/Simulink software. Also, some experimental results are presented for practical verification of the proposed grid connected inverter.