Access control in sensor networks is used to authorize and grant users the right to access the network and data collected by sensors .Different users have different access right due to the access restriction implicated by the data security and confidentiality .Even though symmetric-key scheme, which has been investigated extensively for sensor networks, can fulfill the requirement, public-key cryptography is more flexible and simple rendering a clean interface for the Security component .We quantify the energy cost of authentication and key exchange based on public-key cryptography on an 8-bit microcontroller platform .We present a comparison of two public-key algorithms, RSA and Elliptic Curve Cryptography (ECC), and consider mutual authentication and key exchange between two untrusted parties such as two nodes in a wireless sensor network .Our measurements on an Atmel ATmega128L low-power microcontroller indicate that public -key cryptography is very viable on 8-bit energy constrained platforms even if implemented in software.

As a significant verification method, digital signature algorithm introduces a technique to endorse what the contents of the message. This message has not been altered throughout the communication process. Due to this, it increases the receiver confidence that the message was unchanged. However, two issues that required to be addressed are large size of the ciphered data in digital signature and making it closer to the original file.  The objective of this paper is to present the adoption of digital signature as a stegano-image into the main image and the LSB steganographic method is capable to increase the security. The benefits of this encryption algorithm are computational efficiency, digital signature with the size as small as 8 bytes and minimize bandwidth in comparison with other digital signature methods. In messages with the sizes smaller than 1600 bytes, the hashed file reduces the original file up to 8.51%.

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In recent years, renewable energy based power plants, especially wind and solar farms are increasingly installed and operated for electric power generation. Uncertainty nature associated to the generated power of these power plants, arisen from variability of wind speed or solar radiation, effects on different aspects of power system such as reliability, operation, dynamic and so on. Energy storages in connection with renewable power plants can reduce the variability and uncertainty nature of these renewable resources. In recent years the flow batteries such as vanadium redox (VR) with large capacities are developed and so in this paper effect of this largecapacity energy storages on the reliability performance of power system containing large-scale wind and photovoltaic (PV) farms are investigated. The renewable energy-based power plants and also energy storages are different from conventional units, so, for study of power system containing these resources new methods and techniques must be developed. To this end in this paper for reliability evaluation of renewable-energy based power system containing energy storage, an analytical approach is proposed. This approach can be employed both in planning and also operation studies of the power system when large scale wind and photovoltaic farms with energy storages exist. Data associated to wind speed of Manjil and solar radiation of Jask regions both in Iran are utilized for studying the reliability evaluation of RBTS and also IEEERTS in planning phase.

Steganography is a method of sending confidential information in a way that the existence of the channel in this communication remains secret. A collaborative approach between steganography and digital signature provides a high secure hidden data. Unfortunately, there are wide varieties of attacks that affect the quality of image steganography. Two issues that required to be addressed are large size of the ciphered data in digital signature and high bandwidth. The aim of the research is to propose a new method for producing a dynamic hashed message algorithm in digital signature and then embedded into image for enhancing robustness of image steganography with reduced bandwidth. A digital signature with smaller hash size than other hash algorithms was developed for authentication purposes. A hash function is used in the digital signature generation. The encoder function encoded the hashed message to generate the digital signature and then embedded into an image as a stego-image. In enhancing the robustness of the digital signature, we compressed or encoded it or performed both operations before embedding the data into the image. This encryption algorithm is also computationally efficient whereby for messages with the sizes less than 1600 bytes, the hashed file reduced the original file up to 8.51%.