Ali Payandeh

Hamzeh Ghasemzadeh, Ali Payandeh, Mohammad Reza Aref

Due to hostile environment and wireless communication channel, security mechanisms are essential for wireless sensor networks (WSNs). Existence of a pair of shared key is a prerequisite for many of these security mechanisms; a task that key management system addresses. Recently, an energy efficient method based on public key cryptography (PKC) was proposed. We analyze this protocol and show that it is vulnerable to denial of service (DOS) attacks and adversary can exhaust memory and battery of nodes. Then, we analyze this protocol and show that using a more knowledgeable BS this vulnerability can be solved very efficiently. Based on this observation we propose a modified version of the protocol that achieves immediate authentication and can prevent DOS attacks. We show that the improved protocol achieves immediate authentication at the expense of 1.82 mj extra energy consumption while retaining other desirable characteristics of the basic method.

Hamzeh Ghasemzadeh, Ali Payandeh, Mohammad Reza Aref

Security is a critical and vital task in wireless sensor networks, therefore different key management systems have been proposed, many of which are based on symmetric cryptography. Such systems are very energy efficient, but they lack some other desirable characteristics. On the other hand, systems based on public key cryptography have those desirable characteristics, but they consume more energy. Recently based on authenticated messages from base station a new PKC based key agreement protocol was proposed. We show this method is susceptible to a form of denial of service attack where resources of the network can be exhausted with bogus messages. Then, we propose two different improvements to solve this vulnerability. Simulation results show that these new protocols retain desirable characteristics of the basic method and solve its deficiencies.

Hashem Moradmand Ziyabar, Mahnaz Sinaie, Ali Payandeh et al.

Recently, arithmetic coding has attracted the attention of many scholars because of its high compression capability. Accordingly, in this paper a method which adds secrecy to this well-known source code is proposed. Finite state arithmetic code (FSAC) is used as source code to add security. Its finite state machine (FSM) characteristic is exploited to insert some random jumps during source coding process. In addition, a Huffman code is designed for each state to make decoding possible even in jumps. Being Prefix free, Huffman codes are useful in tracking correct states for an authorized user when s/he decodes with correct symmetric pseudo random key. The robustness of our proposed scheme is further reinforced by adding another extra uncertainty by swapping outputs of Huffman codes in each state. Several test images are used for inspecting the validity of the proposed Huffman Finite State Arithmetic Coding (HFSAC). The results of several experimental, key space analyses, statistical analysis, key sensitivity and plaintext sensitivity tests show that HFSAC with a little effect on compression efficiency for image cryptosystem provides an efficient and secure way for real-time image encryption and transmission.