Gholam Reza Moghissi; Ali Payandeh
Abstract
The exact manner of BKZ algorithm for higher block sizes cannot be studied by practical running, so simulation of BKZ can be used to predict the total cost and output quality of BKZ algorithm. Sampling method of enumeration solution vector v is one of the main components of designing BKZ-simulation and ...
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The exact manner of BKZ algorithm for higher block sizes cannot be studied by practical running, so simulation of BKZ can be used to predict the total cost and output quality of BKZ algorithm. Sampling method of enumeration solution vector v is one of the main components of designing BKZ-simulation and can be divided into two phases: sampling norm of solution vector v and sampling corresponding coefficient vectors. This paper introduces a simple and efficient idea for sampling the norm of enumeration solution v for any success probability of enumeration bounding functions, while to the best of our knowledge, no such sampling method for norm of enumeration solution is proposed in former studies. Next, this paper analyzes the structure and probability distribution of coefficient vectors (corresponding with enumeration solution v), and consequently introduces the sampling methods for these coefficient vectors which are verified by our test results, while no such a deep analysis for sampling coefficient vectors is considered in design of former BKZ-simulations. Moreover, this paper proposes an approximation for cost of enumerations pruned by optimal bounding functions.
H. Ghasemzadeh; A. Payandeh; M. R. Aref
Abstract
Due to wireless nature and hostile environment, providing of security is a critical and vital task in wireless sensor networks (WSNs). It is known that key management is an integral part of a secure network. Unfortunately, in most of the previous methods, security is compromised in favor of reducing ...
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Due to wireless nature and hostile environment, providing of security is a critical and vital task in wireless sensor networks (WSNs). It is known that key management is an integral part of a secure network. Unfortunately, in most of the previous methods, security is compromised in favor of reducing energy consumption. Consequently, they lack perfect resilience and are not fit for applications with high security demands. In this paper, a novel method is proposed to improve the security of key management system based on broadcast messages from the base station. Another problem with WSNs is the cryptographic materials (such as private keys) stored in dead nodes. Adversaries may exploit these nodes to mount more effective attacks. Any secure key management system should also address this problem. It is argued that in the proposed method keying materials of dead nodes lose their validity, and therefore are of no use for an adversary. Finally, it is shown through simulation that the proposed method is almost three times more energy-efficient than conventional certificate-based key management systems.