الفهرس 
chapter 1Only 14 pages are availabe for public view
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Abstract
Security has become a challenge in wireless sensor networks (WSNs). For achieving security in WSNs, cryptography plays an important role. The present symmetric and asymmetric cryptography can offer the security levels but with many limitations. For instance key maintenance is a great problem faced in symmetric encryption techniques whereas speed is the problem of asymmetric encryption techniques even though key maintenance is easy. A hybrid encryption method that combines both symmetric and asymmetric key can provide high security with minimized key maintenance. In this thesis, anew security protocol using combination of both symmetric and asymmetric cryptographic techniques is proposed. This protocol provides three cryptographic primitives, integrity, confidentiality and authentication. It is a hybrid encryption method where elliptical curve cryptography (ECC) and advanced encryption standard (AES) are combined to provide encryption. XOR-DUAL RSA algorithm is considered for authentication and message digest-5 (MD5) for integrity. The results show that the proposed hybrid cryptographic protocol gives better performance in terms of computation time, the size of cipher text, and the energy consumption in WSN. It is also robust against different types of attacks in the case of image encryption.