Abstract: Wireless sensor networks are a current highly developed technology of networks and are employed in many application areas like in military for surveillance purpose. WSN gather data from sensor node and send it to another sensor node. Due to the distributed nature, restricted computing power, memory space and use in some sensitive application, security is a major problem, so security is very important to transfer the data from one node to another node. To provide security in this LiSP protocol is used. This paper include how much energy is consumed for secure communication between sensor nodes and base station. In this paper, encryption and decryption operation use the block cipher rather than stream cipher and key is used to create security protocol. Encryption algorithm contains two inputs, one is the user input another is the key. To produce lightweight security protocol dynamic key is used. In this paper dynamic key is generated by using different types of random number generator like RC4, Blum Blum shub and wichman random number generator. After that find out how much time and energy is consumed by this protocol. This paper contains protocol which provide secure and efficient data transmission withminimum energy and time consumption so it makes it harder and difficult to break the security of data.

Keywords: Wireless sensor networks, dynamic key, RC4, blum blum shub, whichman, encryption, decryption, one time pad, lightweight protocol.