Energy Efficient Encryption using Counter mode of operation in Wireless Sensor Network A. Shish Ahmad, B. Dr. Mohd. Rizwan Beg CSE Department, Integral University, Lucknow, India Abstract- Sensor networks are deployed for various monitoring applications. The reporting should be in secure manner so that the adversary can’t forge the data and can be prevented from any disclosure. In this paper we have identified those calculations which are not necessary to be performed on sensor node for securing the network, shifted to base stations to save the energy at nodes. Using pre-processing approach saves energy consumption at nodes for producing Secured/ Encrypted data. So here we are proposing EEECMO method Energy Efficient Encryption using Counter mode of operation in such a way that before the deployment, the base station process the part of the security algorithm that involve the key in the setup phase. In this fashion, we are getting secure communication network without the distribution of the key among the sensor nodes and also minimizes energy consumption at sensor node. Key Words- Sensor network, Security, confidentiality, Block Cipher, Encryption and Decryption, , Counter mode, pre-processing, Stream Cipher. 1. Introduction Wireless sensor networks have become a promising future to many applications, such as smart houses, smart farms, smart parking, smart hospitals, habitat monitoring, building and structure monitoring, distributed robotics, industrial and manufacturing, and national security. In addition to common network threats, sensor networks are more vulnerable to security breaches because they are physically accessible by adversaries. Imagine the damage caused by compromised sensor network in sensitive military and hospital applications. These are often deployed in unattended environments, thus leaving these networks vulnerable to passive and active attacks by the adversary. The conversation between sensor nodes Can be eavesdropped by the adversary .The adversary can be aware of the conversation between the sensors and can forge the data. Sensor nodes should be resilient to these attacks. Since Sensor nodes are resource constrained and run on battery, energy consumption should be low to make it operate for many days. Confidentiality is very much concern in battle- field scenarios, where fraudulent node impersonate as a legitimate sensor. Security in ad hoc networks is an essential component for basic network functions like packet forwarding and routing and network operation can be easily jeopardized if countermeasures are not embedded into the basic network functions at the early stages of their design. The disclosure threat involves the leakage of Security information from the system to a party that should not have seen the information and is a threat against the confidentiality of the information. Data confidentiality is a core security primitive for ad hoc networks. It ensures that the message cannot be understood by anyone other than the authorized personnel. With wireless communication, anyone can sniff the messages going through the air, and without proper encryption all the information is easily available. Due to the small battery backup of Sensor Node, security algorithm must consume low power. Symmetric key are efficient for providing security services like confidentiality. Security Solutions should minimize the amount of computation and communication required to ensure the security services to accommodate the limited energy and computational resources of mobile, ad hoc-enabled devices. Generally DES algorithm is a basic building block for providing data security. To apply DES in a variety of applications, four `”modes of operations have been defined. These four modes are intended to cover virtually all the possible applications of encryptions of encryption for which DES could be used. Here we are proposing Energy Efficient Encryption using Counter mode of operation (EEECMO) using DES algorithm for providing confidentiality in such a way that total energy consumption decreases at Sensor node. Using the property of property of pre-processing in CTR, we pre-process those steps which is not necessary to be performed at sensor node to base station. The Proposed method uses the key at the base station only to produce the credential that play role to encrypt the sensed data at Sensor nodes/sensor aggregator, so there is no need to distribute the key in sensor network. It saves a lot of problem arises to distribute the key as well as saves energy to distribute the key. 2. Counter MODE (CTR)