Wireless Sensor Network (WSN) plays a vital role in emerging sensing technology. They are used in various fields such as military operations, healthcare applications, traffic control, and home applications. Even sensor can monitor, pressure, humidity, noise level, temperature, soil makeup and other properties. Wireless Sensor Network can be of consist of different types of sensors like thermal, visual, infrared, acoustic and radar. Wireless Sensor Network (WSN) is broadcast nature of the wireless communication so it becomes easy for the attacker to send false data or false information to compromise the entire network due to which there are high chances that causes problem in making decision. Here the solution proposed is MAC (Message Authentication Code), Authentication is necessary for many administrative tasks informally; data authentication allows a receiver to verify that the data really is sent by the claimed sender. If the message is from claimed sender then the message or information is accepted or if the message is from not from the claimed sender then the message or information is not accepted