Smart building using IoT technique is used to maintain a home in a smarter way. In order to enhance the security in a home the various combinations of a sensor are used. In that PIR and MQ-6 sensors plays a major role. The data from these sensors are sent to the Arduino board and get stored in the cloud. In this paper home monitoring system along with intrusion, detection technique is used. For data security, Wireless Sensor Network (WSN) playa a major role. To facilitate data encryption, a method namely Triangle Based Security Algorithm (TBSA) based on efficient key generation mechanism was proposed.