Sensor networks are constructed with the set of sensor devices. Sensor device transfers the data to other nodes. Radio frequency is used for the data transfer process. Bandwidth and Traffic factors are considered in sensor networks. Data aggregation technique is used to transfer the sensed data from the sensor node to the base station. Privacy homomorphism encryption technique is used with the data aggregation process in sensor networks. Cluster heads can directly aggregate the cipher text without decryption. The base station only retrives the aggregated result, not individual data. Recoverable property supports the sensing data extraction from the aggregated data values.