A probabilistic encryption based min/max computation in wireless sensor networks

Wireless sensor networks (WSNs) have wide range of applications in military, health-monitoring, smart-home applications, and in other commercial environments. The computation of data aggregation functions like MIN/MAX is one of the commonly used tasks in many such WSN applications. However, due to privacy issues in some of these applications, the individual sensor readings should be kept secret from others. That is, the base station should be the only entity who should receive the output of MIN/MAX function and the individual sensor readings should not be revealed either to other sensor nodes or to the root node for confidentiality reasons. Existing Secure Data Aggregation (SDA) techniques for computing MIN/MAX are based on either order preserving or privacy homomorphic encryption schemes which are either inefficient or insecure. Along this direction, this paper proposes two novel solutions for securely computing MIN/MAX functions in WSNs using probabilistic encryption scheme. The first solution works for WSNs with no duplicate sensor readings whereas the second solution acts as a generic method and works even for duplicate readings but is less efficient compared to the first method. However, the second solution is much more secure compared to the existing protocols. The security of the proposed protocols is justified based on the well known quadratic residuosity assumption. We empirically analyze the efficiency of our schemes and demonstrate the advantages of the proposed protocols over existing approaches.