Token Based Privacy Preserving Access Control in Wireless Sensor Networks

In large scale Wireless Sensor Network the network owner and the users of the sensor network may be different. A distributed access control module allows the users to access data from the network for which the user has privileges. The users of such a network required the privacy of their identity and access patterns from the network and other users. To support this user privacy previous works proposed techniques where a user sends a query with a signature generated based on a group of authorised users. With such a technique the sensor nodes verify the query and know it is a valid signature without being able to know the actual signer of the query. Due to this signer ambiguity in such an approach the dishonest or malicious users are not identified. In this paper, we present Token based Privacy Preserving Access Control (TPPAC) algorithm which preserves essential user privacy and identify the dishonest user. A set of tokens are distributed to different user groups by the network owner. A network user sends the query with signature based on the group and the token. This is verified by the sensor nodes and token count is stored. When a threshold value is exceeded for the token count it is reported to network owner for necessary actions. The experimental results show our algorithm is attack resilient and efficient that provides distributed privacy preserving access control.