Developments in micro electro mechanical systems (MEMS) and wireless networks are opening a new domain in networking history. Sensors; often called "smart dust" are low cost small tiny devices with limited coverage, low power, smaller memory sizes and low bandwidth, will play a key role in collecting and disseminating data from the fields where ordinary networks are unreachable for various environmental and strategical reasons.

There have been significant contributions to overcome many weaknesses in sensor networks like coverage problems, lack in power and making best use of limited network bandwidth, however; work in sensor network security is still in its infancy stage. This paper is an effort to introduce the security issues in wireless sensor networks, highlight the current research efforts, and to determine the future directions to solve the unresolved issues.

The remainder of this paper is organised in the following way. Section 2 provides a brief...