Protocols for Secure Communication in Wireless Sensor Networks

Abstract
Wireless sensor networks are comprised of large numbers of resource-constrained
and wirelessly communicating computing devices. Advances in computing
and communication technology have made it possible to integrate sensing capabilities,
wireless communication interfaces, and microprocessors into tiny devices
that allow to embed compuational power in arbitrary environments. The
applications of wireless sensor networks range from surveillance and environmental
monitoring to healthcare and the provisioning of context information
for computing applications. Many of these applications have a direct impact
on the welfare of human beings or are of high economic significance. Security
breaches might lead to grave consequences, so it is important to protect
wireless sensor networks against such threats.
The specific characteristics of wireless sensor networks make them vulnerable
to attacks on their communication channels and their hardware. Cryptographic
mechanisms can be employed to protect against some of the possible
attacks: eavesdropping on messages is countered by encryption, and the injection
of messages by the attacker is prevented by authentication. Unfortunately,
direct physical access to the sensor nodes allows an attacker to manipulate them
almost arbitrarily. In particular, nodes could be compromised and then made to
execute malicious code injected by the attacker. Tamper resistance mechanisms
applied to the nodes’ hardware, concealment, surveillance and other techniques
may be used to mitigate such attacks. However, they cannot be completely prevented
and therefore, any communication security scheme being used must be
sufficiently resilient to tolerate a certain amount of compromised nodes. Consequently
an important objective is to limit the impact of a set of compromised
nodes on the legitimate operation of the network to a minimum.
This objective can optimally achieved by cryptographic mechanisms that establish
a direct security relationship between communicating end-points. This
limits the influence that a single compromised node has to its own resources.
Thereby, it cannot tamper with messages that originate at other nodes. However,
such mechanisms are overly resource demanding for many sensor nodes
in terms of computational or communication complexity, especially due to the