Protocols for Secure Communication in Wireless Sensor Networks

Chapter 1
Introduction
1.1 Background
Wireless sensor networks are comprised of small, low-cost, resource-restricted
devices that have the capability to communicate and interact with their environment,
either only passively by sensing certain parameters, or also actively by
triggering actuators. The major limiting factor in their design and operation is
their restricted energy supply. Their computational capabilities are comparable
to those found in embedded systems, as they are based on similar hardware designs.
Sensor nodes employ wireless communication in order to exchange data
with their peers. This is based mostly on radio communication, but there are
some designs that employ alternatives, such as optical communication.
Initially, sensor networks were conceived for military applications, for example
to track moving objects in inaccessible terrain. Due to their small size
and low cost, they would allow for concealed deployment in large quantities.
Recently they also have aroused interest in civilian applications, for example
as monitoring tools in health applications, to collect environmental data, or to
improve agriculture.
In many application scenarios, security is a critical property of sensor networks,
for example in the healthcare domain where sensitive data is handled.
Without adequate security, the acceptance of sensor networks as a tool will
likely be limited. It is therefore important to understand what the risks are
when operating a sensor network in a sensitive environment, and how these
risks can be countered.
Sensor networks are vulnerable against attacks from the outside as they are
using an openly accessible medium for communication. This allows an attacker
to intercept messages, or interfere with transmissions, for example by jamming
the radio channel or replaying intercepted messages. Insider attacks are possible
if the attacker manages to inject his own sensor nodes into the network