Protocols for Secure Communication in Wireless Sensor Networks

5.5. Related Work 155
separation.
Figure 5.15: An example for circle based geographic multi-path routing. The crosses indicate
the centers of the circles
Spatially separated paths are also created by the approach proposed by Voigt
et al. [185] with the intention of avoiding interference between transmitting
nodes. The goal is to allow the transmission of messages on multiple paths
at almost the same time. To that end, a “forbidden zone” between sender and
target is established, which is a corridor of a certain width through which a
message may not be routed. Two paths around this corridor, one on each side,
are established for routing. If the corridor is broad enough, interferences are
minimized.
5.5.3 Threshold Security
Generally, the attacker model in a multipath environment is determined by an
upper bound k, where k is the number of compromised paths between a fixed
source and a fixed destination [165]. Compromising a path means either that
messages on this path can be read by the attacker (a passive attack, breaking
the secrecy), or that messages can be manipulated or injected by the attacker
(an active attack, breaking the resilience).