In this thesis, we consider the problem of providing emergency support when existing communication infrastructure is unavailable. We propose using opportunistic communications (oppcomms) among mobile devices carried by civilians for the
dissemination of emergency information. With oppcomms, devices exchange mes-
sages at a close range of a few to tens of meters with limited or no infrastructure
and messages are carried over multiple hops in a "store-carry-forward" manner by
exploiting human mobility. We specifically look at the evacuation component of
emergency response and propose an emergency support system (ESS) based on oppcomms to provide evacuation guidance to civilians in small-scale and large-scale
urban emergencies in the absence of other means of communication. We evaluate the
evacuation performance of ESS and investigate the communication characteristics
of oppcomms for emergency support by simulation experiments. Our evaluations
show that ESS improves evacuation by up to 31% and 14% compared to shortest
path evacuation in large and small scale emergencies, respectively, and by up to 9%
compared to a static-node based building evacuation system. We also investigate
the resilience and security of oppcomms for emergency support under node failures
and network attacks. We consider insider attacks where some nodes participating
in oppcomms are compromised and misbehave. We investigate three different types
of misbehaviour, including dropping packets, signal jamming and a hybrid attack
on routing and evacuation that uses data falsification. Our evaluations show that
node failures up to 20% are well-tolerated, and that data falsification has the most significant effect on evacuation by decreasing performance by up to 54%. In order to
improve resilience of the system to such attacks, we propose a collaborative defense
mechanism that combines identity-based cryptography and content-based message verification, and show that our defense mechanism improves performance by up to
50% in the presence of attacks.