24-01-2013, 10:06 AM
Design and Implementation of TARF: A Trust-Aware Routing Framework for WSNs
1Design and Implementation.pdf (Size: 663.31 KB / Downloads: 89)
Abstract
The multi-hop routing in wireless sensor networks (WSNs) offers little protection against identity deception through replaying
routing information. An adversary can exploit this defect to launch various harmful or even devastating attacks against the routing
protocols, including sinkhole attacks, wormhole attacks and Sybil attacks. The situation is further aggravated by mobile and harsh
network conditions. Traditional cryptographic techniques or efforts at developing trust-aware routing protocols do not effectively address
this severe problem. To secure the WSNs against adversaries misdirecting the multi-hop routing, we have designed and implemented
TARF, a robust trust-aware routing framework for dynamic WSNs. Without tight time synchronization or known geographic information,
TARF provides trustworthy and energy-efficient route. Most importantly, TARF proves effective against those harmful attacks developed
out of identity deception; the resilience of TARF is verified through extensive evaluation with both simulation and empirical experiments
on large-scale WSNs under various scenarios including mobile and RF-shielding network conditions. Further, we have implemented a
low-overhead TARF module in TinyOS; as demonstrated, this implementation can be incorporated into existing routing protocols with
the least effort. Based on TARF, we also demonstrated a proof-of-concept mobile target detection application that functions well against
an anti-detection mechanism.
INTRODUCTION
Wireless sensor networks (WSNs) [2] are ideal candidates
for applications to report detected events of
interest, such as military surveillance and forest fire
monitoring. A WSN comprises battery-powered senor
nodes with extremely limited processing capabilities.
With a narrow radio communication range, a sensor
node wirelessly sends messages to a base station via
a multi-hop path. However, the multi-hop routing of
WSNs often becomes the target of malicious attacks.
An attacker may tamper nodes physically, create traffic
collision with seemingly valid transmission, drop or
misdirect messages in routes, or jam the communication
channel by creating radio interference [3]. This paper
focuses on the kind of attacks in which adversaries
misdirect network traffic by identity deception through
replaying routing information. Based on identity deception,
the adversary is capable of launching harmful and
hard-to-detect attacks against routing, such as selective
forwarding, wormhole attacks, sinkhole attacks and Sybil
attacks [4].
DESIGN CONSIDERATIONS
Before elaborating the detailed design of TARF, we
would like to clarify a few design considerations first,
including certain assumptions in Section 2.1 and the
goals in Section 2.3.
Assumptions
We target secure routing for data collection tasks, which
are one of the most fundamental functions of WSNs. In
a data collection task, a sensor node sends its sampled
data to a remote base station with the aid of other intermediate
nodes, as shown in Figure 1. Though there could
be more than one base station, our routing approach is
not affected by the number of base stations; to simplify
our discussion, we assume that there is only one base
station. An adversary may forge the identity of any legal
node through replaying that node’s outgoing routing
packets and spoofing the acknowledgement packets,
even remotely through a wormhole.
Goals
TARF mainly guards a WSN against the attacks misdirecting
the multi-hop routing, especially those based
on identity theft through replaying the routing information.
This paper does not address the denial-of-service
(DoS) [3] attacks, where an attacker intends to damage
the network by exhausting its resource. For instance, we
do not address the DoS attack of congesting the network
by replaying numerous packets or physically jamming
the network. TARF aims to achieve the following desirable
properties:
High Throughput Throughput is defined as the ratio of
the number of all data packets delivered to the base
station to the number of all sampled data packets. In
our evaluation, throughput at a moment is computed
over the period from the beginning time (0) until that
particular moment. Note that single-hop re-transmission
may happen, and that duplicate packets are considered
as one packet as far as throughput is concerned. Through-
put reflects how efficiently the network is collecting and
delivering data. Here we regard high throughput as one
of our most important goals.
Routing Procedure
TARF, as with many other routing protocols, runs as a
periodic service. The length of that period determines
how frequently routing information is exchanged and
updated. At the beginning of each period, the base
station broadcasts a message about data delivery during
last period to the whole network consisting of a few
contiguous packets (one packet may not hold all the
information). Each such packet has a field to indicate
how many packets are remaining to complete the broadcast
of the current message. The completion of the base
station broadcast triggers the exchange of energy report
in this new period. Whenever a node receives such a
broadcast message from the base station, it knows that
the most recent period has ended and a new period has
just started. No tight time synchronization is required
for a node to keep track of the beginning or ending of a
period. During each period, the EnergyWatcher on a node
monitors energy consumption of one-hop transmission
to its neighbors and processes energy cost reports from
those neighbors to maintain energy cost entries in its
neighborhood table; its TrustManager also keeps track of
network loops and processes broadcast messages from
the base station about data delivery to maintain trust
level entries in its neighborhood table.