In such a case, when a node is compromised and
the stored keys are extracted, the damage is limited to the local area (e.g.,
the neighbors of the compromised node). Several e?®ective key management
schemes have been proposed, such as LEAP [10], SPINS [14], etc., and these
schemes can provide unique pairwise keys for each pair of nodes. However, the
cost is to have many keys to handle and manage.
2.2 Attacks on Link Layer
The link or medium access control (MAC) layer provides channel arbitration
for neighbor-to-neighbor communication. Contention-based MAC protocols
that rely on carrier sense, which let nodes detect if other nodes are transmitting,
are particularly vulnerable to several attacks. Some of the typical attacks
on the link layer are listed below.
Collision
Sensor nodes communicate with each other through a shared wireless channel.
An adversary can cause a collision by concurrently transmitting a packet
within the interference range. One byte of collision can corrupt an entire
frame. A corrupted routing packet or MAC control frame may cause large
protocol overhead. For example, a corrupted acknowledgement message could
407
Xiaojiang Du and Yang Xiao
induce costly back-o?® in some MAC protocols, e.g., IEEE 802.11 MAC [40].
Error-correcting codes can be used to provide certain defense to the collision
attack. However, error-correcting codes would not work if lots of bits received
are corrupted.
Pages:
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639