ABSTRACT
Due to the broadcast nature of the wireless channel, information
transmitted over a wireless network can be accessed by unautho-
rized users, also referred to as eavedroppers. Ensuring that only
the legitimate receiver will be able to decipher the transmitted
information has been traditionally achieved by cryptographic
approaches operating at various layers of the network protocol
stack, e.g., WEP (LAN, 1990), at the link layer, SET (SET, 1997),
at the application layer, IPSec (IPSec, 2000), at the network layer,
TLS/SSL (SSL, 1996), and WTLS (WAP, 2002) at the transport layer.
However, cryptographic protocols, mainly developed for wireline
networks, impose significant challenges to wireless devices, which
typically have limited resources. They require significant storage
overhead (Liu et al., 2006) and computational power, thus impacting
battery life (Potlapally et al., 2006). Further, they rely on secret
keys, and key distribution and management over wireless networks
is difficult and expensive (NIST Report, 2009). It should be noted
that a cryptographic approach does not prevent an unauthorized
user from receiving the transmitted packet; it just makes it
computationally difficult for the unauthorized user to decrypt the
message contained in the packets.
