Trust - Peer-to-Peer Computing: Applications, Architecture, Protocols, and Challenges - page 154

that ECC will dominate the area of developing public key cryptosystems in
WSNs [Gura et al., 2004].
Malan et al. [Malan et al., 2004] presented a public key infrastructure
(PKI) based on ECC to be executed on the MICA2 Mote. They argued that
by carefully implementing the multiplication of points on elliptic curves, PKI
for secret keys' distribution is tractable on the MICA2 platform. In fact, ECC
is believed to offer security computationally equivalent to that of RSA with
significantly smaller key size. For instance, a 163-bit ECC key is computa-
tionally equivalent to a 768-bit RSA key [Lorincz et al., 2004]. ECC offers an
alternative solution to make public key cryptography become feasible on lower
power sensor devices.
6.11 Case Study: PPLive
Similar to the incentive aspect discussed in Chapter 5, PPLive does not
incorporate any systematic trust management facilities in the client programs.
Again this approach works because the PPLive client programs are proprietary
and under centralized control. Thus, mutual trust between peers is handled
by default. However, when malicious behaviors abound (if they have not,
they will), proper trust management controllable at the user level has to be
included.
6.12 Summary
Table 6.3 gives a qualitative comparison of different trust management ap-
proaches proposed for Internet-based P2P systems. In general, for each peer,
local trust scores are based on just a sum of prior transaction ratings. But dif-
ferent approaches are employed for the global aggregation step. Based on the
simulation results reported, most of the approaches perform well in terms of
convergence rate, trust aggregation accuracy, and message overhead. One par-
ticular point to note is that the recently proposed GossipTrust scheme [Zhou
and Hwang, 2007a] is the only approach that can work under an unstructured
P2P network. This is important because future P2P systems are likely to be
unstructured to achieve a higher scalability. Reputation systems [Lethin, 2001]
are also considered as promising solutions.
Recently, there are numerous other interesting trust management schemes
proposed [Lin et al., 2007,Lu et al., 2007a,Nakajima et al., 2007,Schmidt et al.,