Page 56 - Trust in ICT 2017

1 Trust in ICT

in building initial trust bootstrapping, coalition operations without predefined trust, and authentication of
certificates generated by another party when links are down or ensuring safety before entering a new zone.
In addition, trust management has diverse applicability in many decision making situations including intrusion
detection, authentication, access control, key management, isolating misbehaving nodes for effective routing
and other purposes.
As shown in Figure 6, trust management, including trust establishment, trust update and trust revocation in
MANETs is also much more challenging than in traditional centralized environments. For example, collecting
trust information or evidence to evaluate trustworthiness is difficult due to changes in topology induced by
node mobility or node failure. Further, resource constraints often confine the trust evaluation process only
to local information. The dynamic nature and characteristics of MANETs result in uncertainty and
incompleteness of the trust evidence, which is continuously changing over time [115].

Figure 6 – Trust Management Tasks break down

Figure 7 – General Trust Model with Trust Metrics and Technical Attributes

Due to the unique characteristics of MANET environments and the inherent unreliability of the wireless
channel, the concept of trust in MANETs should be carefully defined. The main properties of trust in MANET
environments can be summarized as follows (See Figure 24).
Although many trust management schemes have been proposed to evaluate trust values, no work clearly
addresses what should be measured to evaluate network trust. [35] defined trust in their model as reliability,
timeliness, and integrity of message delivery to the intended next-hop. Also most trust based protocols for
secure routing calculated trust values based on the characteristics of nodes behaving properly at the network
layer. Trust measurement can be application dependent and will be different based on the design goals of
proposed schemes.

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