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Trust in ICT 5

III.4.3 Service flow

Figure III.8 – Intermediate device selection service flow

 Detailed flow description (Figure III.8)
1) A user wants to exchange information with another peer in multi-hop device-to-device
environment.
2) The user's smartphone requests the social information of other devices (e.g., node 1 and node 2)
and its community of interest value.
3) The trust information provider collects relevant information from other devices.
4) Then, the trust information provider calculates trust indices of devices.
5) The trust information provider notifies the trust index to the user’s smartphone. After that, it judges
which nodes have enough authorization to send information.
6) If node 1’s trust index is the highest value, the user's smartphone makes decision that node 1 has
enough authorization to send information and select the transmission path with node 1. Then, it
starts to send information.

III.5 Used car transaction service

III.5.1 Description
While the used car market has been growing consistently in worldwide, there exists inevitable distrust in
used car transactions. Comparing to purchasing a new car, buying a used car involves high level of uncertainty
and risk. The market for used car is called as “the market for the lemons”, which is produced by asymmetric
information, in which a buyer can not accurately assess the exact condition of the car through examination
before sale is made while a seller can more accurately assess the condition of the car prior to sale. Specifically,
owners of good cars will not sell their cars while only owners of defective cars will sell their cars. When a
seller is going to sell their used vehicle, he or she has a weak motivation of disclosing the problems in the car.
As a result, consumers are hardly satisfied with the used cars because of unexpected car trouble. General
transaction model and each entity’s information level of a used car are depicted in Figure III.9.

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