Page 76 - Trust in ICT 2017

1 Trust in ICT

The evidence of trust guarantees may be coming from different sources including users reviews and ratings,
from various estimations such could be an estimation of popularity, then from third party services assessing
the QoS and data (e.g. detection of accuracy of a wind sensor by comparing the data with the data of other
wind sensors in the same area) or performing static code analysis to detect possible negative effects of the
execution, etc.

8.2.3.1 Trust Network in Friend of a Friend (FOAF) scheme [79]
Friend-Of-A-Friend (FOAF) is one project that allows users to create and interlink statements about who they
know, building a web of acquaintances. The FOAF schema [24] is an RDF vocabulary that a web user can use
to describe information about himself, such as name, email address, and homepage, as well as information
about people he knows. In line with the security mentioned before, users can sign these files so information
will be attributed to either a known source, or an explicitly anonymous source. People are identified in FOAF
by their email addresses, since they are unique for each person.
In this project, a schema was introduced, designed to extend foaf:Person, which allows users to indicate a
level of trust for people they know. Since FOAF is used as the base, users are still identified by their email
address. Trust schema adds properties with a domain of foaf:Person. Each of these new properties specifies
one level of trust on a scale of 1-9. The levels roughly correspond to the following:
1) Distrusts absolutely
2) Distrusts highly

3) Distrusts moderately
4) Distrusts slightly
5) Trusts neutrally
6) Trusts slightly
7) Trusts moderately
8) Trusts highly

9) Trusts absolutely.d
Trust can be given in general, or limited to a specific topic. Users can specify several trust levels for a person
on several different subject areas. Users can specify topic specific trust levels to refine the network. For
example, Bob may trust Dan highly regarding research topics, but distrust him absolutely when it comes to
repairing cars. Using the trust ontology, the different trust ratings (i.e. "distrustsAbsolutely,"
"trustsModerately," etc.) are properties of the "Person" class, with a range of another "Person". These
properties are used for general trust, and are encoded as follows:
<Person rdf:ID="Joe">
<mbox rdf:resource="mailto:bob@example.com"/>

<trustsHighly rdf:resource="#Sue"/>
</Person>

Another set of properties are defined for trust in a specific area. They correspond to the nine values above,
but are indicated as trust regarding a specific topic (i.e. "distrustsAbsolutelyRe," "trustsModeratelyRe," etc.).
The range of these topic specific properties is the "TrustsRegarding" class, which has been defined to group
a Person and a subject of trust together. The "TrustsRegarding" class has two properties: "trustsPerson"
indicates the person being trusted, and "trustsOnSubject" indicates the subject that the trust is about. There
are no range restrictions on this latter property, which leaves it to the user to specify any subject from any
ontology.

8.2.32 Konfidi – Trust Network using PGP and RDF [80]
A RDF schema is used with the FOAF to represent trust relationships and a rating system. The Kondifi is also
same approach to Trust.

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