Trust is first of all a mental state, an attitude towards
another agent (usually a social attitude). Delegation
necessarily is an action, a result of a decision, and it also
creates and is a (social) relation among X, Y, and the action A.
Considerations on UMA Trust Model UMA trust model can be showed
through the tree phases of the entire process: The first two
phases can be consolidated in a unique and fundamental element
that we call Bootstrapping Trust. Through UMA, which is an user
centric Identity management system, a Subject is able to control
what information will be revealed for what purpose with which
parties. Based on these elements, the following table describes
the main factors that we consider relevant to measure the level
of trustworthiness for each party involved in the protocol:
Bootstrapping trust in UMA is referred to the initial process to
create a trust relationship among the three main parties:
Authorizing User, Host and Authorization Manager. The following
picture shows the possible alte