  An access control model called Zero Trust Architecture (ZTA) has attracted
attention. ZTA uses information of users and devices, called context, for
authentication and authorization. Zero Trust Federation (ZTF) has been proposed
as a framework for extending an idea of identity federation to support ZTA. ZTF
defines CAP as the entity that collects context and provides it to each
organization (Relying Party; RP) that needs context for authorization based on
ZTA. To improve the quality of authorization, CAPs need to collect context from
various data sources. However, ZTF did not provide a method for collecting
context from data sources other than RP. In this research, as a general model
for collecting context in ZTF, we propose a method of linking identifiers
between the data source and CAP. This method provides a way to collect context
from some of such data sources in ZTF. Then, we implemented our method using
RADIUS and MDM as data sources and confirmed that their contexts could be
collected and used.
