  Access control is the enforcement of the authorization policy, which defines
subjects, resources, and access rights. Graph-structured data requires
advanced, flexible, and fine-grained access control due to its complex
structure as sequences of alternating vertices and edges. Several research
works focus on protecting property graph-structured data, enforcing
fine-grained access control, and proving the feasibility and applicability of
their concept. However, they differ conceptually and technically. We select
works from our systematic literature review on authorization and access control
for different database models in addition to recent ones. Based on defined
criteria, we exclude research works with different objectives, such as no
protection of graph-structured data, graph models other than the property
graph, coarse-grained access control approaches, or no application in a graph
datastore (i.e., no proof-of-concept implementation). The latest version of the
remaining works are discussed in detail in terms of their access control
approach as well as authorization policy definition and enforcement. Finally,
we analyze the strengths and limitations of the selected works and provide a
comparison with respect to different aspects, including the base access control
model, open/closed policy, negative permission support, and
datastore-independent enforcement.
