In order to provide certified security services we must provide indicators that can measure the level of assurance that a complex business process can offer. Unfortunately the formulation of security indicators is not amenable to efficient algorithms able to evaluate the level of assurance of complex process from its components. In this paper we show an algorithm based on FD-Graphs (a variant of directed hypergraphs) that can be used to compute in polynomial time (i) the overall assurance indicator of a complex business process from its components for arbitrary monotone composition functions, (ii) the subpart of the business process that is responsible for such assurance indicator (i.e. the best security alternative). Categories and Subject Descriptors K.6.5 [Management of Computing and Information Systems]: Security and Protection; C.4 [Performance of Systems]: Measurement techniques; Reliability, availability, and serviceability; G.2.2 [Discrete Mathematics]: Graph Theory—Hyperg...