This is a formalization of bounded-deducibility security (BD security), a flexible notion of information-flow security applicable to arbitrary transition systems. It generalizes Sutherland's classic notion of nondeducibility by factoring in declassification bounds and trigger, whereas nondeducibility states that, in a system, information cannot flow between specified sources and sinks, BD security indicates upper bounds for the flow and triggers under which these upper bounds are no longer guaranteed.BSD License
[2021-08-12] Generalised BD Security from I/O automata to nondeterministic transition systems, with the former retained as an instance of the latter (renaming locale BD_Security to BD_Security_IO). Generalise unwinding conditions to allow making more than one transition at a time when constructing alternative traces. Add results about the expressivity of declassification triggers vs. bounds, due to Thomas Bauereiss (added as author).