2 research outputs found
Universal Composability is Secure Compilation
Universal composability is a framework for the specification and analysis of
cryptographic protocols with a strong compositionality guarantee: UC protocols
are secure even when composed with other protocols. Secure compilation tells
whether compiled programs are as secure as their source-level counterparts, no
matter what target-level code they interact with. These two disciplines are
studied in isolation, but we believe there is a deeper connection between them
with benefits from both worlds to reap. This paper outlines the connection
between universal composability and robust compilation, the latest of secure
compilation theories. We show how to read the universal composability theorem
in terms of a robust compilation theorem and vice-versa. This, in turn, shows
which elements of one theory corresponds to which element in the other theory.
We believe this is the first step towards understanding how can secure
compilation theories be used in universal composability settings and
vice-versa
Toward an Algebraic Theory of Systems
We propose the concept of a system algebra with a parallel composition
operation and an interface connection operation, and formalize
composition-order invariance, which postulates that the order of composing and
connecting systems is irrelevant, a generalized form of associativity.
Composition-order invariance explicitly captures a common property that is
implicit in any context where one can draw a figure (hiding the drawing order)
of several connected systems, which appears in many scientific contexts. This
abstract algebra captures settings where one is interested in the behavior of a
composed system in an environment and wants to abstract away anything internal
not relevant for the behavior. This may include physical systems, electronic
circuits, or interacting distributed systems.
One specific such setting, of special interest in computer science, are
functional system algebras, which capture, in the most general sense, any type
of system that takes inputs and produces outputs depending on the inputs, and
where the output of a system can be the input to another system. The behavior
of such a system is uniquely determined by the function mapping inputs to
outputs. We consider several instantiations of this very general concept. In
particular, we show that Kahn networks form a functional system algebra and
prove their composition-order invariance.
Moreover, we define a functional system algebra of causal systems,
characterized by the property that inputs can only influence future outputs,
where an abstract partial order relation captures the notion of "later". This
system algebra is also shown to be composition-order invariant and appropriate
instantiations thereof allow to model and analyze systems that depend on time