Section: New Results

Quantitative behaviours

Several measures have been proposed in literature for quantifying the information leaked by the public outputs of a program with secret inputs. In [32] we studied how to quantify the information leaked by a deterministic or probabilistic program when the measure of information is based on min-entropy or Shannon entropy. A direct computation of these quantities is often infeasible because of the state-explosion problem. In our paper, we model the program as a pushdown system equipped with multi-terminal decision diagrams (ADDs) and propose algorithms to compute said entropies.

The advantage of this approach is that the resulting algorithms can be easily implemented in any BDD-based model-checking tool that checks for reachability in deterministic non-recursive programs by computing program summaries. We demonstrate the validity of our approach by implementing these algorithms in a tool Moped-QLeak.