Summary: A Modal Deconstruction of
Access Control Logics
and Mart´in Abadi2,3
Carnegie Mellon University
University of California, Santa Cruz
Microsoft Research, Silicon Valley
Abstract. We present a translation from a logic of access control with
a "says" operator to the classical modal logic S4. We prove that the
translation is sound and complete. We also show that it extends to logics
with boolean combinations of principals and with a "speaks for" relation.
While a straightforward definition of this relation requires second-order
quantifiers, we use our translation for obtaining alternative, quantifier-
free presentations. We also derive decidability and complexity results for
the logics of access control.
In computer systems, access control checks restrict the operations that users, ma-