We present a simple, yet powerful, approach for the specification
and enforcement of authorizations regulating data release among data holders collaborating in a distributed
computation, to ensure that query processing discloses only data whose release has been explicitly authorized. Data disclosure is captured by means of profiles, associated with each data computation, that describe the information carried by the result. We also present an algorithm that, given
a query plan, determines whether it can be safely executed and produces a safe execution strategy. The main advantage
of our approach is its simplicity that, without impacting expressiveness, makes it nicely interoperable with current
solutions for collaborative computations in distributed database systems.