  Sharing confidential information in distributed systems is a necessity in
many applications, however, it opens the problem of controlling information
sharing even among trusted parties. In this paper, we present a formal model in
which dissemination of information is disabled at the level of the syntax in a
direct way. We introduce a subcalculus of the pi-calculus in which channels are
considered as confidential information. The only difference with respect to the
pi-calculus is that channels once received cannot be forwarded later on. By
means of examples, we give an initial idea of how some privacy notions already
studied in the past, such as group creation and name hiding, can be represented
without any additional language constructs. We also present an encoding of the
(sum-free) pi-calculus in our calculus.
