  In this paper, we deal with the formal verification of an encryption scheme
for Wireless Sensor Networks (WSNs). Especially, we present our first results
on building a framework dedicated to modelling and verification of WSNs
aspects. To achieve our goal, we propose to specify WSNs models written in
Petri nets using Promela constructs in order to verify correctness properties
of them using SPIN Model checker. We first specify in Promela a Petri net
description of an encryption scheme for WSNs that describes its behavior. Then,
correctness properties that express requirements on the system's behavior are
formulated in Linear Temporal Logic (LTL). Finally, SPIN model checker is used
to check if a specific correctness property holds for the model, and, if not,
to provide a counterexample: a computation that does not satisfy this property.
This counterexample will help to detect the source of the eventual problem and
to correct it.
