Nowadays, we are confronted with a spectacular increase in IoT (Internet of Things) use in all aspects of human activities. Unfortunately, this development generated new vulnerabilities, exposing these systems to increasingly significant threats representing new security problems that must be solved. Furthermore, the ubiquitous availability of resources in the IoT context has also enabled an intruder to carry out more sophisticated attacks. However, the actual protection solutions are installed haphazardly. For this reason, developing new formal techniques is of the utmost importance. The lack of consideration of the formal aspect in the IoT context prompted us to define a new algebraic calculus allowing the modeling and securing of attacks in the IoT context. This paper presents a new ambient calculus called SCAC(Secure Conditional Ambient Calculus) to model IoT attacks and to suggest protection solutions. We show that the proposed calculus offers an efficient and simple modelling by an example.