Cold chain supervision is essential in our everyday life to ensure healthy fresh and frozen products and distribution of efficient vaccines. A network of sensors attached to the carriers palettes is investigated in the French CAPTEURS project. In case of cold chain failures, alarms are generated and registered in nearby sensors so any sensor of the same network can report the failure problem. This sensor based solution is price competitive, but for reliability guarantee, for instance, to avoid carriers to hide temperature problems occurring during transportation, it requires introducing few security functions. This paper describes a light and simple security solution that fits the cold chain context and gives feedback on the first tests