Technology is profoundly changing the way we live. If on one hand Cloud computing has transformed today’s computing landscape, on the other hand the spread of mobile devices is changing our everyday life. Because the Cloud infrastructures perform intensive computing tasks and offers unlimited data storage, people and companies started benefit from engaging mobile apps that would not otherwise be possible. For these reasons, in order to maintain the competitive advantage, companies are now deciding to adopt mobile multi-Cloud strategies for their products and services. In this work we propose a mobile secure storage approach primarily oriented to guarantee confidentiality and integrity issues concerning data stored on smart devices which are part of a multi-Cloud environment. In this paper we presented and discussed our Android app, we called “ARIANNA”. It enables and integrates our experimental multi-Cloud framework, which description is present in literature. Moreover, in order to evaluate our proposal, we conducted several experiments by considering the mobile application in a real multi-Cloud environment scenario.