Enforcing security properties in a Cloud is a difficult task, which requires expertise. However, it is not the only securityrelated challenge met by a company migrating to a Cloud environment. Indeed, the tenant must also have assurance that the requested security properties have effectively been enforced. Therefore, the Cloud provider has to offer a way of monitoring the security. In this paper, we present a solution to express the assurance properties based on the security requirements of the tenant and to deploy these assurance properties. First, we introduce a language that expresses the assurance based on the tenant's security requirements. Secondly, we propose an infrastructure that deploys the assurance in a Cloud environment. This solution aims to be easy to use: the assurance directly results from the high-level expression of the tenant's security requirements, and no additional action is needed from the tenant. Consequently, we address one of the greatest drawback of security and assurance -the complexity of their configuration -while providing a complete assurance mechanism.