A survey showed that the possibility of missing security  is the number one reason for most users not to use the cloud (Rittinghouse  & Ransome, 2009). The trust in the cloud has to be established through making  sure that the data is stored securely and an access management is implemented  so only entitled users are able to access it. This depends on the enforcement  of security policies by the provider, e.g. access control and data encryption.