Cloud storage services are currently a commodity that allows users to store data persistently, access the data from everywhere, and share it with friends or co-workers. The number of cloud services is growing rapidly but with low interoperability between them; consequently, managing and sharing files between users of different cloud storage is very difficult. To address this problem, specialized cloud aggregator systems emerged that provide users a global view of all files in their accounts and enable file sharing between users from different clouds. To remove the need to trust the cloud providers, Crypto Cloud solution provides the full encryption of stored data, allowing to use multiple cloud storage providers to securely store files.