Digital safe: Secure synchronization of shared files

Cloud Storage services are increasingly adopted by users to outsource their data. These services tend essentially to synchronize data across user´s devices and to share them between different users. Two issues raise when dealing with synchronizing shared data. First, synchronizing data that are already encrypted by users to multiple destinations may clearly introduce key and access control management challenges. Second, it is essential to deal with the states constrains of the owner and the consumer. In fact, neither the owner who shared the data nor the consumer are usually connected at the same time. In the context of probative value storage of sensitive data, we focus mainly on the security requirements while considering a timely-file sharing. The shared data are synchronized for the legitimate user only for a specified period of time. A Synchronization Protocol for Digital Safe (SyncDS) is proposed and the Attribute Based Encryption (CP-ABE) is adapted to meet the data sharing requirements. In fact, a formal security validation is provided to demonstrate the safety of the proposed protocol. In addition, an implementation of the timely-file sharing is performed on the CP-ABE toolkit and integrated into the digital safe synchronization framework.