Most of the data outsourced to the cloud is prone to changes. Such changes include appending new data, modifying chunks of existing data, or deleting parts of the outsourced data. Besides the classical challenge of synchronization that cloud service providers should solve when multiple users update outsource concurrently, we should also ensure in TREDISEC that our security mechanisms work seamlessly in the presence of dynamic data. Namely, a cloud customer should not be impelled to download her (entire) data to perform a small change. Ideally, this requirement should be met in all the TREDISEC use-cases. However, in TREDISEC we prioritise the file sharing use-cases.