Securely accessing encrypted cloud storage from multiple devices

Cloud storage services like Dropbox, Google Drive and OneDrive are increasingly popular. They allow users to synchronize and access data from multiple devices. However, privacy of cloud data is a concern. Encrypting data on client-side before uploading it to cloud storage is an effective way to ensure data privacy. To allow data access from multiple devices, current solutions derive the encryption keys solely from user-chosen passwords which result in low entropy keys. In this thesis, we present OmniShare, the first scheme to allow client-side encryption with high-entropy keys combined with an intuitive key distribution mechanism enabling data access from multiple devices. It uses a combination of out-of-band channels and cloud storage as a communication channel to ensure minimal and consistent user actions during key distribution. Furthermore, OmniShare allows the possibility of reducing communication overhead for updating encrypted data. OmniShare is freely available on popular platforms