To provide secure cloud services to its users, a cloud provider needs to cater for both end-to-end security, which covers the transfer of data between the user and the cloud provider, and data-at-rest security, which concerns the security of the data stored in the cloud provider premises. Encryption can provide proven solutions to both. At the same time, storage efficiency in multi-tenancy environments can be enhanced by mechanisms such as deduplication, which reduces the storage cost by allowing users to share same pieces of data, without the users being aware of the underlying mechanisms. Ideally we would like to combine encryption with multi-tenancy; however, well encrypted data will not exhibit any common pieces that can be leveraged by deduplication mechanisms. Therefore, GRNET requires a mechanism which provides data security features while supporting multi-tenancy in the cloud. The process must be simple but also secure enough for the end-user so that cloud use becomes both practical and trustworthy.
GRNET operates, at a production level, a fully functional cloud Infrastructure as a Service (IaaS) called ~okeanos. The ~okeanos service offers both computing and storage resources on demand to thousands of users. As the number of users increase, in tandem with their needs, it becomes imperative to handle resources such as storage more efficiently. An obvious solution is to adopt deduplication techniques for all kinds of data. However, this entails computational cost; moreover, it is not yet clear how to couple deduplication with increased security guarantees, such as those offered by strong cryptography, in a multi-tenant environment.
GRNET offers its cloud services via the open source Synnefo cloud management stack, developed by GRNET. Interaction with Synnefo is done through a well-defined, OpenStack-compatible API. Unfortunately, deduplication and encryption are currently beyond the scope of OpenStack. For online file storage (as opposed to block or volume storage), GRNET already offers deduplication for files, using content-addressable storage. However, there is, as of yet, no fully-fledged deduplication solution for all kinds of data; additionally, there is currently no solution offering the combination of deduplication with end-to-end and data-at-rest security.
Expected Outcomes and Contribution of TREDISEC
GRNET would like to achieve stronger data isolation to enforce the access control against unauthorized physical data access in the cloud scenario. As with Use Case 1, GRNET expects to combine its own engineering strengths with the research excellence of the TREDISEC partners so that novel encryption in multi-tenancy solutions can be brought into a production environment.