Cloud computing allows delivering information technology power on demand. Be it either the hosting of a certain web application or the outsourcing of an entire server or data center by means of virtualization. Applying these techniques however goes along with handing over the ultimate control of data to a third party. This paper investigates the application of Nimbus as a cloud resource and shows an example implementation for retaining data control to the user, based on virtual machine images encrypted on the client side. This means that the procedures involved for verifying validity and accessing the virtual machine are entirely provided by the cloud client. We provide a sample implementation of a secure virtual machine consisting of an encrypted partition, containing the data to be hosted, and a boot system, containing the logic to verify and access the encrypted partition. The details of the implementation are depicted, as applied on a cloud resource available within the AustrianGrid project.

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