Multi-level Crypto Disk: Secondary Storage with Flexible Performance Versus Security Trade-offs

Secondary storage devices have become increasingly vulnerable to security attacks as they are now accessed remotely, attached to mobile devices, or used in other previously unanticipated operating environments. Storage vendors have responded to this by offering solutions that encrypt data on the fly-in software or device firmware-before recording. The performance versus security trade-off offered by these secure devices is limited due to their use of only a single level of data encryption. To address these limitations, we propose the Multi-level Crypto Disk (MLCD), a generic storage device with multiple crypto levels for encoding data. Using stochastic modeling, we derive optimal policies to dynamically select crypto levels for data in an MLCD to achieve desired performance versus security trade-offs.