Multi-level Crypto Disk: Secondary Storage with Improved Performance vs Security Trade-offs

Hard disk drives are becoming increasingly vulnerable to security attacks as they are now accessed remotely, attached to mobile devices or used in other previously unanticipated operating environments. Protecting data while at rest has emerged as a chief concern for storage vendors who have introduced secure disks in the market. These devices are capable of encrypting data on the fly before recording on the media. In this work, we show the inadequacies of current single level encryption hard disk drives in exploiting performance vs security trade-offs and propose secure disks with multiple crypto levels. We focus on modeling such devices and propose stochastically optimal policies to dynamically select crypto levels for disk data in order to maximize a notion of security that we call ”goodness of Security” while adhering to performance bounds. Simulation studies using synthetic and real disk traces show that our proposed policies achieve better levels of security than the best current practices without violating the performance bounds.