What is LKM

According to a recent Cloud Security Alliance Report, insider attacks are the third biggest threat in Cloud Security. A malicious-insider can access the low-level device, and recover the sensitive and confidential information which had been deleted by the customer with a belief that the data no more exists physically. Though proposals for secure deletion of data exist, specifically transparent per-file secure wiping extensions, however, they are not efficient and reliable. In this chapter, we propose an efficient and reliable transparent per-file-wiping filesystem extension called restfs. Instead of overwriting at file level which is found in existing wiping extensions, restfs overwrites at block level to exploit the behavior of filesystems for efficiency and reliability. We empirically evaluated the efficiency of restfs using Postmark benchmark and results indicate that restfs can save 28-98% of block overwrites which otherwise need necessarily to be performed in existing wiping extensions. In addition, it can also reduce the number of write commands issued to the disk by 88%.