Page mapping scheme to support secure file deletion for NAND-based block devices

As the amount of digitized private data grows, security requirements such as irrecoverable file deletion are gaining importance. Existing secure file deletion tools, which repeatedly over-write the contents to be deleted, do not work properly with NAND-based block devices because these devices perform out-of-place updates on over-write requests, retaining the original data. This paper presents a method for secure file deletion in NAND-based block devices. The presented scheme maintains the over-write count and the physical locations of the original data. If the over-write count exceeds a predefined threshold, the scheme finds the original data that has been invalidated by previous over-write operations and removes the original data using the block erasure operation. The erased data is irrecoverable. Trace-driven simulation shows that the presented scheme reduces the total I/O time up to 104 % under a realistic workload compared to existing file deletion schemes.