Secure deletion myths, issues, and solutions

Abstract

This paper has three goals. (1) We try to debunk several held misconceptions about secure deletion: that encryption is an ideal solution for everybody, that existing data-overwriting tools work well, and that securely deleted files must be overwritten many times. (2) We discuss new and important issues that are often neglected: secure deletion consistency in case of power failures, handling versioning and journalling file systems, and metadata overwriting. (3) We present two solutions for on-demand secure deletion. First, we have created a highly portable and flexible system that performs only the minimal amount of work in kernel mode. Second, we present two in-kernel solutions in the form of Ext3 file system patches that can perform comprehensive data and metadata overwriting. We evaluated our proposed solutions and discuss the trade-offs involved.