Paper Title: Efficient Data Sanitization in Modern NAND Flash-Based SSDs

Paper Abstract: As data privacy and security become key requirements, securely erasing data from a storage system becomes as important as reliably storing data in the system. Unfortunately, in modern NAND flash-based SSDs, it is challenging to irrecoverably erase (i.e., sanitize) a file without large performance or reliability penalties. In multi-level cell NAND flash memory, physically destroying a page’s data 1) may require multiple reads and writes to copy the valid pages stored in the same cells and 2) can affect the reliability of the pages stored in the adjacent wordlines. We propose Evanesco, a new data sanitization technique specifically designed for high-density 3D NAND flash memory. Unlike existing techniques that physically destroy stored data, Evanesco provides data sanitization by blocking access to stored data. By exploiting existing spare flash cells in the NAND flash chip, Evanesco efficiently supports two new flash commands that disable access to deleted data at page and block granularities, respectively. Since a locked page (or block) can be unlocked only after its data is physically erased, Evanesco provides a strong security guarantee even against an advanced threat model.

Paper Author: Jisung Park, Senior Researcher and Leturer, ETH Zürich

Author Bio: Jisung Park is Senior Research and Lecturer in SAFARI Research Group at ETH Zürich. He has worked on the efficient design of NAND flash-based storage systems to improve performance, reliability, lifetime, and security/privacy. He earned his bachelor's degree in Computer Science and Ph.D. degree in Electrical Engineering and Computer Science at Seoul National University in 2011 and 2019, respectively.