R&D: Hide-and-Seek, Hiding Secrets in Threshold Voltage Distributions of NAND Flash Memory Cells

ACM Digital Library has published, in HotStorage ’23: Proceedings of the 15th ACM Workshop on Hot Topics in Storage and File Systems, an article written by Md Raquibuzzaman, Aleksandar Milenkovic, and Biswajit Ray, The University of Alabama in Huntsville, Huntsville, AL, USA.

Abstract: “In this paper, we propose a new page-writing technique to hide secret information using the threshold voltage variation of programmed memory cells. We demonstrate the proposed technique on the state-of-the-art commercial 3D NAND flash memory chips by utilizing common user mode commands. We explore the design space metrics of interest for data hiding: bit accuracy of public and secret data and detectability of holding secret data. The proposed method ensures more than 97% accuracy of recovered secret data, with negligible accuracy loss in the public data. Our analysis shows that the proposed technique introduces negligible distortions in the threshold voltage distributions. These distortions are lower than the inherent threshold voltage variations of program states. As a result, the proposed method provides a hiding technique that is undetectable, even by a powerful adversary with low-level access to the memory chips.“