Privacy Protection NAND Flash System With Flexible Data-Lifetime Control by In-3-D Vertical Cell Processing

Abstract

This article proposes a privacy-aware data-lifetime control NAND flash system (PDLCS) that changes the data-lifetime flexibly for privacy protection. The proposed PDLCS consists of four proposed techniques: 1) inverse Huffman-coding ${V}_{{\text {TH}}}$ modulation (IHVM); 2) immediate delete command (IDC); 3) adaptive lifetime extension (ALE); and 4) adaptive lifetime reduction (ALR), with In-3-D vertical cell processing of 3-D NAND flash memories. This system realizes both short- and long-term data lifetimes. Furthermore, data lifetime can be extended or shortened at any time. This cannot be realized by conventional 2-D NAND flash memories because data lifetime is controlled by the lateral charge migration in 3-D NAND flash memories. The proposed PDLCS secures privacy data and, thus, is a universal solution for future secure storage, which is not resolved by software techniques.