Flash Watermark: An Anticounterfeiting Technique for NAND Flash Memories

This article demonstrates a novel technique for watermarking commercial off-the-shelf NAND flash memory chips. The technique uses repeated program-erase stressing to selectively control the physical properties of the flash cells and hence imprint watermark information into the flash media in an irreversible manner. It is accompanied by a watermark reading method that uses program disturb effects to extract the physical properties of flash memory cells containing watermark. The experimental evaluation, using several commercial flash memory chips, shows that the proposed technique offers robust watermarks that cannot be easily altered using fault injection attacks such as localized heating. We demonstrate a low bit error rate ( <; 1%) in the retrieved watermark data and moderately high-speed watermark imprinting (≈1 kb/s) and watermark retrieval (≈32 kb/s). The proposed technique does not require any hardware modifications, making it a cost-effective anticounterfeit solution for a wide range of NAND-flash-based storage products.