An encryption approach to secure modification and deletion for flash-based storage

Reliable erasing of data from storage devices is a critical component of secure data management and is well understood for magnetic disks. However, flash memory has unusual electronic limitations that make in-place updating impossible. Many secure deletion techniques have been proposed to improve both information security and erasing reliability. This paper investigates secure modification further. First, a formal definition of the levels of reliable erasing over flash-based systems is introduced. Then, an encryption strategy and key (ESK) security module are implemented. This module encrypts confidential files and forces all the generated keys and other relevant information of each file to be stored in the same blocks. Consequently, when securely modifying or deleting files, the ESK module erases as few blocks as possible. Experimental results show that the proposed module can improve the level of information safety and can reduce the number of page copies and block erases due to reliable erasing.