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Reliably Erasing Data From Flash-Based Solid State Drives

Interesting paper by Wei at all.

“.. Sanitizing storage media to reliably destroy data is an essential aspect of overall data security. We have empirically measured the effectiveness of hard drive-centric sanitization techniques on flash-based SSDs. For sanitizing entire disks, built-in sanitize commands are effective when implemented correctly, and software techniques work most, but not all, of the time. We found that none of the available software techniques for sanitizing individual files were effective. To remedy this problem, we described and evaluated three simple extensions to an existing FTL that make file sanitization fast and effective. Overall, we conclude that the increased complexity of SSDs relative to hard drives requires that SSDs provide verifiable sanitization operations ..”

“Reliably Erasing Data From Flash-Based Solid State Drives”
Michael Wei, Laura M. Grupp, Frederick E. Spada, and Steven Swanson – last access 16 March 2011 – ( The Paper )

“.. In research that has important findings for banks, businesses and security buffs everywhere, scientists have found that computer files stored on solid state drives are sometimes impossible to delete using traditional disk-erasure techniques.

Even when the next-generation storage devices show that files have been deleted, as much as 75 percent of the data contained in them may still reside on the flash-based drives, according to the research, presented at the Usenix FAST 11 conference in California. In some cases, the SSDs, or sold-state drives, incorrectly indicate the files have been “securely erased” even though duplicate files remain in secondary locations.

The difficulty of reliably wiping SSDs stems from their radically different internal design. Traditional ATA and SCSI hard drives employ magnetizing materials to write contents to a physical location that’s known as the LBA, or logical block address. SSDs, by contrast, use computer chips to store data digitally and employ an FTL, or flash translation layer, to manage the contents. When data is modified, the FTL frequently writes new files to a different location and updates its map to reflect the change ..”

“Flash drives dangerously hard to purge of sensitive data”
Dan Goodin, The Register UK, 21 February 2011 – last access 16 March 2011 – ( News Article )



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