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 later, 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.
So, what can we do ?According to scientists at the University of California at San Diego, different wiping techniques left varying levels of information behind. Up to 67% of data remained when using Mac’s OSX secure wipe. Up to 58% of data was recoverable when using British HMG IS5. Pseudorandom wipes were the worse, up to 75% of wiped data was recoverable.
Maybe wiping the entire free space would be a solution, but it is a large waste of ressources in order to get rid of only one file.
Flash drives dangerously hard to purge of sensitive data ? The Register
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