Researchers from the University of California have concluded that performing a secure deletion of the contents of an solid-state drive is not a simple matter. There are two aspects to the problem: One involving the use of built-in drive command to securely erase data from the entire hard disk drive, and the use of software tools to sanitize individual files in order to preserve the file system.

Of 12 SSD drives that were examined, only seven drives were found to support the ATA Security instructions for secure purging of data. Moreover, it was discovered that two of these had an implementation bug that prevented the appropriate erase command from being executed; another was hard-coded so that the command was executed successfully--despite the fact that all its data was still intact and very much accessible.

In addition, while the conclusion that most software that works on erasing the contents of an entire drive works "most" of the time, the same cannot be said for single-file deletion. According to a table summarizing the results on page 7 of the report (.pdf), 4 percent to 75 percent of a file's content remained intact on average in tests, making it necessary to sanitize single-files at least twice.

In closing, the authors noted that an alternative way to obliterate data on a storage device would be the use of cryptographic sanitization techniques, in which the entire contents of an SSD are encrypted by default. Rather than deleting the entire drive, an erase command might entail the purging of the decryption key to render the data unrecoverable. Personally, the use of cryptographic capitalization is an option that appeals to me--that's assuming no undiscovered implementation bugs allow the decryption key to be somehow recovered.

For more on this story:
- check out this article at ITPro
- check out this article at eWeek
- check out this article at ZDNet

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