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Deleted but Not Gone

By Thomas J. Fitzgerald
November 3, 2005

Maintaining privacy in the era of digital information requires work on a number of fronts, whether fending off spyware, protecting important files with encryption or configuring a Wi-Fi hot spot to keep interlopers off a wireless network.

One basic privacy measure, however, is easily overlooked: proper data destruction.

Deleting confidential data completely is essential when donating or selling old computers, and it can also help maintain privacy on computers that may end up lost or stolen. And for businesses looking for ways to comply with the security requirements of laws like the Sarbanes-Oxley Act, a sound policy on data control and destruction is crucial.

Data is Recoverable Until Overwritten

When normal deletion methods like the Recycle Bin or the delete command are used, the computer's operating system, for the sake of speed, creates an illusion that data has been deleted. In fact, it merely earmarks that region of a disk or drive as being available for new data to overwrite the old data. Until that overwriting occurs, the old data can be retrieved with undelete programs and tools used by data recovery labs and law enforcement agencies.

There are, however, several options for securely eliminating data from hard disks, U.S.B. flash drives and other storage media. These programs overwrite data with meaningless characters to render it unrecoverable with today's data recovery techniques. Some of the programs can overwrite entire drives, while others can single out individual files or other information saved by a computer's operating system or programs like Web browsers. Shredding machines that can destroy diskettes, CD's and DVD's are also available.

Completely Overwrite Hard Drive Data with WipeDrive

One program for wiping entire disks on Windows computers is WipeDrive from WhiteCanyon ($39.95 at www.whitecanyon.com). It offers 12 overwriting methods, including the Defense Department standard with three overwrites, although the company's president and chief executive, Steve Elderkin, said methods that use a single pass are almost always enough to render data unrecoverable.

"If you overwrite it once, it's gone," Mr. Elderkin said. But doing more than one overwrite is probably a good idea for disks more than five years old and also for smaller drives, as well as for peace of mind, he said.

WipeDrive has been available since 1996, Mr. Elderkin said. A single pass takes three to five minutes for each gigabyte of disk space, depending on factors like a disk's speed. The program can examine all sectors of a disk to verify whether overwriting was successful.

WhiteCanyon also offers MediaWiper ($39.95), a program that can overwrite data on removable storage devices like U.S.B. flash drives, memory cards, diskettes, Zip drives and external hard drives connected to U.S.B. and FireWire ports. It offers four overwriting methods, including an option with 12 passes. It also has a verification feature that can examine all sectors of a drive.