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If you keep business, medical, or personal financial information on
disks, simple file deletion or drive erasure isn’t enough to protect
the data when disposing of the equipment.
Besides identity
theft, data loss may leave you or your institution liable under federal
laws such as HIPAA, Sarbanes-Oxley, Graham-Leach-Bliley or other state
laws. Criminal penalties include fines and prison terms up to 20 years.
Not to mention the civil suits that can result.
There are
several approved methods for data sanitation that satisfy these legal
requirements or meet even more stringent corporate or government
secrecy requirements. Many methods for sanitizing data include deleting
files, drive formating, block overwrite, in-drive secure erase,
physical drive destruction, degaussing, and encryption.
Block erase is most commonly used. While it is much better than no
erase, or file deletion, or drive formatting, it is vulnerable to
incomplete erasure of all data blocks, like data blocks reassigned by
drives, multiple drive partitions, host protected areas, device
configuration overlays, and drive faults.
Currently, with Mac
OS X 10.4.10, Disk Utility supports drive formating and three different
block erase methods, but recent documents from US Government’s National
Institute of Standards and Technologies (NIST 800-88) state that new ATA drives built secure erase is more secure. This built-in secure erase offer the same level of security as physically destroying the drive, but the drive can be re-used and it doesn't impact the environment with the by-products of destroying the media.
Disk Utility
Disk Utility is a Mac OS X utility that
performs disk-related tasks, it has graphical-user-interface (GUI) an
command line versions. It supports disk erasing, formating and
partitioning. For example below is the interface for erasing media.
Also, supports three levels of block overwrite. It supports a zero-out
erase, a 7-pass erase, or a 35-pass erase. A zero-out erase sets all
data bits on the disk to 0, while 7-pass and 35-pass use Gutmann
algorithms of varying complexity to overwrite the disk.
Darik's Boot and Nuke ('DBAN')
Darik's Boot and Nuke ('DBAN') is a popular open source block overwrite
self-contained boot floppy that securely wipes the hard disks of most
computers. DBAN will automatically and completely delete the contents
of any hard disk that it can detect, which makes it an appropriate
utility for bulk or emergency data destruction.
DBAN for currently DOES NOT support Apple computer hardware. The
developer is requesting Mac donations to develop & test the
software for the Apple computer hardware. For more information on Mac
donation, see the web page:
http://dban.sourceforge.net/ppc.html
Secure Erase - ATA Drives Built-in Command
Secure Erase is a set of commands embedded in most ATA drives built
since 2001. Secure Erase overwrites every single track on the hard
drive. That includes the data on “bad blocks”, the data left at the end
of partly overwritten blocks, directories, everything.
This functionality is recognized by the US Government’s National Institute of Standards and Technologies ( NIST 800-88)
as equivalent to magnetically wiping a drive (degaussing) or physically
destroying it. The National Security Agency and the National Institute
for Standards and Testing ( NIST 800-88)
gave it a higher security rating than external block overwrite
software. External block overwrite software includes Apple's Disk
Utility, Darik's Boot and Nuke ('DBAN'), etc.
The University
of California at San Diego hosts the Center for Magnetic Recording
Research. Dr. Gordon Hughes of CMRR helped develop the Secure Erase
standard.
There is a Freeware Secure Erase Utility, that is a DOS executable, HDDerase.exe, that can be run from a floppy/CD-ROM bootable DOS disk.
Currently, there isn't support or a port for Mac OS X. Maybe, Apple
would be interested in adding support for "secure erase" embedded in
ATA drives? If you want this support, please file a feature request in
Apple's BugReporter.
Summary
So, with Mac OS X computers you could use Disk Utility and use a block
overwrite like 7-Pass Erase or 35-Pass Erase, which according to some
recent papers isn't secure enough. Or physical destroy hard disks, by
degaussing, disintegration, shredding, or other means is not only
hazardous, but has limited effectiveness, like if fragment sizes aren't
small enough to recover data, etc.
There are products like EDT's Digital Shredder that
implement the "secure erase" technology that allows secure &
complete removal of data but the disk drives can be reused.
Hopefully, in the future there will be support for the "secure erase"
technology in Apple's Disk Utility or other 3rd party Mac OS X utility
to support these new data sanitation security levels.
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