Information Technology Reference
In-Depth Information
crime lab), but bear in mind that the files might still exist in your Time
Note that if your Mac has a solid-state hard disk (SSD), such as those fitted
to MacBook Air and Retina MacBook Pro computers, securely erasing files or
the trash in the ways described next is ineffective and likely unnecessary
because SSDs employ TRIM to clean up old data.
1
The best method of protect-
ing an SSD (or any kind of storage disk) from data snoops is to encrypt its
Securely Emptying the Trash
To securely empty the trash, simply click and hold the trash icon in the Dock
until the context menu appears (or right-click the Dock icon). Let go of the
mouse button and then hold down the
COMMAND
key. The menu will change
to read Secure Empty Trash. Click to do so. You can also open a Finder win-
dow and click the Secure Empty Trash entry on the Application menu.
Be aware that deleting files securely takes significantly longer than deleting
unsecurely. With a very full trash can, it might take hours. The work of
securely emptying the trash will take place in the background, however.
Always Emptying the Trash Securely
To always securely empty the trash, open a Finder window and click the
Application menu and then Preferences. Then click the Advanced tab, and
check Empty Trash Securely.
Wiping Individual Files
While there's no built-in method of securely obliterating individual files on
the desktop, short of moving them to the trash and then selecting to securely
empty it, you can use the command-line tool
SRM
to delete files and then
overwrite the space with random data.
SRM
is perhaps one of the most danger-
ous commands available on your Mac, however, so use it carefully!
Next I explain how to use it at the command line, before explaining how it
can be used to create a simple Automator service for use in Finder windows
and on the desktop.
1.
See
HTTP://ARSTECHNICA.COM/SECURITY/2011/03/ASK-ARS-HOW-CAN-I-SAFELY-ERASE-THE-DATA-FROM-MY-SSD-DRIVE/
,
although if you've fitted a third-party SSD to your Mac, see also
HTTP://WWW.GROTHS.ORG/
