Secure your files
Keep your precious data safe
SKILL LEVEL
Anyone can do it
IT WILL TAKE
5 minutes
YOU’ll NEED
Disk Utility, an external hard drive or flash drive, GPGTools (optional) The permissions system in OS X lets you keep personal files segregated, not just in user account folders but on external drives, too. However, this isn’t difficult for someone to get into – once someone’s picked this basic lock, they have access to everything in your filing cabinet.
Encrypting files provides a more robust way to protect their contents. Files are scrambled in a way that makes them unreadable unless a person can provide a password. Encryption capabilities built into OS X can be applied to your files in several ways that are suited to different scenarios. An empty drive can be formatted so anything you add to it is encrypted from the outset. This can also be applied to a volume that only takes up some of the drive’s capacity. This method is appropriate if you’ve just bought a new drive (or erased an old one), whether that drive will stay on your desk or if it's a portable one whose contents you need to keep secure as you carry it around for use on various computers.
Back up before you go
It’s possible to encrypt a Mac-formatted volume that already contains files, although it’s a good idea to make a copy of those files elsewhere before using this route in case an unexpected software problem occurs during the encryption process.
If you only want to encrypt a few files, an alternative is to create an encrypted disk image. You might have encountered disk images if you’ve downloaded software from outside of the Mac App Store; they are files with the suffix DMG that, when opened, appear in the Finder as if you’ve attached a physical drive. An enclave can start out small, and grow up to a preset maximum allocated size as you add files to it.
When creating an encrypted drive, volume or image, you need to set a password that’s required to access its
Encrypting files scrambles them so that they’re unreadable without a password or key
contents. The same old advice about setting a strong password – one with a mix of uppercase and lowercase letters, numbers and symbols, and which isn’t short – applies here.
These options are fine if you only need to use a disk or image with a Mac, but they won’t work with Windows and Linux out of the box. An app called HFSExplorer allows encrypted images to work with Windows, but it’s unable to write back to them. We hoped to overcome this by showing you how to use TrueCrypt, a free way to encrypt disks that’s been available since 2004, and which is available for OS X, Windows and Linux – or it was until the project was recently abandoned. Unfortunately, the latest version of TrueCrypt (7.2) is a limited version intended to help existing users migrate already-encrypted data to an alternative format, while the last full-featured version (7.1) has been pulled from the official site. Essentially, TrueCrypt appears to be dead in the water.
Just in case
There is a fallback option that encrypts files – but not whole disks – so you can carry them around more safely. In fact, the security firm Symantec makes software called Drive Encryption, but it costs you £84 per copy, whereas we want a free option. However, the PGP (Pretty Good Privacy) technology on which this is built has been around for more than 20 years, and free implementations are available for various operating systems. Sadly, the last Mac version to include a whole disk encryption feature was released years ago for the classic Mac OS, but PGP also allows for individual file encryption. We’ll show you how to leverage this to keep files secure while in transit. Alan Stonebridge