Why Encrypt External Drives?

If you carry client files, financial records, or patient information on a USB drive or external hard drive, that data is at risk if the drive is lost or stolen. Anyone who finds the drive can plug it in and read everything on it.

Encryption scrambles the data so it can only be accessed with a password. Even if someone finds your drive, they cannot read the files without the correct password.

This is especially important for:

Healthcare and allied health providers handling patient records
NDIS service providers managing participant data
Accountants and bookkeepers with client financial information
Any business subject to the Australian Privacy Act

Encrypting a USB Drive on Windows (BitLocker)

Windows Pro and Enterprise editions include BitLocker, a built-in encryption tool.

Step 1: Insert Your Drive

Plug in your USB drive or external hard drive
Open File Explorer and find your drive under This PC

Step 2: Turn On BitLocker

Right-click on the drive
Select Turn on BitLocker (or Show more options > Turn on BitLocker on Windows 11)
Wait for BitLocker to initialise

Step 3: Choose a Password

Check Use a password to unlock the drive
Enter a strong password (at least 12 characters, mix of letters, numbers, and symbols)
Re-enter the password to confirm
Click Next

Step 4: Save Your Recovery Key

BitLocker will ask you to save a recovery key in case you forget your password. Choose one of:

Save to your Microsoft account (recommended if you use one)
Save to a file (store this file somewhere safe — not on the same USB drive)
Print the recovery key

Click Next after saving the key.

Step 5: Choose Encryption Mode

Select Encrypt entire drive (more secure, takes longer)
Select Compatible mode if you plan to use the drive on older Windows computers
Click Next, then Start encrypting

The encryption process may take several minutes to a few hours depending on the drive size.

Using Your Encrypted Drive

Every time you plug in the drive, Windows will prompt you for the password before you can access the files.

Encrypting a USB Drive on Mac (FileVault/Disk Utility)

Method 1: Right-Click Encryption (macOS Ventura and Later)

Plug in your USB drive or external hard drive
Open Finder
Right-click (or Control-click) the drive in the sidebar
Select Encrypt [drive name]
Enter a password and password hint
Click Encrypt Disk

The drive will be encrypted in the background. This works for drives formatted as APFS.

Method 2: Using Disk Utility

If the right-click option is not available:

Open Disk Utility (search for it with Spotlight: Cmd + Space, type "Disk Utility")
Select your external drive in the sidebar
Click Erase
Choose format: APFS (Encrypted) or Mac OS Extended (Journaled, Encrypted)
Set a password
Click Erase

Warning: Erasing the drive deletes all existing data. Copy your files off the drive first, encrypt it, then copy the files back.

Using Your Encrypted Drive on Mac

When you plug in the encrypted drive, macOS will ask for the password. Enter it to mount the drive and access your files.

Important Considerations

Cross-Platform Compatibility

BitLocker (Windows) encrypted drives can only be read on Windows computers with BitLocker support
FileVault/APFS (Mac) encrypted drives can only be read on Mac computers
If you need to use the drive on both Windows and Mac, consider using a third-party tool like VeraCrypt (free, open-source)

Choosing a Strong Password

Your encryption is only as strong as your password. Use:

At least 12 characters
A mix of uppercase, lowercase, numbers, and symbols
A passphrase is even better: "PurpleFrog$Jumping42!" is strong and memorable

Do not use the same password as your email or computer login.

Storing Your Password Safely

Save the password in a password manager
Keep a written copy in a secure location (not taped to the drive)
For BitLocker, make sure the recovery key is saved somewhere accessible

Performance

Encryption may slightly slow down file transfers, especially on older USB 2.0 drives. On modern USB 3.0 or USB-C drives, the difference is barely noticeable.

What About Cloud Storage Instead?

If you are regularly carrying sensitive files on external drives, consider whether cloud storage (like OneDrive or Google Drive) might be a safer alternative. Cloud files are encrypted automatically, backed up, and accessible from any device without carrying a physical drive.

External drives are still useful for large files, offline access, or specific compliance requirements, but for everyday document sharing, cloud storage reduces the risk of lost drives.

Troubleshooting

"BitLocker is not available" on Windows

BitLocker requires Windows Pro or Enterprise. Windows Home does not include BitLocker.
If you have Windows Home, you can use the free tool VeraCrypt instead.

Forgot the password

For BitLocker: Use the recovery key you saved during setup
For Mac FileVault: The drive is very difficult to access without the password — there is typically no recovery option unless you saved the password in your Keychain

Drive is very slow after encryption

This is normal during the initial encryption process
After encryption completes, normal speeds should resume
USB 2.0 drives may remain slower than USB 3.0 drives

Need Help?

For help encrypting drives or setting up data protection for your business, contact helpdesk@netlumait.com.au or call 1300 521 162.

How to Encrypt a USB Drive or External Hard Drive