How to encrypt external hard drive on your Mac

Disk drive

Data security and privacy are extremely important to prevent its misuse and theft of information. What are your options for protecting your files from access by unauthorised people? Let's take a look at encrypting an external disk on the Mac.

There are numerous algorithms that work to encrypt data and make it difficult or impossible for unauthorized users to access the information. In this article, we will discuss how an external hard drive can be encrypted on a Mac system, decrypting the drive and recovering data from an encrypted hard drive.

Encrypting a hard drive

Encryption is process in which the original data is scrambled digitally to hide the actual content. There are many encryption algorithms available to perform this operation. It’s a process to secure most confidential and private data from any unintended use.

On the Mac an external drive can be encrypted using a user-entered password. It provides two encryption algorithms, which are 128-bit AES and 256-bit AES. The 128-bit algorithm is fast, but the 256-bit algorithm is more secure. However it works slightly more slowly.

Users can select one of the methods based on the sensitivity of the data residing on the drive that is to be encrypted. For financial data and extremely sensitive information stored on the drive, 256-bit algorithm is advisable to strongly secure the information. Here’s how to do it:

Note: It is a best practice to backup your data before encrypting it in case things go awry.

  1. Select the drive icon on the desktop and right click it. If the drive does not appear on the desktop, go to Finder, Preferences and on the General tab, select the option to show disks.
  2. Select the Encrypt option. 
  3. Choose a password (if this password is lost, you will lose all access to the drive). The best way is to write down the password somewhere to refer later or store it in a password storing application.
  4. Press Encrypt Disk to start the encryption process.

The process may take hours depending on the size of data stored on the disk and the process cannot be stopped once started.

An alternative encryption option is to erase the drive and format it in Mac OS Extended (Journaled, Encrypted). This method works fast as there will be not data to encrypt. Here’s how to do it:

  1. Go to Applications/Utilities and open Disk Utility.
  2. Select the drive and click on Erase.
  3. Select the format as Mac OS Extended (Journaled, Encrypted).
  4. Erase the disk. At the prompt, enter the desired password (if this password is lost, you will loose all access to the drive).

Note: This alternative method will completely erase the data stored on the drive so make sure there is nothing on it you want to keep. It is advisable to take a backup before encrypting. Once a drive is encrypted, a password is required to access the external drive when connected.

Decrypt an external hard drive

An external hard drive will need to be decrypted to take a backup or perform a recovery process to fix bad sectors and many other reasons. 

Note: Decrypting an external hard drive will result in a complete loss of data.

To decrypt the external hard drive, go through the following steps:

  1. Open the Terminal application from Applications/Utilities.
  2. Enter the command diskutil cs list.
  3. Copy the long alphanumeric code that appears on the terminal.
  4. Enter the command diskutil cs delete [long code].

This process will result in an empty drive without an encryption.

In the latest versions of Mac OS X, an external drive can also be decrypted by following these steps:

  1. Open Disk utility from Applications/Utilities.
  2. Select the drive to decrypt.
  3. Choose the Unlock option from Disk Utility drop-down menu on the top.
  4. Enter the password to unlock it.
  5. Then select Turn off Encryption from the File menu drop-down list to start decryption.

Mac data recovery on encrypted hard drive

Nothing is impossible in this world and not even loosing important files from an encrypted Mac hard drive or password protected Time Machine external backup drive. Fortunately, there are some applications to help you recover encrypted Mac hard drive, which is such a relief. But remember you must not forget the password even if your encrypted hard drive data is deleted or erased. 

Author: Douglas Gordon



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