Update of previous blog post to handle High Sierra: “How to Make an Encrypted Area on your Mac HD to Store Sensitive Information”

This posting is an update of previous blog post:  http://grannyjoans.blogspot.com/search?q=encrypted

“How to Make an Encrypted Area on your Mac HD to Store Sensitive Information”

 The previous blog post needs to be modified to handle Macs which have High Sierra Operating System installed.

The MacOS High Sierra operating system introduced APFS (Apple File System) to Mac computers. APFS replaces Mac OS Extended (HFS+) as the default file system for solid-state drives (SSDs) and other all-flash storage devices.
Disk Utility in macOS High Sierra can format most storage devices using either file system. If you need to manually reformat, consider these points:
    •    APFS requires macOS High Sierra. Earlier versions of Mac operating system don't mount APFS-formatted volumes.
    •    APFS is optimized for solid-state drives (SSDs) and other all-flash storage devices.
    •    Disk Utility tries to detect the type of storage you're formatting, then shows the appropriate format in the Format menu. If it can't detect the type of storage, it defaults to Mac OS Extended, which works with all versions of macOS.

Eventually, it becomes necessary to set up a logical system and place to safely keep myriads of personal information like password logins, financial statements and such.   The Disk Utility application on your Mac offers a means to create a Disk Image on your hard drive or external flash storage drive that is encrypted and accessible with a single password where you can store your digital information.  I have opted to use the Mac OS Extended file system as I still have devices and Older Macs where I need to be able to access these important files.

Below is the method to create such a disk image when using High Sierra System:

(1)  Open Disk Utility (located in the Applications/Utilities folder on your Mac).

(2)  Click on the File menu, select New and Blank Disk Image.

A dialog and options box for creating the New Blank Image file will appear on the screen:

       
 (3) Enter a name in the Save As field.  Enter this same name in the Name field (e.g. Test Storage Box)

(4)  Next, select a folder or destination for storing this newly created (e.g. Test Storage Box.dmg) file onto your hard drive under drop-down Where field.  You can store the .dmg file directly on one of the computer's hard drives, either an internal or external hard drive.  It is probably a good idea to check to see if there is enough room available on whatever hard drive you choose.   Note: This .dmg file can always be moved from the Desktop to the main hard drive (i.e. used to boot). If, however, it is moved from the desktop to some other hard drive then a "copy" will be generated which may result in confusion.

(5)  Type in a size for the image file in the Size field.  Select a size that will be large enough to sufficiently contain all the data or document files that you plan to place in this secure disk image.

(6)  Select Mac OS Extended (Journaled) from the Volume Format drop-down menu if you plan to copy this disk file to a Mac with previous operating system or a device that doesn’t support the APFS file structure.

(7)  Select either recommended 128 bit AES or 256-bit AES encryption.  It is my guess that recommending 128-bit encryption, may have something to do with additional time required for the 256-bit encoding method.  However, many feel 256-bit encryption is unnecessary. 
Note an article by Seagate, a hard disk manufacturer, (reference link:  http://www.seagate.com/staticfiles/docs/pdf/whitepaper/tp596_128-bit_versus_256_bit.pdf ) states that anything that could crack a 128-bit encrypted file would also be able to crack a 256-bit encrypted file ... with little additional time or effort. They currently estimate it would take 77,000,000,000,000,000,000,000,000 years on average to crack just one encryption under the following assumptions:
 

• Everyone in the world (all 7 billion people) work together and simultaneously to crack the key to your encrypted file. 
        

• And each person uses 10 computers running 24/7. 
  

• And each computer can test 1 billion key combinations per second.

(8)  Select read/write disk image for Image Format.

(9) Select Partitions type.  Single GUID Partition map is good one.

(10) Enter a secure password, one that you will use to access this Disk Image.  Many experts recommend at least 10 characters, with with at least one character being in a different case (capital letters and non capital letters) and at least one character being non alpha numeric (i.e. $, %, ^ etc).
  

(11) Click Save to create the encrypted Disk Image file (e.g. Test Storage Box.dmg) that will appear in the location you specified. You can Quit the Disk Utility application at this time.

Now you will be able to use this mounted Disk Image (e.g. Test Storage Box.dmg) to store any sensitive data.  Double click on this desktop icon or .dmg file. The Disk Image (e.g. Test Storage Box) will appear on your desktop and can also be viewed in your sidebar, like a normal drive, adding files, opening, editing and copying files to it.  Merely, drag the documents or files that you wish to keep secure into the Disk Image icon or into the opened icon window.   When finished, merely eject the mounted desk icon (e.g. Test Storage Box icon), by dragging to the trash where you should see the eject arrow as you place the desk icon image over the trash. 


In the future when you wish to access the secure files, double click this .dmg file (e.g. Test Storage Box.dmg) to mount the  file to your desktop.   You will be prompted to enter your password in the dialog window and click OK.   Note: it is important to leave the box unchecked to deselect 'Remember password in my keychain' option.  Otherwise, your password will not be required to gain access to your encrypted file.

In summary, there are two files that are created using Disk Utility:
    •    One file will be .dmg file (e.g. Test Storage Box.dmg) — note the .dmg extension. This is the file to double click for mounting.   
    •    The other file (e.g Test Storage Box) icon will appear on the desktop.  This file does not have an extension and is the file to move to the trash or to eject for unmounting.
 



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