Dec 17, 2011 Mount a DMG from the Command Line in Mac OS X Dec 17, 2011 - 14 Comments A helpful command line tool called hdiutil is included in Mac OS X that allows disk image files (.dmg extension) to be mounted directly from the Terminal, without the need of using the GUI. You can create an empty disk image, add data to it, then use it to create disks, CDs, or DVDs. In the Disk Utility app on your Mac, choose File New Image Blank Image. Enter a filename for the disk image, add tags if necessary, then choose where to save it. Sep 07, 2009 I've also noticed this time around that if I mount a dmg manually with the Disk Utility, and contains an installation package, that it starts the 'Installer' utility, but it just bounces on the dock and becomes unresponsive to anything but a Force Quit. So add that to the list: - Disk Image Mounter - Archive Utility - Installer Utility.
I don’t know about you, but I still haven’t got over the death of TrueCrypt. It was a fantastic program for making encrypted folders in all respects, and its demise was totally unexpected.
Now I know that it has a successor – VeraCrypt – and it is more or less twin siblings. But VeraCrypt still doesn’t feel the same. And I have had lots of issues opening encrypted folders using VeraCrypt, and losing valuable files in the process.
Dec 21, 2017 This allows you to use Disk Utility to wipe your entire drive—or repartition it. Partition Drives and Format Partitions. Disk Utility shows internal drives and connected external drives (like USB drives), as well as special image files (DMG files) that you can mount and access as drives.
But if you use a MacOS computer, then you don’t need VeraCrypt, because Disk Utility will make your encrypted folders for you.
Encrypted Folders With MacOS Disk Utility
It wasn’t that long ago that I showed you how to format a USB stick or SD card using Disk Utility. Many MacOS users routinely overlook Disk Utility, but it is really a nifty little program. The encryption abilities is just the icing on the cake.
An encrypted folder on MacOS has the file format DMG (similar to many MacOS software installation programs). DMG stands for “Disk Image”, and is not much different than an ISO file on Windows. Once the DMG folder has been created, you simply “mount” it to open it, and you can start dragging items in.
The process to make an encrypted DMG folder is absurdly simple.
Open Up Disk Utility
Obviously you are not going to get very far without opening Disk Utility! You will find it in the “Utilities” sub-folder of the “Applications” folder. It doesn’t matter which area of the computer is currently highlighted. When it comes time to make the disk image, you will be asked where you want to save it.
Start a New Blank Image
Go to the Menu bar and choose File–>New Image–>Blank Image.
Start Filling Out The Details Of The Encrypted Folder
Here is where you set up and configure the container to your specifications. Let’s go through each one.
- Save As : What you want it to be called on the computer. This will be the name seen by everyone who has access to your computer.
- Where : Where on the computer you want to save the newly created folder. Obviously you can move this afterwards. It is not fixed in one place.
- Name : The name you alone will see when it is mounted and open on the MacOS system.
- Size : The size you want your container to be. One important thing to note is that whatever size you specify will be instantly taken by your computer. So if you specify 100MB, then 100MB will be immediately deducted from your hard drive space – even if there is nothing in the folder yet.
- Format : Always choose MacOS Extended (Journaled).
- Encryption : See the next section for this part.
- Partitions : Always choose Single partition – GUID Partition Map.
- Image Format : If you want to add and remove files from the image file, then choose read/write disk image.
Choose Your Encryption Protocol
When you drop down the Encryption menu, you are given 2 options. 128-bit AES encryption, and 256-bit AES encryption.
Essentially, both are extremely secure, but the 256-bit version is more secure than the 128-bit version. The only downside (as the menu says) is that if you encrypt with 256-bit, you are going to see a noticeable time-lag.
However, unless you are hiding Top Secret files, or running Wikileaks from your MacOS computer, then the 128-bit version will be more than sufficient.
Set The Password
When you choose the encryption standard that you want, it will immediately ask you to set a password. Obviously it goes without saying to choose an extremely strong password. No dictionary words. Instead, a combination of letters and numbers.
If you can’t think of one yourself, you can make it easier on yourself, by clicking the key icon, and a Password Assistant will open up. Next to “Length“, slide the slider along to the number of characters you want. Under “Type”, choose which kind of password you want. As I said, the letters and numbers one is the most secure, but ultimately it is up to you.
It will then show you a password you can use under “Suggestion”, and under “Quality”, the green bar will tell you how secure it thinks the password is. If for some reason you don’t like that password suggestion, drop the menu down, and you will get lots more suggestions.
Choose one, then copy and paste the password into a secure document. If you lose the password, you lose access to the disk image!
Wait For The Encrypted Container To Be Made
When you have filled in all of the details, and you have clicked “Save”, it will create the disk image folder for you. When it has been made, click “Done”….and you are done.
Go to the Finder location where you told it to save the disk image, and it will be sitting there open waiting for you. To access it, go to the folder name in “Devices”.
Double-Click To Mount & Open The Folder
To normally open the folder (such as when it is closed), double-click the DMG file and a window will jump up, demanding the password. It should be noted at this point that you cannot copy and paste passwords into the box. You need to type them manually.
For obvious reasons, you do not want to have checked “Remember password in my keychain“. Otherwise, when you put the mouse cursor inside the password box, the password will automatically be entered!
Kind of defeats the whole purpose of encryption doesn’t it?
Drag Your Files Inside The New Window
Once you have successfully entered the password, the folder will appear in the Devices section. Click on it to enter the folder. You can now view the contents, delete files from the folder, and add new files.
When you want to close the encrypted disk image folder again, click the upwards arrow icon next to the folder name. This will dismount the folder and close it.
Conclusion
TrueCrypt and VeraCrypt may have its legions of fans (and I was one of them). But MacOS (and Windows, for that matter) have their own built in encryption tools. You just have to know where to look.
I just solved this myself, having clicked on a related 'More Like This' link after I posted...
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After double clicking the .dmg file in my download directory and automatically launching Disk Utility, I selected the .dmg disk image in the left-hand column. I then clicked over to the 'Restore' tab in the top-center of the Disk Utility panel.
In the upper row of control buttons, I clicked the 'Open' icon. This was not an obvious choice because it is small and 'Open' is not the function I was seeking. If you roll-over that icon it says it is for mounting or unmounting a disk.
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The disk image then mounted on the first try AND once it was mounted the 'Open' icon name suddenly changed (greyed-out) to read: 'Mount.' A bit of an odd and elusive process but much easier than other more invasive procedures (like 'repairing permissions') to recreate that auto-mounting capability I had lost...
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Jul 5, 2011 9:31 AM