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Ivan's picture

Password protected disk image

Ever had to password protect some files and folders on your computer but didn't feel like switching on FileVault? You can create a disk image that's protected with the same level of 128bit security.

Open Applications/Disk Utility and click New Image. Name your disk image, select where you want it to be saved, choose the desired size and select Encryption: AES-128. Disk Utility will ask you for a password to protect your new disk image. If you choose the password to be included in your keychain you will not need to enter the password to open it once you're logged in. However, I suggest you not to use this option, since the whole purpose of this exercise is to create a disk image that's password protected from all users.

After a few seconds your password protected folder will be mounted. Note that you will have two icons. One is the .dmg file that contains the physical data for your disk image and the other one is the actual virtual disk image that you can use as any other mounted disk, except that this is one is password protected.

Now you can copy all the files and folders you want to hide from your boss or your wife. :) Once you are done with your file operations you can eject the disk image, but don't trash the .dmg file! That would mean trashing the contents of your password protected disk image.

The nice thing about this .dmg file is that you can move it around. Put it on your iPod or USB memory stick and you will be able to mount it on any Mac if you know the password.

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Anonymous's picture

Cool tip, the only drawback that this .dmg file can be trashed by an admin, so if i keep my important files in it and someone gets frustrated by not being able to open it, he might just trash it and I would loose the whole thing. Is there a way to prevent against trashing it?

Anonymous's picture

I have created a password protected disk image but I cannot open it when logged in to students. This file was placed in the shared folder. I have changed the permissions for the .dmg but not change. DeepFreeze is off. Something is preventing it from mounting on to the student desktop. I have used BatChmod to change permsissions and that did not work. What am I missing?

Anonymous's picture

if you select the dmg file and press CMD + I you can choose to lock the file which will prevent it from being deleted

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