How to password protect a folder on your Mac

“Not all of your files are meant to be seen by everyone,” Henry T. Casey writes for LAPTOP.

“Your friends and family may not appreciate this truth, but that’s just the way it is sometimes,” Casey writes. “Luckily, MacBook owners can protect their sensitive files from prying eyes by password protecting specific folders.”

“Many paid programs offer similar functionality, but we prefer this free method built into [the Mac by] Apple that allows folders to be turned into protected disk images,” Casey writes. “We tested this on a MacBook Pro running macOS Sierra version 10.12.6 but research shows it works the same way going as far back as Mac OS X 10.6, Snow Leopard.”

Simple instructions for password protecting a folder on your Mac here.

MacDailyNews Note: When you’re finished using the documents on the secure disk image, be sure to eject the disk image. As long as it’s available on your desktop, anyone with access to your computer account can use the documents on it. To access the data in a disk image, just double-click it. When it appears on your desktop, and you can add, remove, and edit files on it just as you would with a disk. Lastly, for true security, don’t add the encrypted image’s password to your Mac’s Keychain!


  1. Skip a step and open the Utilities folder directory using:


    On recent Macs, go for 256-bit AES encryption for future-proofing. You’re not going to notice a slower speed.

    If your folder is going to be large and you’re going to be syncing it across Macs, start in Disk Utility with File:New Image:Blank Image. Set it up with the name, size and encryption you’d like. But notice the added popup menu ‘Image Format:’. Instead of ‘read/write’, choose ‘sparse bundle disk image’. (Note that older versions of macOS don’t provide sparse bundles).

    Why sparse bundle? The resulting disk image is broken up into small pieces called ‘bands’. You can view them inside the disk image package. They’re numbered and lettered 0 – z10. When the bundle is synced, only the changed bands are updated. This saves MASSIVE file size copying of the whole thing, which is what you’d have to do with a regular .DMG or regular old sparse disk image. For example, as you add, remove or change anything in your encrypted folder, Dropbox is only going to bother with the changed bands, which may be only one or two, versus having to sync the whole massive disk image. Incredibly smart stuff from Apple.

  2. Tried this method it’s a pain in the ass, why is there no straightforward lock capability. I assume there must be some easy complex reason at its heart beyond my comprehension because it’s such a basic and obvious requirement that I have been wanting for only the last 30 years of so.

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