Windows – How to Open an Encrypted DMG File

First, mount the dmg image : sudo hdiutil attach <image>.dmg

The image will be mounted to /Volumes/<image>. Mine contained a package which i installed with: sudo installer -package /Volumes/<image>/<image>.pkg -target /

Finally unmount the image: sudo hdiutil detach /Volumes/<image>.

The files on an encrypted disk image are encrypted.

As you can see currently you can have 128 bit AES and 256 bit AES. As is pointed out 256 bit will be slower but more secure, however both methods will leave your data encrypted, until it is decrypted.

The real issue is how strong the password for the encrypted volume is. If the password is not a random string of characters, but based on a dictionary word with substitutions of 1 for i etc, the files while encrypted might as well not be.

Ensure your password is based on a long sentence where you use all punctuation marks, include spaces, numbers and special characters.