Tag Archives: dmg

Mac OS X

Changing How OS X Handles Archives

When you open a dmg or zip file (which we’ll refer to as an “archive” in this article), a tool called Archive Utility is opened briefly to extract the archive and then by default create a folder in the same directory the archive was located. After extracting the contents of the archive, the archive is left as-is, showing the new folder in a Finder screen. This type of workflow works for a lot of people. But not all.

This is why Apple built a Preference pane for the Archive Utility. To access, simply open Archive Utility, click the Archive Utility menu and click Preferences.

Screen Shot 2013-01-09 at 4.15.15 PM

You then see the Archive Utility Preferences. Here, there are a few fields that can change the default behavior of how OS X handles archives. Each field is as follows:

  • Save expanded files: Sets whether extracted files stay in the directory the archive was in or go into a custom directory, used for all expanded archives.
  • After expanding: Configures what happens after an archive is expanded. The default behavior is to leave the archive alone, but archives can also be moved to the trash or deleted immediately (bypassing the trash). Additionally, as with the expanded files, archives can, once extracted, be moved to a static location (e.g. onto a NAS).
  • Reveal expanded item(s) in Finder: This checkbox controls the new Finder window opened when an archive is expanded. To disable that feature, uncheck the box.
  • Keep expanding if possible: This checkbox expands an archive inside an archive if one exists.
  • Save Archive: When creating a new archive, allows the user to define whether that archive is saved in the same directory the files being archived were in (the default behavior) or whether the resultant archive is stored in a static location.
  • Use archive format: By default, a compressed .dmg file is created. If this is too slow or if compression is not desired, then an archive can be uncompressed using this field. Additionally, a zip can be created rather than a dmg (e.g. if you’ll be exchanging the archive with Windows users).
  • After archiving: this option allows users to configure whether the files placed into the archive are to be kept or deleted once an archive is created. Additionally, files can be saved to a static directory.

The ability to control such features allows a data wrangler with a pretty well defined workflow to proceed much more quickly than would be otherwise possible according to how the person managing the data goes about their business. For example, if I know that every dmg file I get should be extracted, the contents moved to a share and then deleted, that can be the default behavior programmed and therefore I have less clicks of the mouse or steps to complete my process. Apple has, as usual, put good logical thought behind the default settings used. Therefore, be careful when changing settings.

sites Xsan

Xsanity Article on XsanDebugged

Posted a little article on the XsanDebugged tool over at Xsanity. Thanks to Aaron for approving it. Hope you enjoy the tool!

Mac OS X Mac OS X Server Mac Security

How to Crack a DMG Password

A dmg file is a compressed file structure, capable of containing folders, files, etc.  Dmg files can be used for a variety of purposes, from encrypting a home directory (ie – FileVault) to encrypting a file structure manually.  A dmg file can be encrypted fairly simply. From Disk Utility, create a dmg file by clicking on the File menu and selecting New and then Blank Disk Image. This will bring up a screen where you can provide a name for your home folder and a size, then select either AES 128 or AES 256, which is a bit slower.
Encrypted Disk Image

Go ahead and click on Create and then at the resultant password screen go ahead and provide a password to be used.  And let’s just go ahead and uncheck the option to create an entry in Keychain for the password.

Encrypted Disk Image createIf you would rather do so from the command line I covered how to do so in a previous post.

Now let’s download Spartan, a tool built by Ryan Kubasiak. Now download a dictionary file. I just used one of these (and for expedience sake I paired down the contents to only have about 100 possible passwords, one of which was mine). Now go ahead and open Spartan, clicking on Go! at the splash screen.

Spartan

Spartan

At the Choose a File screen, browse to and then select your password file, clicking Choose once you have done so. At the next Choose a File screen browse to and then select your dmg file which you would like to crack the password for. The password file will then be read into RAM and the password cracking will commence.

Spartan Password Progress Screen, Crack Password, Spartan!, dmg

According to the length of your password this could take a long, long time, but when it’s done you will have your password, assuming it was in the dictionary of passwords you used.  Dictionary files can be downloaded from a variety of sources, some collections taking up gigabytes upon gigabytes of space and covering every possible keyboard combination.  Therefore, the longer the password that you use and the more complex the password is, the longer it will take to break the encryption.

“So, would your holiness care to change her password?” – The Plague