Replacing FileGuard with Disk Images

Table of Contents

Formats and Encryption Options

Converting Safes into Disk Images

Creating Disk Images as Substitute for Safes

 

Among the tools provided by Apple with Mac OS X, the disk images are very similar to FileGuard safes.

Formats

There are many kind of disk images, but the most commonly used are the following ones, which refer to 4 different uses:

Compressed: the usual format to freeze a folder content taking up less possible space. Once created, the resulting disk image is read-only (it cannot be modified any more). This way to store files become useless: either you keep the disk image on your startup drive as a reference, or your archive it on a dedicated external medium. Read/write: the default format when continuing to work with files and to hide them from inquisitive eyes. Cons: its size is determined at the disk image creation (a 40MB disk image volume will take 40MB of real disk space). It remains effective for cases where the size must be set from the beginning, in order to limit fragmentation, for example. Sparse disk image (Sparseimage): this format behaves like the standard Read/write, without its disadvantage: it grows bigger as it fills. It always requires to define its size during its creation. Sparse bundle disk image (Sparsebundle): this format is equivalent to Sparseimage, except that it is adapted to the local and networked incremental backups (like Time Machine or Personal Backup do), because, instead of creating a monolithic file of only one block, it gathers a package of bands. Pros: the modification of only one file affects only one band, and not the entire disk image, which turns backups more efficiently, even for a disk image sizing many GB. Cons: bigger than sparseimage when created.

Encryption Options

Mac OS X manages by default 2 encoding schemes: AES-128 and AES-256.
The choice of one compared to the other depends on the depth of encryption needed, the level of compatibility aimed, and the power of the Mac to complete the task

AES-128 is the first encryption format available. Ideal choice for older Macs, or when the disk image needs to be opened with a system equal or older than Mac OS X 10.4. AES-256 is an improvement of the former and an option for Mac OS X 10.5 or Newer.

Disk image creation is handle by Disk Utility. This application is available from "Utilities" subfolder of "Applications" folder.

How to convert FileGuard safes into disk images?

The simplest method to convert a FileGuard safe into a disk image is to use Disk Utility facilities: all disk images mounted on the Mac are also shown in the sources list on the left side of its main window. This property also applies to FileGuard safes.  Once opened, the source file and the associated volume are revealed in the sources list of Disk Utility. 

Warning :
The method described below is simple and fast, particularly if safes are archived using "Compressed" disk image format. But, it suffers from a huge disadvantage if converting safes to continue working on: disk image format “Read/write” proposed wastes disk space in a terrible way (i.e.: if the FileGuard safe was defined with a size of 100 MB, the resulting disk image will take 100 MB of disk space, even if the safe uses only 10 MB of its volume). It is not  awkward for small safes, but is a huge problem for multi-GB sized safes. If the available disk space is scarce, prefer any of "sparse disk image" formats (sparseimage or sparsebundle): follow How to create FileGuard safes' replacement disk images section's instructions to carry out this kind of transfer.

Here is how to convert a FileGuard safe into a new disk image:

- Open the FileGuard safe using the Finder.
- Open Disk Utility application.
- In the list of the available sources, select the name of the safe.
- Click on New image button located in the toolbar, or use the command in the menu File > New > Disk Image from “safe's name”.

- A sliding panel appears, asking new disk image settings:

Name the disk image. By default, the selected name is duplicated into “Save As” field. Define where to save. Simplest choice is to save it on the Desktop. Choose Image Format according to your usage: Compressed: adapted for archiving to view later if needed. Read/write: to continue working with your documents. The other formats are even more specialized. They do not bring any significant benefit to use. Choose Encryption option: AES 128 bits which is faster, or AES 256 bits which is more secure. Click on Save button to create the new image disk.

- A progress indicate bar displays the task being completed. . The creation time of the new disk image is proportional to the contents of the safe to convert.
- A standard dialog box for entering passwords appears if any of the encryption option is chosen:

Type the disk image password. Type once again the same password into "Verify" field. Looking for inspiration? Click on Key shaped button to open system's password generator. Check the box or leave it uncheck to Remember password in keychain. Click on OK button to confirm the creation of the new disk image.

- Once the copy is done, the new disk image appears under the Sources sidebar of the Disk Utility main window.
- Double-click on the disk image to open its volume in Disk Utility as well as under the Finder.

- The conversion is complete.
- Put away the safe using its contextual menu.

- Archive your safe or move it to the trash.
- Apply the same process to the next safe.

Notes : 
Once converted with Disk Utility, the icon of the safe is kept, not its password.
When many safes need to be converted, proceed one by one. Don't forget to Put Away the safe before moving to the next.
Even if it appears simpler, don't use Convert command: this will transform the sparseimage file into an unreadable document by the safe itself.

How to create disk images as substitutes for safes?

As mentioned above, although rapid and simple, the direct conversion of a FileGuard safe into a “read/write” disk image uses lots of disk space.  The Disk Utility application offers an alternate method to take advantage of a more versatile Sparse disk image formats (more commonly called sparseimage and sparsebundle) in order to create disk images as substitutes for safes. This is useful when you are trying to safe disk space

The idea is to open the source safe, create a brand new Sparseimage or Sparsebundle disk image, and transfer the safe's content to the new disk image using the Restore command of the Disk Utility application.  This is particularly adapted to copy large volumes. Here is how to do it:

- Open the FileGuard safe using the Finder.
- Still using the Finder, note its size through Get Info window: see File menu > Get Info command.
- Launch Disk Utility.
- Click on New image button located in the toolbar, or use the command in the menu File > New > Blank Disk Image…
- In the Save As dialog:

Give a name to the new file. Define where to save. Simplest choice is to save it on the Desktop. Name the volume too. The easiest solution is to copy-paste the name of the new file. Allocate a size equal to or bigger than the original safe itself. Choose Encryption option: none, 128 bits AES or 256 bits AES. Choose the appropriate Image Format: sparse disk image (Sparseimage) or sparse bundle disk image (SparseBundle). Create the blank disk image by clicking on the Create button. (Then the resulting file could be moved around at will.)

- A progress indicate bar displays the task being completed. 
- Standard dialog for entering password appears if any of the encryption option has been chosen:

Type the disk image password. Type once again the same password into "Verify" field. Looking for inspiration? Click on Key shaped button to open system's password generator. Check the box or leave it uncheck to Remember password in keychain. Click on OK button to confirm the creation of the new disk image.

- In the list of available sources, a new entry appears.

- Select the safe's name, under private.sparseimage disk image.
- Click on Restore tab: the Source field is automatically filled by the selected volume in the sources.

- Drag-and-drop the blank disk image volume into the Destination field.
- Click on Restore button.

- Confirm the deletion of the new volume contents.
- Enter your admin password.
- Disk Utility unmounts each disk image to check them first and then copy the source into the destination.
- Once done, both volumes are mounted back.
- Eject every disk image volume.
- Remove both disk images from the Sources list by dragging-and-dropping them outside.
- Repeat the operation for each substitute disk image you need to build from a FileGuard safe.