Virtual Drives/Encrypted Disk Images

[JDN]

I was reading another thread about password protecting files, i know this cannot be done, but people suggested virtual drives by creating a .dmg file or making an encrypted disk image.

Could people please provide pros and cons of the above two suggestions, with guides as to how to do them? This could create a good reference point for future newbies.

 

[disconap]

A .dmg is a disc image, so that's really just one suggestion.

It would be pretty easy. Just go into disc utility, click "new image", and choose the encryption message in the menu. When created, disc utility will ask you to create a password. Do so and you're done!

 

[disconap]

Actually, having just tested this method, I seem to be able to mount and unmount the image without the password. I can also copy and delete it. So this may not be the best way...

 

[NATO]

You shouldn't be able to mount an AES-128 Encrypted disk image without a password

 

[JDN]

Ah, ok then, what about accessing the disk image? And do you just click and drag to the disk image to add files?

 

[NATO]

To use the disk image, I double click on the image file which will ask me for my password before mounting the image as a drive on my desktop. Then I just drag files to it etc, basically using it as if it were just another folder/hard drive on the system. Once I'm done, drag it to the trash or press CMD+E to unmount it. Then all you need to do is repeat the process should you wish to access files on it again

 

[JDN]

When you unmount the diskimage, where does it go? How do you re-mount it?

 

[thewhitehart]

You just double-click the file again. Don't throw away the .dmg, but you can 'unmount' it by dragging it to the trash.

 

[JDN]

Oh right, yeh, i get you. Sweet!!

I really like this idea. Its a great way to keep all my important info under lock, and whos going to notice a .dmg file really anyway?!

 

[NATO]

Basically when you double click on a DMG, it 'unpacks' it in such a way so that you can access it like it was a hard drive. Once you unmount it, everything is packed away in the DMG file again, awaiting you to double click it again so it can be used once again.

Edit - Just noticed your post above. I agree, Encrypted Disk Images are immensely useful, especially where you have a select amount of files you want encrypted. File Vault is a bit excessive where a disk image would do!

 

[disconap]

You shouldn't be able to mount an AES-128 Encrypted disk image without a password

Yes, you're right. Even though I disabled the "add to keychain" option, the password got added to my keychain. Odd, that.

 

[JDN]

I tried to create a disk image in disk utilities by clicking the 'new image' icon at the top. I called it Me.dmg and when it was creating it an error message came up saying "Unable to create disk image, resource in use" or something to that effect.

Hm, whilst writting this, i went back to to the disk utility to check the error message and a whole new tab came up when i pressed 'creat new image' icon. Can you only create images up to 8Gb?

[edit] I hadnt selected the Macintosh HD. I have to select this to get the disk image saved to it dont i?

[edit2] Scratch that, selecting Macintosh HD was the problem in the first place. When you select the file size, say 10Gb, is that the size of the file from the beginning or just the file size limit?

 

[NATO]

Yeah, you just navigate to any location on your hard drive where you want the DMG to be, just like you're saving a file really. As long as you have enough space of course

DMGs can be a lot bigger than 8GB, I've got one which is 100GB and it works fine

 

[JDN]

Yeah, you just navigate to any location on your hard drive where you want the DMG to be, just like you're saving a file really. As long as you have enough space of course

DMGs can be a lot bigger than 8GB, I've got one which is 100GB and it works fine

Im guessing by this the size you select is the size taken up from the start then.
That would make sense, this being a virtual disk and all.

 

[NATO]

Im guessing by this the size you select is the size taken up from the start then.
That would make sense, this being a virtual disk and all.

If you select a sparse disk image, I think it will grow once it fills the allocated space, although it won't shrink again automatically if you remove stuff from it. You can 'compact' it again though which will do this, but obviously you have to initiate this manually

 

[disconap]

If you select a sparse disk image, I think it will grow once it fills the allocated space, although it won't shrink again automatically if you remove stuff from it. You can 'compact' it again though which will do this, but obviously you have to initiate this manually

Unless "sparse" is a setting, this won't work. I tried last night with a 40mb test dmg, and it wouldn't let me copy files that passed this limit. Unless that's something you can do in Tiger and not in Panther...

 

[DXoverDY]

Unless "sparse" is a setting, this won't work. I tried last night with a 40mb test dmg, and it wouldn't let me copy files that passed this limit. Unless that's something you can do in Tiger and not in Panther...

It is a setting. You tell it to create a 100gig DMG. But a Sparse Disk instead of just a normal DMG and it will create a small one and grow to the size of the files inside it. It's under Format when you create a new image.